[Regulation effects of various training modes on source-sink relation of cotton]

With the removal of vegetative branches plus the maintenance of early fruiting branches as the control, the effects of various training modes on the source-sink relation of field-grown cotton were examined in 2005 and 2006. The results showed that compared with the control, either the removal of vegetative branches plus the removal of early fruiting branches (I), the maintenance of vegetative branches plus the removal of early fruiting branches (II), or the maintenance of vegetative branches plus the maintenance of early fruiting branches (III) could increase the leaf area per plant significantly, with the average maximum LAI across the two years increased by 10.3%, 28.3%, and 9.5%, respectively, and resulting in the decreases of the load per leaf area and the ratio of sink to source. I and II alleviated the leaf senescence of cotton plants as indicated by the enhanced leaf chlorophyll content and the reduced percentage of yellow leaves and C/N ratio of functional leaves, and II also induced the late-maturing of cotton plants. III had no significant effects on senescence alleviation. I produced approximately equal seed cotton, but II and III produced 6.4%-15.6% less and 6.3% more seed cotton than the control, respectively. It was concluded that either the maintenance of vegetative branches or the removal of early fruiting branches could be an effective pathway to regulate the ratio of sink to source, C/N, and maturity performance of cotton plants.