Response of three almond cultivars subjected to different irrigation regimes in Guadalquivir river basin

Abstract

Almond (Prunus dulcis Mill.) has been traditionally associated to marginal areas in Andalusia, being cultivated under rainfed agriculture conditions. In the last few years, it has been progressively introduced in many irrigated areas of the Guadalquivir river basin which has promoted a growing interest about irrigation water management for this crop i.e. the potential irrigation requirements, or the best irrigation strategy under sub-optimal conditions (aiming at obtaining balanced nut yields, saving water without affecting yield). This work examines the response of three almond cultivars (cvs. Guara, Marta and Lauranne) subjected to different irrigation regimes in a semi-arid Mediterranean environment (SW Spain). The trial was conducted over two seasons (2017–2018), in a commercial orchard with three irrigation regimes: i) a full-irrigation treatment (FI), which received 100% of crop evapotranspiration (ETC) as a control; ii) an over irrigated treatment (150-ETC), which received 150% of ETC during the whole irrigation period; and iii) a regulated deficit irrigation treatment (RDI65) which was irrigated at 100% ETC during the whole irrigation season, except during the kernel-filling period, when it received the 65% of ETC. In order to assess the crop water status, the leaf water potential (Ψleaf) and the stomatal conductance to water vapour (gs) were measured. At the end of each season, the yield, kernel unit weight and irrigation water productivity were determined. Significant differences in physiological behaviour and yield responses among cultivars were found. According to the final yield obtained during the experimental seasons, Guara and Lauranne did not show significant improvements in the 150-ETC in relation to FI and RDI65, whereas cv. Marta showed significant improvements under 150-ETC. Moreover, yield response followed the physiological trend observed in the different irrigation treatments for each cultivar. Those cultivars (Guara and Lauranne) that had not shown significant differences in terms of yield, evidenced a similar pattern in terms of gs, unlike Marta. The obtained results allow us to conclude that there is a clear differential response in terms of the cultivar, taking into account the adaptation capacity of different cultivars to different irrigation doses.