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Supporting the ethical development and stewardship of seed

On-farm Variety Trials:A Guide for Organic Vegetable, Herb,and Flower Producers

This publication was made possible through funds from the

Risk Management Agency.


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Table of ContentsIntroduction.................................................................................................................................................3Benefits of On-farm Variety Trials for Organic Growers........................................................................... 3

Organic seed and the National Organic Program regulations.................................................... 4

Expanding market potential and attracting new customers.......................................................5Addressing crop stresses...............................................................................................................6

Planning the Trial........................................................................................................................................7Identifying trial goals...................................................................................................................... 7

Prioritizing crops............................................................................................................................. 7

Choosing trial varieties and acquiring seed................................................................................. 7

Including a check variety............................................................................................................... 8

Doing the Trial.............................................................................................................................................9Observational trials........................................................................................................................ 9

Experimental design - replicated variety trials...........................................................................10Genetics by environment interaction..............................................................................10

Field effect........................................................................................................................ 10

Consistent treatment....................................................................................................... 11

Randomization................................................................................................................. 11

Population size................................................................................................................. 11

Trial layout........................................................................................................................ 12

Marking and mapping the trial....................................................................................................13

Evaluating the Trial.................................................................................................................................. 14Quantitative vs. qualitative traits................................................................................................ 15

Evaluation traits to consider....................................................................................................... 15

Data collection..............................................................................................................................15

Making Sense of the Data....................................................................................................................... 16Viewing the data...........................................................................................................................16

Identifying the winners................................................................................................................ 17

Statistics....................................................................................................................................... 18

Appendices............................................................................................................................................... 18A: Organic seed availability......................................................................................................... 18

B: Public variety trials in the Pacific Northwest......................................................................... 19

C: Additional seed and variety information resources.............................................................. 19

D: Variety trial planning case study............................................................................................ 20

E: Sample evaluation form and variety trial planning worksheet.............................................21

References................................................................................................................................................22Special thanks to the USDA Risk Management Agency (RMA), who has provided support for the

publication of this guide and associated series of educational workshops. For more information on

other risk management education publications and programs visit www.rma.usda.gov
http://www.rma.usda.gov/http://www.rma.usda.gov/


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Introduction

Farming can feel like one gamble after another,but the most successful farmers know that goodrisk management strategies can make all thedifference in increasing farm stability and

profitability. Since the advent of agriculturefarmers have engaged in trials. They haveexperimented with new cultivation techniques andinputs, explored alternative and diversifiedmarkets, and initiated innovative pest and diseasemanagement practices. The complexity ofoperating a farm and the demands of the marketcan appear overwhelming, but engaging in on-farm trials can help refine production practices,keep innovation alive, and foster the sense ofwonder that draws many to farming in the first

place. Variety trials are an important, althoughoften overlooked, tool for managing risk.Choosing the right crops and varieties for thelocal climate, field conditions, and market cansignificantly minimize loss and increaseagricultural success while avoiding the expense ofinvesting in poorly adapted or poorly performingvarieties. Conducting on-farm variety trials helpsidentify varieties that can:

Minimizing crop loss due to pests Maximize yields Fill key market and production niches Identify the best organic seed sources

Following basic scientific methods whenconducting on-farm variety trials brings a level ofassurance to results whereas simply trying a newvariety without a good experimental design cangive misleading and even invalid information.This guide provides training in basic, on-farmexperimental design, as well as tools to efficientlyand effectively manage on-farm trials and utilizetrial results. Using this guide you can learn howto:

Minimize efforts and improve results byefficiently integrating trials into standardfarming practices

Source varieties for trials Assess field conditions and layout variety

trials Manage data collection and assessment

The target audience of this publication is organicvegetable, herb, and flower producers. Theprimary goal is to teach this group of producershow to conduct on-farm variety trials and use theresults of trials to direct their variety selection andseed purchasing choices in a manner thatminimizes farm risk. The funding for thispublication was provided by the USDA RiskManagement Agency (RMA). RMA supports riskmanagement education for producers of specialtycrops (such as organic growers) that do notqualify for federal crop insurance. This guide mayalso be very useful for additional audiencesincluding conventional producers, seed producers,plant breeders, gardeners and producers of grainand commodity crops, but the content is directedtoward the target audience.

Benefits of On-farm Variety Trialsfor Organic Growers

While all producers can benefit from conductingon-farm variety trials, organic producers havesystem-specific needs that make trials all the morevaluable. For example, organic producers havefewer allowable inputs for mitigating crop peststhan their conventional counterparts, and as such,appropriate crop genetics are all the more crucial

for success. Organic producers are also faced witha lack of genetic research and educationalinformation, as the vast majority of seed industryand public variety trial programs are conductedand managed in non-organic systems.Additionally the traits or issues important to anorganic producer may be different than the traitsprioritized in a conventionally managed trial. Forexample, pest issues, fertility requirements, andmarket demands may differ between the twosystems.

Even a variety trial with results that indicate thereis no suitable organic alternative to a given non-organic variety or source are valuable in that itdemonstrates that the farmer is acting in goodfaith to follow the organic regulations guidelines.It also provides good information on alternativevarieties in case a farmers standard variety isdropped from availability, which happens all too

Organic Seed Alliance www.seedalliance.org

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often. Additionally, if on-farm variety trial infor-mation is shared, it has the potential to improvefuture availability of appropriate organic seedsources by providing plant breeders with informa-tion that can help them set priorities for futurebreeding efforts for organic growers, and by pro-viding seed companies with information about theneeds of organic farmers.

Organic seed and the NationalOrganic Program regulationsIn addition to farm management benefits, on-farmvariety trials are a useful tool for organicproducers to minimize risk by evaluating andadopting varieties of available organic seed. Notonly is there the potential that organic seed maybe better suited to organic growing conditions, but

organic growers are required to use organic seedsources when commercially available. On-farmtrials can aid in organic seed adoption andcompliance with organic seed regulations.

Organic producers who gross more than$5,000/year from organic crops must be certifiedby a USDA-accredited certification agency. Thoseearning less than $5,000/year can market crops asorganic without being certified, but are stillsubject to the National Organic Program (NOP)

standards. A list of accredited agencies and theorganic regulations are available on the USDANOP website: www.ams.usda.gov/NOP

The NOP organic seed standard states: 205.204 Seeds and planting stock practice

standard

(a) The producer must use organically grownseeds, annual seedlings, and planting stock:Except, that:

(1) Nonorganically produced, untreated seedsand planting stock may be used to produce anorganic crop when an equivalent organicallyproduced variety is not commerciallyavailable, except, that organically producedseed must be used for the production of ediblesprouts;(2) Nonorganically produced seeds and plant-

ing stock that have been treated with a sub-

stance included on the National List of syn-

thetic substances allowed for use in organic

crop production may be used to produce an or-

ganic crop when an equivalent organically

produced or untreated variety is not commer-

cially available.

The term commercially available is defined inthe regulations as:

the ability to obtain a production input in anappropriate form, quality, or quantity to fulfillan essential function in a system of organicproduction or handling, as determined by thecertifying agent in the course of reviewing theorganic plan.

