Assessment of grape bunch temperature variability in Vitis vinifera L. cv. Shiraz

Abstract

Different sensor types are available to assess grape bunch/berry temperature, but to study its variability within complex grapevine canopies is difficult. The variability in light exposure and temperature in and around berries on a bunch can be affected by canopy architecture and the positioning/orientation of bunches and berries within the canopy. In addition to this, row orientation as well as the mesoclimate surrounding a vineyard may also impact on the diurnal patterns of temperature change of bunches/berries. In this study, the methods of measuring diurnal and spatial variability in bunch light interception and temperature were studied. Macroclimatic data from automatic weather stations, thermal imaging, thermocouple and quantum sensor measurements were used to determine the spatial and temporal (diurnal) variability in bunch/berry surface temperature, berry temperature and light microclimate. Results indicated how mesoclimate effects can be transferred at different sensor levels. The extreme spatial and temporal variability in bunch surface temperature as well as berry temperature, especially under direct radiation conditions, was highlighted. Some perspectives on accumulative effects of grape temperature are presented. Issues around sensor placement and sensor technical difficulties are discussed.