Phenology, growth, and yield of almond cultivars under organic and conventional management in southwestern Spain

Aim of study: To advance implementation of sustainable agriculture from organic production system on almond crop by means of the assessment of physiological and agronomical responses of commercial almond cultivars. Area of study: Irrigated almond in the Guadalquivir River Valley. Material and methods: Physiological and agronomic aspects of almond such as defoliation, phenology, tree growth, N and P leaf reserves, susceptibility to aphids and fruit yield were assessed on five almond cultivars under organic and conventional production management during four consecutive seasons from 2017 to 2021. Main results: A lower flower density, tree growth, and almond production, an earlier and more intense defoliation degree, and a higher susceptibility to aphids were observed in the organic plot compared to the conventional orchard. 'Lauranne' was the cultivar that showed the best productivity under organic and conventional management. 'Marcona' showed the higher flower density and medium vigor, although was the most susceptible cultivar to aphids and the less productive cultivar under both managements. Research highlights: Cultivation of irrigated almond still presents numerous difficulties, especially the control of pests and diseases due to the use of environmentally friendly pesticides which are less effective than chemicals. These pathogenic factors and others such as nutrition especially affect the yield of the crop, although the differences with the conventional system are reduced over time. Despite these difficulties, the high added value of organic almonds together with the increasing demands by consumers of healthy environmental practices and food safety are a stimulus to continue and develop research on sustainable agriculture.