Effect of pruning and plant spacing on the growth of cherry rootstocks and their influence on stem water potential of sweet cherry trees
Gonqalves, B.; Santos, A.; Silva, A.P.; Moutinho-Pereira, J.; Torres-Pereira, J.M.G.
Journal of Horticultural Science and Biotechnology 78(5): 667-672
The aims of this work are to describe the effects of pruning and planting density on growth and water relations of ungrafted and grafted sweet cherry trees. A trial with cherry rootstocks 'Prunus avium', 'CAB 11E', 'Maxma 14', 'Gisela 5' and 'Edabriz' was begun in 1997. Pruning severities were applied to the rootstocks (0, 30, 60 and 90% of the vegetative growth was removed corresponding to P1, P2, P3 and P4 treatments, respectively) after planting to two plant spacings (S1 = 0.25 X 1.0 m and S2 = 0.45 X 1.5 m). Canopy, root growth and leaf water potential (leaf) were quantified throughout the growing season. Pruning significantly affected root length and root weight of the rootstocks. Uncut plants (P1) showed a heavier and expanded root biomass (231 g and 108 m) than the intensively pruned plants (P4) (187 g and 75 m). The greater root biomass was obtained with the spacing/pruning combination, S1/P1 (285 g), and the smaller with S1/P4 (180 g) and S2/P4 (176 g). psi(leaf) varied significantly between the rootstocks and plant spacing but not with pruning. 'Maxma 14' and 'P. avium' attained the lowest values of midday psi(leaf), -2.28 and -2.04 MPa, but the highest values of predawn psi(leaf), -0.29 and -0.25 MPa, respectively. Generally, with high density (S1), the rootstocks exhibited lower predawn and midday psi(leaf). In 1998, cultivars 'Burlat', 'Summit' and 'Van' were grafted onto rootstocks and a trial was installed in 1999. Predawn and midday stem water potential (Stem) on cherry trees, measured in 2002, were affected significantly by the rootstock/genotype combination. Cultivars grafted on 'P. avium' and 'Maxma 14' showed the less negative midday psi(stem), -1.36 and -1.42 MPa respectively, so these rootstock genotypes perhaps induced a higher drought resistance to the scion. Recorded data show that the scion-rootstock interaction with regard to production performance under water deficits may be an important consideration in cherry tree planting strategies.