Note that price is not mentioned and therefore notconsidered a component of commercialavailability, which reinforces the importance ofon-farm variety trials for demonstrating quality

and form of organic and non-organic seeds foundon the market.

Seed trials as an organic compliance issue:As the organic marketplace matures, greaterattention is being paid to the more subtle, less-defined, and often decidedly vague aspects of theregulation. The use or non-use of organic seedsand claims of commercial availability orequivalent varieties are an important example ofthis situation. Presently, the consensus among

most certifiers is to require documentation thatshows that reasonable attempts have been madeon the part of the farmer to source organic seed.For the most part this has meant showing that thevarieties used by the farmer are not available inorganic form.

In some crops there may be cases where only onevariety will meet market demands and suit condi-tions on a given farm. However in many casesmore than one variety can be suitable. Variety tri-

als can help organic farmers evaluate newly avail-able organic varieties, adopt suitable organic seedsources and demonstrate compliance with the reg-ulation.

It is widely understood and accepted that varietalcharacteristics such as timing of maturity, cold orheat tolerance, pest resistance, waterrequirements, color, size, appearance, and so on,


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http://www.ams.usda.gov/NOPhttp://www.ams.usda.gov/NOP


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are critical to the success of organic farmers. Assuch, certifiers do not generally second-guessfarmers decisions about variety selection.However, trials of organic varieties are currentlyaccepted by some certifiers to evaluate neworganic varieties as they become available, and todemonstrate commercial unavailability ifavailable organic varieties are not suitable to theoperation. With an ever-increasing list of seedvarieties available in organic form, it is suggestedthat in the future organic producers may berequired to use organic seeds on the market ratherthan the non-organic varieties they areaccustomed to.

One aspect of the organic standards thatdifferentiates organic production from non-organic production is the requirement to have

cultural practices in place to justify the use of anyoff-farm inputs to manage fertility, weeds, andpests. There are also limits to the availability ofallowed materials to use on organic farms to dealwith weeds and pests. For example, manual,mechanical, and cultural practices are used tocontrol weeds in an organic system, while mostconventional systems rely on herbicides. Some ofthe most common cultural practices used are theuse of cover crops, crop rotation, and the use ofresistant varieties.

Expanding market potential andattracting new customersA classic mistake that farmers may make invariety selection is to look over the fence of thebest grower in the area and grow whatever he orshe is growing. However, as progressive farmersknow, if you can stay innovative, offer alternativevarieties, and choose crops that attract customers,then it will be your fence the neighbors peer over.Producing the first tomatoes of the season or thelast fall lettuce for Thanksgiving salads requirescareful variety selection. On-farm variety trialsallow you to identify the varieties that fit a marketniche, produce optimally in a given plantingwindow, extend your production and salesseasons, and provide increased security in yourfarm plan.

On-farm variety trials can increase economicsecurity of a farm and expand market potential byidentifying:

Varieties that meet local climaticchallenges

Varieties that fit different productionwindows, allowing continuous availabilityover time and extending the season

Novel crops to fit market niches

Varieties with good market qualities likeflavor or visual appearance

Climatic challenges and extended seasons:Agricultural markets have traditionally followed

the cycle of the seasons. However, today theproduce seasons are blurred as world-widedistribution allows year-round tomatoes andavailability of off-season produce includingasparagus, zucchini, and spinach. While thisinternational market grows, there are anincreasing number of customers who are devotedto local food, recognizing that fresh, seasonalproduce nearly always has the best flavor, tends tofollow seasonal cravings, supports localeconomies, and reduces environmental impacts.

Farmers who cater to local markets and build areputation for quality know that local, seasonalproduce can compete well with imported goods.However, local climatic constraints may challengeless-adapted crops. Many varieties have beendeveloped specifically for the conditions of themajor areas of production such as celery andartichokes for cool, maritime climates andtomatoes for hot, Central California valleys.


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Genetic diversity allows crops to be adapted toregions far from their centers of origin. Forexample, chile peppers, originally from Centraland South America, are now part of the Hungarianand Thai diet and corn from Mexico fed theNative tribes of the Northern Plains of the US.This diversity means that some varieties willperform better than others under climatic andenvironmental challenges. There are tomatoes thatwill set fruit sooner than others after a cool springand some kales will survive or even continue toproduce through cold winter temperatures.Identifying varieties with such qualities offers anability to expand offerings and extend the seasonto fill early and late production windows.

Sequential sowings:By planting a variety trial you can identify

optimum varieties for each specific plantingperiod. For example, some lettuce varieties resistbolting and form heads under hot summerconditions while others offer frost tolerance forlate-season sowing. By sowing your lettuce trialrepeatedly throughout the season you can identifythe best variety for each production window,creating a strategy for sequentially planting theoptimum variety for each sowing date.

Part of why I am interested in placing our existingvarieties within the trial plots is that I haven't ever

done a scientific trial of them. We have not yet

been able to compile useful data, and would like

to know what part of the season an old favorite

like Waldmanns, for instance, actually performs

best. None of them perform perfectly all season. I

have a strong hunch that each variety within a

type has its favorite part of the season. River

Bean, Arctic Organics, Palmer, AK, lettuce grower

New crops and varieties:

Experimentation is one of the joys of farming trying something unusual, whether it is a piece ofequipment or a different planting rotation.Identifying novel, interesting crops or varieties ofa crop you already produce can be a way todifferentiate yourself in the marketplace andattract new customers. Farmers market customers,chefs, and specialty distributors are intrigued byunusual or exceptional varieties, varieties with a

story, superior flavor, or intriguing color.Eventually these more obscure crops find theirway into the supermarket, but they tend to gettheir start from local sales by innovative growers.The heirloom tomato craze of the last decade wasa prime example of this market phenomenon.

Colored carrots (non-orange) are a currentexample of a new crop appearing at farmersmarkets and in bags of mixed frozen vegetables.Many obscure varieties of common crops have notbeen bred for commercial production or mayeven, as in the case of colored carrots, haveevolved in climates very different than thosefound in production areas of the United States.Many colored carrots, particularly the red ones,evolved in warmer climates and require littlechilling (vernalization) to induce bolting,therefore when planted under cool springconditions they bolt readily.

Conducting an on-farm variety trial prior toexpanding production of new, unknown varietiesprevents the difficult lesson of losing a crop. Forsmaller markets, such as restaurants and farmersmarkets, sharing samples from the trials with yourcustomers not only garners consumer feedback,but also builds demand from the sneak previewof what new, interesting crops will come in thefollowing year.

Addressing crop stressesIndividual plants and crop varieties vary in theirresponse to crop stresses. This genetic breadthoffers an opportunity to enhance crop growth


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under environmental, pest, pathogen, and climaticconstraints by identifying varieties least affectedby the stress conditions.

