Effect of Irrigation Regimes on Grain Growth Indices of Three Winter Wheat (Triticum aestivum L.) Cultivars Under the Iranian Conditions

An experiment was conducted during 2004-2006 at the Agricultural Research Station, Islamic Azad University, Khorasgan Branch, Isfahan, Iran. The purpose of this study is to study the effect of deficit irrigation regimes on the grain growth rate and the effective grain filling period of the bread wheat (Triticum aestivum L.) cultivars. A split plot layout arranged in randomized complete block design with four replications was used. Irrigation regimes (irrigation after 70 mm (IJ, 90 mm (I2) and 110 mm (I3) cumulative evaporation from class A evaporation pan) were considered as the main plot and three wheat cultivars (Mahdavy, Ghods and Roshan- Backcross) as subplots. The I¡ and I2 did not differ significantly for grain growth rate (GGR) and effective grain filling period (EGFP). Delay in irrigation from the I2 to the I3 caused significant reduction in grain growth rate and effective grain filling period. Trend of changes in grain weight was similar in the I¡ and the I2. In all samplings, delay in inigation from the I2 to the I3 reduced grain weight. Cultivars differed significantly in respect to grain growth. The effect of grain growth rate on 1000-grain weight was more pronounced than effective grain filling period. Obtained results indicate that irrigation after 90 mm cumulative evaporation from class (A) evaporation pan might be suitable for the grain weight of winter wheat under similar the conditions to this experiment where irrigation water during grain filling period is not abundant.