Response of high yielding rice varieties to NaCl salinity in greenhouse circumstances

Salinity is one the biggest constraint to obtain crop potential yield throughout paddy fields in some part of the coastal line of rice cultivated area in Iran. In order to find resistant varieties and study the reaction of some newly released high yielding varieties to different levels of salinity of irrigation water an experiment was conducted at the Rice Research Institute of Iran-Amol station in a greenhouse. Eight varieties, cultivated in pots, were tested with three levels of salinity (2, 4 and 6 dS m-1: S1, S2 and S3, respectively) along with control (S0: EC = 0.8 dS m-1) with 3 replications. The results showed that salinity adversely affected yield, number of tillers per pot, filled and unfilled spikes, fertility and 100 grain weight, but increased number of unfilled tillers. The average of rice yield loss threshold was calculated 1.3 dS m-1. On average, number of panicle and number of filled spikes accounted for 80 and 59% of total variation of grain yield, but it decreased by increasing in salinity level. There was a high correlation between yield and number of panicle and grain weight per panicle.