Early Growth and Development of Seedlings Lab - 9 Early Growth and Development of Seedlings Objectives Legume and seed grass caryopsis identification

9 Early Growth and Development of Seedlings Objectives Legume and seed grass caryopsis identification Germination Ragdoll test and germination Environmental factors and management practices influencing germination Factors influencing planting depth and seedling emergence Definitions Early Growth and Development of Seedlings Knowledge of the parts of a seed , the fertilized, mature ovule of a flowering plant, is important in being able to recognize good, quality seed. Even before planting begins, a crop’s yield can be limited by poor-quality seed. A farmer wouldn’t buy a piece of equipment without examining the quality first; when buying seed, the same scrutiny should be used. In both cases, looking at the individual parts is important in determining the overall performance. A. Legume seed and grass caryopsis identification 1. Dicotyledons Legume family plants ( Fabaceae ) are dicotyledonous since they have two “seed leaves” called cotyledons in their embryo. The embryo , or immature plant, along with the seed coat and the food source (which can either be the cotyledons or a specialized storage structure called the endosperm) make up the three basic components of the seed. Some common legume crops are soybeans, alfalfa, red clover and peas. In lab, we will carefully remove and examine the outer covering of a water-soaked soybean seed, similar to the one in Figure 1. This thin covering serves as a seed coat, named the testa. The testa is a valuable protective covering against soil borne diseases and insects. On the seed coat, there is an oblong mark or scar, called the hilum . This is the point where the seed was attached to the pod. Hilum Objectives:  Identify the legume seed and grass caryopsis structures, explain their functions and describe characteristics of good quality seed.  Identify factors affecting seed quality.  Explain dicot and monocot germination and seedling development.  List the environment factors that influence germination and explain how good management can influence these factors.  Explain how method of emergence and environmental conditions influence planting depth of corn, small grains, and soybeans.

color differs considerably and is useful in identifying different varieties. The micropyle is an opening representing the point of entry into the ovule for fertilization and is usually hard to see but it is located near the hilum . Observe the two cotyledons when the two halves are separate. They serve as the food source for the germinating legume seedlings. Therefore, high seed quality begins with disease-free cotyledons. The two cotyledons are attached at one end of the cotyledonary node (joint or meeting place). Above the cotyledonary node is the epicotyl (plumule), consisting of the growing point and embryonic leaves.