Propagation and Breeding

Figure 3.1 The female reproductive organ is called the carpel. The carpel is made up of a stigma and ovary connected by the style. The male reproductive organ is a stamen. The stamen consists of anthers, which contain the pollen grains, suspended on a thin filament. Pollen grains land on the stigma, which has a sticky surface, and develop a pollen tube that grows downward through the style until it reaches the ovary. The ovary contains ovules (eggs), and the pollen grains produce sperm. The sperm cells travel down the pollen tube and fertilize the ovules. The ovary grows into a fruit and the other parts wither away.

Seed formation is initiated by changes in environmental conditions, such as the difference in daytime and nighttime temperatures and the relative number of hours of daylight versus darkness, and also by the production of plant hormones. The process begins with the development of flower buds. Pollination occurs after the flower blooms and involves the deposition of the male pollen onto the female stigma. Pollination is followed by fertilization, which is required to produce viable seeds.

Fertilization occurs when sperm cells from the pollen grain reach the ovules in the ovary and combine with an egg. The fertilized egg develops into a seed that contains an embryonic plant in a dormant state. Reproductive structures are illustrated in Figure 3.1.