intro for thesis

8/2/2019 Intro for Thesis

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Rice is one of the most popular grains in the world. It is consumed as a staple by nearly every

culture except those on the fringes of the planet. Rice is a semi-aquatic plant that requires

constant moist conditions for survival. Thus rice can only be grown in certain regions. Yet it is

relatively easy to grow and has great storing qualities.

FROM WIKI:Rice is theseedof themonocotplantsOryza sativa(Asian rice) orOryza

glaberrima(African rice). As acereal grain, it is the most importantstaple foodfor a large part of

the world's human population, especially inAsiaand theWest Indies. It is the grain with the

third-highest worldwide production, aftermaize(corn) andwheat, according to data for 2009.[1]

Since a large portion of maize crops are grown for purposes other than human consumption,

rice is the most important grain with regard to human nutrition and caloric intake, providing more

than one fifth of thecaloriesconsumed worldwide by the human species.

Rice is a major food staple and a mainstay for the rural population and their food security. It is

mainly cultivated by small farmers in holdings of less than 1 hectare. Rice is also a wagecommodity for workers in the cash crop or non-agricultural sectors. Rice is vital for the nutrition

of much of the population in Asia, as well as in Latin America and the Caribbean and in Africa; it

is central to the food security of over half the world population. Developing countries account for

95 percent of the total production, with China and India alone responsible for nearly half of the

world output.

Rice Rice is a plant of Asian origin. The earliest record of rice in the world comes from Non Nok Tha in

Thailand, where it dates back to 3500 BC. First evidence of Oryza sativa (Scientific name of rice) is found

in North Bihar dated to 2000-2300 BC as well as in Hastinapur dates back to 100-800 BC (Randhawa,

1980). No wonder 90% of the world?s area under rice is in Asia and also about 90 percent of world riceis produced and consumed in Asia. In 7 countries of Asia, namely, Bangladesh, Cambodia, Laos,

Myanmar, SriLanka and Vietnam, 90% of people are rice eaters, while in 6 other countries, namely,

Indonesia, Japan, Korea Republic, Taiwan and Thailand, the percentage of rice eaters is 70-80 percent

(De Datta, 1981). In India and China, which together hold about half the worlds rice area, about 63-65

percent people are rice eaters.

A

s if rice farming werent
http://en.wikipedia.org/wiki/Seedhttp://en.wikipedia.org/wiki/Seedhttp://en.wikipedia.org/wiki/Seedhttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Oryza_sativahttp://en.wikipedia.org/wiki/Oryza_sativahttp://en.wikipedia.org/wiki/Oryza_sativahttp://en.wikipedia.org/wiki/Oryza_glaberrimahttp://en.wikipedia.org/wiki/Oryza_glaberrimahttp://en.wikipedia.org/wiki/Oryza_glaberrimahttp://en.wikipedia.org/wiki/Oryza_glaberrimahttp://en.wikipedia.org/wiki/Cerealhttp://en.wikipedia.org/wiki/Cerealhttp://en.wikipedia.org/wiki/Cerealhttp://en.wikipedia.org/wiki/Staple_foodhttp://en.wikipedia.org/wiki/Staple_foodhttp://en.wikipedia.org/wiki/Staple_foodhttp://en.wikipedia.org/wiki/Asiahttp://en.wikipedia.org/wiki/Asiahttp://en.wikipedia.org/wiki/Asiahttp://en.wikipedia.org/wiki/West_Indieshttp://en.wikipedia.org/wiki/West_Indieshttp://en.wikipedia.org/wiki/West_Indieshttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Wheathttp://en.wikipedia.org/wiki/Wheathttp://en.wikipedia.org/wiki/Wheathttp://en.wikipedia.org/wiki/Rice#cite_note-prodstat-0http://en.wikipedia.org/wiki/Rice#cite_note-prodstat-0http://en.wikipedia.org/wiki/Rice#cite_note-prodstat-0http://en.wikipedia.org/wiki/Food_energyhttp://en.wikipedia.org/wiki/Food_energyhttp://en.wikipedia.org/wiki/Food_energyhttp://en.wikipedia.org/wiki/Food_energyhttp://en.wikipedia.org/wiki/Rice#cite_note-prodstat-0http://en.wikipedia.org/wiki/Wheathttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/West_Indieshttp://en.wikipedia.org/wiki/Asiahttp://en.wikipedia.org/wiki/Staple_foodhttp://en.wikipedia.org/wiki/Cerealhttp://en.wikipedia.org/wiki/Oryza_glaberrimahttp://en.wikipedia.org/wiki/Oryza_glaberrimahttp://en.wikipedia.org/wiki/Oryza_sativahttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Seed


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hard enough. It is

patently clear now that

humans have gone

and made it a whole

lot harder. And, in a

cruel irony, while the rich, developed

countries are the ones that have

produced most of the greenhouse

gases that are causing climate change,

it will be the poorer countries in the

tropicsmany of them reliant on

rice to keep their populations from

hungerthat will be worst affected.

As Earth warms up, one of

the biggest concerns is the effect

on agricultureyet there has

been relatively little research

investigating the fundamental

question of how humanity will

feed itself in a changed climate.

How will higher temperatures and

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Drying is the process of simultaneous heat and moisture transfer. It is the removal of

excess moisture from the grains. Once dried, the rice grain, now called rough rice, is

ready for processing. Proper drying results in increased storage life of the grains,

prevention of deterioration in quality, reduction of biological respiration that leads to

quality loss of grains, and optimum milling recovery.

