Fruit set Patterns as Related to Ovary Development in Four Commercial Pistachio Cultivars

This experiment was carried out in 2003-2004 to determine fruit set patterns in four pistachio cultivars (Akbari، Ahmad Aghaie، Kalle Ghouchi and Ohadi) to find out the correlation between final fruit set and embryonic sac development، and as well between primary fertility and final fruit set. In a field experiment، inflorescence schematic shape and position of flowers (on inflorescence on the basis of ovary developmental size) were precisely monitored. In addition، the position of fruits، and final fruit set were recorded at the end of the season again. For an inspection of embryonic sac، ovules from different size ovaries were excised followed by fixation، sectioned، stained and then were investigated. The results indicated that flowers located at the end of cluster or on bunchlets had higher fruit set (20. 5% and 27. 44%، respectively). Most of the large flowers positioned at the top of bunch and bunchlets، although few in number (11℅)، developed into fruits (by 45℅). Eighty nine percent of flowers were of the lateral type، but their only 8℅ developed into fruits. Fruit set in type one flowers was maximum (32℅). There were no significant differences observed among cultivars for fruit set، and no significant differences as regards fruit set between on and off-years either. Ahmad Aghaie cultivar had the highest embryo sac fertilization. However، the overall embryo sac development and fertility were not significantly affected by cultivar. Flowers type one had the highest rate of developed embryo sac and fertilization (87. 5% and 37. 5℅، respectively). Fertilization for the second and third types of flowers were recorded as 18. 75% and 12. 5℅، respectively، about equal to their fruit set.