The Effects of Deficit Irrigation on the Early Splitting of Pistachio Nuts and Aflatoxin Contamination

The cracking of pistachio nuts is the major source of mold contamination as well as pests and aflatoxins.

The effects of deficit irrigation on pistachio-nut cracking were evaluated at two irrigation intervals(25 days and 45 days) and five omissions of the irrigation time. The frequencies of hull early splitting and cracking weredetermined in nuts.

All and all, long irrigation intervals and deficit irrigation since late April until early June were critical andincreased the early splitting rate (up to 90%) in comparison with regular irrigation. The highest frequencies of the earlysplitting of pistachios were observed due to the drought stress at early June ranging from 7.7 percent to 9.6 percent. Deficitirrigation in July increased the rate of pistachio hull cracking significantly. The averages of the hull early splitting andcracking formation were by 37 percent and 18.5 percent higher in 45 days of irrigation intervals compared with 25 days,respectively. The contents of B1 and B2 aflatoxins in hull early splitting and cracking were 223.4 µg.kg-1 and 25.47 µg.kg-1,respectively. In hull cracking fruits, aflatoxin B1 and B2 were 111.06 µg.kg-1 and 9.71 µg.kg-1, respectively.

In general, to reduce the risks of aflatoxins in pistachio nuts, it is critical to manage irrigation in April andJune.