In the country three methods are used for drying the paddy grains, namely :

Sun drying Mechanical drying

Chemical drying

Sun Drying

Sun drying is a traditional method of drying the paddy grains. In fact, the major

quantity of produce is being dried in the country by this method. Sundrying is the

most economical method of drying grains. Grains are spread on drying surfaces

such as concrete pavement, mats, plastic sheets and even on fields to dry naturally.

Mechanical Drying

Mechanical drying process means drying the grains by ventilating natural or heated

air through the grain mass to get it evaporated the moisture from it. Mechanical

dryers are more reliable since drying could be done anytime of the year.

Chemical Drying

Chemical drying method involves the spraying of common salt solution with specific

gravity of 1.1 to 1.2 on the ears of the mature paddy crop. This treatment reducesthe moisture content from 29% to 14.5% after four days.

Drying palay on the road, which is a practice that most farmers do, is wasteful as it can result in

0.7 to 8.7% rice losses, according to the 1996 report of the Bureau of Postharvest Research and

Extension (BPRE).

Cognizant of this problem, the Department of Agriculture through its various agencies has been

distributing several units of the Maligaya flatbed dryers.
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The Philippine Rice Research Institute (PhilRice), for one, is expected to finish soon the

distribution of 20 Maligaya flatbed dryers, its share of the 709 proposed dryer units under the

project Mechanical drying support to farm clusters. Twelve of the 20 units have already been

installed in Bulacan, Nueva Ecija, and Pampanga as early as October last year while the

remaining 8 units are expected to be installed this month in Sta. Cruz, Zambales and in the rest

of the municipalities of Nueva Ecija and Pampanga.

On the other hand, around 200 dryer units have been installed by BPRE in the remaining

provinces of the country since last year while another 500 units will be installed this year.

Post harvest:In developing countries, post-harvest losses destroy about 15 to 16

percent of the

rice crop. This figure is even greater (as much as 40 to 50 percent) in countries

where there are challenging natural events and climatic conditions, such as

regular heavy monsoons. The rice post-harvest system concept is an efficient,

modern approach that focuses on preventing post-harvest losses and ensuring

the quality and safety of the rice crop during its processing and storage. The

system also includes procedures that add value to both primary and secondary

rice products, as well as by-products.

Some stages in the rice post-harvest system are more critical than others,

particularly in tropical and subtropical areas where rice is more vulnerable to

damage and more likely to suffer qualitative and quantitative losses. Among

these critical stages, drying and storage are especially important. Some

technological advances have been made in the area of rice storage techniquesand equipment, and FAO is playing an important role by contributing to the

transfer of new post-harvest technologies for storage, which include small metal

silos for storing grains at the household level (see photos). The metal silo for

household use varies in capacity from 100 to 4 000 kg. For a family of five

people, a silo of 1 tonne capacity can maintain the quality and safety of rice for

up to a year, thereby contributing significantly to household food security. A silo

of this size costs about US$55 and lasts for between 15 and 20 years.

Regarding the other critical post-harvest operation for rice drying efforts

are being made to improve small rice driers. For example, small portable electric

fan driers have been developed by IRRI, and are becoming an important ally to

small- and medium-scale rice farmers in terms of increasing their food security

and ensuring the safety of their rice crops. Rice farmers are beginning to

understand and accept the need to invest in post-harvest technologies because

not only are these technologies affordable, but they also offer the potential to


5/26

increase profits by adding quality and commercial value to the final products.

Total rice post-harvest losses for

Asia are estimated to have been

about 14 percent in 1997, whichrepresented about 77 million

tonnes and US$7.7 billion. Most of

these losses occurred as a result of

inadequate storage and drying

operations.

Efficient storage is critical for

rice, and between 4 and 6 percent

of total rice crops are lost during

storage. FAO recommendes use of

the small metal silo as a feasible

and valuable option for reducing

small- and medium-scale rice

farmers food losses. This

technology is already improving

the socio-economic conditions of

agricultural communities.

The rice post-harvest systemfocuses on both preventing food

losses and improving the efficiency

of the technologies that are used

to add value to rice and its byproducts. The aim is to generate

more employment and income and,

consequently, to improve food

security, which is one of FAOs

most important mandates.

Rice farmers are willing to investin post-harvest technologies that

are affordable and add quality and

commercial value to rice products.

I


6/26

f youre a rice farmer

anywhere in Asia, you

are likely to experience

high postharvest grain losses.

Total losses from harvest to

market can reach 3050%

in value, which means that,

conservatively, farmers are

losing around US$30 per

ton of rice harvested. For

an average four-member

farming family, an additional

$30 can go a long way.

Studies by the International

Rice Research Institute (IRRI)

in Cambodia, Indonesia, and

the Philippines have found that

postharvest losses occur mainly

because of spoilage and wastage

at the farm level, delay in drying, poor storage, poorly maintained or outdated rice mills,

and losses to pests throughout

the postharvest chain. These

losses result in lower quality

rice for consumption or sale,

smaller returns to farmers,


7/26

higher prices for consumers, and

greater pressure on the environment as farmers try to compensate by growing more rice.

The PPWG

With the urgent need to solve

postharvest problems in developing countries, the Postproduction Work Group (PPWG)

was formed in 2003 under

the Irrigated Rice Research

Consortiums (IRRC) Phase

II. By the end of the first year,

the PPWG established partnerships with stakeholders from

the public and private sectors

in Cambodia, Indonesia, Lao

PDR, Myanmar, and Vietnam.