Individual plants and crop varieties vary in thefollowing:

Pest tolerance and resistance Drought tolerance Nutrient utilization Heat and cold tolerance Pollution tolerance Timing of maturation Day length requirements

There is an axiom in plant breeding that states,Always breed under the conditions of intendeduse. The same rings true for conducting varietytrials, Always trial under the conditions of

intended use. If the crop stresses are not presentin the trial, then the genetics for resistance ortolerance will not be expressed or apparent in theevaluations. As such, the trial must be establishedunder the right conditions and timing to ensure thevarieties are exposed to the intended cropchallenges. For example, if your spinach crop issubject to downy mildew early season but not inthe fall, and your goal is to find a good downymildew resistant variety, then obviously the trialmust be planted early spring. Similarly, if you

want to identify a good bolt-resistant spinachvariety then it should be planted to ensure it isexposed to the long-day bolting conditions of latespring and early summer. It is also important toremember that organic conditions are often verydifferent from conventional and as such, relyingon conventional trial data as your sole source ofinformation is a risky venture.

It is important to keep in mind that many of theabove-mentioned crop challenges may occur in

patterns across the field. For example, aphidsoften move into a field from the direction ofprevailing winds, cold pockets form in low areasof the field, and soilborne diseases andsymphylans often occur in patches of the field.Replication in the trial is a tool to account for thisvariability in conditions. However, blocks shouldalso be set up to increase uniformity of conditionsas much as possible (see Trial Layout).

Planning the Trial

Identifying trial goalsIt is important to articulate trial goals in order toensure that the seed sourcing, trial planning, andexperimental design will result in the desired

information. Variety trials require time andattention. The trial goals determine the optimumtiming of planting, how the crop should bemanaged, how large the plot size should be, whento evaluate the trial, and how to interpret trialresults.

Prioritizing cropsSince trials of every crop are not usually practicalyou will have to decide how to prioritize efforts.On a diversified farm it can sometimes be difficult

to do this. Clearly efforts would be well spent tooptimize production of the largest farm crop orone that brings the greatest economic return. Atthe same time, this crop may routinely receivepriority and production practices and varietyselection have likely already been refined.Perhaps it is the new and less familiar crops thatshould receive emphasis. Integrating annual trialsinto your long-term farm plan will provideguidance in making these decisions.

Choosing trial varieties and acquiringseedSeed acquired for your variety trial should reflectthe goals of the trial and reflect your farmmanagement approach. If you are only interestedin using readily available seed that your favoriteseed company carries then it makes sense tosimply approach your seed companyrepresentative for suggestions of varieties. If youare interested in identifying the best variety inexistence regardless of the source, then your

search should have a broader reach. If the bestvariety is not commercially available, perhaps youwould consider producing your own seed stock orapproaching your seed company representativeand asking if they would consider carrying it.

Ralphs Greenhouse, a 100-acre farm in Mount

Vernon, Washington, is located near Osborne

Seed Company. Tim, the farms production


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manager, wants to start producing Brussels

sprouts and cauliflower, two new crops for the

farm. Since Osborne Seed representatives are

familiar with the farm location and climatic

conditions and they have a good working

relationship, he asked them for recommendations

for his trial. Tim is also interested in identifying

good organic seed sources for his Brusselssprouts and cauliflower, so he sourced additional

organic seed varieties from other companies to

include with Osbornes organic and non-organic

recommendations.

Before seeking out varieties it is helpful to createas complete a description as possible of ideal cropcharacteristics, or desired traits. This will help youarticulate what you are looking for when sourcingseed and guide your variety selection process. The

list of desired traits will also serve later as yourcriteria for evaluating the trial. For example, yourdescription might include quality criteria alongwith basic plant growth parameters like days tomaturity and height. You may want to be the firstgrower with tomatoes at the farmers market, butyou also want a variety that fits your market andproduction system. So your description might be ared, flavorful, salad-size tomato that isdeterminate (to minimize trellising) and is lessthan 75 days to maturity.

Appendix A includes a list of resources forfinding organic seed sources, public variety trialinformation, and other useful seed resources.Following are general sourcing considerations andrecommendations.

Seed companies:Seed companies are a good place to start lookingfor recommendations, but remember that they arein the business of selling seeds, so dont simply be

swayed by the pretty pictures and gushingdescriptions. Many seed companies have regionalsales representatives who specialize inrecommending varieties for local conditions andmarkets. Seed companies that conduct their ownfield variety trials will also tend to have morespecific variety recommendations. Some seedcompanies even offer free seed or other

compensation in exchange for conducting on-farmvariety trials on cooperating farms.

Public trials:Traditionally, public variety trials were a typicalservice of county Extension assisting growers inidentification of regionally-specific, locally-adapted varieties. A decline in federal and statefunding has reduced this service in many areas.Today, though not available in every county, thereare a few programs in the Pacific Northwest thatconduct vegetable variety trials on universityresearch farms and cooperating growers farms.Their results are very useful for gaininginformation about variety traits and regionalperformance. However, it is valuable to considerthat some public trials can be limited in range ofvarieties and locations evaluated and in some

cases are not conducted in organic productionsystems. (See Appendix B for information onpublic vegetable variety trial programs in thePacific Northwest.)

Networking seed and informationexchanges:Networking with other growers through regionalconferences, farmers markets, or seed exchangesis a fun way to find interesting varieties whilegleaning information from other growers or even

sharing on-farm variety trial results. Local growergroups may even be interested in planning localon-farm variety trials strategizing evaluations ofdifferent crops on different farms to maximize thegain of trial efforts. Check with localfarmer/gardener groups for opportunities or evenstart a seed and trial information exchange in yourarea.

Including a check varietyAlways include your farms standard variety in

your trial, also called a check or benchmarkvariety. Your check or standard variety is afamiliar point of reference to compare all othervarieties in the trial. Including a check variety isimportant to:

1. Compare the conditions of the season to

normal conditions If you know yourstandard variety does not usually getdisease, but it did this year, then you


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would be able to recognize that the diseasepressure is higher than normal and may beinfluencing other varieties in the trial morethan it would under a low disease-pressureseason.

2. Compare the performance of the trial

varieties to your standard variety Thishelps answer whether you should switchyour standard variety to a new one.

3. Communicate results to others If thestandard variety is well known then youwill be able to use it as a point of referencefor explaining results of the trial to otherssuch as co-workers, seed companyrepresentatives, or researchers. Forexample, This tomato produced ripe fruitthree weeks earlier than Early Girl!

Doing the Trial

A variety trial is a scientific experiment in whichthe hypothesis is that some of the varieties havemore desirable characteristics or genetic traitsthan the others. The goal of the experiment is toidentify the best varieties for the location, marketor production system. As with any scientificexperiment, following a rigorous experimentaldesign increases the likelihood that the results

measured will truly be due to the treatment (in thiscase the variety) rather than from an externalinfluence. The experimental design provides astatistical basis for measuring the likelihood thatyour results are accurate.

When varieties are grown and evaluated in oneplot each on the farm, this is considered to be anobservational trial. When varieties are planted inmultiple plots on the farm following a replicatedexperimental design, this is considered to be a

replicated trial. Replicated trials require moreattention and effort, but provide greater assurancethat the results are accurate.

Plot: The plot is the fundamental experimentalunit. The term plot refers to a single location of

the field planted with one variety. Each plot

usually includes several plants of the variety.

Each block includes a plot of each variety.

