Master Gardener Volunteer Core Preparation: Session 2b-- Guest Presentation: Zachary Stansell

Plants and People; From the Perspective of Broccoli

A bit about Today...-Zach Stansell, PhD student at Cornell in Horticulture.

-I work with broccoli, and I'd like to draw on my personal work as an example of larger patterns in the relationships between plants and people.

-One of the most exciting things about plants is that there's seemingly an exception to everything!

What are we talking about?!● Almost every slide today could be a full lecture (or

semester long class!)

● Crash course in plant parts and functions (buckle up!)

● Where do modern plants come from?(+ breeding terminology)● How are all plants related to each other? (Plant phylogeny) ● How does the environment affect plants?● What is required for plant growth and development?

What The heck is a plant?

● mainly multicellular, ● predominantly photosynthetic ● eukaryotes ● Kingdom Plantae

Green algae, is a plant

Monotropa uniflora (ghost plant) IS a plant

Brown algae, NOT a plant

Purple Coral Fungus - Clavaria zollingeri, NOT a plant

DIvisions of Plants:

What are the Plant Basics?Form vs Function:

What's the difference?

How does a plant's form affect its function?

Why do we care?

Plant Form (Cellular)Important Distinctions:

CELL WALL:mainly cellulose

CHLOROPHYLL:Pigment found in

chloroplasts, essential for photosynthesis

VACUOLE:Many purposes, always in

plants, sometimes in animal cells

3 Main Plant cell types:Parenchyma cells: storage, support, photosynthesis, transfer

Collenchyma cells: physically support and flexibility of growing plants

Sclerenchyma cells: Stone cells and fiber-- strong mechanical support, not alive at maturity

Plant Tissues:MANY different tissue types- here's 3 esp. important ones:

Meristematic: Cell division (growth) occurs

Epidermis: outer surfaces of leaves/stems/roots

Vascular: Xylem and Phloem; responsible for transport (xylem ~ water/minerals, phloem ~ food)

Seed Producing Plants:Major ways to classify seed plants:

Gymnosperms:"Naked Seeds" (aka pines/spruce/fir)

Angiosperms:"Flowering Plants" -monocot vs dicot? One or two seed leaves ?

Shoots and Roots:Shoots: Above ground (stems,leaves,flowers, fruit, seed)

Root System: Below ground.

Stem Anatomy:Stems support the leaves, buds, and vascular system

Some weird stems:

- Bulbs (onion/tulip)

- Tubers (potatoes)

Stems may be arranged in many ways. Check out the "Plant parts and characteristics" activities today!

BudsBuds are embryonic and undeveloped shoots which make leaves,stems, and flowers.

Roots...What are roots good for?

● anchoring the plant● absorbing nutrient/water● store food● typically ___20-30___% of

plant's total volume● Two types of root systems:

○ fibrous or tap root

History of Plant Domestication Why don't you see broccoli in the wild?

Centuries of human selection for taste, size, yield, morphology, color, storage,...

In one species, notice the difference:

Centers of Origin: Plant domestication

Why are these centers of diversity important?● We can locate wild relatives ● Find related species ● Discover new genes (i.e. disease

resistance, heat tolerance)

Plant breeding terms● Undomesticated (Wild) Plant:

○ "unimproved" by human selection● Open-Pollinated:

○ pollination by wind, insects, or the gardener. ○ "True to seed".

● Self-Pollinated: ○ Perfect flowers (pollen and stigma present). ○ Sometimes included as "Open-pollinated" to distinguish from hybrids.

● Heirloom: ○ Must be open or self pollinated○ Must be over 50 years old. ("New Heirloom"? oxymoron!)

● Landrace:○ Traditional use, open-pollinated, locally adapted.

Plant breeding terms (cont.)● F1 Hybrid

○ bred from two specific parents○ does NOT breed true○ often powerful "Hybrid Vigor"

● Cultivar○ "cultivated" + "variety"○ Can be clones, seed produced,

genetically modified

New Way:

* "-Omics" (aka genomics or proteomics)

-DNA/RNA/Proteins

-As species diverge, DNA will mutate or undergo natural or human caused selection.

-We can use changes in DNA sequence to trace ancestry.

How are plants classified into families?Old way:

* vascular vs nonvascular

* gymnosperm vs angiosperm

* monocotyledon vs dicotyledon

* annual vs perennial

* deciduous vs evergreen

* chemistry

* other observable traits

How are plants classified:

http://www.zo.utexas.edu/faculty/antisense/DownloadfilesToL.html

Cultivar Type A specific cultivar of broccoli

How are plants classified into families?Value of scientific names (Binomial Nomenclature)

Brassica oleracea var. italica 'Green Magic'

Genus. Brassica is a genus in the "Mustard" family. Often called "Crucifers"

Species. Includes broccoli,kale, cabbage, collards, etc

Botanical Variety Italica means broccoli. Early cultivation in Italy led to the name.

Plants in their Environments:A story of collards:

Collard Greens history•

•→

•

•

Environmental Factors: NutrientsMacronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), sodium (Na)

Micronutrients:boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni). and cobalt (Co)

Environmental Factors: SpacingHow far apart should plants be placed?

- when plants are too close, they compete for light, nutrients, water.

- when too far apart, you lose yield from having too few plants.

Environmental Factors: Light & Day LengthLonger days: more growth, more transpiration, more stress?

Day length sensitivity: Plants may be either long-day, short-day or day-length insensitive.

Environmental Factors: WaterWhat is water stress and how do plants deal with it?

Drought tolerance vs avoidance:

● Avoidance: changing leaf orientation,closing stomata, dropping leaves

● Tolerance: changing osmotic turgor, or cell wall elasticity

Environmental Factors: TemperatureVariation in broccoli head quality with heat stress:

● Broccoli grown on East Coast is heat sensitive during floral initiation.

● Plants will not produce marketable heads, or will not head at all.

● The East Coast Broccoli Project is working to breed broccoli hybrids which can "handle the heat"

Environmental Factors: TemperatureYear round production of broccoli for eastern markets can also be achieved using staggered plantings:

Basic Process for plant growth:What do plants need for growth and reproduction?

Plants grow and thrive when:

Photosynthesis, Respiration, and Transpiration are in balance!

Basic Process for plant growth: Photosynthesis"Light into chemical energy"

Plants convert ______% of solar energy into chemical energy?

3 to 6

Basic Process for plant growth: RespirationRespiration is chemically the inverse of photosynthesis.

It turns Food into Energy.

Basic Process for plant growth: TranspirationTranspiration is the movement and loss of a plant's water to the environment via evaporation.

What percentage of a plant's water is used for growth and metabolism?? _____

The rest is lost to transpiration and guttation.

Plants open and close stomata to control transpiration.

0.5-3%

Thank you!any questions?