Effects Of Planting Density On Growth And Development Of Uniformly Sown Winter Wheat

In order to explore the response of uniformly planted winter wheat to planting density in South Xinjiang,the experiment was conducted in the Tarim agriculture experimental station with multiple spike type variety Xindong 22 and large spike type variety Xindong 50 were used as materials,and five plant density of 123/m²,156/m²,204/m²,278/m² and 400/m² which were uniformly sown in the field,the effects of different planting densities on the growth and development of winter wheat of different panicle types,dry matter accumulation,changes and dynamics of operation,grain filling characteristics,yield and its components under the condition of uniform sowing were investigated.The the varieties and optimal planting density of winter wheat were selected.The results are as follows:（1）Under uniform sowing conditions,the total number of tillers of winter wheat populations of different spike-type varieties increased with the increase of planting density,and the fertile tiller rate for the two varieties all showed a downward trend with the increase of planting density.Suitable planting density is conducive to planting fertile tillers.The plant height increased with the planting density increases,and the stem diameter decreases with the increase in planting density.Suitable planting density can reduce plant height,increase stem diameter,and reduce the risk of lodging;internode length,total internode length,and the ratio of internode under the panicle to total internode length,I value,upper three-leaf length,upper-three-leaf width,and upper-three-leaf area all decrease with the increase of planting density,indicating that proper reduction of planting density of winter wheat with different spike types can reduce the length of lower internodes and increase the lower internode proportion of the total length,which is conducive to the even distribution of the upper leaves.The appropriate planting density is conducive to the absorption and utilization of light,and the appropriate planting density can enhance the lodging resistance of winter wheat.（2）Under uniform sowing conditions,the leaf area index（LAI）of winter wheat with different spike types appeares a single-peak curve,and reaches the maximum at the heading stage.Before overwintering,the LAI of winter wheat with different spike types increases with the increase of planting density.After heading,the effects of the plant density on the LAI of different panicle varieties changed significantly.The LAI of both varieties increased first and then decreased with the increase of planting density.The LAI of the multi-spike variety Xindong 22 reahces the maximum at the 1.56×10⁶ plants·hm^-2 treatment,while the LAI of the large-spike variety Xindong obtaines the maximum at the 2.78×10⁶ plants·hm^-2 treatment.The appropriate planting density is conducive to constructing a reasonable population,increasing light interception,promoting dry matter accumulation,and increasing yield.（3）Under uniform sowing conditions,the dry matter accumulation（DMA）of different spike-type winter wheat cultivars showed a gradual increase as the growth development,reaching maximum at maturity.The DMA of different spike-type cultivars before heading increased with the increase of planting density.After heading,the planting density effects on the DMA of different panicle varieties changed significantly.Both panicle varieties showed that the dry matter accumulation first increased and then decreased with the increase of planting density;multi-panicle varieties,Xindong 22,the DMA after anthesis,the contribution rate of dry matter to the grain after anthesis,and the grain yield were the highest in the 1.56×10⁶ plants·hm^-2 treatment,and the large-eared variety Xindong 50 was the highest in the 2.78×10⁶ plants·hm^-2 treatment;the grain yield is closely related to the DMA after anthesis,the appropriate planting density is conducive to the accumulation of dry matter after flowering and the increase in the contribution rate of the grain.（4）The Logistic equation was used to simulate the grain filling process under uniform sowing conditions,and the relevant parameters of winter wheat grain filling of different spike-type varieties were analyzed.The coefficients of determination of the Logistic equation fitting of different spike-type varieties were all above 0.996,which could accurately reflect the grain-filling process;both the two different spike-type varieties,the thousand-grain weight,maximum filling rate,average filling rate,stage grain yield,and stage filling rate of winter wheat at the filling stage showed a downward trend with the increase of planting density,which was the highest under treatment 1.23×10⁶ plants·hm^-2;the thousand-grain weight of wheat was closely related to the maximum filling rate and average filling rate;The stage grain yield is closely related to the stage filling rate,but not to the stage filling duration.Appropriately reducing the planting density can alleviate the intra individual competition and increase individual advantages,which is beneficial to increase the grain filling rate,optimize the filling process,and increase the thousand-grain weight.（5）Under uniform sowing conditions,the ear number of winter wheat with different ear-type varieties increased with the increase of planting density,which was the highest in 4.0×10⁶ plants·hm^-2treatment and the lowest in 1.23×10⁶ plants·hm^-2 treatment;the number of ears and 1 000-grain weight decreased with the increase of planting density,and both cultivats got the highest in 1.23×10⁶ plants·hm^-2treatment,the lowest in 4.0×10⁶ plants·hm^-2 treatment;the grain yield increased first and then decreased with the increase of planting density,and there were significant differences between the two varieties.The multi-spike cultivar of Xindong 22,the yield components was more coordinated at the 1.56×10⁶plants·hm^-2 treatment,and the yield was the highest.The large-spike cultivar Xindong 50 at 2.78×10⁶plants·hm^-2 treatment,the yield composition factors are more coordinated,and the yield is the highest.To sum up,under the condition of uniform sowing in southern Xinjiang,the suitable planting density of multi-spike variety Xindong 22 was 1.56×10⁶ plants·hm^-2,and that of large-spike variety Xindong 50was 2.78×10⁶ plants·hm^-2.