Characteristics And Adaptability Of High-yielding Varieties Of Direct Seeded Early Rice In Different Ecological Regions

The study aimed to explore the characteristics of high and stable yield of double-season mechanical direct seeding early rice varieties,and to screen out a batch of early indica rice varieties suitable for mechanical direct seeding in Jiangxi double-season rice region,which provided theoretical basis for breeding and cultivation of southern double-season mechanical direct seeding rice varieties.With 21 early indica rice varieties as experimental materials,artificial mechanical direct seeding was carried out in three different ecological regions of Jiangxi province(North Jiangxi,Central Jiangxi and South Jiangxi).Cluster analysis,combined variance analysis and GGE biplot were used to systematically study the high and stable yield characteristics of double-season mechanical direct seeding early indica rice varieties.The main research results are as follows:The yield of different cultivars was significantly affected by genotype,environment and interaction effect.Cluster analysis of yield of tested varieties in each ecological region showed that high-yield varieties in North,Middle and South Jiangxi accounted for38.10%,19.05% and 23.81% of the total,respectively.Tan Liangyou 83 had the highest yield and the best stability,followed by Wufengyou 286 and Zhuliangyou 171 varieties,and Yong 3 Youhuazhan had the lowest yield,while Liangyou 287 had good high yield but poor stable yield.Duncan’s new repolarization difference multiple comparisons showed that Tanliangyou 83,Lingliangyou 722,Yongyou 9380,Zhuliangyou 39,Zhuliangyou 538 can all adapt to the three ecological regions better,and the comprehensive evaluation is the best.Linear regression model analysis showed that the variation degree of Poyang pilot project was the smallest,and Tan Liangyou 83,Wu Fengyou 286,Zhu Liangyou 171 and Yong You 9380 had the best high and stable yield in the three pilot projects.Yield is positively correlated with effective panicle,grain number per panicle,total spikelet number and daily output,and each correlation coefficient of high-yield varieties is greater than that of medium-yield and low-yield varieties.Path analysis showed that 1000-grain weight and daily output of high-yield varieties had the greatest direct effect on yield.Compared with medium and low yield varieties,the effective panicle,grain number per panicle and total spikelet number of high yield varieties increased significantly,and 1000-grain weight and daily output had significant advantages.It showed better ability of early growth and rapid development.The tiller growth rate,peak seedling number and panicle formation rate were significantly increased,and the tiller decline rate was significantly reduced.Dry matter production at heading stage and maturity stage was significantly higher for high-yield varieties than that for medium and low-yield varieties,and high-yield varieties have significant advantages in dry matter output rate,apparent conversion rate and apparent conversion rate.For high-yield varieties,LAI was significantly higher than that of medium-yield and low-yield varieties,indicating a large photosynthetic area.The plant type is compact,the upper three leaves are reasonably arranged,and the solar radiation utilization rate is high.The characteristics of high chlorophyll content,slow leaf senescence,better light energy utilization efficiency of the population,stable supply and transportation of photosynthetic products and the like lay a material foundation for high yield of direct seeding rice.In conclusion,under the condition of machine direct seeding,the early indica rice varieties with high and stable yield had the characteristics of moderate growth period,good early onset,high tillering and ear formation rate,large total spikelet number,large dry matter production after flowering,high dry matter output and transportation efficiency,and high daily output,etc.According to the comprehensive characteristics of various varieties,Tan Liangyou 83,Wu Fengyou 286,Zhu Liangyou 171 and Yong You9380 had good high yield and stability,and moderate maturity,which was suitable for direct seeding of early rice in Jiangxi double cropping rice region.