Impact of rising temperatures during dormancy on key yield components in almond

Abstract

Agriculture must adapt to the effects of climate change, with temperatures expected to rise in the coming de cades. Deciduous fruit trees rely heavily on temperature regimes during dormancy, requiring low temperatures in winter and mild temperatures in early spring to exit this phase. This study aims to assess how high temperatures at different dormancy stages negatively impact on almond trees. To investigate this, mobile greenhouses were placed in the field for two seasons at different chill accumulation stages to alter dormancy progression in almond trees, simulating different future climate scenarios increasing temperatures. Additionally, various management strategies were tested, including intensive pruning and flower bud reduction, to determine their potential to minimize climate change effects, and early defoliation to not allow the tree accumulating all the carbohydrates reserves. The results showed that key yield components were affected in nearly all climate scenarios tested across both seasons. Insufficient chilling significantly reduced final yield, while increased temperatures in February, right before bloom, were equally detrimental for almond trees. Early defoliation decreased fruit set by increasing abnormal flower percentages and reducing yield compared with non-treated trees. Intensive pruning did not show significant differences improving yield and fruit set. Flower bud reduction increased fruit set, but it was not enough to improve final yield. These findings highlight high pre-bloom temperatures as a critical factor in almond performance and underscore the need to develop adaptive strategies to mitigate their negative effects in future climate change scenarios