Now, with the IRRC in its

third phase, the PPWG continues to pursue its objectives of

increasing farmers incomes

through improved postharvest

management and technology,

and building a network of

trained postharvest researchers

and extension workers, including stakeholders from the

private sector. We showcase

below some of the benefits

arising from these activities.

Safe seed storage


8/26

with the Super Bag

Farmers in Battambang

Province in Cambodia can

attest that the Super Bag is

an inanimate superhero in its

own right. Typically, farmers store three bags of seeds

with 70 kilograms (kg) each

for their own fields. The hot,

humid conditions cause the

germination ability of farmers

seeds to drop quickly. When

they finally use the seeds after

56 months of storage in their

homes, often less than 50%

germinate in the fields. By

comparison, upon using the

Super Bag for seed storage,

farmers were able to maintain germination rates above

90% and reduce the amount

of seeds required. The Super

Bag allows cereal grains and

other crops such as coffee to

be stored safely for extended

periods of 612 months. One

farmer reported that he sold


9/26

an additional 70 kg of seeds

in the market, earning him an

additional income of $9. A

Super Bag costs only $1 and

can be reused (as long as it is

not punctured), cutting back on

cost per harvest.

The PPWG now focuses on

> continued on page 2

Women in Lao PDR manually threshing paddy. (Photo by G. Claessens) 2

Ripple JanuaryFebruary 2007

evaluating hermetic storage systems with farmers (Indonesia,

Vietnam, Cambodia, Lao PDR,

and Myanmar) and rice millers/traders (Vietnam, Myanmar,

and Indonesia). Samples from

farmers trials taken for milling

and trials with rice millers have

proven that hermetic storage

also increases head rice (grain

fraction that has at least 75%

of the whole undamaged kernel

length) recovery significantly.

Better quality and price

through mechanical dryers

One of the main culprits for


10/26

quality deterioration of seeds

is delayed or improper drying,

especially when rice is spread

in the open to dry under the

sun. Mechanical dryers are the

only way to assure high-quality

products, especially in the wet

season with frequent rains and

high relative humidity.

At Nong Lam University

in Ho Chi Minh City, Vietnam, the PPWG trained dryer

manufacturers from Lao PDR,

Myanmar, and Cambodia on

manufacturing and performance

testing of dryer components

(see Postharvest information

and technology exchange:

lessons learned from Vietnam

in RIPPLE, Vol. 1, No. 1).

A manufacturer in Lao

PDR who attended the training built low-cost, farm-level

dryers that he plans to demonstrate and promote in key

provinces throughout the

country. In Cambodia and

Vietnam, farmers groups and


11/26

cooperatives are installing their

own flat-bed dryers. Another

training participant from the

Myanmar Rice and Paddy

Traders Association (MRPTA)

produced various dryer prototypes, a low-cost dryer with

a 1-ton batch capacity for the

farm level, and flat-bed dryers

with up to 4-ton batch capacity for the commercial sector.

The Associationwhich

has installed eight flat-bed

dryers at rice mills and five

others for farmer groupsnow

visits different provinces in

Myanmar to demonstrate the

dryers to farmers and millers

(see At a glance: postharvest activities in Myanmar

in RIPPLE Vol. 1, No. 3).

Mechanical dryers add

cost to the drying process. To

minimize drying cost, a new

rice hull furnace was developed

in Vietnam as an alternative

to kerosene burners used in

most rice dryers (see New rice


12/26

husk furnace on page 6). The

PPWG assists national partners

in continuous adaptation of the

drying systems to local conditions and farming systems to

provide appropriate drying

technology options for farmers,

traders, and rice millers, and

to help manufacturers produce

commercially viable machines.

Decisions based on market

information

Knowledge is power and,

for farmers, knowledge on

up-to-date market information

can empower them in making

informed decisions on what

to produce, where to sell, and

what quality grade to achieve

to maximize their returns

from rice harvests. Farmers

An overview of rice post-harvest technology: use of small metallic

silos for minimizing losses - D.J. Meja

Agricultural Industries Officer, Agricultural and Food Engineering Technologies Service, FAO,Rome, Italy

INTRODUCTION


13/26

Rice (Oryza sativaL.) is a staple food consumed by over half the world population. The totalworld production of unmilled rice (paddy) is around 592 million tonnes (Mt) (based on theaverage production for 2000 and 2001). Ninety percent of this total is grown in developingcountries, mostly in Asia, while Latin America and Africa produce 3.8 and 2.8 percent,respectively (FAOSTAT, 2001).

It is estimated that by 2025, 10 billion people will depend on rice as a main food and demandwill reach about 880 Mt. Many Asian countries and international institutions agree to thestrengthening of national programmes for policy and financial support to research, seedproduction and extension of hybrid rice (FAO, 2001). In fact, there has been an expansion ofarea under high-yielding varieties (HYV), and in 1998 more than 90 percent of irrigated areas inAsia were under HYVs (Evenson, 1998). Methodology on the impact of the improvement ofproductivity on postharvest operations has been developed by FAO for several crops includingrice (Phan, 1998). As HYVs are increasingly used, the post-harvest system must be improved,including infrastructure development and also the dissemination of technologies, allowing smalland medium farmers to prevent food losses and consequently to achieve the food securitywhich is a priority of FAO in its fight against hunger.

