Investigation of Various Levels of Salinity and Irrigation Water on Yield ‎and Yield ‎Components of Cotton (Gossipium hisutum) under Full Irrigation and Partial Root-‎Zone Drying‎

In order to investigate the effect of different methods, levels and salinity of irrigation water ‎on cotton, a two-year experiment was carried out‏ ‏at the Hashemabad Cotton Research Station ‎in Gorgan city.‎‏ ‏The experiment was performed in a randomized complete block design with ‎three replications. So, four salinity levels of irrigation water (1, 4, 8, 12 dS/m) as main factors, ‎four different levels of irrigation water‏ ‏‎(33, 66, 100 and 133% of water requirements) was ‎considered as the first factor and two irrigation methods (complete irrigation and Partial Root ‎Dry irrigation/PRD) were considered as the second factor. The results showed that compared ‎to control, cotton yield decreased by 41%, 22% and 19%, in 12, 8 and 4 dS/m salinity, ‎respectively. The water use efficiency was reduced at rate of 30, 18 and 16 percent. As the ‎salinity of irrigation water increased, the average weight of the boll, fiber index, earliness and ‎the fibers decreased significantly. As the moisture level increased, the yield of cotton, average ‎boll weight, the number of seed in a boll and the number of bolls increased significantly. In ‎additional the water use efficiency of the 133, 100 and 66% treatments compared to 33 ‎percent decreased by 32, 16 and 10 percent,‎‏ ‏respectively. The cotton yield under133, 100 and ‎‎66% treatments decreased by 32%, 16% and 10%, respectively, compared to the 33% of the ‎water requirement. Although PRD reduced crop yields by 15 percent compared to full ‎irrigation treatment, but the water use efficiency increased by 36%.‎‎‎‎‎‎