棉花氮素营养特性研究进展

目的研究长期不同施氮量、绿肥还田及耕作方式对棉花生长、产量和品质的影响，以期为棉株生长的最佳土壤和养分管理提供技术支撑。方法2013年在美国田纳西大学西部试验站的长期定位试验点 (1981至今) 进行三因素裂区试验，即：主区为施氮量，共设4个不同施氮量处理 (0、34、67和101 kg/hm²) ；覆盖作为裂区，设不覆盖和覆盖豆科绿肥(毛苕子)处理；耕作方式为再裂区，设免耕和传统耕作处理。测定不同处理下棉株不同生育期生物量及皮棉产量和纤维品质。结果在不覆盖毛苕子情况下，棉花早期生长时的生物量和皮棉产量随施氮量的增加而增加；施氮量高于67 kg/hm²处理下，棉花的皮棉产量和品质并未表现出较好的结果。在覆盖毛苕子后，与传统耕作相比，免耕可显著增加棉花皮棉产量，棉花纤维长度则显著减小。结论在不覆盖毛苕子的情况下，适氮 (67 kg/hm²)对促进棉花早期生长、增加棉花产量和减少生产投入有十分显著的作用。长期免耕并配合绿肥覆盖这一措施可以在棉花生产上进行推广运用以提高产量。

Soybean cultivar performance as influenced by tillage system and seed treatment

PurposeTo study the effects of long-term different nitrogen application rates, green manure, and tillage on cotton growth, yield, and quality in order to provide technical support for the optimal soil and nutrient management of cotton growth.MethodTreatments of four N rates (0, 34, 67, and 101 kg/hm²) under two cover types (no cover and cover with hairy vetch) and two tillage systems (no-tillage and conventional tillage) with four replications from a long-term field trial at the University of Tennessee West Tennessee Research and Education Center, U.S.A which was established in 1981 were used in 2013 to determine plant biomass, lint yield, and fiber quality of cotton.ResultUnder no cover, the biomass at the early growth stage and lint yield of cotton increased with the increase of nitrogen application rate. The lint yield and fiber quality of cotton didn’t show better results when the nitrogen application rate was higher than 67 kg/hm². Compared with traditional tillage, no-tillage increased cotton lint yield significantly but decreased fiber length.ConclusionUnder no cover, 67 kg/hm² is the optimal nitrogen application rate which improves plant early growth and yield of cotton with hairy vetch; meanwhile, it decreases the production costs of cotton. Use of long-term no-tillage integrated with a cover crop may be used in cotton production for increasing cotton yield.