The rice post-harvest system requires improvement in the use of resources for research anddevelopment, particularly with regard to the level of post-harvest losses. These losses areattributed to a combination of factors during production and post-production operations (DePadua, 1999).

This paper presents an overview of the main postharvest operations traditionally used by ricefarmers in developing countries and the importance of post-harvest technologies for minimizingrice losses. Inadequately performed drying and storage operations contribute to increasedlosses. The advantages of the household metallic silo are discussed and it is proposed as afeasible and suitable alternative - highly recommended by FAO - for small and medium ricefarmers. While this study does not address drying operations in detail, it should be noted thatthey are complementary to storing.

Post-harvest system

The post-harvest system consists of a set of operations which cover the period from harvestthrough to consumption. An efficient post-harvest system aims to minimize losses and maintainthe quality of the crop until it reaches the final consumer. When food losses are minimized, bothfood security and income increase, and this is of vital importance for small and medium farmers,particularly in developing countries. From a socio-economic point of view, the implementation ofan efficient post-harvest system in any community must provide equitable benefit to all thoseinvolved in the system (Grolleaud, 2001).

Post-harvest losses

The traditional concept of post-harvest losses - for the main part quantitative losses - is currentlychanging. Many post-harvest specialists recognize that measurement of post-harvest losses is avery relative concept for various reasons; for example, losses could be determined as a functionof theoretical yield, real yield, soil and fertility conditions, variety etc. Then there are the otherlosses which are not normally measured, such as agricultural inputs, time, manual labour, lostopportunities etc. In spite of the above, when post-harvest losses are assessed - whether ingrains, cereals, fruits or vegetables - the most practical approach (and therefore the norm)


14/26

continues to be quantitative measurement. To obtain reliable data of post-harvest losses, it isnevertheless important to establish a methodology which takes into account a range of factors(cultivar size, plot size etc.). Data should be supported by basic statistical analysis in order tounderstand how efficiently a post-harvest system works (Calverley, 1994). Likewise,observations and rapid appraisal in situby an expert may help to identify how efficiently a post-harvest operation system works within a rural community and for a specific crop.

The post-harvest system for rice deserves special attention: rice is a major staple food in theworld and is mostly produced in developing countries where the implementation of post-harvesttechnologies is urgent in order to prevent food rice losses. It has been estimated that rice post-harvest losses may be as high as 16 percent. A study carried out in China revealed that totalpost-harvest losses ranged from 8 to 26 percent, with storage and drying the most criticaloperations (Ren-Yong et al., 1990).

Main post-production operations used by rice farmers

Paddy pre-harvesting operations

The quantity and quality of final milled rice depend on the efficiency of farming management,field operations and post-harvest operations. Decisions are taken from planting through toconsumption of the rice crop. Initial decisions about the variety to be planted determineintrinsically desirable characteristics and depend upon consumer preference as well as thetechnical capacity of the farmers during production and post-production operations. Thesecharacteristics in turn become factors which influence efficiency, grain loss magnitude, choice ofharvesting and threshing technology, rate and quality of the drying and dehusking process, andeventually total recovery of the milled rice. Then there are the wrong practices at the plantingstage which can lead to losses: planting of red rice admixture, attacks by rodents and birds,poor weeding and a harvest maturity date which can be too early or too late.

It is important to point out that the differences in varieties planted in certain localities also affectthe final milled rice, as the high-value rice market usually prefers a pure and single variety.Nevertheless, for reasons of biodiversity and more sustainable agriculture, planting differentvarieties (although not necessarily in the same field) is an excellent strategy for improved foodsecurity. Sometimes, high management is required to monitor planting in order to preventvarieties becoming mixed; on the other hand, varieties are sometimes deliberately mixed toproduce special characteristics, such as consistency of flavour, which cannot be found in a purevariety.

During pre-harvest operations, efficient technology and input management, as well as timelinessof activities, are important, and this applies also to postharvest operations for good yield andquality and in order to obtain good prices for the milled rice and byproducts. Correct timing at

harvest is essential to avoid losses incurred by harvesting too soon or too late. Immature grainsharvested too early result in a high percentage of brokens and low milling recovery, while ifharvesting is delayed, the crop is exposed to insects, rodents and birds, in addition to the risksof lodging and shattering. The optimum harvest time should be chosen depending on the varietyplanted (Lantin, 1997).

Table 1 shows the losses incurred if the rice is harvested 1 week early and up to 4 weeks lateon the basis of the maturity date of the crop.


15/26

In general, the correct time to harvest is 1 week before the maturity date.

Others indicators for optimum harvesting time for rice are as follows:

When the rice has reached the exact date of maturity or numbers of days after heading(usually 28-34 days).

When 80 percent of the grains have changed from green to straw colour. When at least 20 percent of the grains at the base have a hard dough stage. When the grain moisture content is between 21 and 24 percent. When the hand-dehulled grain, as indicated by daily tests near the projected harvested

date, is clear and hard.

TABLE 1Grain losses at different harvesting times based on crop maturity

Losses (%) 0.77 3.35 5.63 8.64 40.70 60.46

Harvesting time (weeks) -1 0 +1 +2 +3 +4

Maturity date

Source:Almera, 1997.

Harvesting

Harvesting includes numerous operations, including: cutting the rice stalk; reaping the panicles;laying out the paddy-on-stalk or stacking it to dry; and bundling for transport. Correct harvestingand handling operations can considerably reduce post-production losses. Excessive handlingcreates problems in terms of both quality and quantity.

