膜下滴灌对棉花根系、地上部分生物量及产量的影响

通过膜下滴灌田间试验，采用根钻双向采样法，研究了不同灌溉量（2618、2947、3600和4265 m³·hm^-2）对棉花根系分布、地上部分生长及产量的影响.结果表明：不同灌溉量影响棉花根系及地上部分生长状况.各水分处理棉花根系主要分布在膜下，占根系总生物量的60.65%～73.45%，而膜间占39.35%～26.55%.水分亏缺增加了根系下扎深度和深层根系生物量，增大了根系水平分布范围.不同水分处理棉花生物学特性及干物质累积与分配存在显著差异.水分过量处理（4265 m³·hm^-2）的棉花株高、倒四叶宽、果枝数、蕾数均增加，干物质积累速率加快，根冠比及干物质在营养器官中的分配比例增大，生物产量提高，但同时蕾铃脱落率也增加，经济产量的形成受到抑制.水分亏缺或过量都影响棉花干物质在不同器官及不同生育时期的累积与分配,使产量降低.本试验条件下3600 m³·hm^-2是最适宜的灌溉量.

Effects of drip irrigation under mulching on cotton root and shoot biomass and yield.

By using bidirectional sampling method with soil drill, the effects of different amounts of drip irrigation (2618, 2947, 3600 and 4265 m3·hm-2) under mulching on the root distribution, aboveground growth, and yield of cotton was studied in field. The results indicated that irrigation amount affected the root and shoot growth significantly. In all irrigation treatments, cotton root was m ainly distributed in mulched area, occupying 6065%〖KG-*2〗-〖KG-*7〗7345% o f total root biomass, while only 3935%〖KG-*2〗-〖KG-*7〗2655% was distribut ed in bare area. Water stress increased rooting depth, root biomass, and the ext ent of lateral rooting. Significant differences were observed in the biological characteristics and the biomass accumulation and allocation of cotton plant amon g different irrigation treatments. Over-irrigation (4265 m3·hm-2) incr eased plant height, width of inverse fourth leaf, and amounts of branch and bud, and thus, accelerated biomass accumulation rate. Over-irrigation also increase d the root/shoot ratio and the proportion of biomass allocated to vegetative org ans, but increased the fruit abscission rate and therefore reduced the economic yield. It was suggested that both excessive soil moisture content and water stre ss could affect the biomass accumulation and allocation in different cotton orga ns and at various life stages. Under the conditions of our experiment, 3600 m3 ·hm-2 was the optimal irrigation amount.