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近几年来,美国试种棉花窄行密植,行距由原来100厘米左右改为20—40厘米,每亩株数由2600—8000株增加至30000株以上。据估计,1971年得克萨斯州平原地区种植窄行棉花12万亩,1972年种植30万亩,1973年准备种植60万亩以上。目前,培育出适合窄行密植的棉花新品种只有“矮秆佩马斯特”。美国育种者正在努力培育适于其他地区窄行密植的棉花新品种。棉花窄行密植的优点是:(一)缩短结铃期,使棉花生育期从175—225天减为135天左右。密植棉花结铃时间不到一星期,而一般棉花至少需四星期。由于密植棉花成熟期一致,因而提高了棉花纤维的质量。(二)窄行密植棉花一般每株结桃3—5个,但由于单位面积株数增加,所以产量显著提高。同时能较好地利用土地的空间和土壤营养。(三)节约灌溉用
In recent years, the United States tried to plant cotton narrow row close planting, spacing from the original 100 cm to 20-40 cm, the number of acres per acre from 2600-8000 increased to more than 30000. It is estimated that in 1971 the Texas plain planted 120,000 acres of narrow-row cotton, planted 300,000 acres in 1972, and planted more than 600,000 acres in 1973. At present, only “Dwarf Pemaste” is bred for new cotton varieties suitable for narrow row and close planting. American breeders are working hard to cultivate new cotton varieties suitable for narrow row planting in other areas. The advantages of narrow row cotton planting are: (1) to shorten the period of bolting and reduce the growth period of cotton from 175-225 days to 135 days. Close cotton boll bell less than a week, while the general cotton at least four weeks. Due to the consistent maturity of the dense cotton, cotton fibers thus improve the quality. (B) Narrow row of densely packed cotton generally peach 3-5 per plant, but due to an increase in the number of units per unit area, so the yield increased significantly. At the same time, better use of land space and soil nutrients. (C) saving irrigation