Effect of Water Loss on Germination Ability of Maize (Zea mays L.) Pollen

The correlation between water content and viability of maize pollen grains was studied on the basis of the germination ability of pollen from a single cross hybrid. There was found to be close correlation between viability of the grains and their tolerance to desiccation. Most of the pollen grains in the hybrid examined survived a reduction by almost 50 per cent of the original water content without loss of normal function. With water loss greater than this, less vigorous pollen grains died or lost their ability to form pollen tubes. Consequently, when pollination was carried out using pollen with a water content reduced by more than 50 per cent, only the most tolerant pollen grains survived to take part in the competition which precedes fertilization. Dry pollen grains required a longer period to establish adhesion to the stigma surface and to initiate pollen tubes than pollen grains with higher water content, but otherwise their behaviour was normal. If more than 80 per cent of the original water content was lost, disturbances occurred in the physiology of the grains surviving the treatment. This was exhibited as death or a reduction in rate of pollen tube growth. Drying of pollen by an amount which does not irreversibly damage the more tolerant grains could possibly be used as a means of pollen selection.