| The tillering stage is a key period for rice growth.During this period,low-temperature is easy to cause delayed chilling of rice,which leads to retarded growth,poor development,reduced yield and quality.?-aminobutyric acid?GABA?,salicylic acid?SA?and proline?Pro?have important regulatory effects on growth and development of crop under adverse conditions.In order to explore the effects of applying GABA?G?,SA?S?and Pro?P?and their mixtures?GS,GP,SP,GSP?on the growth,yield and quality of rice in cold-region under cold-water stress at the tillering stage,GABA,SA and Pro with different concentrations as the main area,rice varieties?cold-tolerant variety Dongnong 428 and cold-sensitive variety Songjing 10?as the sub-area,15?cold-water irrigation for 10 days at tillering stage,spraying the same amount of fresh water normal irrigation?CK?and cold-water stress?Cold?was used as a control to screen the optimal application concentration of three exogenous substances.Based on this,to study systematically the effects of single optimum concentration of three kinds of exogenous substances and their mixtures on growth and development,photosynthetic characteristics,yield formation and quality of rice in cold-region,to clarify the effects of single application and compound application of three exogenous substances,to reveal the mechanism of three kinds of exogenous substances improve the cold-resistance of rice in cold-region,to provide theoretical basis for cold-resistant cultivation technology of rice in cold-region at the tillering stage.The main findings are as follows:?1?Compared with cold-water stress,the number of tillers,plant height,leaf area index,efficient leaf area ratio,high efficient leaf area ratio,photosynthetic potential,dry matter accumulation and yield of rice in cold-region increase with exogenous substances GABA,SA and Pro;in the treatment of three kinds of exogenous substances at different concentrations,the application of 2 mmol·L-1 GABA,2 mmol·L-1 SA and 30 mmol·L-1 Pro,Dongnong 428 and Song jing 10 has the highest output growth,which is the most suitable application concentration.With 2mmol·L-1 SA the effective panicle number and the output growth of rice in cold-region is the largest.?2?Compared with cold-water stress,single optimum concentration of GABA?SA?Pro and their mixtures increased plant height,number of tillers and panicle rate of rice in cold-region,and the effect of combined application was better than that of single application.In the compound treatment,the plant height,the highest number of tillers,the final number of tillers and the panicle rate of GS were the highest,but there was no significant difference in final number of tillers between Dongnong 428 and normal irrigation under this treatment.The plant height and the highest number of tillers of Songjing 10 were the highest when SP was applied,but there was no significant difference in plant height between Songjing 10 and normal irrigation under this treatment.The final tiller number and panicle percentage of Songjing 10 were the highest when GSP was applied,and the final tiller number of Songjing 10 was not significantly different from that of normal irrigation under this treatment.?3?Compared with cold-water stress,the root activity,total root length and total surface area of rice in cold-region were significantly increased by applying GABA,SA,Pro and their mixtures at tillering stage.The root activity of rice in cold-region increased most when SP was applied at tillering stage.The application of GABA,Pro and their mixtures with SA could improve the total root length and total surface area of rice in cold-region at tillering stage under cold-water stress.The total root length and total surface area under combined application at tillering stage were larger than those under single application.?4?Compared with cold-water stress,single optimum concentration of GABA?SA?Pro and their mixtures increased significantly leaf area index,efficient leaf area ratio,high efficient leaf area ratio,photosynthetic potential and chlorophyll content of rice in cold-region,and the effect of combined application was better than that of single application.The leaf area index of Dongnong428 was the highest at heading stage under SP treatment,efficient leaf area ratio,high efficient leaf area ratio,the photosynthetic potential and chlorophyll content during the whole-growth period of Dongnong 428 were the highest under GS treatment.The leaf area index at heading stage,photosynthetic potential and chlorophyll content during tillering stage to heading stage were the highest under SP treatment,and efficient leaf area ratio,high efficient leaf area ratio and the chlorophyll content during milky stage to maturity stage of Songjing 10 were the highest under GSP treatment.Under the compound treatment,the leaf area index of rice in cold-region at heading stage was not significantly different from that of normal irrigation.There was no significant difference in efficient leaf area ratio between Dongnong 428 and normal irrigation under compound treatment,and there was no significant difference in high efficient leaf area ratio between Dong nong 428 and normal irrigation under SP,GS and GP treatments.There was no significant difference in efficient leaf area ratio and high efficient leaf area ratio between Songjing 10 and normal irrigation under SP and GSP treatments.?5?Compared with cold-water stress,with single optimum concentration of GABA?SA?Pro and their mixtures,the total dry matter weight and colony growth rate of rice in cold-region increased significantly,and the effect of combined application was better than that of single application.In the compound treatment,the total dry matter weight and colony growth rate of Dong nong 428 were the highest in each period when GS was applied.The total dry matter weight of Song jing 10 was the highest at each stage with SP treatment.The colony growth rate of Songjing 10 was the highest with GSP treatment,and there was no significant difference in total dry matter weight from SP treatment at maturity stage.?6?Compared with cold-water stress,with single optimum concentration of GABA?SA?Pro and their mixtures,strong and weak grain filling parameters of rice in cold-region,the maximum growth rate?GRmax?and the average growth rate?GRmean?increased,while the time to reach the maximum grain rate?Tmax?and the completed total growth at 90%active filling stage?D?decreased.Strong and weak grain filling parameters GRmax and GRmean of Dongnong 428 showed G<S<P<GSP<GP<SP<GS,Tmax and D showed GS<SP<GP<GSP<P<S<G,strong and weak grain filling parameters GRmax and GRmean of Songjing 10 showed S<G<P<GS<GP<SP<GSP,grain filling parameters Tmax and D showed GSP<SP<GP<GS<P<G<S.?7?Compared with cold-water stress,with single optimum concentration of GABA?SA?Pro and their mixtures,the effective panicle number,grain number per panicle and yield of rice in cold-region increased significantly,quality of rice improve.and the effect of combined application was better than that of single application.In the compound treatment,the yield of Dongnong 428was the highest under GS treatment,which is 91.82%of normal irrigation level.The overall improvement effect of rice quality of Dongnong 428 was the best under GSP treatment,but the yield of Dongnong 428 under GS treatment was significantly higher than that of GSP treatment.The yield of Songjing 10 under GSP treatment was the highest,reaching 91.60%of the normal irrigation level,and the overall improvement effect of rice quality under this treatment was the best.In terms of yield and quality,the application of GS and GSP had the best regulation effect on Dongnong 428and Songjing 10 under cold-water stress at tillering stage. |
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