New and emerging tools developed for the vineyard: Presentations at the VIII Int. Symposium on Irrigation of Horticultural crops (Lleida-Spain)

Abstract

Latest work lead by Dr Fuentes with collaborations with colleagues in Australia and Chile was presented at the VIII International Symposium on Irrigation of Horticultural Crops (Lleida-Spain). Specifically, one oral presentation and two posters were delivered: • Low cost infrared scanner for estimating grapevine water status (oral) • Almond crop coefficients calculation including day and night-time tree water uptake and transpiration (poster) • Orchard water status variability assessed using proximal and aerial infrared thermography(poster)

Summary

Projected climate change and its variability predict increased temperatures, higher evaporative demand and water scarcity over a large portion of Australia. These projections have increased the pressure to obtain high quality fruit production with more efficient water use. Several studies have demonstrated that carefully imposed water stress improves stone fruit quality parameters. However, most of the conventional methods to monitor plant water status are based on manual point measurements, which have low spatial coverage, and are resource expensive and time consuming. This seriously constraints the efficient assessment of spatial variability of water status from orchards caused by heterogeneous soil characteristics, poor irrigation distribution uniformity and/or variability in canopy structure/architecture. This work has demonstrated the capability of unmanned aerial vehicles (UAVs) in detection of water stress for a stone fruit orchard (peach and nectarine). Furthermore, it was thought until recently that night-time water uptake for C3 and C4 plants corresponded to stem and organ rehydration. Any water loss at night-time was considered minimal, corresponding to cuticle conductance of leaves with no significant conductance through the stomata. Recent studies have shown that this knowledge was incomplete. In a climate change scenario, where night-time temperatures have been forecasted to increase at a higher rate compared to diurnal temperatures, night-time water losses for non-stress and mild stress water conditions may be exacerbated (Fuentes et al. 2013; 2014). Furthermore, counter-intuitively, elevated CO2 may increase nocturnal water loss (Zeppel et al. 2012). Current methodologies and modelling algorithms to estimate ETreal, assume stomata conductance at night-time to be zero. Therefore, accurate crop coefficient calculations need to incorporate these important night-time water losses, which are not coupled to photosynthesis, hence reducing water use efficiency.