Study On Differences Of Varieties And Its Mechanism In Rice Spikelet Sterility Induced By High Temperature

In this study,100rice combinations in China were used to evaluate their heat resistant properties.42of large-area application rice varieties in China were subject to heat stress at35℃and38℃.Mechanisms of spikelet fertility were analyzed for different heat resistant rices. The main resultsshowed as the following:3rice varieties and42of large-area application rice varieties were used to study the influence ofdifferent temperatures on the fertilization rate in flowering period. The results showed that in hightemperature, with the increasing of humidity, the fertilization rate of varieties is reduced and thefertilization rate of most varieties under35℃has no significant difference campared with outdoorcontrol. However, under38℃the fertilization rate of most varieties showed great difference and thedifferences among varieties were able to reflect. Large-area application rice varieties have almostadapted to35℃, but their fertilization rate of most varieties were sensitive to38℃. It also showed thatit is suitable to set temperature of the evaluating varieties at38℃.100combinations were used to evaluate their heat resistant properties during flowering. The riceplants were subjected to heat stress at38℃for3days from50%spikelets flowering. Based on relativespikelet fertility rate, they were divided into heat tolerant varieties, semi-heat tolerant varieties and heatsensitive varieties. Therefore, Y liangyou646, Guangzhan63-4S/R558, Yixiang5979, Y liangyou2andY liangyou896belonged to heat tolerant varieties, whereas Ⅱyou838, Fengyou199and Jingchuyou37to heat sensitive variety. Research of cultivar origin of varieties of different heat-tolerance indicated thatmost heat tolerant varieties that have the same female lines show the same heat resistant. It concludedfemale lines are more important to heat tolerant of hybrid rice.12different heat resistance rice combination were used to study mechanism of sterility. The resultsshowed that during3days high temperature, sensitive the fertilization rate varieties decreased more thanheat resistant varieties on fertilization rate. To the same variety, pollen activity in high temperature hasno significant difference compared with CK and pollen activity is not the direct reason to make floretssterility. After high temperature treatment, degree of anther dehiscence different rice varieties showedsignificant difference. Heat-resistant varieties tended to amplify the degree of anther dehiscence, andsensitive varieties tended to maintain or fall that. Heat-resistant varieties have more pollen grains on thestigma and better powder properties. Correlation analysis was carried out on the floret characters.Results showed that the fertilization rate had no significant correlation with pollen grains activity, highlysignificantly positive correlation with degree of anther dehiscence and significantly correlation with thenumber of pollen grains on the stigma. Moreover, degree of anther dehiscence had significantly positivecorrelation with the number of pollen grains on the stigma. It concluded that amplifying the degree ofanther dehiscence caused the number of pollen grains on the stigma and was the main reason to impactfloret sterility with high temperature.