| The South Hunan Province is rich in light and heat resources and abundant rainwater,so it is suitable for the development of double season rice.However,the spatial and temporal distribution of rainfall is uneven,and there are many hilly and slope cultivated land,and the water conservation and storage capacity is weak,which seriously affects the high yield and stable yield of rice.In order to explore the suitable irrigation method and chemical control agent for double season rice in South Hunan Province,field experiment was carried out in Hengyang County,Hunan Province from2019 to 2020,using zhongjiazao17 and shengtaiyou018 as materials.The irrigation methods(flooded irrigation,W1;intermittent irrigation,W2;wet irrigation,W3)and chemical regulation(Zhuanggubao,C1;chitooligosaccharide,C2;prochlorazate,C3;non-chemical control,C4;Tianda 2116,C5)on the quality,drought tolerance and yield formation of double season rice in South Hunan.The main results are as follows:1.Effects of irrigation methods and chemical regulation on rice population quality:compared with W1 treatment,W2 treatment significantly reduced tiller death,significantly increased leaf SPAD value,LAI,high-efficiency LAI,high-efficiency leaf area ratio and upper three leaf area at full heading stage,and promoted dry matter accumulation and transportation of paddy rice,while W3 treatment had no significant effect.Compared with non-chemical control,C3 and C5 treatments significantly improved rice population quality,C1 treatment also had a certain effect,while C2treatment had no obvious effect.2.Effects of irrigation methods on root characteristics and leaf physiological characteristics of rice:there was no significant difference in root fresh weight between W2 and W3 treatment and W1 treatment,but root volume was smaller than W1treatment,and root dry weight was larger than W1 treatment.Root water content of W1treatment was higher than W2 and W3 treatment at all growth stages,and significantly higher than W3 treatment at maturity stage.W3 treatment significantly increased the root shoot ratio,while W2 treatment significantly increased the root bleeding of single stem in the middle and late growth stages of late rice.W2 treatment significantly increased the activities of antioxidant enzymes,pro content and soluble sugar content in leaves of late rice,and decreased the content of MDA in leaves.However,there was more precipitation in the growth period of early rice,and there was no significant difference in leaf physiological characteristics among different irrigation treatments.3.Effects of irrigation methods on root characteristics and leaf physiological characteristics of rice:there was no significant difference in root fresh weight between W2 and W3 treatment and W1 treatment,but root volume was smaller than W1treatment,and root dry weight was larger than W1 treatment.Root water content of W1treatment was higher than W2 and W3 treatment at all growth stages,and significantly higher than W3 treatment at maturity stage.W3 treatment significantly increased the root shoot ratio,while W2 treatment significantly increased the root bleeding of single stem in the middle and late growth stages of late rice.W2 treatment significantly increased the activities of antioxidant enzymes,pro content and soluble sugar content in leaves of late rice,and decreased the content of MDA in leaves.However,there was more precipitation in the growth period of early rice,and there was no significant difference in leaf physiological characteristics among different irrigation treatments.4.The effect of irrigation mode and chemical control on the yield of double season rice:the average two-year total yield of W2 treatment was 14.25t/hm~2,5.28%higher than that of W1 treatment,and the yield of W3 treatment was slightly lower than that of W1 treatment;from the perspective of yield composition factors,the effective panicle number of W2 treatment was 5.24%higher than that of W1 treatment.Compared with C4 treatment,the average effective panicle number and seed setting rate of C3 treatment in 2019 increased by 11.64%and 5.14%,respectively.The effective panicle number,seed setting rate and 1000 grain weight of C1 treatment increased by 4.49%,3.78%and 2.55%respectively.The total yield of C3 and C1treatment in the two seasons increased by 10.90%and 8.08%,respectively.In 2020,the effective panicle number and seed setting rate of C3 treatment increased by 8.09%and6.38%,the effective panicle number and seed setting rate of C5 treatment increased by5.96%and 6.82%respectively.The yield of C3 and C5 treatment increased by 9.27%and 6.21%respectively,and the yield of C2 treatment was slightly higher than that of C4 treatment.Conclusion:irrigation methods and chemical regulation have significant effects on population quality,drought tolerance and yield of double cropping rice in southern Hunan.The trend among years is basically the same,but there is a slight difference among seasons.The law of early rice among treatments is not obvious as that of late rice.In general,intermittent irrigation,spraying prochlorazate or Tianda2116 after turning green can significantly improve the quality of rice population and enhance the drought tolerance,which is conducive to obtaining high yield. |
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