Research concerning the influence of climate condition over the phenological stages at walnut tree (Juglans regia L.)

Abstract

Carrying out the phenological stages of vegetation and fruit set in walnut is determined by the cumulative action of daily average temperatures exceeding 10°C, value considered as biological limit of walnut cultivars. In climate conditions from last few years, some changes was observed about values of the sum degree of active temperature necessary onset the phenological stages of walnut tree. The research was conducted during 2009-2013 by six walnut cultivars with different fruit maturation period, existing in the experimental plot from Research Station for Fruit Growing Iasi, Romania. The paper aims to determine the active thermal balance needed to carry out the fruiting phenophases and comparing the results with data cited in the literature.