بهمن پناهی
علی تاج آبادی پور
جلال الدین محمدمحزونی
حسین علوی
حیدر معصومی
علیرضا طلایی

Generally, the hull of pistachio fruit would be remain intact until prior to harvest time, but sometimes the hull crack and shell splits on a limited numbers of pistachio fruits occur before yield harvest. One of probable factors which affect on hull cracks would be humidity fluctuations and/or temperature changes during growth and development season. This study was carried out in order to found possible relation between round-the-clock humidity fluctuations and temperature changes during fruit growth and development season on hull cracks from 2001 to 2004 for 4 years. 10 twenty five-year-old trees of "Ohadi" in pistachio plantation areas of Kerman, Rafsanjan and Anar were selected. Humidity and temperature changes in experimental orchards were recorded by thermo-hydrograph instruments during summer season. 10 fruit clusters were harvested on sampling time and the samples were forwarded to laboratory in order to determine the early splitting percentage, irregular hull cracking percentage, B 1 aflatoxin and total aflatoxin content. A completely randomized design was used for evaluation of characteristics and the means were compared by Duncan's test at 5% level. The results indicated that the evaluated characters in various areas and different experimental years of study were significantly differed. The early splitting percentage, irregular hull cracking percentage and the contents of yield contamination to Bland total aflatoxin in Kerman area showed the highest level and in two other areas (Rafsanjan and Anar) with this order contained the lowest content. It was concluded that the sort of area with consideration of humidity fluctuations and temperature changes during fruit growth and development season could be effective on occurrence of different kinds of cracks, but another important factor like alternate bearing could intensify them and could change occurrence of these kinds of cracks from year to year.