The sequence of manual harvesting, field drying, bundling and stacking in traditional systemscan cause losses of between 2 and 7 percent (Toquero and Duff, 1974). At this stage, lossescan occur when secondary tiller panicles are missed when the sickle cuts 60 cm above groundin lowland rice. Also, delayed harvest causes shattering losses during harvesting and transport.

Harvesting methods

There are a variety of different methods for rice harvesting, with traditional manual methodsprevailing in developing countries:

Panicle reaping

This is accomplished by using a hand-held cutting tool (Yatabin the Philippines, Ani-aniinIndonesia, Kaein Thailand, Espigadorain Bolivia). The method is used in areas wheretraditional varieties are resistant to shattering. Resistance to shattering is particularly importantduring handling and when transporting the bundles of panicles from field to house. The labourtime required for this method is 240 labour-hours/ha (done mostly by women and olderchildren), which is four times that required with the hand-sickle method. It remains popularbecause of the social custom of chatting while working. In addition, it generates income amongthe landless rural population and is suitable for hilly and terraced areas.


16/26

Long stalk cutting by sickle

This is a widely used manual method presenting different styles in the design. It requiresbetween 80 and 180 labour-hours/ha. The stalk is cut about 10 to 15 cm above the ground orwith a stalk length of about 60 to 70 cm for easy bundling and threshing. Reaping efficiencydepends on various cultural practices, plant density and variety, degree of lodging, soil

conditions and the skill of the harvester. Lodged paddy and saturated soils may considerablyreduce the cutting rate.

Modern mechanical methods

These methods are generally used when labour is scarce; otherwise, harvesting is generally stilldone with a sickle in most developing countries. The use of mechanized harvesting methods insome areas depends upon the custom and suitability of the machine and other socio-economicfactors. Some examples of these machines are:

Reaper binder: once very popular, it is currently being replaced by the combine. Themachine cuts and bundles stems together and lays them in the field in a singleoperation.

Combine: very popular, its adoption in Japan, Korea and other Asian countries is slowonly because of its high cost. The binder can harvest 0.05 ha/hour. A similar, largemodel was developed in Thailand to resolve the problems of scarcity and cost of labour;Viet Nam may also adopt mechanized methods because of economies of scale. Someother Asian countries import second-hand, large combines for harvesting the basic ricecrop. In commercial rice production, large combines are generally used in countries suchas Brazil and Uruguay in Latin America, in Europe and in the United States of America.In Africa, on the other hand, these machines (introduced through international aidprogrammes) have had little impact because of the lack of maintenance facilities.

Stripper harvester: an innovation from IRRI and an adaptation of the rotary strippingcombine principle developed by Silsoe Research Institute in the United Kingdom, itworks with varieties which are non-lodging, medium height, with erect panicles and lowto medium shattering (Naphire, 1997).

There continue to be constraints for farmers in developing countries to the adoption ofmechanical harvesting methods: low income, reluctance to move away from traditional methods,poor mechanical aptitude, the desire to save straw for off-farm uses, lack of access to the field,excessive moisture content, uneven ripening etc. Other limiting factors are the high cost ofimported equipment and the fact that machinery management must be competitive with therelatively low cost of labour (IRRI, 1997).

Transport

In developing countries, transportation of paddy from the field to processing areas is performedmainly by humans and animals, and sometimes using mechanical power. In hilly areas wherepaddy fields are terraced (e.g. Bhutan, Nepal, some parts of the Philippines and Indonesia) thepaddy is transported in panicles or bundles of long stalks using human or animal power. Thesetraditional methods of transport, which are related to the harvesting and field drying activities,very often result in high grain losses. Small and family-sized volumes of paddy are generallytransported in bags from the house storage to the small rice mill on foot, in bullock carts, by


17/26

bicycle, using small vehicles or with public transport - whatever means is available andaffordable. Other methods of transport include donkey, buffalo and even boat.

In some places, the practice is to windrow the cut paddy in the field to dry for 3 to 7 days,depending upon the weather conditions. Losses are even greater, especially if harvesting isdelayed with respect to the crop maturity date. In addition to the losses incurred in cutting, wind-

rowing, sun-drying, collecting and bundling of the cut crop, there are those when the bundledpaddy-in-straw is loaded onto the persons back to be carried to the house.

Grain then falls en route, especially with the transportation of shattering varieties, and also whenthe carrier (usually a woman) stops to rest. Nevertheless, some farmers prefer this method forboth cultural and practical reasons, as the straw can be used as animal feed.

The large losses incurred are the principal drawback to manual transport. Threshing of thepaddy in the field and transportation in bags (40-75 kg) can minimize grain losses, however.Sun-drying of the paddy can also be done in the yard of the house rather than on stalks in thefield. The normal practice in Asia is to bring the paddy from the field to the roadside manually orusing animal power; it is then transported to the drying area or rice mill by motor vehicle (e.g.tricycle, power tiller with trailer, tractor with trailer, truck or lorry). The loading and unloading ofthe bags require additional labour costs, and these are normally assumed by the buyer.

In developing countries and advanced developing countries, the paddy is harvested by combineand is handled and transported in bulk. The paddy is unloaded from the combine by an augerconveyor and loaded into a waiting lorry or tractor-trailer located on the field road (part of theinfrastructure for mechanized rice production). The paddy is then unloaded from the lorry ortrailer onto a floor hopper in the rice mill area to be conveyed to a mechanical dryer. Finally,commercial rice is bagged at the rice mill and normally transported to wholesale and retailmarkets by means of vehicles. This mechanized procedure results in much lower losses (Lantin,1997).

