Irrigation alone cannot counteract adverse climatic effects on macadamia yields in South Africa
Thomas Bringhenti1, Issaka Abdulai1, Munir Hoffmann2, Elsje Joubert3, Marco Moriondo4, Reimund P. Rötter1, Peter Taylor5
1University of Göttingen, Dept. of Crop Sciences: Tropical Plant Production and Agricultural Systems Modelling (TROPAGS), Germany
Macadamia is a high value tree nut crop experiencing a considerable rise in global demand. South Africa is the world largest producer of macadamia nuts, with production areas rapidly expanding in the country. However, yields are highly variable and have been declining in recent years, in conjunction with increasingly severe climate change impacts in the region. Therefore, to sustainably increase the productivity and climate-resilience of macadamia orchards, the effect of environmental factors on the trees’ vegetative and reproductive cycles needs to be better understood. To this end, we quantified the extent to which climatic and soil factors drive macadamia yields in Levubu (South Africa) along an altitudinal gradient (600-950 m a.s.l.), for irrigated and rainfed orchards, separately. For this we applied mixed-effects models on historical production data for the years 2010-2021 from 247 orchards. On this background, the role of irrigation in counteracting the impact of abiotic stresses on macadamia phenology and productivity was evaluated.
Keywords: Abiotic stress impact, altitudinal gradient, climate change, irrigation systems, Macadamia spp., yield limiting factors
Contact Address: Thomas Bringhenti, University of Göttingen, Dept. of Crop Sciences: Tropical Plant Production and Agricultural Systems Modelling (TROPAGS), Grisebachstr. 6, 37077 Goettingen, Germany, e-mail: thomas.bringhentiuni-goettingen.de