Effects Of Irrigation On Yield And Quality Of Rice Under High Temperature

As the main rice production areas in China,the middle and lower reaches of the Yangtze River have great significance in ensuring China’s food security.However,rice in the middle and lower reaches of the Yangtze River is often affected by high temperature stress,especially in flowering and filling stage.In recent years,in order to adapt to the cultivation of high-quality rice and people’s nutritional needs,it is necessary to understand the changes of rice quality under high temperature stress.In this experiment,Liangyoupeijiu(LYPJ),a rice variety sensitive to high temperature,and iiyou602,a rice variety insensitive to high temperature,were treated with high temperature and irrigation from heading and flowering stage.There were four treatment levels T1: normal temperature and normal temperature water(control);T2:high temperature and normal temperature water;T3:high temperature and cool water(underground water);T4: normal temperature and cool water.The high temperature treatment was realized by the self-designed mobile warming facilities in the field.The water layer in the field was kept at 5-10 cm during water treatment.When the water layer was lower than 5 cm,supplementary irrigation was carried out to 10 cm.The main results are as follows.1.The yield of LYPJ and II you602 decreased significantly under high temperature conditions.Under the condition of irrigation and constant temperature water,the yield,grain number per ear and grain filling of the two varieties decreased 34.5% and 29.8%,16.7% and 23.7%,18.4% and 25.5% respectively,respectively,and the weight of the LYPJ decreased by 4.3%;Under the condition of irrigation cool water,the yield of the two varieties was increased by 5.9% and 4.4% respectively,and the grain filling decreased by 25.0% and 22.4% respectively.2.The effect of irrigation well water on rice canopy temperature was not significant.Compared with the control T1,the highest values of daytime mean temperature were T2 > T1,T3 > T1,T4 < T1,and the temperatures of T2 and T3 were1 ～ 2.5 ℃ higher than that of the control,while the temperatures of T4 were 1.0 ℃lower than that of the control.The lowest values of daytime average temperature were T2 > T1,T3 > T1,T4 > T1,and the temperatures of T2 and T3 were 0.4 ～ 1.0 ℃ higher than that of the control,and T4 was 0.8 ℃ higher than that of the control;The results showed that the average temperature of rice canopy at night was T2 > T3 > T1 > T4,with the highest value of 38.7 ℃ and the lowest value of 18.4 ℃ at T3;The highest value of night average temperature at T2 was 37.9 ℃,and the lowest value was18.3 ℃;At T1,the highest temperature was 36.2 ℃ and the lowest was 18.4 ℃;The highest value of T4 night average temperature is 35.2 ℃,and the lowest value is16.7 ℃.Compared with the control T1,the highest values of night mean temperature were T2 > T1,T3 > T1,T4 < T1,T2 and T3 were 1.7 ～ 2.5 ℃ higher than the control;The lowest temperature at night was T1 > T4,T2 > T4,T3 > T4,which were 1.6 ～ 1.7 ℃higher than T4.3.Under T4 treatment,chalkiness decreased by 29.3%,protein content increased by 7.9%,gel consistency and Amylose content decreased by 14.5% and 7.1%,respectively;Under T3 treatment,the gel consistency and Amylose content of LYPJ decreased by 42.9% and 8.6%,respectively,and the protein content increased by 15.4%;The chalkiness and protein content of Ⅱ you 602 decreased by 36.8% and 11.9%respectively,while gel consistency and Amylose content increased by 22.3% and 7.0%respectively.