Effect of Salinity on Yield and Yield Components of Watermelon Cultivars

In this experiment the effect of salinity on yield, yield components and other characteristics of three watermelon cultivars Charleston Gray, Crimson Sweet and Sugar Baby were studied in Birjand at Amirabad Experimental Station. The experiment was performed during 2001 and 2002 growing seasons, using three water sources of 1.4 (check), 5.5 and 10.5 dsm-1 electrical conductivity. The design of the experiment was split plot in randomized compelet block with three replications. The three electrical conductivities of irrigation water were the main plots and three cultivars as sub plots. The salinity treatments were applied after 2nd to 3rd leaves stage. Based on the results of combined analysis, the effect of salinity on fruit yield, fruit number per plant, fruit weight, fruit length, and flesh diameter were significant at 1%, and on sink diameter at 5% level. These parameters were decreased with increasing salinity. In severe salinity (10.5 dsm-1), compared to control, the percentages of decrease for parameters were 76, 60, 42, 26, 21.4 and 22.8 respectively. Decrease of fruit yield in Charleston gray, Crimson Sweet and Sugar Baby in 5.5 dsm-1, was 21.4,24.3 and 33.6% and in10.5 dsm-1 75,70 and 77% respectively. Charleston gray and Crimson Sweet had higher fruit yield than the Sugar Baby in saline conditions. The threshold tolerance to salinity for Charleston gray, Crimson Sweet and Sugar Baby was 8, 8.1 and 6.8 ds/m respectively. The correlations between fruit yield and fruit number per plant, fruit length, sink diameter, flesh diameter and friut diameter were significant with r = 0.5, 0.7, 0.43, 0.54 and 0.58 respctively. Based on the results, cultivars Charleston gray and Crimson Sweet cultivars seem to be more suitable for saline conditions than the Sugar Baby cultivar.