Effect of Air Temperature during the Early Grain-filling Stage on Grain Fissuring in Rice

Abstract

We conducted field and pot experiments to elucidate the effect of meteorological conditions during grain filling on grain fissuring in rice. A total of 13 cultivars were grown in paddy fields in 1997, 1998, 1999, 2001 and 2003. The percentage of fissured grains was closely related with the temperature and solar radiation condition during the early stage of grain filling. A high temperature and long sunshine hours during this period increased the grain fissuring of all cultivars tested. Especially, the average daily maximum temperature during 10 days after heading showed the highest correlation with the percentages of fissured grains. In the pot experiments, high temperature treatments at split periods during grain filling were done using growth chambers. Given at 6 to 10 days after flowering, during which the dry weight of spikelets was 14 to 40 percent of that at maturity, caused the greatest grain fissuring. We concluded that high temperatures during the early stage of grain filling increases the rice grain fissuring at maturity.