Application of anti-transpirant under greenhouse conditions of grapevines (Vitis vinifera cv. Riesling and cv. Müller-Thurgau) reduce photosynthesis

Abstract

The increasing temperatures, caused by the global change, lead to an earlier onset of developmental stages, changes in productivity and physiology of different crops and will challenge the growers in the future. Depending on the seasonal conditions the onset of flowering is approximately 10 days earlier compared to the long term average and the ripening phase is elongated. Berries are able to accumulate photosynthates over a longer and warmer time period. The sugar content in the berries increases and results in higher alcohol contents in wines. The aim of this study was to investigate the effect of anti-transpirants (AT, Vapor gard – VG and NuFilmP – NuF) on photosynthesis under greenhouse conditions to possibly translate this approach to field conditions altering the sugar accumulation in the berries. Therefore a greenhouse experiment was conducted with potted Riesling and Müller-Thurgau grapevines. With non-invasive techniques (gas exchange, chlorophyll fluorescence and Multiplex®) the physiological state of potted grapevines were measured. Plants showed a reduced photosynthesis rate, stomatal conductance and total soluble sugars (under field conditions, data not shown) compared to control plants. It is proposed that spraying of anti-transpirant can be a new tool to regulate the sugar content in the berries as an alternative to mechanical defoliation.