Plant SciencePlant ScienceCSES 1203CSES 1203

Dr. SkulmanDr. Skulman

Week IWeek I

Seed GerminationSeed Germination

Seed GerminationSeed Germination

Is germination the beginning of a plant’s life Is germination the beginning of a plant’s life cycle or the end or is it both beginning and end?cycle or the end or is it both beginning and end?

Annual seed bearing plants do the following Annual seed bearing plants do the following things according to the calendar:things according to the calendar: SpringSpring-seed is planted, germination follows,-seed is planted, germination follows, SummerSummer-plants grow, flower, and form seed,-plants grow, flower, and form seed, FallFall-seed ripens, is harvested or falls from plant,-seed ripens, is harvested or falls from plant, WinterWinter-seed is dormant or in storage,-seed is dormant or in storage, SpringSpring-seed is planted, yearly cycle is complete.-seed is planted, yearly cycle is complete.

TaxonomyTaxonomy

KingdomKingdom-All plants (500,000 species)-All plants (500,000 species)DivisionDivision-Seed producers (spermatophyta), -Seed producers (spermatophyta),

and non-seed producers and non-seed producers ClassesClasses : :

** gymnosperm (naked gymnosperm (naked seed)seed)** angiospermangiosperm (seed (seed produced produced in in an ovary) normal an ovary) normal flower.flower.

We will examine angiosperm germinationWe will examine angiosperm germination

Monocot (hypogeal) germinationMonocot (hypogeal) germination

Dicot (epigeal) germinationDicot (epigeal) germination

Requirements for germinationRequirements for germination

Proper temperatureProper temperature, varies by species, varies by species WaterWater OxygenOxygen LightLight (not for all species, some grasses) (not for all species, some grasses)

Seed dormancySeed dormancy

Resting period for seed between harvest Resting period for seed between harvest and plantingand planting

Can last from several weeks to many Can last from several weeks to many yearsyears

Dormancy delays germination until Dormancy delays germination until conditions become favorableconditions become favorable Soybeans in ArkansasSoybeans in Arkansas

Harvested in Fall (followed by winter-unfavorable)Harvested in Fall (followed by winter-unfavorable) Planted in Spring (conditions now favorable)Planted in Spring (conditions now favorable)

Role of water in germinationRole of water in germination

Water absorbed by seed from soilWater absorbed by seed from soil Water causes seed to swellWater causes seed to swell Releases hormones in seedReleases hormones in seed Hormones stimulate enzymes to break Hormones stimulate enzymes to break

down down stored starchstored starch to to glucoseglucose (C (C66HH12120066))

Glucose is a simple plant sugar that is Glucose is a simple plant sugar that is used to provide energy for germinationused to provide energy for germination

Roles of Temperature and Oxygen Roles of Temperature and Oxygen in Germinationin Germination

OxygenOxygen- all living cells require oxygen for - all living cells require oxygen for respiration; plant cells of root, stem and respiration; plant cells of root, stem and leaves are actively growingleaves are actively growing

TemperatureTemperature- physiological reactions - physiological reactions within plants are influenced by within plants are influenced by temperature; too high or too low stops temperature; too high or too low stops reactions in plantsreactions in plants

Moncots and dicotsMoncots and dicots

Dicots:Dicots: Examples, oak trees, beans, clover, shrubsExamples, oak trees, beans, clover, shrubs Leaves have netted venationLeaves have netted venation Taproot systemTaproot system

MonocotsMonocots:: Examples-corn, grass, wheat, rice, cattailsExamples-corn, grass, wheat, rice, cattails Long, slender leaves with parallel veinsLong, slender leaves with parallel veins Fibrous root systemFibrous root system

Monocot Leaves Dicot Leaves

Other comparisons between monocot and dicot plants

Class Seed Germination Discussion Questions: 1. As a farmer, why would you want seed to germinate all at the same time?

2. Why do farmers/gardeners till their land before planting seed?

3. In the spring some farmers will apply herbicides to the soil for weed control. Why would extended herbicidal activity be an advantage?

What foods are derived from germinated seed?

1. Sprouts such as Mung bean or “alfalfa” sprouts

2. Barley grain is used to make beer and wiskey. However, the grain cannot be useddirectly, but must first be modified. What is this “modification”?

Malting – a process where the grain is initially germinated and then oven dried to different stages of color.

The End

Monocot (hypogeal) germinationMonocot (hypogeal) germination