Threshing

During threshing the paddy kernel is detached from the panicle, an operation which can becarried out either by rubbing, impact or stripping. Rubbing may be done with trampling byhumans, animals, trucks or tractor; however, the grain becomes damaged. Mechanicalthreshers adopt mainly the impact principle, but there is also a built-in stripping action.

With a paddy thresher, the unthreshed paddy may be either held or thrown in. In the hold-ontype, the paddy is held still in the cylinder while spikes or wire loops perform impact threshing. Ina throw-in machine, whole paddy stalks are fed into the machine and a major portion of thegrain is threshed by the initial impact caused by bars or spikes on the cylinder.

In a conventional threshing cylinder, stripping may also be used for paddy threshing; impulsivestripping normally occurs with impact threshing. In a throw-in thresher, large amounts of strawpass through the machine and some designs use straw walkers to initially separate the loosegrain from the bulk of the straw and chaff (Lantin, 1997).

IRRI developed the Votex Ricefan thresher. A portable machine, as well as being suitable forboth paddy panicles and paddy stalks, it may be adapted for wheat, corn, soybean and beans.


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The Votex Ricefan thresher has been widely accepted among Bolivian paddy farmers (Tern,1996) and may be either manually or power-operated.

Manual threshing is pedal-operated and involves: treading; beating the panicles on a tub,threshing board or rack; or beating the panicles with a stick or flail device. The thresher consistsof a rotating drum with wire loops which strip the grain from the panicle when the paddy is fed

by hand. This equipment is portable, can be used in hilly areas and is easily operated bywomen.

In power threshing, the harvested crop is trampled by tractor or truck tyres in developingcountries. The grain is separated from the straw by hand and then cleaned by winnowing.

Losses may occur during threshing for various reasons:

In manual threshing by beating, some grains remain in the bundle panicles and a repeatthreshing is required.

Grain is scattered when the bundles are lifted just before threshing. Grain can stick in the mud floor. Birds and domestic fowls feed on the grain (Lantin, 1997).

Drying

Paddy as a living biological material absorbs and gives off moisture depending on: paddymoisture content, relative humidity of the air and temperature of the surrounding atmosphere.The respiration of the paddy is manifested in various ways: decrease in dry matter weight;utilization of oxygen; evolution of carbon dioxide; and the release of energy in the form of heat.However, respiration is negligible when the moisture content is between 12 and 14 percent.

By and large, paddy is harvested with moisture content of 24 to 26 percent (higher in the rainy

season and lower in the dry season). It has a high respiration rate and is susceptible to attacksby micro-organisms, insects and other pests. The heat released during the respiration processis retained in the grain and in the bulk due to the insulating effect of the rice husk, resulting inlosses in terms of both quantity and quality. Therefore, harvested grain with high moisturecontent must be dried within 24 hours: to 14 percent for safe storage and milling, or at most 18percent for temporary storage of 2 weeks when it is not possible to dry any faster. Delayeddrying may result in non-enzymatic browning (stack-burning), microbial growth and mycotoxinproduction in parboiled rice (NRI, 1991).

Square areas (10 x 10 m) of concrete have been successfully used for sun-drying in ruralcommunities of rice farmers in Bolivia (Tern, 1996). Small rural farmers in these regions alsouse tarpaulins for paddy sun-drying. The main constraint of sun-drying is the dependence on

good weather conditions, which can become a serious problem, particularly in tropical rainycountries.

Losses due to bad drying practices range from 1 to 5 percent and it is mainly the quality which isaffected. Good drying is crucial for minimizing post-harvest losses, since it directly affects safestorage, transportation, distribution and processing quality.

A temperature of 43C is recommended for drying paddy for seeds and this can be achievedwith shade drying. Higher temperatures can lead to physicochemical disorders in the grain


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(Zheng et al., 2000). The cheapest drying method is sun- or solar drying, practised by farmers,cooperatives, commercial millers and government grain agencies in most developing countries.Between 70 and 90 percent of the field harvest retained in the farm is sun-dried, with the workgenerally performed by women and children. Drying usually takes place on paved areas next tothe warehouse and rice mills; the paved areas slope slightly so that water can drain away duringthe rainy season.

Early harvesting when moisture content is high helps minimize shattering losses in the field. Incrops of high-yielding varieties it is necessary to dry large quantities of wet grain in the shortesttime so as to minimize rice spoilage. An artificial or mechanical dryer speeds up the dryingprocess, reduces handling losses, maintains grain quality and gives better control during drying.

The temperature for drying paddy should not be higher than 54.4C for food grain using the drybatch system. Low temperatures help preserve the rice aroma principle 2-acetyl-1-pyrroline(Itani and Fushimi, 1996).

The choice of a drier system depends on several factors: drying capacity requirement, ease ofinstallation and operation, portability, full heat source and the initial cost of purchase. A widerange of drying equipment and methods are available for rough rice, and computer models havebeen developed to assist agricultural research workers or farmers in their selection of dryers fora given crop and situation (Dissanayake, 1991).

The adoption of an artificial drying system by rice farmers has numerous constraints:

High fuel costs. Small farmers producing a small volume of paddy can easily use sun-drying. It is popular belief that the bleaching effect of sun-dried paddy results in whiter grains

than artificially dried paddy. Lack of capital for investing in artificial dryers. Lack of know-how about the drying technology (Andales, 1996).