Observational trialsObservational trials can be very useful, especiallyif variability is minimized (see Field effect andConsistent treatment), but their limitations shouldbe kept in mind. Because conditions such as soiltype, sun exposure, or irrigation may vary across

the field there is a risk that differences inperformance of varieties are due to variable fieldconditions rather than genetic or seed qualitydifferences. We have all seen uneven irrigation orchanging soil types resulting in variable plantgrowth across a field. Replicating helps accountfor this sort of variability. Two of the benefits ofobservational trials over replicated trials are anability to evaluate a larger diversity of materialand a greater ease and simplicity in planting. Ifthe same varieties are included in trials repeatedover seasons then confidence in results mayincrease. For example, if a variety showsconsistent performance over two or three years,then it is likely to continue to perform well.

Some crops are best evaluated inside as well as outside,such as the core sizes of these cabbages

Observational trials are useful for:

An initial screening to evaluate whether avariety merits consideration for areplicated variety trial.

Evaluating the overall composition, or uni-formity, of a strain of a variety in an ade-quately large population.

Checking for trueness-of-type or otherseed quality concerns.


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Identifying variety traits, or potentialstrengths or weaknesses of a variety, withconsideration of potential field variability.This sort of information gains strengthwhen replicated over time, over multiplelocations, or is followed up with areplicated trial.

Experimental design - replicatedvariety trialsThe experimental design refers to how theexperiment, in this case the variety trial, is set upor arranged in the field. The most common andappropriate design for variety trials is called aRandomized Complete Block Design (RCBD). Itallows for testing as many varieties as desired, butmust include two or more. (Three or more

replications are recommended and required toconduct statistics). Each variety is grown in a plotin each block; and in each block, plots (varieties)are arranged in a randomized order. Blocks shouldideally be located where there is as little variationin conditions within and between blocks aspossible. Where variability exists, blocking is atool to account for field variability; and wherevariability exists, blocks should be arranged sothat the variability in conditions within the blocksis less than between blocks. In this manner all

varieties are evaluated under each condition(block), giving each variety an equal opportunityto perform. (See Trial layout for a diagram of anRCBD.) Replication and randomization are theessential elements of the experimental design thathelp separate out the treatment effects (varietyperformance) from the field effects (variation inthe environment).

Genetics by environment interaction:There is a scientific premise called genetics by

environment interaction, or GxE. What thismeans is that both the genetics and theenvironment (climate, soil, pest conditions etc.)affect plant growth. The goal of the on-farmvariety trial is to identify the optimumcombination, i.e. the genetics that result inoptimum crop performance under the localenvironmental conditions. Take care to minimizeenvironmental variability across plots within thetrial to ensure that the genetic component is truly

measured. Some seed company and public trialsare conducted across multiple locations with thegoal of identifying the genetics that perform in avariety of environmental conditions and thereforeserve multiple markets. There is no exact industrystandard for number of trials, but breeders usuallywant to see data from at least nine year-locations(some combination of years and trial sites) beforedeciding to release a variety.

The term genetics describes the geneticcomposition or combination of genes that gives a

crop variety a unique set of heritable traits.

Breeders use the term genotype (geneticpatterns) to describe the genetic contribution andphenotype (observed traits) to describe thecombined environmental and genetic forces

acting on a variety. Here we use the term genetics

to describe the genotype.

Field effect:The field effect refers to the influence thatvariable field conditions have on the performanceof the plants in the field. For example, if the fieldis on a slope and the soil is richer on the downhillside, then plants planted on the downhill side maygrow larger because they grew in better soilconditions, not because they had superiorgenetics. Likewise, plants grown on the southwest

side of a field may grow larger because theyreceive more afternoon sun, or smaller if they aresun-sensitive and their roots are dried out by theafternoon sun. Patterns often exist in the fieldwhich affect crop growth including soil quality,soil texture, soil pH, soil fertility, drainage, pestpressures (insect, weed, disease, and animals), sunexposure, irrigation variability, temperaturevariation (cold pockets), and pollution. Somesources of environmental variation are relativelyfixed, like soil type and production practices,

while others are more random, like weather andclimate. Pests (diseases, insects, and weeds) maybe either fixed or random depending on theorganism. The soil insects called symphylans areusually found in the same spot year after year andwould be regarded as a fixed effect, whereasaphids blown into the plots from another regionwould be a random effect. Fixed sources ofvariability can be compensated for by the use of


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randomization whereas random sources ofvariability require testing over locations and/orseasons (seasons as used here may be differenttimes of year or different years; the objective is toobtain data in a number of different growingenvironments). The goal of the experimentaldesign is to minimize the effects of environmentalvariability on trial results by blocking replicationsso that field variation is minimized within blocks.In essence, you replicate in the trial to account forfixed effects and repeat the experiment over timeto compensate for random effects.

Consistent treatment:All management practices should be consistentacross all trial plots including irrigation, soilfertilization, pest management, cultivation andweeding, staking, or any other horticultural aspect

of crop production. If practices are not consistent,differences in performance may be the result ofunequal treatments as opposed to geneticdifferences in varieties. For example, if half thefield was cultivated and the other half leftuncultivated, then the plots in the uncultivatedsection would have an unfair disadvantage as theywere subject to greater weed competition.Conduct plot management operations by block tominimize variation within each block. Forexample, complete the cultivation of an entire

block before stopping for the day so that all plotsin that block received consistent treatment(cultivation).

This small-scale vacuum seeder allows establishing trialplots using the same techniques as in regular production.

Randomization:Randomizing plots within each block helpsincrease the assurance that the results of theevaluation are due to genetic difference betweenvarieties rather than due to variation in theenvironment (field effects). The more replicationsyou include the greater the assurance thatmeasurements will reflect differences in thevarieties rather than variation in the field.Randomizing is also important to minimize theinfluence that varieties have on one another. Forexample if each variety was planted in the sameorder in each block then one variety planted nextto another very tall, vigorous variety might beunfairly affected by the competition for light andnutrients.

The order of plots may be randomized by any

basic randomization tool such as drawingnumbers from a hat. An easy method is to markall of the plant stakes for each block and then mixthem up and walk the block inserting whicheverstake comes to hand first to mark the first plot andcontinue down the row marking plots in thismanner.

One exception to randomization is that the firstblock may be planted in the numbered order of thestakes while the next blocks must be randomized.

This is acceptable because randomizing thesuccessive blocks ensures that varieties in eachblock are in a different order. You may want tohave your varieties in a particular order in the firstreplicate if you plan to use your variety trial as ademonstration plot.

Population and plot size:The size of plots in the trial should be largeenough that the resulting number of plantsprovides a good representation of the whole

population. The greater the plot size andpopulation size, the more representative thepopulation will be. However, the larger the plotthe more difficult it may be to manage, especiallyif there is a large number of varieties and three ormore replications. In general, when evaluatingopen-pollinated varieties of self-pollinated cropsfewer plants are necessary to get a representativesampling than in cross-pollinated crops due to the


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generally greater inherent genetic variability incross-pollinated populations.

