Successional Analysis Of The Major Agronomic Trait And Disease Resistance Of Japonica Rice Varieties In Jiangsu Province

Rice is one of the three most important grain crops in China.High yield of rice is one of the effective ways to ensure food security in China.Breeding new rice varieties with high yield and comprehensively analyzing their main yield characters and resistance characteristics can provide reliable experimental data for the popularization of new varieties and scientific basis for breeding new rice varieties.In this study,the data of 91 conventional japonica rice varieties approved by Jiangsu Province during the 10 years from 2008 to 2017 were extracted and analyzed,including yield and yield components,resistance to blast,sheath blight and bacterial blight.All the results are as follows:1.The yield level of middle-maturing late japonica rice varieties increased gradually,and the positive correlation between yield and seed setting rate was significant.The key factor was the increase of seed setting rate.How to increase the number of solid grains,effective panicle and 1000 grain weight is the main attack direction in the breeding of new varieties of mid-late maturing japonica rice.2.The yield level of early-maturing late japonica rice varieties increased gradually,and the positive correlation between yield and effective panicle,seed setting rate and1000-grain weight was significant.The main factors were effective panicle,seed setting rate and 1000-grain weight.How to increase the number of grain per panicle was the main direction of early-maturing and late-maturing japonica rice varieties breeding.3.The yield level of late-maturing medium-japonica rice varieties increased gradually,and there was a significant positive correlation between the yield and the number of grains,seed setting rate and 1000-grain weight.The main factors were the number of grains,seed setting rate and 1000-grain weight.How to increase effective panicle is the development direction of late maturing medium japonica rice breeding.4.The yield level of middle-maturing medium-japonica rice varieties increased gradually,and the yield was positively correlated with effective panicle,seed setting rate and 1000-grain weight,but negatively correlated with the number of real grains.How to increase effective panicle,seed setting rate and 1000-grain weight was the development direction of medium-maturity medium-japonica rice varieties breeding.5.There was a positive correlation between the yield,plant height and growth period of middle-maturing late japonica rice varieties;The yield of early-maturing late japonicarice varieties was negatively correlated with plant height and growth period,and plant height was positively correlated with growth period;The correlation coefficients of yield,plant height and growth period of late-maturing medium-japonica rice varieties were negatively correlated;the yield of middle-maturing medium-japonica rice varieties was negatively correlated with plant height and growth period,and plant height was positively correlated with growth period.6.Among the 91 conventional japonica rice varieties examined and approved by Jiangsu province,16 varieties were resistant to rice blast,accounting for 17.6%.There were15 varieties resistant to rice leaf blight,accounting for 16.5%.There were 20 rice sheath blight resistant strains,accounting for 22%.But only 6(6.6%)were double or multiple resistant.It can be seen from the data that the comprehensive resistance of new japonica rice varieties approved by Jiangsu Province is not ideal,and there is great room for improvement in resistance.