| Heilongjiang is located in the northeast agricultural area,low temperature chilling injury is one of the important factors restricting rice production in this area.Tillering stage is one of the key periods of rice growth,and cold injury is harmful to rice growth and yield at this time.Exogenous salicylic acid(SA),proline(Pro)and ?-aminobutyric acid(GABA)play an important role in crop stress resistance.At present,the research mainly focuses on the mechanism and effect of the concentration of three exogenous substances on the mitigation of chilling damage to crops,but the effect of the application time of the three exogenous substances on crops is rarely reported.Therefore,it is of great significance to study the optimum spraying time of three exogenous substances under cold water stress at tillering stage for the establishment of chemical control cultivation techniques to prevent low temperature and cold damage in cold region japonica rice at tillering stage.In this experiment,Dongnong 428 and Songjing 10 were treated with cold water stress for 10 days at tillering stage,(Cold)treated with cold water stress without spraying exogenous substances and(CK)treated with normal irrigation as control,and 7 kinds of application time treatments were set up,for the 3 days before cold water treatment and 2 Day before treatment,1 day before treatment,the day of treatment,1 day after treatment,2 days after treatment,3 days after treatment.They are recorded as(D-3,D-2,D-1,D0,D1,D2,D3).The effects of the application time of three exogenous substances on the growth and development,dry matter accumulation and transport,yield and yield components of japonica rice under cold water stress at tillering stage were studied.The optimum spraying time of exogenous substances under cold water stress at tillering stage was determined,which provided the basis for the establishment of chemical control cultivation techniques to prevent low temperature and cold damage in cold region japonica rice at tillering stage.The main research conclusions of this test are as follows:(1)Spraying exogenous SA,Pro and GABA could alleviate the inhibition of cold water stress at tillering stage on plant height and tiller of Dongnong 428 and Songjing 10.As for the final plant height,the effect of exogenous SA and Pro was the most obvious under D0 treatment.the increase of Dongnong 428 and Songjing 10 treated with exogenous SA D0 was 27.81% and22.52%,respectively,compared with Cold treatment.The increase of exogenous Pro D0 treatment was 25.13% and 21.71%,respectively,compared with Cold treatment.The effect ofexogenous GABA was the most obvious in D-1 treatment,which was 27.43% and 27.40%higher than that of Cold treatment,respectively.As for the final tillering,the effect of exogenous SA,Pro and GABA was the most obvious.the increase of exogenous SA Dongnong428 and Songjing 10 D0 treatment was 28.57% and 30.56%,respectively,compared with Cold treatment.The increase of exogenous Pro and GABA D0 treatment was 30.55% higher than that of Cold treatment.(2)Spraying exogenous SA,Pro and GABA could alleviate the inhibition of cold water stress at tillering stage on leaf growth stress of Dongnong 428 and Songjing 10,and effectively increase leaf area index,high efficiency leaf area index and high efficiency leaf area rate.For leaf area index and high efficiency leaf area index,the effect of D0 treatment was the most obvious in the three exogenous substances of the two varieties.For high efficiency leaf area rate,the treatment effect of exogenous SA and GABA Songjing 10 was the most obvious,while that of Dongnong 428 was the most obvious.The effect of D-1 treatment on both varieties of exogenous Pro was the most obvious.(3)Spraying exogenous SA,Pro and GABA could alleviate the inhibition of cold water stress at tillering stage on dry matter accumulation and apparent output rate of stem and sheath at each growth stage of Dongnong 428 and Songjing 10.Regarding the total dry matter accumulation of plants,the exogenous SA was the most effective in treating D-1.The increase of D-1 treatment was 62.55% and 54.67% compared with the treatment of Cold,and the exogenous Pro Dongnong 428 showed D-1.The treatment effect was the most obvious,compared with the Cold treatment,the increase was 68.22%,while the Matsuzaka 10 showed the most obvious D0 treatment effect,compared with the Cold treatment,the increase was50.54%,and the exogenous GABA two varieties were the most obvious D0 treatment effect.The increase in D0 treatment compared with the Cold treatment was 62.21% and 52.07%,Regarding the apparent yield of stem and sheath at heading stage,both exogenous SA and Pro showed the most obvious D0 treatment effect.Exogenous GABA Dongnong 428 showed the most obvious effect of D0 treatment,while Songsong 10 showed the most obvious effect of D-1 treatment.(4)Spraying exogenous SA,Pro and GABA could alleviate the inhibition of cold water stress at tillering stage on photosynthetic potential and population growth rate of Dongnong 428 and Songjing 10.With regard to photosynthetic potential and population growth rate,the treatment effect of exogenous SA and Pro was the most obvious,while that of exogenous GABA was the most obvious.(5)Spraying exogenous SA,Pro and GABA could alleviate the inhibition of cold water stress at tillering stage on yield formation of Dongnong 428 and Songjing 10.The effects of D0 treatment on effective panicle number,grain number per panicle,seed setting rate,1000-grain weight and yield of exogenous SA and Pro were the most obvious.compared with Cold treatment,exogenous SA D0 treatment had the most obvious effect on effective panicle number,grain number per panicle,seed setting rate,1000-grain weight and yield.The yield increased by24.80% and 27.64% respectively,which was equivalent to 89.57% and 93.62% of that of CKtreatment,respectively.compared with Cold treatment,the yield of exogenous Pro D0 treatment increased by 24.70% and 27.18%,respectively.It was equivalent to 89.49% and 93.27% of CK treatment,respectively.The effect of exogenous GABA treatment with D-1 was the most obvious.compared with Cold treatment,the yield increased by 23.05% and 27.62% respectively,which was equivalent to 88.31% and 93.59% of CK treatment,respectively.With regard to harvest index,the effect of D0 treatment was the most obvious in exogenous SA,Pro and GABA varieties. |
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