Effects Of Variety And Density On Cotton Boll Formation And Boll Internal Yield Composition

In order to clarify the influence of varieties and planting density on the formation of cotton yield under the one-film three-row planting mode,the experiments were conducted at the Xinjiang Alar Experiment Station(40°51′N,81°30′E)of the Cotton Research Institute of the Chinese Academy of Agricultural Sciences from 2020 to 2021.E)Carry out a two-factor split-plot test,with the variety as the main plot(P1zhong 641 and P2 zhong 88),and the planting density as the secondary plot(set 3 density treatments,M1:12×104 plants/hm2,M2: 18×104 plants respectively)/hm2,M3: 24×104 plants/hm2),set up 3 repetitions to study the effects of different varieties and densities on cotton agronomic indicators,dry matter accumulation,canopy structure,boll formation law,yield unit and quality,etc.The following conclusions:(1)Planting density significantly affects the plant height,the number of fruit branches per plant,and the number of fruit nodes per plant.The single plant structure of cotton at high density became more compact,the plant height,number of fruit branches,number of fruit nodes,and the first node of fruit branches were significantly lower than those of low-medium-density cotton,and the organ shedding rate was higher than that of low-medium-density cotton,and too high a population was not conducive to shaping good plant type.The dry matter accumulation in the two years showed an "S"-shaped curve change.The M3 density treatment of the two varieties gave play to the group advantage,and the total dry matter content was significantly higher than that of the M1 and M2 density treatments throughout the growth period.The increase in planting density can effectively increase photosynthesis.However,due to the fierce competition between individuals and the imbalance of nutrient distribution,the high-density population did not achieve the ideal yield;the simulation results of dry matter accumulation of the two varieties showed that the planting density was set at 12×104 plants/hm2.Dry matter accumulation per plant was 93.11 g/plant(2020)and 73.94 g/plant(2021)for P1M1,and 77.54 g for P2M1./plant(2020)and 104.05 g/plant(2021),the duration of rapid accumulation will be prolonged due to the increase of planting density.(2)The leaf area index increased with the increase of planting density.The leaf area index of all treatments reached the maximum in the full bloom period.The M3 density of the two varieties maintained the highest level of leaf area index throughout the growth period.Effectively maintain the leaf area index of the later group to ensure the accumulation of photosynthetic products in the later period.The results of light interception curve fitting also show that the peak light interception of the cotton group appears in the full bloom period,and increasing the planting density is conducive to the interception of light energy in the later group.(3)The smaller the planting density is,the more favorable the upper fruiting branches are to form bolls and flocks.The higher the planting density,the greater the contribution of the lower bolls to the bolls of a single plant,and the smaller the proportion of peripheral bolls;varieties have different effects on the weight and lint of single bolls in different parts.Very significant effect.Density had no significant effect on the single boll weight of the lower bolls,but significantly affected the single boll weight of the middle and upper bolls.The planting density had no significant effect on the lint of different parts.Correlation analysis showed that the planting density had a very significant positive correlation with the lower bolls,the inner bolls and the Fuqian peach,and had a significant positive correlation with the middle bolls and Fuqian peach.moderate increase in the planting density could increase the lower bolls,the middle bolls,the middle bolls,and the peach.The number of bells,futao and fuqiantao in the group.(4)Low-density planting can obtain more seeds.The effect of planting density on seed index,seed surface area,single seed lint weight and single fiber weight is not significant.Correlation analysis shows that increasing the number of seeds inside the boll can effectively increase the number of seeds.Lint weight,fiber density and lint.The number of bolls per plant and the weight of each boll decreased gradually with the increase of planting density.The seed cotton yield of P1 two years showed a trend of first increase and then decrease with the increase of planting density.Among them,the medium-density M2 group achieved the highest yield in two years.5 724 kg/hm2(2020),5 833 kg/hm2(2021),the results of P2 varieties are different in two years,the highest yield of M3 density treatment is 5 157 kg/hm2 in 2020,and the highest yield of M2 treatment in 2021 is 5 679 kg/hm2,the two-year change is inconsistent,and the reason is analyzed,and the P2 variety may be more sensitive to weather changes.Correlation analysis showed that yield was significantly positively correlated with single seed cotton weight and seed index,and extremely significantly negatively correlated with single boll seed number,indicating that seed index and single seed seed cotton weight determined yield,and single boll seed number More may result in loss of production.Variety,planting density and position of fruit branches have different effects on cotton quality.Variety has a very significant effect on all quality indicators,indicating that variety is the main factor affecting quality.the elongation rate is the best,except for the elongation rate,other quality traits are not significantly affected by the density.