Recommended minimum number plantsper plot in a replicated variety trial to evalu-ate population

Crop Min. # of plantsCorn 30

Brassicas 30

Carrots 50

Radishes 50

Tomatoes/Peppers 10

Squash/Cucumbers 10

Beans (bush varieties) 30

Beans (pole varieties) 10

Lettuce (heading varieties) 10

Lettuce (leaf varieties) 25

Spinach 25

Peas 30

Ideally plots should be large enough that thepractices used represent your normal farmingpractices. For example if you normally plant yourcabbage on 36-inch centers and field cultivatewith a tractor then a small garden trial with 24-

inch spacing and hand hoeing may result in somevarieties performing differently than they wouldunder normal conditions. Similarly if youusually apply drip irrigation, then overheadirrigation may skew results. For best results,include your variety trial within your productionfield of that crop so that all production practicesare the same as for commercial production. Plotsmay need to be a certain size in order to usenormal planting and management practices. Forexample, a minimum amount of seed may be

required to plant with a seed drill or vacuumplanter and the planting equipment may need torun a certain distance in order to functionproperly. Similarly mechanical harvestingequipment may require a certain size scale inorder to operate appropriately.

Another variable to consider in determining plotsize is number of rows to include per plot. Single

row plots allow you to place more varieties inyour trial, but may give more variable resultsbecause of fewer plants per plot and potentialcompetition between varieties in adjacent plots.With three or four row plots, the center one or tworows can be evaluated. While this approach takesmore space, it does minimize inter-plotcompetition and produces more accurate data. Aswith plot length, minimum number of rows maybe determined by equipment. For example, yourplanter may only plant six rows at a time.

Border rows around your experimental plots willminimize the edge effect whereby plots withoutborders will tend to be more productive becausethey lack competing plants around them. As such,data from un-bordered plots around the outside ofthe trial will be biased towards greater

productivity than in the center of the field. Borderrows should be planted not only on the sides ofthe trial, but at the top and bottom of the field aswell.

Trial layout:Before laying out the trial it is useful to create amap of the field, diagramming any sources ofvariability. Aerial photographs, if available, arealso useful to view field variability.

From an aerial view, it is easy to see variability in soil type,vegetation, and field edge effects important considerations

in deciding where to establish your trial.

Mark on your map or aerial photo any differencesin soil type, irrigation type, disease or pestpockets that you are aware of, wind and sundirection, and temperature gradients such as cold


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air drainages on a hill slope. The map is a tool foryou to decide where to place each trial block.Blocks may be adjacent (RCBD) or in differentareas of the farm (replication by location), butblocks should be placed in a manner thatminimizes variability within the blocks.Variability should also be minimized between theblocks as much as possible, but providing uniformconditions within the blocks achieves the intent ofblocking. In the following example note howblocks are placed to minimize variability of soiltexture within the blocks.

Clay soil Clay-loam Loam soil

Block 1 Block 2 Block 3

Decreasing amounts of clay in soil --------->

Case study of an experimental design:Jamie Kitzrow of Springhill Farm is conducting afennel variety trial. He has been planting thevariety Orion, but he wants to see if there are anyother varieties available that perform better on hisfarm.

To do this, he sources fivefennel varieties, four newvarieties plus his standardvariety, Orion. Jamie first

numbers each variety for thetrial, 1=Zefa fino,2=Perfection, 3=Fino,4=Orbit, and 5=Orion. Hethen starts one flat of eachvariety (172 cell plug tray)planning on planting fiftyplants per plot. In order tocollect useful data from histrial, Jamie wants to plantthree blocks or replications

and has prepared three bedsfor the trial, one bed perreplication. He will plant eachvariety (fifty plants per plot)into each block (bed),randomizing the order ofvarieties in each block.

Note: Blocks can also be in different sections of

the same row, but separate rows makes it easy totrack where one block ends and another begins.

Each square in the diagram in the left columnrepresents fifty plants of that variety. It is helpfulwhen marking tags in the field to label them withthe variety number and replication number to keeptrack of blocks. For example: variety #1 in thefirst block would be labeled 1-1, variety #2 in thefirst block would be 2-1, variety #4 in the thirdblock would be 4-3 etc. The order of varieties inthe first block does not need to be randomized,but the order must be randomized in the secondand third blocks. (See Randomization.)

Wooden survey stakes are useful for marking a trial, and along tape measure is handy for evenly spacing plots, asabove. It is best to establish the trial in the middle of the

field under uniform conditions to avoid edge effects.

Marking and mapping the trialOnce block areas are identified you are ready tolayout and mark the trial. You must decide onyour plot size and then mark each plot in the fieldensuring there is enough room for equal sizedplots of each variety in each block. Tags or stakes

are necessary to mark plots and to identify whereto plant each variety and recall the location ofeach plot for future evaluations. Ideally youshould conduct what is called a blind trial. In ablind trial a letter or number is assigned to eachvariety rather than listing the variety name oneach stake. This helps eliminate bias whenevaluating varieties. It is crucial however to notloose the code for which variety each letter or


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number represents or else the entire trial valuewill be lost.

Common farm materials may be used as plotmarkers including irrigation flags or surveystakes. Wooden stakes or even paint stirring sticksmake good markers, are relatively low cost, andare biodegradable in case one gets demolished inthe field. Permanent marking pens work on thewood, but may fade in bright sun. So if markingwith permanent pens, either rewrite mid season oruse your map to confirm markings at the end ofthe season. Irrigation flags (plastic squares on thinwire commonly used to mark irrigation in thefield) are also low cost and available at most farmstores. Permanent pens will also write on theplastic flags. The benefit of the flags is theyusually survive being run over by a tractor, but

they are not biodegradable and over time canresult in lots of metal wire and plastic flags in thefield. Labels can also be printed on weatherprooflabel paper and placed on small plastic stakes.

Once the stakes are placed in the field, it is criticalto create a field map. Stakes are easily lost,stepped on, run over by a tractor, or fade in thesun. Your plot map will be critical when youreturn to evaluate the trial. A simple piece ofnotebook paper or graph paper will suffice, but be

sure to make at least two copies and file one in asafe location.

Evaluating the trial

Sample data collection and evaluation sheets areavailable in Appendix E and online atwww.seedalliance.org These sheets are useful forcollecting data in the field. Excel is a helpfulprogram for inputting and analyzing data

collected. A formatted Excel file for data inputand analysis is available at www.seedalliance.org

The trial evaluation should be a combination ofdata collection and notes. Collecting data,including measurements and scored traits, is auseful tool for developing a clear picture ofindividual traits and provides a record for laterreference. It is also helpful in comparingdifferences between replications to assess the field

effects vs. treatment effects. Field notes allow acomplete assessment of the variety integratingoverall impressions and capturing finer notes ondetails that may get missed in the data. Bothelements should be used in concert in the finalanalysis and decision making process about futurevariety selection or trial plans.

Evaluation criteria can be extensive or focuseddepending on the intent of the trial and amount oftime available. Because farmers are very busy, werecommend narrowing the list of evaluationcriteria to those that are most important (five orsix at most). These key traits should be identifiedin the trial planning and variety selection process(see Choosing trial varieties and acquiring seed).You can also walk the field and take notes tocapture any missed details. At the end of the

evaluation, it is also helpful to give each varietyan overall score.

