Temperature responses of pollen germination in walnut (Juglans regia L.)

Abstract

This study was carried out in order to determine the effects of different temperatures (16±1 °C, 19±1 °C and 27±1 °C) with various sucrose concentrations (10, 15 or 20% sucrose) on the pollen germination of ‘Şebin’, ‘Kaplan 86’, ‘Yalova 3’, ‘Pedro’, ‘Hartley’ and ‘Franquette’ walnut cultivars in 2007 and 2008. Pollens were also subjected to tetrazolium (TTC) test to determine their viability level. Temperature had significant effect on the germination percentage. Pollen germination rates increased significantly with increasing temperatures in walnut cultivars studied. The highest germination rates were recorded at 27 ±1 ˚C temperature in both years (26.94-73.98%; 22.78-70.86%), respectively. The rate of pollen viability of all the cultivars tested was high (> 75%). The highest pollen germination percentage was obtained from 15% and 20% sucrose concentrations in both years.