Formation of Seed and Fruit

Formation of Seed and Fruit 

Seed and Fruit Development:       

• The goal of reproduction, in every living organisms including plants, is to create offsprings for the next generation.  

• One of the ways that plants can produce offpsrings is by forming (making) seeds. The flowers must be pollinated in order to produce seeds and fruit.  

• Seed development is initiated by fertilization. The integuments of the fertilized ovule persist and get transformed into the seed coat of mature seed. 

Bean seed (Dicot): 

• After fertilization, the zygote develops into an embryo composed of two cotyledons, a hypocotyl, and an epicotyl.  

• The surrounding ovule tissues form the seed coat, which provides protection. The outer seed coat is testa and the inner thin, membranous is tegmen.  

• The endosperm produced by double fertilization may be absorbed by the cotyledons, supplying nutrients to the developing embryo. 

• During fruit development, the ovary wall changes into pericarp, which can have three layers: exocarp, mesocarp, and endocarp.  

• In dicots like beans and peas, the fruit usually develops as a pod containing many seeds.  

• As the fruit grows, it helps to disperse seeds through dehiscence (splitting open) or other means including wind, water, or animal transport. 

Bean seed (Dicot)  

Maize grain (Monocot) 

• Monocot seed formation begins with double fertilization.  

• The zygote matures into an embryo with a single cotyledon, known as a scutellum in monocots.  

• Endosperm, which is usually abundant, supplies nourishment to the developing embryo. As the seed grows, protective seed coverings develop around it.  

• Fruit development occurs with ovary wall thickening, and other flower parts may also contribute to fruit formation.  

• Monocots, such as grasses, generally produce caryopsis fruit, in which the seed coat is fused with the fruit wall.  

• This fusion preserves the seed while also aiding in its spread and germination when conditions are favorable. 

V.S. Maize grain (Monocot)

Significance of seed and fruit formation 

• Fruits provide nourishment to the developing seeds.  

• Fruits protect the seeds in immature condition.  

• Seeds serve as important propagating organs (units) of plants. 

Dormancy 

• Dormancy is a temporary state of metabolic arrest that facilitates the survival of organisms during adverse environmental conditions. Structural or physiological adaptive mechanism for survival is called dormancy.  

• Mature seeds, even in favorable conditions, are dispersed during dormancy, and viable seeds germinate only after the end of the dormancy period.