Study On The Relationship Between Growth And Yield Of Summer Direct-seeded Hybrid Rice And Density Of Seedlings In Field

The key to study the effect of different planting densities on the growth and yield of summer direct-seeded hybrid rice in hilly rice fields in northeastern Sichuan,field experiments were performed using 32 hybrid rice varieties as materials.The test set five kinds of field density(the number of remaining seedlings per unit area in the three-leaf stage of direct-seeded rice seedlings),namely T1-7000 plants / 667 ?,T2-10500 plants / 667 ?,T3-14000 plants / 667 ?,T4-17500 Plants / 667 ? and T5-21000 plants / 667 ?,the growth and development,economic traits and yield levels of the tested rice varieties under different treatments of seedling density were analyzed and compared.The differences classified the tested varieties.The main results are as follows:1.There were differences in the occurrence rate and number of stem borer in hybrid rice under different densities of seedling retention.The peak occurrence time of the tiller number per hybrid rice advances with the increase of the number of retained seedlings,and the final effective tiller number decreases with the increase of the density of the retained seedlings;Density increases ahead of time.Too high and too low seedling density will lead to an increase in invalid tillers per unit area,and the proportion of invalid tillers will be the lowest at a density of 10500 plants per 667 square meters.2.The density of retained seedlings has an important effect on the panicle structure of hybrid rice.At different seedling densities,the average effective tillering ratio of hybrid rice was secondary tillering> primary tillering> main stem> third tillering,and its second tillering number> first tillering number> third tillering number.The number of primary tillers and the number of secondary tillers decreased as the density increased.Compared with T1,the number of primary tillers in the other four treatments decreased by 16.1%,35.5%,38.7%,and 58.1%,respectively;the number of secondary tillers decreased,respectively.25.9%,28.2%,45.9%,60.0%;the proportion of primary tillering and secondary tillering varies irregularly with density;tertiary tillering is almost non-existent or very small,and a few varieties have tertiary tillering ears at low seedling density.At high seedling densities,all varieties did not have three tillers.3.The effect of seedling density on yield traits was: compared with T1 treatment,the effective panicle number per unit area increased by 27.3%,and the number of grains inserted,the number of solid seeds,the seed setting rate and the weight per ear decreased by 3.03%,4.54%,1.5%,and 5.4%;the effective ears per unit area increased by 41.8% under T3 treatment,and the number of grains inserted,the number of seeds,the seed setting rate and the weight per ear decreased by 9.2%,10.2%,1.1%,and 10.5%,respectively;T4 The effective ears per unit area increased by 48.4%,and the number of grains per seed,number of seeds,seed setting rate and weight per ear decreased by 13.4%,14.3%,1.1% and 14.0% respectively;the effective ears per unit area increased by 43.6% under T5 treatment.,The number of grains inserted,the number of solids,the seed setting rate and the weight per ear decreased by 18.5%,19.5%,1.0% and 19.5%,respectively.4.Seedling density treatment has a significant effect on rice yield,but the yield response to density of different varieties differs.Under 5 density treatments,the average yield of the tested varieties was T4,which was 9440.6 ? / hm2,and the rest were the yields treated by T3,T5,T2,and T1,which were 9307.1kg / hm2,9174.8kg / hm2,respectively.9024.0kg / hm,8445.8kg / hm2.Among them,T1 was significantly lower than the other 4 treatments,and T2 was significantly lower than the T4 treatment.Among the 32 tested varieties,2 varieties had the highest production density corresponding to T1 treatment,4 varieties had the production density corresponding to T2 treatment,and 15 varieties had the highest production density corresponding to T3 treatment.There were 9 varieties The corresponding density of the highest yield was T4 yield,and the corresponding density of the highest yield of the two varieties was T5 treatment.It shows that under the conditions similar to the experimental conditions,the density of seedlings in the field of summer direct-seeding cultivation of most hybrid rice varieties should be in the range of 14000-17500 plants / 667m2.Too large or too small may affect their yield levels.5.Correlation analysis showed that the correlation between yield and yield traits of hybrid rice showed the same trend under different treatments of seedling density.Yield was positively correlated with effective panicle,thousand-grain weight per panicle weight and seed setting rate,and with the number of grains and the number of grains.The number was negatively correlated,and the path analysis also showed that the effective ear,grain number and grain number had a greater direct effect on yield,but the contribution rate to yield was different under different seedling density treatments.The results of this study can provide a clear reference for the determination of reasonable planting density and selection of varieties of direct-seeded rice in the summer in the hilly rice region of northeastern Sichuan.