Abstract:

In order to clarify the effect of potassium fertilizer management on grain filling and chalkiness at high temperature during rice filling stage, in this study, two temperature treatments were set for 20 days at ambient temperature and high temperature during the grain filling stage. Three potassium fertilizer management methods were set up at different temperatures, K1 (10∶0 for basal fertilizer∶flower-promoting fertilizer), K2 (7∶3 for basal fertilizer∶flower-promoting fertilizer) and K3 (3∶7 for basal fertilizer∶flower-promoting fertilizer), and the grain filling process and chalkiness of grains under each treatment were determined. The results showed that the high temperature at the grain filling stage shortened the active grain filling stage, reached the maximum grain filling rate in advance, and increased the grain filling rate within 15 days after anthesis, but the grain filling rate decreased rapidly after 15 days after anthesis, and the grain filling rate decreased after 20 days after anthesis, and the grain filling curve fluctuated greatly, which increased the chalky rice rate and chalkiness of grains. Under high temperature conditions, compared with K1, K2 and K3 both prolonged the active grain filling period, delayed the time to reach the maximum grain filling rate, reduced the grain filling rate within 20 days after anthesis, and alleviated the effect of high temperature on rice during the grain filling stage, and after reaching the peak of grain filling, the grain filling rate decreased more gradually, and the grain filling rate decreased more slowly after 20 days after anthesis, and the occurrence of grain chalkiness was reduced, and the chalky rice rate and chalkiness decreased with the increase of the proportion of flowering fertilizer. Although K3 could minimize the occurrence of grain chalkiness at high temperature during grain filling stage, there was no significant difference in yield from K1. Therefore, in the practice of rice production, potassium fertilizer should be applied in accordance with the ratio of base fertilizer and flower-promoting fertilizer of 7∶3, and potassium dihydrogen phosphate can be sprayed to alleviate the harm of high temperature stress if the high temperature is encountered during the filling period.

Key words: rice, potassium fertilizer, high temperature, grain filling, chalkiness