Long-term summer pruning in peach trees. Is it an advisable cultural practice?

Abstract

This work deals with the effects of pruning on vegetative growth, yield and fruit quality, along with the plant water status of extra early-maturing peach trees during four consecutive growing seasons (2012-2015). Trees were drip irrigated in the Mediterranean conditions of Murcia (Spain) in a clay-loam soil. Two pruning treatments were imposed: winter pruning (WP), which was carried out during dormancy (December) in order to maintain the vase-type tree architecture, and a summer pruning (SP) consisting of the elimination of the water sprouts just after harvest (May). Plant water status indicators were assessed from the midday stem water potential (Ψstem) with a pressure chamber. Canopy tree cover (TC) was obtained by zenithal imagen analysis. The percentage of effective shade was estimated from the TC and the solar angle. Yield and fruit quality were evaluated at each harvest. Fruits were separated in the field by manual calibration into 7 fruit diameter categories. The total pruning weight of SP trees was on average 12 kg tree-1 (dry matter), which is slightly higher than that of WP trees. The contribution of SP to total pruning was nearly 35%. TC was significantly lower in the SP treatment, which resulted in an improvement in the plant water status of about 0.10-0.30 MPa with respect to WP trees in summer, and leading to a reduction in water consumption during periods of high evaporative demand. No significant differences were detected between WP and SP treatments in the yield components studied. Summer pruning can be considered an acceptable cultural practice to mitigate the drought effects in early-maturing peach trees, while maintaining yield.