The effect of different time of irrigation on occurrence of early split of pistachio nuts.
2006
Sedaqati, Naser | Taj Abadi, Ali | Ali Pour, Hamid | Azad, Ahmad | Esmaili Ranjbar, Ali | Alavi, Hossein | Panahi, Bahman
Early split (ES) fruits are known as undesirable products, that both the fruits hull and shell split before maturing. These fruits are usually invaded by insects and molds, especially those that produce the potent toxins aflatoxins. The present study was carried out in Rafsanjan , s suburb pistachio orchards during 2001-2004 for 10 treatments including two irrigation intervals (25days, 45days) and five irrigation skippings in each irrigation interval. During the growing season, amount of ES , irregular cracked , blank and shell split pistachios was evaluated in experimental plots. Our results indicated that long irrigation intervals and deficit irrigation of pistachio trees in late April until early June increased substantially (untill 90%) ES formation in comparison to regular irrigation plots, at harvest stage. The most of ES pistachios observed in treatments that affected by drought stress in early june (T4,T8) amont of 7.7% and 9.6% respectively. Whatever the skipping in irrigation closed to end of growth season amont of ES pistachios was reduced , however , there was no special trend in related to created pistachios, but deficit irrigation in july increased the amont of irregular cracked pistachios. Average percentage of ES, cracked and blank pistachio was increased 37% , 18.5% and 38.8% in 45 days irrigation interval in compare to 25 days respectively, however , about shrank and shell split pistachios between irrigation interval treatments difference was no significiant. For aflatoxin measuring, 120 samples were collected, and pistachio fruits were classified to 3 groups, according to their appearance characteristics, including ES, fruits having cracking hull, and fruits with intact hull. Amount of B1 and B2 aflatoxin in ES pistachios were 223.4ppb and 25.47ppb (on average) respectively. In cracked hull fruits aflatoxin B1 and B2 were 111.06ppb and 9.71ppb (on average) respectively. Although, the toxin was observed in non of intact hull pistachio fruits. with attention to high level of aflatoxin in ES pistachios, and that the suitable irrigation plays an important role in producing healthy pistachio nuts, we found that proper irrigation management prevents producing ES pistachios and is assumed as an important step for decreasing of aflatoxin contamination in pistachios at orchard conditions.
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