determination of the best harvest time of pistachio nut based on physiological and biochemical indices

this study was done to evaluate the effects of harvest time on some factor of ‘ahmadaqaie’ pistachio nuts in rafsanjan. in three consecutive years (2009-2012) during three stages of friut ripening (40, 70 and 100 percent of hulling), fruit was harvested and physiological and biochemical parameters were measured. the experiments were conducted as randomized complete block design with compound analysis in three replications. most of the traits were influenced by harvest time more than latitude and length of piistachio. the highest amount of protein (20.5%), chlorophyll content (6 mg) and inflorecence bud retention (61%) was in immature nuts (40 percent). pistachios harvested in stage two (70%) had the best quality and quantity despite of green kernal and good taste of immature pistachio nuts. although third harvest (100%) increased the dry weight and percent of nut splitting, but have some problems including increasing early splitting, endocarp yellowing, nut drop under the trees, and finally difficult to harvest operations which will increase fungal infections and reduce the nutritional value. in the best time of harvesting in normal condition, the nutritional value, splitting and dry matter were high that roughly coincides with the 70 to 80 percent ripening stage.