Changes Of Carbon And Nitrogen Metabolites At Grain Filling Stage And Their Effects On Yield And Quality In Rice

As one of the most important food crops in China,rice(Oryza sativa L.)is very important in food production both in China and in the world.Metabolism is the most basic life activity process of plants.Carbon and nitrogen metabolism largely determines the growth and development of rice as well as the formation of quality and yield.The grain filling stage is the key period for the formation of rice yield and quality.Therefore,it is of great significance to understand the effects of carbon and nitrogen metabolism on rice yield and quality during grain filling stage for realizing high quality,high yield and high efficiency of rice.In this study,4 early maturity indica rice varieties(lines)and 6 late maturity indica rice varieties were used as research materials.By studying the variation characteristics of carbon and nitrogen metabolite contents in leaves of different rice varieties at 10 d,20d and 30 d after flowering during grain filling period and their effects on yield and quality,The aim was to clarify the relationship between the coordinated transformation rules of carbon and nitrogen metabolism of different rice varieties during grain filling period,and to enrich the physiological basis for the study of carbon and nitrogen metabolism of rice,so as to provide a theoretical basis for realizing the cultivation technology of rice with high quality and high yield in field production.The main research results are as follows:(1)The amino acid content of A1 and A2 of early maturing rice varieties ranged from 318.97-2204.26 μmol/mgprot,and that of B1 and B2 of late maturing rice varieties ranged from 647.24-2889.48 μmol/mgprot.All the four rice varieties showed a gradually increasing trend with the postponing of grain filling stage.A3,A4 and B3 showed a trend of decreasing first and then increasing,and all reached the peak values in T3 stage,which were 2437.07 μmol/ Mg Prot,3278.44 μmol/Mg Prot and 1393.57μmol/ Mg Prot,respectively,and the contents of amino acids increased to different degrees with the delay of time.B4 increased first and then decreased with the delay of grain-filling time,while B5 and B6 showed a downward trend all the time.The highest amino acid contents at T1 stage were 3422 μmol/mgprot and 5229.21μmol/mgprot,respectively.(2)The changes of soluble sugar content in rice varieties A1,A3 and A4 were the same as the changes of amino acids,which all showed an increasing trend or a decreasing trend first and then an increasing trend.The peak values of A1 and A3 were 26825.43 μg/g and 34354.83 μg/g at T3 stage,and the peak values of A4 were27382.63 μg/g at T1 stage.The soluble sugar content of A2 was the same as that of A3 and A4 cultivars,and reached the highest at T3,26825.43 μg/g,with significant difference among cultivars.However,the change of soluble sugar content of the late maturing rice varieties was different from that of the early maturing rice varieties.All the six rice varieties showed a decreasing trend.The highest values at T1 stage were15785.27μg/g,14664.74μg/g,14714.42μg/g,16113.40μg/g,14038.34μg/g,14793.07μg/g,respectively.(3)The content of ascorbic acid in early maturing rice varieties A1,A3,A4 and late maturing rice varieties B1 decreased significantly with the delay of grain-filling time.The content of ascorbic acid in T1 reached the peak of 1076.34 gprot/L,1468.43gprot/L,1574.28 gprot/L,800.98 gprot/L,while the other varieties showed a trend of increasing first and then decreasing,and the content of ascorbic acid reached the peak at T2.The peak values of A2-B6 varieties were 1992.11 gprot/L,778.56 gprot/L,1077.45 gprot/L,588.95 gprot/L,754.78 gprot/L,656.24 gprot/L,respectively.(4)The soluble protein content of early and late maturing rice varieties decreased gradually with the delay of time,and reached the peak value at T1,A1-A4 were 17.05μg/prot,18.60 μg/prot,26.52 μg/prot,28.16 μg/prot,respectively.The peak values of B1-B6were9.44 μg/prot,9.92 μg/prot,10.51 μg/prot,12.08 μg/prot,9.47 μg/prot,8.34μg/prot,respectively.(5)Amino acids in leaf carbon and nitrogen metabolites had extremely significant or significant effects on amylose,brown rice percentage,gel consistency,mitten rice percentage,and grain weight,grain number per panicle,plant height,grain number per panicle and total grain number per panicle of yield components.Soluble sugar had significant effects on rice quality and yield,and had significant effects on whole melled rice percentage,melled rice percentage,transparency,grain weight,seed setting rate,grain number per panicle and solid grain per panicle,and had extremely significant effects on brown rice percentage,amylose content and total panicle number.Ascorbic acid had no significant effects on rice quality and yield,but had significant effects on milled rice percentage,length-width ratio of rice,unfilled grain per panicle and total grain per panicle,and had extremely significant effects on grain per panicle and grain number per panicle.Soluble protein had significant effects on chalkiness,chalkiness grain percentage,whole milled rice percentage,seed setting rate,grain weight,grain number per panicle and transparency,and had extremely significant effects on grain per panicle.