Fruit quality and yield in Vitis Vinifera cv Pinot noir

Abstract

Fruit quality and yield in Vitis Vinifera cv Pinot noir

Summary

This report presents preliminary outcomes of the PhD project of Mr Mark Robertson, supervised by Drs Steve Wilson and Joanna Jones at the Tasmanian Institute of Agricultural Research, University of Tasmania. Three experiments were implemented in an attempt to further understanding about the use of different mechanisms for altering the fruit composition of Pinot Noir in cool climates.

The first experiment focused on the implications of leaf removal for yield and fruit composition. Over three seasons there was no influence of defoliation on anthocyanin concentration, titratable acidity, Brix°or pH. In 2007, there was a significant reduction in bunch number for the 100% defoliation treatment, however yield was not effected in any of the other treatments or years. There was a significant correlation between mean berry mass and anthocyanin concentration, with smaller berries having a significantly higher anthocyanin concentration. The decrease in anthocyanin concentration with increasing berry number suggests that colour development may be related more to internal shading within the bunch than to internal shading within the canopy. There was also a significant relationship between mean berry mass and titratable acidity (TA), with smaller berries having lowers TA values.

Due to the relationship between bunch size and anthocyanin accumulation in the previous experiment, the second experiment aimed to look at the direct effect of shading on the fruit, without altering the canopy. When bunches were shaded, anthocyanin concentration increased with increasing light accumulation. Anthocyanin concentration did not appear to be affected by mean temperature in this study. However the temperatures exhibited in this study were not considered extreme, with the highest mean temperature not exceeding 22°C. It remains to be seen if a decrease in anthocyanin concentration would occur when mean maximum temperature was used. Furthering the relationship between bunch size and colour development, the final experiment was planned in an attempt to alter bunch architecture. Gibberellic Acid when applied at concentrations of 300ppm and above, appeared to significantly influence bunch architecture, with resulting lower bunch densities. These lower bunch densities were associated with higher anthocyanin concentrations at harvest.