To calculate the percentage of pollen germination
The process of an organism growing from a seed or spore is called germination. The process starts with the seed of an organism, and it develops the growth of a pollen tube from the pollen grain of the seed plant.
Generally, pollen grains are a collection of microspores related to plant fertilization. The micropores are found on the male structure of the flowering plants, and it is produced in the anther of angiosperm of the gymnosperms. It carries and transfers the male gametes to the female reproductive structure of the plant. In nature, pollen grains germinate on the compatible stigmas of the carpel. The pollen grain reaches the stigma to begin the process of pollen germination. The germination process starts with the absorption of water and nutrients. The embryo takes water to enlarge the cell. When the pollen grains are released from the anther, they fall on the stigma and absorb water for germination. In nature, germination occurs on the stigma of a flower, and the tube elongates towards the flower’s ovule. The sperm travels through the pollen tube to fertilize in the ovule.
It is the mechanism to transfer the pollen grains shed from the anther to the stigma of the pistil and flowers using external sources to conduct pollination that is divided into three types namely, autogamy, geitonogamy, and xenogamy.
Autogamy: pollination occurs within the same flower. The pollen grains were transferred to the stigma of the same flower.
Geitonogamy: Pollination occurs in the same plant but the pollen grains from one anther are transferred into another stigma of the flower in the same plant.
Xenogamy: The pollen grains from the anther are transferred into another plant stigma.
Double - fertilization
The pollen tube is formed during the nucleus growth, and then it forms two separate male gametes, namely, viable pollen grains and the gametes known as sperm nuclei. In the newly formed sperms, one will fuse with the eggshell in the ovule, whereas the other one will combine with the other nucleus from the ovule to form endosperm. This process is generally known as double-fertilization.
Figure1: Pollen germination
Pollen grains can also be induced to germinate in a synthetic medium. Generally, Pollen can germinate in a sucrose medium. Sucrose provides enough nutrients and carbon sources during germination, also it plays a major role in regulating osmotic pressure in the surrounding environment. The addition of boric acid is necessary for pollen tube growth and tube development during germination. It can form a complex with sucrose for uptaking the metabolism of sugar through the plasma membrane. The presence and addition of calcium are essential for tube germination. During germination, the intine (inner wall) of the pollen grain emerges as a pollen tube through one of the germ pores in the exine (outer wall).
Figure 2: Pollen germinates in microscopic field
| Number of Pollen grains germinated (n) | Total number of pollen grains (N) | Percentage of pollen grains germinated [(n/N)*100] |
| 5 | 50 | (5/10)*100 = 10% |
| 10 | 50 | (10/50)*100 = 20% |