Variety evaluation can occur throughout theseason to capture important traits at differentstages of growth. Most importantly, each varietyshould be evaluated at harvest maturity. Often allof the varieties in the trial will be mature at thesame time allowing evaluation of the entire trialon a given date. However, in some cases varietiesmay differ in maturity dates and the trial willrequire multiple evaluations. It may be useful toevaluate some crops at multiple growth stages ifeach stage may be harvested for a differentmarket. For example, lettuce may be harvested asbaby salad mix, baby heads, or full-head size.Vigor is a useful trait to evaluate at an early


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seedling stage (2-4 leaf stage). Seedling vigor is atrait particularly important in organic productionas it is related to improved competition againstweeds, efficient nutrient utilization, and evenresistance to certain seedling-stage diseases likedamping off.

Efficiency Tip: If evaluating the trial throughoutthe season is too time-consuming to plan, then

just monitor the trial for full maturity and set

aside time to capture key evaluation criteria at

harvest time. The quality of data is more

important than quantity of data.

Quantitative vs. qualitative traitsQuantitative traits are those that can be measuredon a continuous scale such as height, yield, or

fruit size. Qualitative traits are descriptive, such ascolor, flavor, and uniformity. Quantitative datacan be measured directly if time permits andequipment is available. A data collection tool thatmay be used for either quantitative or qualitativetraits is to assign a score, commonly on a scale of1-9, that reflects the trait. For example, if yield isthe trait evaluated then a 1 would be the lowestyielding plot and a 9 would be the highestyielding plot. All numbers should reflect acomparison of the plots of varieties in the field on

the day of the evaluation, so a 9 would be thehighest yielding in the trial, rather than the highestyielding variety you have ever seen. A usefulscale developed by the International Center forTropical Agriculture uses nine points and is easyto translate into a verbal rating system. Rating isas follows: 1=poor, 3=fair, 5=average, 7=good,and 9=excellent. The even numbers in the scalecan be used to achieve finer differentiation. It isimportant to use at least this range of numbers (1-9) in order to differentiate between varieties. If

you use a smaller scale, ratings often fall in themiddle (2 on a scale of 1-3 for example) and it isnot possible to say if one variety was better thananother. This rating scale can be applied todiseases and pests as well as performance traits.

Efficiency Tip: Score traits rather than measuringor counting to save time. (See Qualitative vs.

quantitative traits above.)

Evaluation traits to considerThe evaluation traits should reflect the goals ofthe trial and the desires of the grower, which mayvary from crop to crop. Some traits such asseedling vigor and pest resistance may beparticularly important to organic growers.

Evaluation traits may address market demandssuch as flavor and uniformity as well asproduction constraints such as yield and storagecapacity.Suggested evaluation traits include:

Flavor Yield Length of productivity (i.e. first and final

harvest dates) Seedling vigor Plant vigor Uniformity Rate of pest infection Bolting sensitivity Holding and storage qualities

Seedling vigor is an important variety trait

Data collectionSeeAppendices for sample evaluation sheets and

a trial planning worksheet.


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Data collection steps:1. Begin the evaluation process by first

walking the trial to observe the plots,gaining a feeling for the breadth of traitswithin the field.

2. Every plot should be individuallyevaluated. Do not pool the three replicatedplots for the evaluation or the intent ofreplicating will be lost.

3. Start with the list of all the traits to bemeasured or scored. Walk the field andevaluate each plot for a single trait. Thenstarting back with the first plot repeat theprocess for each trait, one trait at a time.So, for example, all plots are evaluated foruniformity, then all plots are evaluated forvigor, then all plots are evaluated forcolor, etc., proceeding until evaluation of

all the desired traits are recorded.4. Take notes on each plot individually.

Notes might include an overall assessmentor notable details that were not captured inthe data collection or even comparisons ofone plot to the next (i.e. variety #3 is muchmore productive than variety #4).

5. Before leaving the field it is sometimesuseful to rank each variety overall tocapture impressions after going throughthe evaluation process. You may want to

rank them from top to bottom in order ofperformance or it may be useful to assigna number according to future use such as,1 = grow next year, 2 = continue toevaluate, or 3 = drop from consideration.Note that the exercise of collecting data,plot by plot, and taking detailed noteshelps you notice more detail and gain anoverall Gestalt or holistic impression ofeach variety by the end of the evaluationprocess.

6. Evaluate all of the plants in a plot as awhole rather than just assessing the best orworst individuals in the population. Thisapplies to both assigning a score andmeasuring a trait. When measuring, it isbest to assess all of the plants in the plotand compute an average or, if the plot istoo large to measure the whole population,then randomly select a sub-sample to

measure and compute an average for thatplot.

Making Sense of the Data

Once data are collected the task remains of

assessing the results. The first step is to reviewyour trial goals. Was the goal to identify a singlevariety that out-yielded your current standardvariety or the most disease resistant varietyavailable? Or was the goal to identify several newand interesting varieties to expand your offerings?Depending on your goals the data assessment maybe approached from different angles.

Much can be learned from simply looking overthe data without using statistical methods.

Statistics are an additional tool which can be usedto assess the effects of natural variability betweenplots and the likelihood that the differencesmeasured are due to the genetic differencesbetween varieties.

Post-harvest storage quality is a keyevaluation trait for many crops

Viewing the dataEntering the collected data into an Excelspreadsheet makes it easy to look at and calculateaverages. It will also facilitate entering data into


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statistical formulas if you choose. Each plotshould be entered separately into a chart of thetraits evaluated, the varieties and replication (seetable below). Each trait evaluated should beconsidered separately and then compared toidentify the best varieties overall. Lets considerthe following example:

Yield (scale of 1-9)

Variety Rep 1 Rep 2 Rep 3 Average

Var A 7 6 7 6.67

Var B 8 9 2 6.33

Var C 3 4 3 3.33

We can learn a lot by looking at all threereplications along with the average scores. Froman assessment of the averages we would concludethat variety A was the highest yielding variety, but

by comparing individual replications we can seethat variety B actually scored higher in two out ofthree replications. We might consider whathappened to variety B in the third replication. Didit not receive irrigation? Or was the soilcompacted in that plot? We can most confidentlyconclude that variety C was the lowest yielding,but we might consider other traits for A and Bbefore deciding which performed best. As you cansee if the trial had not been replicated and VarietyB had only been planted in the location of the

third replication then you might have dropped itfrom the trial based on poor performance in thatlocation. This is the purpose of replicating.

After looking over all of the traits evaluated youshould begin to get a feeling for which varietiesperformed the best overall. As Dr. John Navazio,OSA Director of Research says, The creamalways rises to the top.

Identifying the winners

It is useful to create an overall rating scale to sortout the varieties and make decisions about how toproceed in the future. If the goal is to pick the topvariety then you might consider ranking all of thevarieties in order of overall performance based onyour identified priority traits. So, number 1 wouldbe the best variety (in this case variety A in thechart above), and you might decide to grow it nextyear. If the top varieties are close you might

decide to drop all but the top two or three and trialthem again the following year to compare asecond season.

