Effect of Deficit Irrigation During Different Phenological Stages of Fruit Growth and Development on Yield of Almond " cv. Mamaei"

To study the effect of deficit irrigation during different phenological stages of fruit growth and development of almond (cv Mamaei) four experiments were separately carried out using radamized complete block design with three replications. In each experiment, levels of deficit irrigation were T1 (100% ETc, full irrigation), T2 (80% ETC, deficit irrigation), T3 (40% ETC, deficit irrigation) and T4 (0 % ETc, drought). In the first experiment levels of deficit irrigation were applied in fruit growth stage, in the second experiment, irrigation levels were applied in kernel growth stage, in the third experiment irrigation levels were applied in harvest stage. Each experiment were separately conducted in 2002 and 2003 growing seasons. The fourth experiment was carried out as split plot arrangement in randomized complete block design with three replications. In this experiment, the main plots were four different stages of growth including: fruit growth, kernel growth, pre-harvest period and post-harvest period. The sub-plots were different irrigation levels. Results showed that deficit irrigation significantly decreased fruit size and increased fruit drop in first experiment (fruit growth stage). Deficit irrigation decreased fruit fresh weight and kernel fresh and dry weight in kernel growth stage, but in pre-harvest period there was not significant effect on fruit and kernel characteristics. Flower bud density and proportion of initial and final fruit set decreased with deficit irrigation in fourth experiment, hence, yield decreased in following year. Results also showed that the effect of deficit irrigation during pre- and post-harvest was more pronounced on decreasing flower bud density in following growing season.