On the Artificial Germination of Pollen of Rice Rlants : IX. Effects of soil temperatures on pollen germination

Abstract

The experiments were carried out in 1958 to know how different soil temperatures affected the pollen germination and to clarify the relationship between the pollen germination and the grain fertility. Three constant temperature water tanks were set in the open air, of which temperatures were adjusted at 33°(Plot H), 28°(Plot M) and 23°C(Plot L) respectivly. Rice Plants (variety"Norin-29") were placed in them from Jul. 7 to Sep. 17, being irrigated with water of the same temperatures. Fresh pollen taken from strong spikelets of the plant each day were subjected to germination tests on the starch paste media. In general the Plot M tended to show high percentages and the Plot L showed low ones at each experimental date during the whole period. But in the Plot H it was nearly intermediate between them, being followed by a later drop of the percentage (Fig. 2). The average percentage of germination of strong panicles which had headed earlier was the highest in the Plot M and was the lowest in the Plot L. The Plot H was found to be ranked between them. Moreover abortive pollen were always found fewer in the Pollen which germinated with high percentages. The grain fertility was measured also with the same materials taken from all plots (Fig. 3). By observing the ears as they appeared, it was found that the grain fertility was always high in the plot M and low in the Plot H, the Plot L showing intermediate values between them. However in the Plot H a later drop of the fertility was observed as well as in the pollen germination. The Plot M showed a higher average percentage of fertile grain of strong panicles than those of the Plot H and the Plot L. These results indicate that the respective soil temperatures affected markedly the pollen germination and the grain fertility. The authors suggest that a certain relationship may exist between the pollen germination and the grain fertility, and the percentage of pollen germination may indicate the vitality of the plant