Propagation and Breeding


Propagation and Breeding
  Propagation of New Plants From Seeds
  Specialized Flowers and Pollination
  Propagation From Cuttings
  Tissue Culture
  Plant Breeding

The female reproductive organ is called the carpel. The carpel
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.