If the goal of the trial is to identify multiple goodvarieties, potentially for different production ormarket niches, then it may be more useful tocreate an overall ranking that separates thevarieties into classes of performance. Forexample, 1 = best performing, ready forproduction; 2 = medium performing, continue toevaluate; 3 = poorly performing, drop from thetrial. In this case each variety would be assignedand overall score of 1, 2, or 3 which wouldindicate how to proceed the following year. Thistype of scoring is also useful in the event that thetop variety is dropped from availability. Then youmay return to your trial data and choose amongthe other varieties that ranked # 1 overall.

Ranking scales are a decision-making tool. Again,the type of ranking you choose to create shouldreflect your trial goals and make sense for use inyour decision making process. The goal of mostvariety trials is to decide whether to replace yourstandard variety with a better variety. Therefore itis useful to consider how each variety compareswith the standard. For multiple year trials considerperformance of a variety over time in comparisonto the standard, check variety. For example,variety A out-performed the standard check inseven out of ten years or 70% of the trials. In asingle year or over multiple years consider howthe performance of each variety offered anadvantage or disadvantage over your standard


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variety. For example, variety A had a 10% yieldincrease over the standard variety. Alternatively ifthe average yield of the standard variety isconsidered 100% then variety A had a 110% yieldadvantage. This sort of comparison helps put intoperspective the potential benefit of replacing thestandard variety with a better performing variety.

Seed cost:Although cost is not a trait that is evaluated in thefield it may be an important factor in decidingwhich variety to grow. Once the data is analyzedand overall scores are assigned it may be useful toevaluate the relative cost of each variety. Forexample, if one variety out-yielded another by10%, but the seed cost twice as much it may notbe worth the yield increase.

StatisticsStatistics are an additional tool to assess the data.Statistical analysis of the RCBD is computedusing an analysis of variance, called ANOVA forshort. An ANOVA may be calculated for eachtrait individually or for the overall score assignedto each plot. The ANOVA provides an estimate ofthe experimental error or variation among thereplications. It also provides a way to test thesignificance of the differences measured betweenvarieties or the likelihood that the differencesmeasured are truly due to difference betweenvarieties rather than differences in theenvironmental conditions. Local Extension agentsmay be available for help with conducting anANOVA and analyzing the data.

Statistical terms:Least significant difference (LSD) the minimumdifference between treatment averages that isrequired to be considered a real difference rather adifference due to chance.

P-value the probability that difference betweentreatments that were considered significant couldoccur by chance. For example a p-value of 95%means that there is only a 5% chance that thedifferences were actually due to chance ratherthan real differences in the treatments (in this casevarieties).

A free statistics program designed for farmerscalled AGSTATS02 is available from OregonState University, Washington State University,and University of Idaho. AGSTATS02 was de-signed for on-farm trials and is available athttp://pnwsteep.wsu.edu/agstatsweb/index.html

Appendix AOrganic seed availability

Agriculture Technology Transfer for Rural Areas(ATTRA):ATTRA provides a list of organic seed suppliers,databases of organic seed, background on theorganic certification regulations, and additionalorganic grower resources.http://attra.ncat.org/attra-pub/altseed_search.php

ATTRA also provides a list of regional sources ofbin-run organic grain seed for organic grainproducers. http://attra.ncat.org/attra-pub/summaries/marketingorganicgrains.html

Organic Materials Review Institute (OMRI):OMRI is a non-profit organization that providesorganic certifiers, growers, manufacturers, andsuppliers an independent review of productsintended for use in certified organic production,

handling, and processing. OMRI has established adatabase of organic seed suppliers and varietiesavailable with the goal of allowing growers andsuppliers a single place to find organic supplies oforganic seed. All listed seed sources are verifiedby OMRI for the validity of their organiccertification. http://seeds.omri.org

Saving Our Seed project of the Carolina FarmStewardship Association:Saving our Seed, a non-profit organization,

provides an organic seed sourcing service inwhich growers may contact their organizationwith wish list requests and Saving our Seed willsearch their database providing lists of organicseed sources and suggestions of alternativecultivars in the case that requested varieties arenot available.http://www.organicseedsourcing.com


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Pennsylvania Certified Organic (PCO):PCO is an organic certification organization thatprovides a list of organic seed suppliers and aguide to organic regulations regarding organicseed and plant materials.http://www.paorganic.org/pdf/2007%20ORG%20SEED%20SUPPLIERS%20O.pdf

Washington State University Center forSustainable Agriculture and Natural Resources(CSANR):The mission of CSANR is to develop and fosteragriculture and natural resource managementapproaches that are economically viable,environmentally sound, and socially acceptable.Rather than duplicate ongoing efforts, the centerstrives to facilitate interdisciplinary linkages andcoalitions between WSU, growers, industry,

environmental groups, agencies, and the people ofWashington. Their website provides resources fororganic producers including a list of sourcesselling organic seed.http://csanr.wsu.edu/Organic/OrganicSeed.htm#sources

Appendix BPublic vegetable variety trials in thePacific Northwest

Oregon State University Vegetable Variety Trials:Each year the OSU Department of Horticulturevegetable breeding program in Corvallis, Oregongrows and evaluates a diversity of vegetablevarieties. Although the trials are not replicatedand are not grown on organically certified groundthey offer a valuable screening of variety traitsand performance in the Willamette Valley region.Each year they release evaluation results for thepublic, and in combination with trials from other

regions of Oregon they publish a list ofrecommendations by region. Recommendationsare available athttp://www.extension.org/news/156Evaluation results are available from Dr. JimMyers and Deborah Kean, (541) 737-3083http://extension.oregonstate.edu/catalog/details.php?sortnum=0624&name=Vegetables&num_results1=31&s=12&num_pages=3&sort=snumbera

Washington State University Vegetable ExtensionProgram:Within the Vegetable Extension Program varietytrials are conducted on cooperating growersfarms and at WSU research stations. Many of thetrials are on-farm, most are organic, and all arereplicated. Variety trial results of watermelon, drybeans, fresh shell beans, edamame, baby corn,winter lettuces, and asparagus are available athttp://vegetables.wsu.edu or by contacting Dr.Carol Miles at (360) 848-6150 [email protected]

Appendix CAdditional seed and variety informationresources

National Plant Germplasm System:The USDA National Plant Germplasm System(NPGS) curates crop varieties at about a dozenlocations around the U.S. and territories. Thecollections house both wild and cultivated species.Plant accessions are cataloged in the GRIN(Germplasm Resource Information Network)available as a searchable database athttp://www.ars.usda.gov/Services/Services.htmSmall quantities of seed can be requested forresearch purposes. While some crop collections

are quite extensive (there are over 12,000accessions ofPhaseolus beans for example),many accessions are unadapted to NorthAmerican climates. In particular, many tropicalvarieties flower and fruit under short days, but areinhibited by the long days found during ournormal growing season. As such, these varietieswill not begin to flower until September, whenthere is insufficient growing season to produce amature crop. Seed quantities from NPGS aretypically small and you are expected to maintain

the variety once you receive it. When using thisresource, it is important to use all informationavailable and choose varieties carefully.

