WW GDT 02
Quantification and characterisation of water stress in grapevines under sub-surface irrigation and selective water stresses with novel measuring techniques
Strever, A E
University of Stellenbosch
De Villiers, Z
Roussouw, G C
Carbon isotope discrimination, photosynthesis measurements and infrared thermometry were evaluated to monitor grapevine water status differences induced by different irrigation strategies.
Results showed that stem water potential correlated best with most of the techniques. Pre-dawn and midday leaf water potentials did not correlate well with measures of leaf temperature, carbon discrimination, or photosynthesis. These measurements were however more useful to quantify the irrigation regime applied. It was found that partial root zone drying vines exhibited the least water deficits during the season followed by a 4x irrigation treatment, compared to the rain-fed treatment. This could also be seen from increased vine vigour at these plots. No significant differences were however found in berry characteristics. Grapevine vigour was shown to have a significant effect on the measurement of water status using physiological parameters.
Carbon discrimination analyses showed close relationships with both stem water potential and stomatal conductance. Very good distinction between irrigation strategies was shown in the seasonal evolution of carbon discrimination, indicating the potential usefulness of this measuring technique.
The partial root zone drying experiment indicated a significant increase in water use efficiency compared to irrigations that received the same amount of water, without any indication of increased water stress. More water deficits indicated by carbon discrimination, stem water potential and stomatal conductance also seemed to result in lower berry TSS levels and smaller berries.
Du Plessis, C, Myburgh, P and Bindon, K A. 2005. The effect of irrigation on grapevine water status and phenolic composition in grapes (Vitis vinifera, cv. Merlot). Poster. 3rd International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.
Bindon, K A, Du Plessis, C S, Oberholster, A and Myburgh, P. 2007. Phenolic profiling of Vitis vinifera cv. Merlot grapes and wines produced under varying conditions of grapevine water status. Poster presented at the 13th Australian Wine Industry Technical Conference. 28 July – 2 August, Adelaide, Australia.
Du Toit, P G, Strever, A E and De Villiers, Z. 2005. Unravelling water stress in conservative and strategically irrigated grapevines. Paper presented at the 3rd International Congress of the South African Society for Enology and Viticulture. 28-30 July, Cape Town, South Africa.
Du Toit, P G. 2006. Water word in wyn verander: Aspekte van wingerdbesproeiing. Presentation at the South African Society for Enology and Viticulture Preharvest Workshop. Elsenburg, Stellenbosch, South Africa.
Rossouw, G C. 2010. The effect of within-vineyard variability in vigour and water status on carbon discriminiation in Vitis vinifera L. cv Merlot noir. MScAgric. University of Stellenbosch, Stellenbosch.
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