S16 - Session O3 - Adaptability of apple, plum and cherry genotypes to diverse South African growing conditions

Authors: Esme Louw *, Iwan Labuschagne, Anika Kock, Chad van Wyk, Tristan Dorfling, Willem Steyn

Adaptation refers to the way in which plants can survive and reproduce in specific environments. In commercial fruit farming a cultivar's adaptability to the production area has a direct effect on the yield and quality of the fruit produced. Adaptability is determined by the genetic composition of the plant (genotype, G), the nature of its environment (E) as well as the interaction between the genotype and the environment. In a diverse production landscape, such as the Western Cape of South Africa, the adaptability of a cultivar directly influences its profitability. Lack of winter chill is one of the main environmental factors influencing the adaptability of deciduous fruit trees in South Africa. Less adapted cultivars show prolonged dormancy symptoms resulting in delayed, protracted and poor bud break and a more basal dominant tree architecture; all aspects that negatively affect yield and quality. Our current project stretches over eight production cycles and aims to describe the GxE interaction of ten different apple, plum and cherry genotypes (30 in total) planted in three contrasting climatic regions in the Western Cape (South Africa). Numerous parameters relating to bud break and tree architecture are measured and the data is analysed using multi-environment trial methods (Additive main effects and multiplicative interaction (AMMI) and Genotype plus genotype environment interaction (GGE) biplots). Results generated over the first two years describe and compare the adaptability of young apple, plum and cherry trees of the different genotypes to the different environments. These results are valuable in both a fundamental and applied way to provide insight into the resilience of deciduous fruit genotypes and offer guidelines to producers when making cultivar choices for plantings/reworks, especially in marginal production regions. It also identifies the key variables that should be assessed to timeously and economically determine the adaptability of a new cultivar.