Study of physiological indices and yield of the rice varieties in north regions of Khuzestan

In order to evaluation of trend yield and physiological indices variation of some current Rice cultivars an experiment was carried out in split-plot arrangement using randomized complete blocks design with three replication. In 2006 and 2007 years at Shavoor Agricultural Research Station in Khuzestan province. For exposing rice cultivars to different higher temperature regimes, main plots were assigned to three sowing dates from 5 May with 20 days intervals and cultivars namely: Hoveizeh, Hamar (heat tolerance) Ghermez Anbori, Champa (heat sensitive) and Danial (relatively heat tolerant) were randomized in sub-plots. The results of combined analysis of variance showed that the highest grain yield was harvested from the second sowing date (26 May). It was the superior to first sowing date (5May) with 62.5 percentages. The reason of higher yield related to superior physiological indices in panicle exertion, LAD in ripening duration and also higher dry matter storage potential. In among cultivars, Hoveizeh was the superior to other cultivars and had higher yield related to Ghermez Anbori, Champa with 50.9 and 36.3 percentage respectively. In spite of heat sensitive cultivars had higher of Maximum leaf area index but their's crop growth rate, net assimilation rate and relative growth rate were lower.