Studies On Key Cultivation Techniques For Direct Sowing Cotton Planted After Wheat Havest Based On Mechanical Harvesting In Cotton

The study was conducted at the experiment station of the Jiangsu Provencial Key Laboratory of Crops Genetics and physiology, Yangzhou University, during2011-2012cotton seasons. Using cultivar Guoxinzaoll-1as main material, the cotton planting pattern was seeding directly after the wheat harvest, the study was focused on key techniques of the planting pattern, including sowing density, chemical control and nitrogen fertilizer application, the growth and development characteristics were also investigation. The objective of this study was to provide basic theory and technical guidance for mechanized seeding and harvesting of direct sowing cotton planted after wheat harvest. The main results were as follows:1.The yield and fiber quality characteristics under different density, chemical control and the nitrogen fertilizer rates for direct sowing cotton planted after the wheat harvest.The seed cotton yield was more than236.75kg/666.7m2and lint yield was more than78.61kg/666.7m2under planting density at6000-7000plants/666.7m2and chemical control Miantaijin rates at78ml/666.7m. The chemical control rates at78ml/666.7m2could improve the fiber length, specific strength and uniformity, however, micronaire value also increased. The highest seed cotton yield was at228.93kg/666.7m2under nitrogen application at10kg/666.7m2, and corresponding lint yield was at80.11kg/666.7m2. The fiber quality was also improved under this level of nitrogen application.2. The growth and development characteristics under different density, chemical control and the nitrogen fertilizer rates for direct sowing cotton planted after wheat harvest.Under the chemical control at78ml/666.7m2, planting density at6000-7000plants/666.7m2, the plant height was at80-120cm, boll-branch length (17-20cm), the first boll-branch height (>15cm) and number of boll-branch (9-10), these growth indeies were better for mechanical harvesting; The appropriate nitrogen fertilizer rate can help to increase plant height, leaf number, the number of boll-branch, groups squaring amount and groups boll number, and is also better for mechanized harvesting. The squaring of the population is concentrated in the7/16(squaring stage) to7/31(early flowering), and boll number of groups are mainly concentrated in8/16-9/20, under the chemical control at78ml/666.7m2, planting density at6000-7000plants/666.7m2, nitrogen application at10kg/666.7m2. It laid the foundation for mechanical harvesting after centralized boll opening.3. The physiological activity characteristics under different density, chemical control and the nitrogen fertilizer rates for direct sowing cotton planted after wheat harvest.The physiological activity determination of main stem function leave showed that:The results of the correlation analysis showed that number of boll before9/20, with the SPAD of peak square period and early flowering period, SPAD of peak flowering period, showed significant positive correlation(under different density and chemical control the correlation coefficients were r7=0.787**、r8=0.800**、r9=0.802**, under different nitrogen fertilizer the correlation coefficients were r10=0.988**、r11=0.923*、r12=0.915*). There are best SPAD under the chemical control at78ml/666.7m2, planting density at6000-7000plants/666.7m2, nitrogen application at10kg/666.7m2; There are a significant positive correlation(under different density and chemical control the correlation coefficients were r13=0.708*、 r14=0.723*、r15=0.672*、r16=0.691*, under different nitrogen fertilizer the correlation coefficients were r17=0.883*、r18=0.949*、r19=0.886*、r20=0.999**) the number of boll in stage of concentrated into a bell from8/16to9/20and the soluble sugar content in early square period、peak square period、early flowering period and peak flowering period; Soluble protein and amino acids promote the groups squaring and boll under planting density at6000-7000plants/666.7m2, the chemical control at78ml/666.7m2, nitrogen application at10kg/666.7m2. Because they gradually increased in peak flowering period and boll opening period, it is better to concentrated into a bell with focused on the supply of reproductive organs.The rate of defoliation and boll opening rate was significantly higher than the control treatment in spraying of defoliation and ripening agent, but also defoliation ripening agent has no effect on the germination emergence for next crop seed.