بررسي اثرات تاريخ كاشت بر فنولوژي و مرفولوژي سه رقم پنبه در گرگان

Effects of Planting Date on the Phenology and Morphology of Three Cotton Cultivars in Gorgan

Planting date is the most important factor influencing most physiological and morphological particulars of plant. Proper planting dates cause the created environmental conditions during the days of emergence, settlement and seedling be desirable for plant. Sahel, Siokra and Deltapain cultivares were sowed on 4ʹh of May, 19ʹh of May, 4ʹʹʹ of June and 19ʹxʹ of June in a split plot experiment in the form of randomized complete block design, with 4 replications. The main factor included planting dates while the secondery factor included cotton cultivar. Five stages of plant phenology (sowing to 100% emergence, 100%emergence to 50% squaring, 50% squaring to 50% flowering, 50% flowering to 50% bolting and 50% balling, open bolls) were studied on the basis of number of days and growing degree days (GDD). With delayed planting date the number of needed days from sowing to emergence, emergence to squaring decreased, but the number of needed days from squaring to flowering, flowering to bolting increased. Bolling periods to opening bolls was alike in all planting dates. With delayed planting date GDD decreased from sowing to 100% emergence but in other stages of phenology with delayed planting date GDD increased. Planting dates dii not have a significant effect on the number of vegetatives branches and the height of plants but number of fruiting branches were influenced by planting dates so that with delayed planting date the number of fruiting branches increased. Also, there werenʹt significant differnces among cultivars for height and fruiting branch number, but for vegetative branch number they were different with Siokra cultivar carrying the most vegetative branches.