Using band dendrometers in irrigation scheduling: Influence of the location inside the tree and comparison with point dendrometer

Abstract

Trunk diameter fluctuation parameters have been common indicators in water relations experiments. In most fruit trees, these parameters have been reported as very sensitive to drought conditions. However, the great variability of the measurements, amongst other factors, has limited their use in commercial orchards. One of the sources of error could be the location of the sensors on the tree, which has been poorly studied. In addition, almost all the studies in horticultural science have been performed with point dendrometers, while in forest research band and point dendrometers have been used. The aims of this work were (i) evaluate the influence of band dendrometers location on mature olive trees (branch or trunk, experiment 2011, and (ii) compare the feasibility of them with point dendrometers (experiment 2012). Wireless Sensor Network band dendrometers were installed in 5 trees during 2011 in the main trunk and in branches. Trunk growth rate (TGR) and maximum daily shrinkage (MDS) were compared in both locations. Individual TGR data of these trees were all around the line 1:1 in the relationship between trunk and branch. Individual MDS data in stressed trees were significantly higher than the line 1:1 in the branch vs trunk relationship. The non-stressed MDS data, however, were not significantly different to this line. During 2012, band and point dendrometers were installed in the main trunk of 3 trees. The location did not affect the values of the indicators in non-stress conditions, but significant changes were found in MDS of stressed trees. The relationship between band and point dendrometer was probably affected by the variability of the trunk itself.