The main causes of losses during drying are as follows:

Grains shattering from stalks or spilling out from bags during transport. Birds and domestic fowls. Spill-out outside the drying area. Over-drying, especially during sun-drying. Delayed drying or no grain aeration, resulting in stack-burning.

Paddy cleaning

This is an important operation and highly recommended not only on a large and mediumcommercial scale, but also on a small scale. It consists of the separation of undesirablematerial, such as weed seeds, straw, chaff, panicle stems, empty grains, inmate and damagedgrains, sand, rocks, stone, dust, plastic and even metal and glass particles. The degree ofcleanness of the paddy reflects to some extent the care applied during harvesting, threshingand handling.

In developing countries, farmers clean the paddy straight after manual threshing. First, they usehand-raking and sifting to remove straw, chaff and other large and dense materials, then


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Long-term storage with 14 percent or higher moisture content, or more than 2 weeksstorage with 18 percent moisture.

Theft and pilferage in the warehouse.

The paddy retained for storage is sun-dried several times and cleaned before loading into thestorage container. The farmer determines the dryness required for storage on the basis of

experience. Dryness is measured by pressing a bunch of grains hard into the hand or bitingseveral grains: a fully dried grain is hard. Paddy is usually stored with a moisture content of 14percent or less. Paddy is normally stored in a 1-tonne-capacity container for 6 to 12 months.Losses in farm storage have been estimated at about 6.2 percent (Ren-Yong et al., 1990).

Milling

Paddy or the rice grain consist of the hull or husk (18-28%) and the caryopsis or brown rice (72-82%). Brown rice consists of: an outer layer (pericarp, tegmen and aleurone layers) called bran(6-7%); the germen or embryo (2-3%); and the edible portion (endosperm 89-94%) (Chen et al.,1998). The rice milling operation is the separation of the husk (dehusking) and the bran(polishing) to produce the edible portion (endosperm) for consumption. Although a theoreticalmill recovery would be between 71 and 73 percent, in practical terms it is possible to obtainbetween 68 and 70 percent from a good variety of paddy. Milling losses can be reduced byadopting small-scale modern rubber roll sheller and introducing parboiling of paddy beforemilling. Table 2 shows the advantages and disadvantages of parboiled rice.

Agronomic impacts of climate variability on

rice production in the Philippines

F.P. Lansigan

a;b;

, W.L. de los Santos

c

, J.O. Coladilla

b

a

Institute of Statistics, University of the Philippines Los Baos, 4031 College, Laguna, Philippines

b

School of Environmental Science and Management, University of the Philippines Los Baos, 4031

College, Laguna, Philippines

c


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Department of Agronomy, University of the Philippines Los Baos, 4031 College, Laguna, Philippines

Abstract

Climate variability is a threat to food production. Typhoons, floods, and droughts caused 82.4% of the

total Philippine

rice losses from 1970 to 1990. In 1990 alone, domestic losses due to climatic constraints amounted to

US$ 39.2 million.

Weather aberrations, climatic fluctuations such as El Nio, and the growing concern for their effects on

agriculture have

stimulated academic, public and policy-level interests on the analysis of the impacts of climate variability

on agricultural

production systems. This paper is presented to discuss the agronomic impacts of climate variability on

rice production in the

Philippines. Long-term climate variability influences sowing date, crop duration, crop yield, and the

management practices

adapted in rice production. Short-term weather episodes can also affect yield by inducing changes in

temperature, potential

evapotranspiration, and moisture availability. The degree of vulnerability of crops to climate variability

depends mainly on

the development stage of the crops at the time of weather aberration. The vulnerability and risk of cropproduction due to

weather fluctuations and climate variability can be minimized if future weather variation can be

adequately predicted and a

suitable process-based ecophysiological crop yield forecasting model can be identified to produce real-

time yield forecasts.

Scientists and farmers must join efforts to further understand cropclimate relationships and formulate

viable, locally adapted

production technologies that will address critical issues such as climate variability. 2000 Elsevier

Science B.V. All rights

reserved.

Keywords: Climate variability; Rice production; Philippines; El Nio

1. Introduction


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The concern on past, present and future weather

aberrations, climate trends, and their effects on agriculture has continued to stimulate research as well

as public and policy-level interests on the analysis

of climate variability and agricultural productivity

(Matthews et al., 1996; IPCC, 1996). It is well recognized that climate variability has a wide range of

direct and indirect impacts on crop production. In the

Corresponding author. Fax: C63-49-536-2402.

E-mail address: [email protected] (F.P. Lansigan).

Philippines, typhoons, floods, and droughts caused

82.4% of the total Philippine rice (Oryza sativa L.)

losses from 1970 to 1990 (PhilRice-BAS, 1994)

(Fig. 1). Weather and climate affect plant growth and

development, and the fluctuations and occurrences of

climatic extremes particularly at critical crop growth

stages may reduce yield significantly (Satake and

Yoshida, 1978; Peng et al., 1996).

Weather and climate have a direct influence on

cropping systems and plant yield. Thus, weather

fluctuations and climate variability play a significant

role in crop growth and yield. Occurrence of abnormal weather episodes during the growing season or

0167-8809/00/$ see front matter 2000 Elsevier Science B.V. All rights reserved.

