ABSTRACT
Pollen physiology has attracted the attention of plant breeders and horticulturists for plant improvement programmes ever since the discovery of the pollen tube by Giovanni Batista Amici, an Italian astronomer and mathematician, while examining the papillate stigma of Portulaca oleracea. An interesting development in the pollen studies is the study of the influence of pollen physiology on the mode of pollination and breeding systems of plants. Each mature pollen grain upon germination produces two nuclei by mitotic division of the haploid nucleus of the dehisced grain. The arrival of a pollen grain upon the stigmatic surface of the gynoecium is stimulated by chemicals secreted by the stigmatic tissues to produce the pollen tube via one or more of the exine pores. Environmental factors, particularly temperature and humidity, greatly affect pollen viability. The most commonly used method for assessing pollen viability is in vitro germination of the pollen grains.
