Deficit irrigation and kaolin foliar application are agronomic practices that have been demonstrated to improve
productivity and physiological response in almond trees but there is no consistent information on the effects on
the kernel composition. The objective of this study was to evaluate the effect of different Sustainable Deficit
Irrigation (SDI) strategies and kaolin application on some physicochemical composition of the cv Ferragn`es
almond (Prunus dulcis (Mill.) D.A. Webb). A randomized block design with five treatments was developed: nonirrigation
(NI), non-irrigation with foliar kaolin application (NI+K), full irrigation (FI), and two levels of SDI
receiving 70% and 35% of evapotranspiration (SDI75 and SDI35). Pomological parameters, volatile profile and
oil composition were analyzed. SDI effect on kernel weight was reduced against full irrigation (FI) but substantially
improved in comparison with the rainfed treatments (NI and NI+K). Irrigation treatments showed a
lower volatile compounds concentration in comparison with rainfed treatment. The fatty acid composition of the
oil was significantly affected, with all the irrigated treatments having higher oleic acid contents than the rainfed
treatments, and therefore an expected increased shelf life. Kaolin application had no positive effects on the nonirrigated
trees, other than an apparent increase in the total volatiles, a tendency also observed in the NI. Moderate
water stress levels (SDI35) improved the synthesis of tocopherols compared to NI, FI and SDI70, which
could be related to the adaptation of the almond tree to drought. SDI35 is therefore regarded as a very interesting
approach, with significant improvements in comparison with non-irrigated trees, and a clear saving on water
against full irrigation without significant pomological and chemical alterations.
The authors acknowledge the financial support of Foundation for
Science and Technology (FCT, Portugal) for financial support through
national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and
UIDP/00690/2020), SusTEC (LA/P/0007/2021) and LAQV (UIDB/
50006/2020 and UIDP/50006/2020). David Barreales thanks FCT for
the Ph.D. grant SFRH/BD/139393/2018. This manuscript is part of
David Barreales’s Ph.D. thesis. The authors thank to the Cooperativa
Agrícola de Alfandega da F´e, Crl. for allowing this research activity in its
almond orchards.
