9 Early Growth and Development of SeedlingsObjectivesLegume and seed grass caryopsis identificationGerminationRagdoll test and germinationEnvironmental factors and management practices influencing germinationFactors influencing planting depth and seedling emergenceDefinitions Early Growth and Development of SeedlingsKnowledge of the parts of a seed, the fertilized, mature ovule of aflowering plant, is important in being able to recognize good, qualityseed. Even before planting begins, a crop’s yield can be limited bypoor-quality seed. A farmer wouldn’t buy a piece of equipmentwithout examining the quality first; when buying seed, the samescrutiny should be used. In both cases, looking at the individualparts is important in determining the overall performance.A.Legume seed and grass caryopsis identification1.DicotyledonsLegume family plants (Fabaceae) are dicotyledonoussince theyhave two “seed leaves” called cotyledonsin their embryo. Theembryo, or immature plant, along with the seed coat and the foodsource (which can either be the cotyledons or a specialized storagestructure called the endosperm) make up the three basiccomponents 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 awater-soaked soybean seed, similar to the one in Figure 1. This thincovering serves as a seed coat, named the testa.The testa is avaluable 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. HilumObjectives:Identify the legume seed and grass caryopsisstructures, explain their functions and describe characteristics of good quality seed.Identify factors affectingseed quality.Explain dicot and monocot germination and seedling development. List the environment factors that influence germination and explainhow 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 micropyleis an openingrepresenting the point of entry into the ovule for fertilization and is usually hard to see but it is locatednear the hilum.Observe the two cotyledons when the two halves are separate. They serve as the food source for thegerminating legume seedlings. Therefore, high seed quality begins with disease-free cotyledons. The twocotyledons are attached at one end of the cotyledonary node(joint or meeting place). Above thecotyledonary node is the epicotyl(plumule), consisting of the growing point and embryonic leaves.