Plant Science CSES 1203 Dr. Skulman Week I Seed Germination

Seed Germination Is germination the beginning of a plant’s life cycle or the end or is it both beginning and end? Annual seed bearing plants do the following things according to the calendar: Spring-seed is planted, germination follows, Summer-plants grow, flower, and form seed, Fall-seed ripens, is harvested or falls from plant, Winter-seed is dormant or in storage, Spring-seed is planted, yearly cycle is complete.

Taxonomy Kingdom-All plants (500,000 species) Division-Seed producers (spermatophyta), and non-seed producers Classes : * gymnosperm (naked seed) * angiosperm (seed produced in an ovary) normal flower. We will examine angiosperm germination

Monocot (hypogeal) germination

Dicot (epigeal) germination

Requirements for germination Proper temperature, varies by species Water Oxygen Light (not for all species, some grasses)

Seed dormancy Resting period for seed between harvest and planting Can last from several weeks to many years Dormancy delays germination until conditions become favorable Soybeans in Arkansas Harvested in Fall (followed by winter-unfavorable) Planted in Spring (conditions now favorable)

Role of water in germination Water absorbed by seed from soil Water causes seed to swell Releases hormones in seed Hormones stimulate enzymes to break down stored starch to glucose (C6H1206) Glucose is a simple plant sugar that is used to provide energy for germination

Roles of Temperature and Oxygen in Germination Oxygen- all living cells require oxygen for respiration; plant cells of root, stem and leaves are actively growing Temperature- physiological reactions within plants are influenced by temperature; too high or too low stops reactions in plants

Moncots and dicots Dicots: Monocots: Examples, oak trees, beans, clover, shrubs Leaves have netted venation Taproot system Monocots: Examples-corn, grass, wheat, rice, cattails Long, slender leaves with parallel veins Fibrous root system

Other comparisons between monocot and dicot plants Monocot Leaves Dicot Leaves

Class Seed Germination Discussion Questions: As a farmer, why would you want seed to germinate all at the same time? Why do farmers/gardeners till their land before planting seed? 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 2. Barley grain is used to make beer and wiskey. However, the grain cannot be used directly, 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) germination