Effects of drought on shoot water relations in “Antoñeta” and “Marta” almonds grafted onto “Garrigues” seedlings and “GF 677” Rootstocks

Abstract

Potted plants of two almond (Prunus dulcis Miller) cultivars, ‘Antoñeta’ and ‘Marta’, grafted onto ‘Garrigues’ and ‘GF677’ rootstocks, were subjected to two different cycles of drought. In one case, the stressed plants were subjected to drought by withholding irrigation for 5 days. In the other experiment, the drought treatment was imposed by reduction of the daily water applied (by 50% with respect to the control plants) during 45 days. Control plants were irrigated daily to 50% field capacity. In both experiments, the water stress induced a decrease of leaf water potential and leaf stomatal conductance. The values of leaf water potential were lower in the trees grafted onto ‘Garrigues’, independently of the cultivar or treatment considered. These trees also showed higher levels of leaf stomatal conductance. The results suggest that ‘GF677’ is more drought tolerant than ‘Garrigues’ seedlings as a rootstock, because it avoided the loss of water via transpiration and maintained the leaf water content under stress. The behaviour of leaf water relations in both cultivars was similar during the long term experiment. However, when the stress was severe, the effect of drought on leaf water potential of ‘Marta’ was higher, indicating that responses for drought resistance in leaves of ‘Antoñeta’ are faster, and probably more efficient, than those shown by ‘Marta’.