Public Seed Initiative (PSI) and FarmersCooperative Genome Project (FCGP) trialed anumber of vegetable accessions from NPGS from2002-2004. They found that varieties from similarlatitudes as North America had the best


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adaptation, and they were able to identify a fewheirloom and landrace varieties of merit.Information on this project can be found athttp://www.plbr.cornell.edu/psi

Organic Seed Partnership (OSP):The OSP program evolved out of the PSI as ameans of giving organic growers wider access tovarieties and breeding lines in the public domain.Begun in 2005, it is coordinated by CornellUniversity, with four hubs across the U.S.involved in trialing and breeding for organicsystems. Hubs in turn work with growersinterested in trialing materials available from theOSP list. The program ends in 2008, butrecommendations from trials should remainavailable.www.plbr.cornell.edu/PSI/OSPrelated.htm

Seed Savers Exchange:Seed Savers Exchange is a non-profit organizationof gardeners who save and exchange heirloomseeds. They also have a seed catalog business.They additionally publish a garden seed inventoryand are a good place to research and source smallquantities of seed that may not be commerciallyavailable. www.seedsavers.org

Appendix DVariety trial planning case studyGreentree Naturals Farm Sugar snap pea varietytrial

Envisioning the Trial:

Diane and Thom of Greentree Naturals inSandpoint, Idaho have been saving their own peaseed of a variety they like on their farm forseveral years. Peas fill an important niche for the

farm as they are a good early spring crop during atime of year when little produce is available at themarket. However, they regularly experience hot,dry spells during June at which time their peaproduction drops off. They want to conduct avariety trial to see if there are any other sugarsnap peas that tolerate the climatic conditionsbetter than the one they currently use but alsopossess the good eating quality of their current

variety. As an organic farm, identifying goodorganic seed sources is also of interest to Dianeand Thom. However, since they plan to save theirown seed which will then be organic, this is notthe top priority.

Trial crop:

Sugar snap peas

Trial goals:

To identify varieties of sugar snap peas thatproduce well, have desirable traits and tolerate thedependably warm, dry spells that occur in mid-June.

Desired variety traits:listed in order ofimportanceProductivity (quantity and length of time), lack of

stringiness, large pod size, good flavor

Trial varieties:

Seven new varieties total + one check variety =eight trial varietiesEach variety will be assigned a number 1-8. Thisinformation will be recorded for reference afterthe evaluation, but the numbers will be used in thetrial to avoid biases in the evaluation process.From organic sources: Sugar Daddy, Cascadia,and Sugar Ann

From non-organic sources: Sugar Snap, SuperSugar Snap, Sugar Sprint, and Sugar Star

Check variety:

Greentree Naturals farm-saved pea seed

Planning the Trial:

Ideal planting date:

Normal planting time of early-mid April as soonas the soil is workable and warm enough to plant.

Number of replications:

Three replications

Plot size:

Ten row-feet per plotPeas are a self-pollinated crop. In general,varieties of self-pollinated crops dont tend tohave as much genetic variability in the population


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1

4

3

2

5

3

2

5

1

4

1

3

7

2

5

1 2 3

replication

7

6

6

7

6 4

as cross-pollinated crops. Therefore smaller plotsizes are needed to get a good evaluation of thepopulation. Diane and Thom prepared three rowsfor the trial so that each replication could be in aseparate row. This arrangement blocks for row torow variability in conditions. Each row is 100 feetlong so with eight trial varieties they can makeeach plot about ten-feet long and have extra spaceto skip the beginning and end of each rowavoiding edge effects. They can also leave one totwo feet between each plot making it easier tokeep the peas in each plot separated forevaluations.

Production methods:

The peas will be grown in the same manner thatthey always follow on their farm, single rows on atrellis with drip irrigation. All plots will be

watered, weeded, and fertilized equally.

Field assessment:

Greentree Naturals Farm is a small, two-acre farmnestled in the valley between the Cabinet andSelkirk mountain ranges inNorthern Idaho. The farmland is fairly flat but the soiltexture varies from a sandyloam to loam across the farm.The weather and prevailing

winds usually come from thenorth through the valley.Trees along one side of thefarm shade some of theeastern side of the field in themorning. Because they usedrip irrigation the watering isfairly consistent, but cansometimes be slightly heavierat the beginning of the rowand lighter at the ends.

Trial layout:

The three rows for the trialwill be placed in a flat area ofthe field where the soil type isconsistent and away frombarriers like trees to avoidshading part of the plot orblocking it from the wind.

This ensures that all plots in the field will besimilarly exposed to the sunny, hot, windyconditions of concern in June. The three rows arein an area with consistent soil conditions. (Seediagram in left column.)

Plot layout:

Seven varieties, each is assigned a numberThree replicationsEach number in the diagram at left represents aten-foot plot of peas of that numbered variety.Each variety is in each replication or block in arandom order.

Trial evaluation:

Evaluation criteria:

Seedling vigor(scale of 1-9, 1 = least

vigorous, 9 = most vigorous) Yield(pounds harvested will be recorded

by plot on each harvest date and thenadded up after the last harvest date)

Length of productivity (record first and lastharvest dates to assess length of harvestwindow)

Lack of stringiness (rated on scale of 1-9,1 = most stringy, 9 = least stringy)

Overall eating quality (rated on scale of 1-9, 1 = least favorite, 9 = best overall)

Evaluation timing:

Seedling vigor(three weeks after planting)

Yieldand length of productivity (eachharvest date)

Lack of stringiness and overall eatingquality (two dates, one early season whenall varieties are being harvested and onelate season when all varieties are stillproducing, but pods may become tough)

Appendix ESample evaluation sheetand varietytrial planning worksheet

Please see manual inserts for a sample evaluationsheet and a variety trial planning worksheet.These documents are available online atwww.seedalliance.org


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Drinkwater, L.E. 2002. Cropping SystemsResearch: Reconsidering AgriculturalExperimental Approaches. Hort. Tech. 12(3):355-361.

Exner, R. and R. Tompson. The Paired-Comparison: A Good Design for Farmer-Managed Trials. Practical Farmers of Iowa.

Green-McGrath, D., L.S. Lev, H. Murray, andR.D. Williams. 1993. Farmer/Scientist FocusSessions: A How-To Guide. Oregon StateUniversity Extension. EM 8554.

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Authors

Completed June, 2007Micaela R. Colley, Organic Seed AllianceDr. James R. Myers, Oregon State University

Organic Seed Alliance

PO Box 772, Port Townsend, WA, 98368360/385-7192

Pictures courtesy of Micaela Colley (OSA) and Dr. John Luna, Oregon State University

Producer-Professional Reviewed

As an institutional standard, all OSA publications are reviewed by both scientific researchers andprofessional producers.

We thank the following for contributions and review of this publication:

John Foster, Oregon TilthDr. Carol Miles, Washington State UniversityNick Andrews, Oregon State UniversityDr. Cinda Williams, University of IdahoDr. Roseanne Leiner, University of AlaskaErin Mirrett, WSDA Organic Foods Program

Brian Andersen, Brian Andersen FarmsRiver & Sarah Bean, Arctic OrganicsAnthony Boutard, Ayers Creek FarmDiane Green, Greentree Naturals FarmJamie Kitzrow, Springhill FarmTim Terpstra, Ralphs Greenhouse

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