| Heat stress is one of the main agrometeorological disasters in China,which seriously affects the yield and quality of rice.In order to explore the method of alleviating the heat stress of rice,Liangyoupeijiu,a late indica rice variety,was used to study the effect of different irrigation and drainage methods on alleviating heat damage in rice flowering and filling period when heat stress occurred in this study.Five treatments were designed in the experiment: T1: Irrigation with well water at an average temperature of 20.55℃,started at 5:00 and stop at the field water layer of 10 cm and drainage at 16:00 every day;T2: Irrigation with well water at an average temperature of 20.55℃,started at 8:00 and stop at the field water layer of 10 cm and drainage at 18:00 every day;T3: Irrigation with pond water at an average temperature of 27.28℃,started at 8:00 and stop at the field water layer of 10 cm and drainage at 16:00 every day;T4: Irrigation with pond water at an average temperature of 27.28℃,started at 8:00 and stop at the field water layer of 10 cm and drainage at 18:00 every day;CK: Maintained the original water layer of 10 cm in the field,supplemented the irrigation pond water to 10 cm in the case of water shortage,the average water temperature is 28.37℃ at 8:00,and no drainaged.The main conclusions of the test are as follows:1.Irrigation treatments had an effect on microclimate of rice field.The daily mean values of the canopy temperature of 40 cm,80 cm and 120 cm in paddy field showed the rule of T1 < T2 < T3 < T4 < CK.The daily minimum and daytime mean values of the canopy relative humidity of 40 cm,80 cm and 120 cm were T2 > T1 > T3 > T4 > CK.The daily average temperature of the soil of 5 cm,10 cm and 20 cm in paddy field showed T1 < T2 < T3 < T4 < CK.During the period from 16:00 to 18:00,the canopy temperature of the 40 cm,80cm,and 120 cm drainages decreased faster than the 18:00 drainages,and the humidity of the 40 cm,80cm canopies increased rapidly.After 17:30 of 5cm soil temperature,T1 and T3 fell faster than T2 and T4,and 10 cm of soil temperature T1 and T3 fell faster than T2 and T4 after 18:00.Compared with the drainage at 18:00,the canopy temperature and soil temperature at the 16:00 drainage treatment decreased faster.The 16:00 drainage was more conducive to slowing down the heat stress.2.H and LE both showed CK> T4> T3> T1> T2,Q showed as T1> T2> T4> T3> CK,G showed as T4> T1> CK> T3> T2;H,LE and G of T1 and T3 declined faster than T2 and T4 from 16:00 to 18:00,respectively.T4 declined faster than CK after 18:00,and the Q values of T2 and T4 were lower than those of T1 and T3.The value of Q had turned to negative in T2 and T4 treatments before drainage.3.Irrigation treatments affected the growth index of rice.The average value of chlorophyll content,Fv/Fm,net photosynthetic rate,leaf area index,and ratio of panicle weight to shoot dry matter weight were all expressed as T1> T2> T3> T4> CK.The average values of chlorophyll(a + b)content in T1,T2,T3,and T4 treatments were 29.68%,22.83%,15.53%,and 7.76% higher than CK,the average values of Fv/Fm were7.04%,5.63%,2.82%,and 2.82% higher than CK,the average values of net photosynthetic rate were 32.22%,42.57%,20.78%,and 15.53% higher than CK,the average values of leaf area index were 40.7%,27.81%,18.2%,and 14.11% higher than CK,the ratio of panicle weight to shoot dry matter weight were 4.99%,3.93%,2.63%,and 2.14% higher than CK.The photosynthetic capacity,leaf area index and ear conversion rate of rice under different irrigation treatments were higher than those of CK,and T1 treatment was the best.4.Irrigation treatments affected rice yield.Thousand kernel weight,seed setting rate and yield were T1 > T2 > T3 > T4 > CK.The thousand kernel weight of T1,T2,T3 and T4 were 4.11%,2.73%,1.02% and 0.41% higher than CK respectively,the seed setting rate was 8.65%,8.1%,5.24% and 2.53% higher than CK respectively,and the yield was 29.70%、25.19%、20.36% and 16.69% higher than CK respectively. |
