Paper Title
Response of Different Growth Stages of Wheat Genotypes to Moisture Tension

Abstract
Climate changing makes the plants in continuous subject to biotic and abiotic stresses. Drought is one of the most severe abiotic stresses which limits the wheat production in Kurdistan region, because the rainfall during the growing season is usually low and not constant, particularly at growth stages has an advantage to make the yield higher and more constant through the year. An experiment conducted to study the effects drought stress imposed at different growth stage on two local cultivated bread wheat genotypes; Aras and Azady grown in the region. The adverse effect of drought stress studied through reduction in morphological and yield characters. Water stress at stem elongation stage caused a significant decrease in plant height. Tillers number per plant severely decreased when irrigation regime exposed at tillering and stem elongation. As well as water regime at stem elongation cause significant reduction in blades leaf area per plant BLA (cm2 plant-1) and shoot dry weight in comparison with control plants. Water regime at stem elongation, heading and grain filling stages caused a significant lowering in yield and yield components; spikes number plant-1, weight of spikes plant-1, and grains number plant-1, 1000-grain weight (g) and grain yield g plant-1. The extent of lowering in yield was higher in Aras, as compared to Azady which tolerate the drought more significantly. Keywords - Wheat, Growth Stage, Spike Number, Grain Yield, Thousand Grain Weight.