تاثير تاريخ كاشت بر عملكرد و اجزاي عملكرد سه رقم پنبه در گرگان

Effects of planting date on yield and yield components of three cotton cultivars

In order to study the effects of planting date on yield and yield components of three cotton cultivars, an experiment was conducted in 2000 at Research station of cotton, Gorgan, Hashem-Abad. Three cotton cultivars, Sahel, Siokra and Deltapain were compared in a randomized complete block design with four replications as splitplot experiment in four planting date (24 April, 9 and 25 May and 9 June). Delayed planting date became the cause of decreased of yield, number of boll in plant, weight of boll and weight of 100-seed. Yield of second planting date as compared with first planting date, the thired planting date as compared with first and fourth planting date as compared with first planting decreased 16, 24 and 43 percent with delaying planting date, respectively. In lieu of, each day of delayed planting date from the 24ʹ of April till the 9" of June the yield of Sahel 50 kg in hectare, Siokra 24 kg in hectare and Deltapain 42 kg in hectare decreased, respectively. Among the yield components the number of boll had high correlation with yield. The Siokra had the highest yield in hectare by including the most boll in plant. With delayed planting date, the number of boll in plant decreased. Among the cultivars, Siokra had the least weight of boll as compared with two other cultivars. But the relative sensitiveness of the Siokra weight of boll to the planting date was less than two other cultivars. The results of this research indicate that higher yield for desired aequisition obtain at 24 April and in delayed planting dates Siokra produces higher yield as compared with two other cultivars. In other words, Siokra adapts itself better with the conditions of different environments and produces higher yield as compared with two other cultivars in delayed planting dates.