Low temperature resistance of developing flower buds of pistachio (Pistacia vera L.) cultivars

Abstract

Percentage freeze damaged flower buds was estimated for four cultivars of pistachio (Pistacia vera L.) ‛Kalle-Ghuchi’, ‛Owhadi’, ‛Ahmad-Aghaei’ and ‛Akbari’ were determined. Samples were collected from bud swell stage to post bloom stage in 2008 and 2009. Four pistachio cultivars showed similar distribution of mortality during blossom bud development from bud swell to post bloom. During this period, the critical temperature for survival among the 4 cultivars in bud swell, green tip, tight cluster, full bloom and post bloom stage was -15°C, -12°C, -8°C, -4°C and -4°C respectively. Therefore, hardiness decreased as the stage of phenophase bud development increased. The tested pistachio cultivars exhibited less damage level in ‛Off’ trees from ‛On’ trees.