A method to predict the time of harvesting based on water consumption and changes in berry composition of table grapes ('Superior Seedless'®) under plastic sheet covering
In table grape cultivation, microclimate, irrigation strategy and canopy management have a large influence on harvesting time. For this reason, there isn't a unique method to assess the proper time of harvesting. The growing degree day (GDD) model can improve the determination of the exact maturity stage, but only if based on vine responses to daily temperature. Likewise, the physical mechanisms of vine perception of environmental conditions needed to be accounted. A maturity-based water use approach can be used to predict berry characteristics. In this study, harvesting time of 'Superior Seedless'® table grape was monitored under plastic sheet covering using total soluble solids (°Brix), titratable acidity (TA) measurements and °Brix/TA ratio. In addition, water consumption (WCons) based on evapotranspiration fluxes, ETc, was used to predict the response of berry to maturity stage, using time dependent meteorological data. The target of this study was to assess the relation between WCons with ratio soluble solids concentration (°Brix) and TA to define the optimal maturity phase. The regression linear model determined the relationship between °Brix and TA and GDD and the WCons. The results revealed correlation coefficients of determination (r2) of 0.84, 0.79 and 0.94 between WCons and °Brix, TA, and °Brix/TA ratio, respectively. The ratio between °Brix and TA was better related parameter with WCons (r2=0.94) than ratio of air relative humidity and air temperature (r2=0.77). The parameterized coefficients of the linear regression model were able to assess the berry composition depending on consumed water. WCons can be used as a basic parameter to determine the optimum harvesting stage of 'Superior Seedless'®.
Tarricone, L., Dragonetti, G. and Verrastro, V. (2021). A method to predict the time of harvesting based on water consumption and changes in berry composition of table grapes ('Superior Seedless'®) under plastic sheet covering. Acta Hortic. 1311, 311-318
grapevine, evapotranspiration, water-use, berry quality, soluble solids