Effect of hydrogen cyanamide (dormex), yolk oil and potassium nitrate on budbreak, yield and nut characteristics of pistachio (Pistacia vera L.)

摘要

Inadequate chilling may delay normal blooming and severely reduce yield of pistachio trees in sub-tropical regions. The present study was conducted in a commerical orchard in Shahmiran, in the south west of the Kerman province of Iran. Hydrogen cyanamide ("dormex" at 0,1.5 and 3%), volk oil (0, 3.5 and 7%) and potassium nitrate (0,1.5 and 3%) were applied to branch units of pistachio trees in 2002 and 2003. These treatments, plus combinations of dormex and volk oil, volk oil and potassium nitrate, and 7% volk oil were applied 4 and 8 weeks before normal budbreak (January 5 and February 4). The chemicals were sprayed on two branches of 'Ahmad-aghaei' trees during the two years of study. Treatments with hydrogen cyanamide (dormex), volk mineral oil and combinations of dormex and volk oil, volk oil and potassium nitrate brought forward budbreak by 15 to 20 days compared with controls, and significantly increased yield of the treated branches, dehiscence of nuts and reduced the blank percentage of pistachio nuts of cultivar Ahamd-aghai. Higher concentrations of dormex and volk oil, in the second application (February 4) and combinations of dormex and volk oil were more effective in increasing the yield per branch. The best treatment was dormex 4%, plus volk oil 7%, during the second application. Potassium nitrate (1.5 and 3%) had no significant effect on yield, dehiscence or blank percentage of pistachio nuts. The results of this study might be applicable to pistachio growing regions with a mild winter.