Laboratory Exercise No. 1
The Seed: Morphology, Polyembryony and Germination
Dela Paz, Lady Daisy DL.
The main idea of the exercise is being familiarize with the seed and seed germination of some species. In this exercise, the students used seeds of various fruits and vegetables and allowed them to germinate. For the first part of the exercise, all the species used exhibited polyembryony. For the second part, Okra showed epigeal germination while on the other hand corn and papaya both exhibited hypogeal germination. INTRODUCTION
The seed, consisting of an embryo, endosperm, and seed coat, is botanically defined as a ripened ovule. Its embryo is produced sexually through the fusion of the egg and sperm cell or asexually through apomixes when embryo develops from the egg cell without fertilization. Apomixes results to plant with the same genotype thus eliminating variability. The endosperm is the food storage tissue of the seed which is a triploid. Two thirds of it comes from the maternal parent while the remaining one third is form the paternal parent. The perisperm and cotyledon are both diploids. However, Perisperm is maternal while cotyledon is equally derived from the maternal and paternal parents. Usually, producing a viable seed requires both pollination and fertilization. But in some instances, there is parthenocarpy or development of the fruit without pollination fertilization, embryo abortion or death during development, or non-filling due to the failure to accumulate required food reserves. All these may lead to development of ‘seedless fruits’. Seed germination is defined as the resumption of active growth of the embryo. During this process, the seed imbibes water, enzymes are activated, growth of embryo is initiated resulting in the rupture of the seed coat and the emergence of the young plant, and finally the establishment of a seedling. Development of the seedlings roots and shoots if important for its successful...
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