PII: S 0 1 6 7 - 8 8 0 9 ( 0 0 ) 0 0 2 2 2 - X130 F.P. Lansigan et al. / Agriculture, Ecosystems and

Environment 82 (2000) 129137

Fig. 1. Annual losses (000 Mg) in Philippine rice production due to typhoons/floods, droughts, and pests

from 1970 to 1990 (adapted


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from PhilRice-BAS, 1994).

during critical development stages may hamper

growth processes resulting in yield reduction. This

makes climate variability a threat to food production

leading to serious social and economic implications

(Geng and Cady, 1991; Hossain, 1997). However, a

clear understanding of the vulnerability of food crops

as well as the agronomic impacts of climate variability enable one to implement adaptive strategies to

mitigate its negative effects.

This paper presents the agronomic impacts of climate variability on rice production systems. These

impacts are described based on results of systemsbased studies and case examples in the Philippines.

Key climate variables and measures of variability are

examined. The analysis distinguishes the impacts of

long-term weather variability and short-term weather

episodes. Some adaptive strategies to climate variability to reduce vulnerability and risk are also

presented.

Suggestions and recommendations for an efficient and

effective analysis of agronomic impacts of climate

variability are also discussed.

Rice Facts

Did You Know?

A Guide to Rice Cookery

Measurements and Yields
http://www.producersrice.com/rice/facts.html#Ahttp://www.producersrice.com/rice/facts.html#Ahttp://www.producersrice.com/rice/facts.html#Bhttp://www.producersrice.com/rice/facts.html#Bhttp://www.producersrice.com/rice/facts.html#Chttp://www.producersrice.com/rice/facts.html#Chttp://www.producersrice.com/rice/facts.html#Dhttp://www.producersrice.com/rice/facts.html#Dhttp://www.producersrice.com/rice/facts.html#Dhttp://www.producersrice.com/rice/facts.html#Chttp://www.producersrice.com/rice/facts.html#Bhttp://www.producersrice.com/rice/facts.html#A


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All About Rice

Rice represents 20 percent of the world's per capita

caloric consumption. More than 50 percent of theworld's population is dependent upon rice for 80percent of its diet.Rice is cultivated in more than 100 countries andon every continent except Antarctica - from sea

level to an altitude of 3,000 meters. To keep pacewith demand, technological advances in productionare occurring rapidly. However, much of the world's rice crop is still dependent uponannual rainfall patterns, such as occur during the Asian monsoon season. Changes in

world weather patterns can easily alter the delicate balance between world supplyand demand, dramatically affecting world rice trade patterns and price levels.World rice trade represents only about 5 percent of world consumption. However,this relatively small amount traded (worth roughly $5.0 billion annually) has a major

impact on world economic and political policies.Well over a hundred countries in the world import rice

annually. Trade in rice is stratified according to rice types.More than three-fourths of the total rice traded in the worldis long grain (Indica) rice. Most of the remainder is medium

or short grain (Japonica) rice. About two-and-one-half-

million tons of aromatic rice, and up to 100,000 tons ofglutinous rice, are traded annually. For exporting nations,meeting market needs entails supplying the type, form,

class and quality of rice that satisfy local taste preferences.The United States is unique as a major exporter of all ricetypes. The U.S. rice industry is able to provide rice in

whatever form desired (i.e. brown, milled, parboiled) and according to the shipmentbasis required (packaged, bagged, bulk, destination bagging, f.a.s., f.o.b., c.i.f.,

etc.). Quality standards for USA rice are closely adhered to and, in addition, arecontinually reviewed and updated. Thus the U.S. rice industry offers productdiversity, availability, reliability, and service unsurpassed in the world.Did You Know?

1. Rice is the staple food for two-thirds of the world's population. The simplegrain has been a popular life-sustaining food for thousands of years because

it is nutritious, versatile, economical, easy to prepare and tastes good!

2. Rice is a complex carbohydrate. Humans need complex carbohydrates in theirdiet because they fuel the body. Complex carbohydrates are stored inmuscles and released as energy as needed.

3. Rice protein, when compared to that of other grains, is considered one of thehighest quality proteins. It has all eight of the essential amino acids,necessary building blocks for strong muscles. Rice is also a good source of

other essential nutrients -- thiamin, riboflavin, niacin, phosphorus, iron and

potassium. Rice contains no fat, no cholesterol and no sodium. This alongwith being nonallergenic and gluten free, makes rice especially well suited for


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persons with special dietary needs.4. Rice offers versatility unsurpassed by an other food. It can be made part of

any meal in recipes for soups, salads, main dishes and desserts.

5. In Asia rice is considered sacred. In Japan there are shrines to the god ofrice.

6. Honda means "main rice field." Toyota means " bountiful rice field."

7. Arkansas is the largest rice producing state in the U. S.8. Rice can be indefinitely cropped in irrigated fields. Some rice fields are

believed to have been continously cropped for more than 2,000 years.

9. There are over 29,000 grains of rice in one pound (based on long grain whiterice).

10.In Japan, rice grains are affectionately called "little buddhas," to encouragechildren to eat rice for the rest of their lives.

11.The Greek poet, Sophocles, in 495 BC mentioned rice in the Tragedies.12.Louis Armstrong signed his autograph "Red Beans and Ricely Yours..."13.In China, the typical greeting is "Have you had your rice today?" The typical

answer is "Yes."

14.In India, it is said the grains of rice should be like two brothers: close but notstuck together.

15.In Thailand when you call your family to a meal you say, "Eat Rice."16.The Japan word for cooked rice is the same as the word for meal.

intro for thesis

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