Effects of irrigation on development and photosynthesis of young apple trees
Irrigation is not common in apple orchards in Germany. Nevertheless, it is likely to become much more important in the future as climate change intensifies. To study the effects of irrigation on young apple trees, a field trial was conducted during 2012 and 2013 in Geisenheim, Germany. Trees of 'Fresco' (WellantTM), 'Jugala' and 'AW 106' (SaporaTM) apples (Malus × domestica Borkh.) were planted in autumn 2011. The aim of the study was to quantify how water deficit and irrigation affect the development and establishment of young apple trees and then integrate this knowledge into the carbon balance model MaluSim developed by Lakso et al. Starting in 2012, three irrigation treatments (including one treatment with no irrigation) were applied and effects on tree growth and physiology were recorded. Weather conditions were very different between 2012 and 2013. While in 2012 there were periods of drought during the whole season, in 2013 there were high precipitation amounts at the beginning of the season and only later dry periods developed. Results of gas exchange, predawn and midday stem water potential, tree growth and light interception measurements in 2013 are presented. Besides the impact of irrigation on tree development, special attention was paid to the effect of low water potentials on leaf gas exchange and, especially, at which threshold, gas exchange was significantly reduced in order to develop a water-photosynthesis function for integration into the MaluSim model framework.
Neumann, L. and Braun, P. (2017). Effects of irrigation on development and photosynthesis of young apple trees. Acta Hortic. 1177, 265-272
gas exchange, predawn and midday stem water potential, tree growth and development, Malus × domestica