Response of Phenological Development Stages, Grain Yield and Yield Components of Bread Wheat Cultivars with Different Growth Habits to Delayed Planting

To study adaptation of different wheat types to delayed planting, an experiment was conducted in split plot layout with RCBD and three replications at SPII, Karaj during 2005-2007 cropping seasons. Planting dates (12 Oct., 11 Nov. and 11 Dec.) and wheat cultivars (Pishtaz and Falat as spring, Toos and Mahdavi as facultative, Soissons and MV-17 as winter cultivars) were in main plots and subplots respectively. Results showed that delayed planting from 12 October to 11 December decreased grain yield (from 7146 to 5665 kgha-1), biological yield (from 18560 to 13410 kgha-1), spike number per square meter (from 551 to 472) and grain number per spike (from 38 to 36.1). Delayed planting from 12 October to 11 December also decreased appeared leaf number at double ridge (6.0 vs. 4.2), vegetative (878 vs. 540 GDD), pre-anthesis reproductive (969 vs 883 GDD), grain filling (815 vs 662 GDD), planting to anthesis (1847 vs 1423), and planting to maturity (2662 vs 2085 GDD) stages. Based on thses results, effects of delayed planting on decrease of plant life cycle occurred via decreasing in all main developmental stages(esp. vegetative stage), but decreasing of vegetative period length in winter type was more than of facultative and spring types ( 400 vs 328 and 278 GDD, respectively) while effect of delayed planting on decrease of pre-anthesis reproductive period length in spring types was more than of facultative and winter types ( 148 vs. 90 and 19 GDD, respectively). Grain filling period in spring, facultative and winter types decreased 125, 173 and 161 GDD, respectively in delayed planting.