The effects of rootstock and scion on early splitting of pistachio thire relation with aflatoxin contamination

Contamination of pistachio fruit to the aflatoxin is one of the most important problems that threatening pistachio exportation and food safety. Aflatoxin is one of the products of secondary metabolites in fungi – i.e. Aspergillus flavus and A. parasiticus. Early splitting and cracks on pistachio hull are one of the most important factors that led to contamination of yield to aflatoxin in orchard. The most important factors which may be affect early splitting and cracks on pistachio hull are kind of cultivar and rootstock. This study was conducted to determine the effects of different rootstocks and scions on aflatoxin production in no.2 pistachio research station of Rafsanjan for 2.5 years. The experiment was a split-plot in a randomized complete block design with four rootstocks (Ahli, Sarakhs, Baneh and Atlantica) as sub-factor and three scions (Ohadi, Kallehghoochi and Ahmadaghaii) as main factor, replicated four times. Samplings were done on early split pistachios with soft and smooth hulls, shriveled and dry hulls, irregular cracked pistachios with soft and smooth hulls, shriveled and dry hulls. After hulling and drying of samples, the content of aflatoxin was measured by HPTLC-Scanner method. Among the under investigation scions, the number of fruits per cluster was the highest in Ohadi scion in compare to Ahmadaghaii and Kallehghoochi scions. The percentage of early splitted pistachios either with soft and smooth hulls or shriveled and dry hulls on Baneh and Atlantica rootstocks were higher than Ahli rootstock. Percentage of early splitting in Ahli scion was lower than Kallehghoochi scion. Percentage of cracks on pistachiohull in grafted scions on Ahli rootstock was the lowest, but showed no significant differences with other rootstocks. Kallehghoochi scion showed the lowest percentage of cracks on pistachio hull in experimental scions and results indicated that rootstocks have no significant effect on percentage of split shells. Ahamdaghaii and Kalehghoochi scions showed higher percentage of shell splitting in compare to Ohadi scion. The Ahli rootstock reduced percentage of blank pistachio nuts in compare to other rootstocks. The highest content of aflatoxin was observed in Baneh and Atlantica rootstocks and the lowest revealed in Ahli rootstock. Among the scions, Ahmadaghaii showed the highest content of aflatoxin. The result indicated that aflatoxin content in early split nuts was higher than nuts with irregular cracked hulls. The highest aflatoxin content was observed in early split pistachios with shriveled and dry hulls and the lowest was in irregular cracked pistachios with soft hulls. The aflatoxin content in all of the samples with intact hull was null.