Analysis On Yield Component Factors In Insect-resistance Hybrid Cotton "BiaoZa A₁" And It's Necessary Cultivation Measure

The comprehensive contribution effects to the yield of insect-resistance hybrid "BiaoZa A₁"was studied by using the design of orthogonal regression rotation of four factors and five levels. The four main agronomic measures were planting density, N application(including P,K), DPC's dosage and fruit branches remaining on leaf branches in cotton cultivation. The results showed that: (1) lint cotton yield changed from 1609.5 to 2337.0Kg. hm^-2, the four cultivation facts all had extremely significant effect on lint cotton yield; boll numbers per ha changed from 692400 to 1073250; single boll weight changed from 4.38 to 5.71 g and the lint percent changed from 41.0 to 42.8%. Different treatments had extremely different effect on yield component factors; (2) According to mathematical model established by lint cotton yield, in 95% confidence interval, when lint cotton yield is more or equal to 2100Kg. hm^-2, agronomic measures comprehensive decision-making should be: planting density 2.151-2.3475 ten thousand individual plant per ha; pure N application 441-463.05 Kg(including P₂O₅ 245.4-267.45Kg,K₂O 245.4-267.45Kg), DPC's dosage 57.45-68.55g, remaining 12.55-13.9 fruit branches on leaf per individual plant. (3) Regarding lint cotton yield model, fixing the random three factors in the zero level, we obtain separately the most appropriate density is 28605 individual plants per ha, most suitable N application is N 240.8Kg.hm^-2, P₂O₅ 120.4Kg. hm^-2 and K₂O 20.4Kg.hm^-2, most suitable DPC's dosage is 71 gram, remaining 7.1 fruit branches on leaf branches per individual plant. (4) Results of path analysis showed that the primary influencing factor to lint cotton yield was bolls per ha(P_1-Y=0.8386), single cotton ball weight ranked the second(P_2-Y=0.4052) and the direct contribution effects of the lint percent was smallest (P_3-Y=0.0875) in yield component factors studied. The information from the above analysis showed: in the technique of breeding and cultivation of "BiaoZa A₁", the main attack direction should be reducing planting density suitably, increasing fertilizer utilization and enhancing bolls per ha with every effort in order to get high lint cotton yield. According to study on the above optimum combination model of main agronomic measure, the corresponding high-yielding way of "BiaoZa A₁" was proposed.