Linking carbohydrate and amino acid reserves in twigs to agro-phenological responses in plum cultivars from contrasting geographic regions

This study assessed the effect of climatic conditions on the production and phenological traits of four plum cultivars (Prunus salicina L. and Prunus domestica L.) grafted on ‘Myrobolan’ rootstock planted in two contrasting experimental zones at INRA Meknes, namely ‘Ain Taoujdate’ in the Saïs plain and ‘Annoceur’ in the foothills of the Middle Atlas, during two consecutive years, 2019–2020 and 2020–2021. Observations were made on production and phenological traits, including flowering and bud burst rates and twigs reserves (total soluble solids ‘TSS’, soluble sugars content ‘SSC’ and amino acids content ‘AAC’) during the dormancy and budburst phases. The results showed that the effect of the climate factor varies according to cultivar and site. Yields expressed by tree fruit load and fruit weight were reduced as a result of the climate, with overall averages of 34% and 23%, respectively. Similarly, budburst and flowering rates were reduced on both sites, with overall averages of 10% and 6%, respectively. The earliest cultivar was ‘Methley’ while the latest was ‘Stanley’ which had significant decreases in ‘TSS’ and ‘SSC’ in twigs against an increase in ‘AAC’ moving from the dormancy and budburst phases. The aim of this study was to gain an idea of the areas likely to be favorable for plum cultivation, taking climatic conditions into account, and to contribute to the understanding of adaptation mechanisms under conditions resulting from global warming.