PurposeTo study the effect of high temperature on japonica rice and screen out high-temperature-tolerant varieties to provide basic materials for high-temperature breeding of japonica rice.
MethodUsing 15 japonica rice varieties from China, Japan and South Korea as materials, through years of field natural high temperature stress and pot temperature control experiments, japonica rice was subjected to high temperature stress with a daily average temperature higher than 32 ℃ or a maximum temperature higher than 35 ℃ for at least 7 consecutive days during heading and flowering. The indexes such as total grain number, grain number, seed setting rate, 1000-grain weight and so on were determined by using a full-automatic digital seed testing machine, and the activities of SOD, CAT and POD were detected by using a enzyme reagent test kit.
ResultIn the field test, S1, S2, S4, S5, S7 and S14 had an average annual seed setting rate of more than 80%, S6, S8, S9, S11 and S13 had an average annual seed setting rate of about 75%, S3, S10 and S15 had an average annual seed setting rate of about 50%. In pot temperature control test, S2, S7, S8 and S9 were the japonica rice varieties with relative seed setting rate above 95%, S1, S4, S5, S6, S11, S12, S13 and S14 were the japonica rice varieties with relative seed setting rate between 75% and 95%, S3, S10 and S15 were the japonica rice varieties with relative seed setting rate between 55% and 75%. Under high temperature stress, SOD, CAT and POD activities are positively correlated with relative seed setting rate (P>0.05), and the antioxidant enzyme activities of each variety after high temperature stress are higher than those of the control group.
ConclusionCombining field and pot experiments, 2 varieties with high temperature tolerance and good comprehensive agronomic traits were selected, they are Aoyu 392 (S2), and Lindao 16 (S7). High temperature tolerant rice varieties have a higher level of antioxidant enzyme activity.
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