Effects of DPC on Agronomic Traits and Economic Characters of Machine-Harvested Cotton in the Yellow River Valley of China and Chemical Control Techniques

[Objective] The aim was to investigate the effects of DPC chemical controlling technique on agronomic traits, yield and quality of machine-harvested cotton in the Yellow River Valley of China, and clarify the reasonable control period and the application amount of DPC. [Method] The new machine-harvested cotton variety Hengmian HD008 was used as the test material, and 3 different DPC treatments were set. [Result] DPC significantly reduced plant height and branch length, reduced branch angle and leaf area, so the rational control can effectively shape the ideal plant type of machine-harvested cotton. DPC had significant effects on yield and yield components, and the proper amount of DPC could increase the number of bolls during hot days, the number bolls in autumn and the total number of bolls. It increased the boll weight and seed index, but decreased lint percentage decreased, and proper amount of DPC could increase the yield. DPC significantly increased the specific breaking strength of fibers, and proper control could improve the uniformity of fibers, but other indexes had no significant influence. [Conclusion] According to the requirements of machine harvest to the agronomic traits of cotton and the growth characteristics of cotton plant, chemical control could begin after floral bud emergence in cotton about every 10 d, and the spraying amount can be controlled according to the growth amount of the main stem. The daily growth amount of plant height should be controlled at 1.5-1.8 cm, and the plant height should be within 75-90 cm.

Breeding of Good-quality High-yield Salt-tolerant and Drought-resistant Hybrid Cotton Variety Hengyou 12

Salt and drought tolerance, high yield and quality, disease and pest resistance of cotton varieties are new requirements for the current situation in cotton production. Hengyou 12 is a transgenic Bt cotton variety bred by hybridizing JD 28 （interspeciflc progeny of upland cotton, sea-island cotton, wild cotton species） as female parent with GK55 （transgenic Bt cotton variety） as male parent. The combining of parents was based on the complementary principle of parental traits. Hengyou 12 with strong heterosis was selected under disease stress, pest stress, salt stress and drought stress. This variety has many excellent characteristics, such as good resis- tance to diseases and pests, high yield, excellent quality, strong drought resistance and salt tolerance. ＇Hengyou12＇ was approved by Hebei Province in 2015, and is suitable for planting in middle and south areas of Hebei and similar ecological areas in the Yellow River basin.