Determination of the most appropriate time of harvest in Iran’s commercial pistachio cultivars in order to optimize the quality of yield.

Determination of the most appropriate time of harvest is one of the most important impressment's factors on yield quality of pistachio. In order to achieve this aim, this research was conducted with determination of physiological maturity point of fruit on some Iran&rsquos commercial pistachio cultivars with usage of qualitative and quantitative indices on fruit from 2001 to 2004 for 4 years. In this research, 10 eighteen-year-old trees of &ldquoAhmadaghaei&rdquo, &ldquoKalehghoochi&rdquo, &ldquoOhadi&rdquoand &ldquoBadami-e-Zarand&rdquowere selected. In each year, during 8 successive weeks (from September to October) sampling was done from experimental trees which were located in cultivar collection block in No.2 pistachio research station affiliated to Iran&rsquos pistachio research institute. A factorial design in a randomized complete block design model was used. In this design different times of sampling as &rdquoa&rdquofactor and different pistachio cultivars as &rdquob&rdquofactor were determined and three selected samples were considered as replicates. On harvest time, the characteristics such as early splitting percentage, hull cracking percentage, hulling percentage, splitting percentage, non-splitting percentage, blank & unripe percentage, amount of ounce, kernel / shell ratio, humidity percentage of fruit, fat content, soluble carbohydrates content, B1 aflatoxin content and total aflatoxin content were measured. The results indicated that evaluated characters in experimental cultivars, different times of harvest and also different experimental years were significantly differed. For example, among experimental cultivars, &ldquoKalehghoochi&rdquoshowed the highest percentage of early splitting, hull cracking and fruit humidity. The highest hulling percentage referred to &ldquoAhmadaghaei&rdquoand &ldquoOhadi&rdquoalso &ldquoAhmadaghaei&rdquocontained the highest percentage of fat in kernel, nut splitting percentage and kernel / shell ratio. &ldquoBadami-e-Zarand&rdquoshowed the highest percentage of soluble carbohydrates, non-splitting, blank & unripe fruits and amount of ounce. &ldquoAhmadaghaei&rdquo, &ldquoKalehghoochi&rdquocontained the highest contamination of nuts to total and B1 aflatoxin and after that &ldquoOhadi&rdquoand &ldquoBadami-e-Zarand&rdquowere located. In general, the appropriate time of harvest is suggested the middle to end of September to avoid contamination of yield to aflatoxin and production of safe yield. With consideration of the highest contamination of &ldquoAhmadaghaei&rdquoand &ldquoKalehghoochi&rdquo, it was suggested an earlier harvest of these cultivars in compare to other cultivars.