| Rice yield,quality and nutrient reutilization are closely related to ratio of spikelet to leaf area(RSLA)in heading stage.Previous studies showed that higher RSLA was beneficial to increase yield and nutrient redistribution,but not good for improving rice quality.Exploring the suitable RSLA which is benefit for yield formation,nutrient elements reutilization and rice quality improvement is the problem urgently to be solved in rice breeding and cultivation.Two japonica rice cultivars,Huaidao5 and Ningjing3 were used as experimental materials.Leaf-cutting and spikelet-thinning treatments were made to regulate RSLA in heading stage.The research mainly studied the effect of RSLA manipulation on yield,quality and NPK reutilization,analyzed the relationship between RSLA and yield components,rice quality indexes,carbohydrate and nutrient translocation,aimed to clarify the appropriate RSLA increasing yield,quality and NPK redistribution synerfistically,provided the theoretical basis for high-yield,high-quality and efficient-nutrient-reutilization japonica rice varieties' breeding and cultivation.The main results were as follows:(1)Regulating RSLA artificially influenced grain filling and rice quality significantly.Leaf-cutting treatments declined initial grain-filling potential and grain filling rate,lengthened active grain-filling period,decreased ripening rate,1000-grain weight,milled rice rate,head milled rice rate,total starch content and amylose content significantly,while increased chalky grain rate and chalkiness degree significantly.Compared with control(L0S0),ripening rate and 1000-grain weight of L1S0 decreased 62.0%-74.2%and 47.1%-63.6%,milled rice rate and head milled rice rate decreased 8.9%-16.0%and 10.3%-19.0%,amylose content decreased 14.7%-31.6%,chalkiness degree increased 44.6%-137.8%;performance of L1/2S0 was the same as LiS0,only the variation range were less.The performance of indexes mentioned above of spikelet-thinning treatments were just on the contrary.There were no significant differences between L0S1/3,L0S1/2,L0S3/5 and L0S2/3.The average ripening rate and 1000-grain weight of spikelet-thinning treatmens increased 0.3%-8.3%and 1.2%-18.7%,milled rice rate and head milled rice rate increased 0.5%-3.2%and 1.7%-13.1%,amylose content decreased 3.5%-34.7%,while chalkiness degree decreased 13.8%-95.7%.There were little difference between the response of rice quality in two varieties to RSLA artificial regulation:Ningjing3 was more sensitive than Huaidao5.(2)Regulating RSLA artificially significantly influenced dry matter and NPK nutrient translocation after anthesis.Leaf-cutting treatments significantly improved dry matter and NPK nutrient transport rate in leaf and stem-sheath:compared with control,dry matter transport rate of L1/2S0 in leaf and stem-sheath increased 27.6%-31.5%and 45.0%-300.2%,respectively,N transport rate increased 7.4%-11.3%and 17.4%-23.8%,P transport rate increased 10.0%-16.3%and 11.5%-14.6%,K transport rate increased 9.5%-13.2%and 17.2%-24.8%.Spikelet-thinning treatments significantly improved dry matter and NPK nutrient transport rate in leaf and stem-sheath.Compared with control,dry matter transport rate of leaf under spikelet-thinning treatments decreased 5.4%-45.9%averagely,transport rate of N,P and K decreased 4.2%-31.0%,9.7%-43.6%and 7.1%-44.2%,respectively;dry matter transport rate in stem-sheath decreased 100.0%-400.2%averagely,transport rate of N,P and K decreased 11.2%-87.7%,8.0%-52.4%and 19.7%-82.4%,respectively.There were no fundamental difference between the response of Huaidao5 and Ningjing3 to RSLA artificial regulation in carbohydrate and nutrient translocation.(3)Ripening rate,1000-grain weight,main indexes of rice quality,translocate rate of dry matter and nutrient in japonica rice were closely related to RSLA in heading stage.Ripening rate,1000-grain weight were negatively related to RSLA,and 1000-grain weight became stable when RSLA was greater than 1.5.Milled rice rate,head milled rice rate and amylose content were negatively related to RSLA,chalky grain rate and chalkiness degree were positively related to RSLA,higher RSLA wasn't good for rice quality formation.There were curve positive correlation between RSLA and tranport rate of dry matter and NPK,which improved as RSLA increased and gradually got close to the theoretical maximum when RSLA around 1.5.Comprehensive considering the relationship between ripening rate,1000-grain weight,main indexes of rice quality,translocate rate of NPK and RSLA,the research put forward that RSLA around 1.5 in heading stage as the appropriate value in conventional japonica rice for improving yield,quality and NPK nutrient reutilization synergistically. |
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