Technical System of Hybrid Seed Production with Perennial Plants of Cotton Sterile Lines

Abstract

It is hard to separate maintainer line and sterile line in two-line-system hybrid breeding, so half of the fertile plants derived from maternal line should be pulled out at bud stage, which increases the cost of seed production and the risk of hybrid seed purity. In this research, taking advantage of specific weather conditions of warm winter and dry winter-spring season in the mid-subtropical zone, we explored hybrid seed production with overwintered perennial sterile plants after eliminating the 50% fertile plants from the nuclear sterile line in the first year. From 2006 to 2011, we investigated various factors that might influence hybrid seed production with perennial cotton sterile plants, including different ages of perennial root, winter-season intercropping of rapid cycling vegetables, pruning times and pruning methods. The results indicated that the perennial plants had extended growth period , its reproductive growth stunted 10 days earlier than that of seedlings with corresponding sowing time, its boll number per plant was significantly higher, while boll weight was slightly lower. The hyrid seed yield in firstand second-year perennial plants was 10.3% to 5.9% higher than that in one year plants. The yield showed non-significant reduction in the third year of prennial production, but significantly reduced by 9.4% to 14.0% in the fourth to fifth years. With the increase of overwintering years, the old root at the basal portion of the plant showed obvious malformation. Within the first five years, the death rate of perennial plants had no relationship with ages of perennial root and field types, but was related to soil water content and pruning methods. The best way for perennial root onverwintering was: no intercropping between winter cotton lines and othen 第 12期 张小军等: 利用宿根进行棉花不育系制种的技术体系研究 1837 crops, no pruning, and leaving the cotton plants in the field for natural overwintering. In the next year, the main stem and early regenerated buds should be pruned at 10 cm above the ground before the rainy season or the first irrigation, then one or two regenerated primary buds should be reserved with water and nutrition managements.