Relationship between Aspergillus section Flavi Growth and Aflatoxin Production with Early Splitting in Pistachio Cultivars

In this research, we evaluated the relationship of early splitting with the growth of Aspergillus section Flavi and aflatoxin production in Iranian pistachio cultivars. From each cultivar, six trees and from each tree, six fruit clusters were randomly harvested at maturity time and their fruits mixed. Finally, healthy fruits, and early-splitted fruits with irregular cracks of each cultivar were separated. The population density of Aspergillus section Flavi fungi in the nut kernel was measured using AFPA and DRBC culture media suspension preparation and serial dilution methods. The amount of aflatoxin in different pistachio samples was measured by high-performance liquid chromatography (HPLC). The results showed a significant difference in Aspergillus section Flavi contamination among different pistachio cultivars. The population density of Aspergillus section Flavi colonies in pistachio cultivars of Shahpasand (74.6667 CFU g-1) and Kal-Khandan (73.6667 CFU g-1) was much higher than other cultivars. The percentage of early-splitting was higher in the Shahpasand cultivar (13.66%) than in other cultivars, followed by the Kal-Khandan cultivar (5.66%). There was a positive and significant relationship between the growth rate of Aspergillus section Flavi and the fruit s early splitting percentage (r = 81%). In other words, with an increase in the early splitting percentage of pistachio fruit, the growth rate of Aspergillus section Flavi increased. It can be said that early-splitting is an unfavorable trait and causes an increase in aflatoxin contamination, and early-splitted fruits of Shahpasand and Kal-Khandan cultivars showed more contamination. Therefore, cultivars with less early-splitted nuts should be considered more in export.