Proceedings of the 2009 Texas Viticulture & Enology Research Symposium

Evaluation of Regulated Deficit Irrigation in Texas

Basinger, A.R. and E.W. Hellman. 2006. Evaluation of regulated deficit irrigation on grape in Texas and implications for acclimation and cold hardiness. International Journal of Fruit Science 6(2):3-22.

ABSTRACT. Deficit irrigation is used increasingly as a vigor management tool and to conserve water in grape vineyards. Several strategies including regulated deficit irrigation (RDI) have emerged, but none has been evaluated in Texas. Deficit irrigation has also been observed to influence vine acclimation and presumably vine cold hardiness. Experiments were established in a commercial 'Cabernet Sauvignon' (Vitis vinifera) vineyard in west Texas to evaluate RDI under local conditions and to study the potential for deficit irrigation to induce earlier shoot acclimation and influence cold hardiness. RDI significantly reduced pruning weights by as much as 46% and increased applied water-use efficiency up to 72%, but had little or no effect on yield components or fruit composition, indicating that these strategies could be useful in west Texas. Deficit irrigation was consistently associated with earlier and more rapid development of periderm on shoots, but had no effect on bud cold hardiness.

Evaluation of Abscisic Acid to Delay bud break of grapevines

Hellman, E.W., S. Shelby, and C. Lowery. 2006. Exogenously applied abscisic acid did not consistently delay budburst of deacclimating grapevine. Journal of the American Pomological Society 60:178-186.

ABSTRACT. An experimental formulation of abscisic acid (ABA; Valent Biosciences VBC-30025) was evaluated for potential to delay budburst of (Vitis vinifera L. winegrapes. Five experiments were conducted during 2004 and 2005 on dormant grapevine cuttings, container-grown vines, and field-grown vines to evaluate rates and/or timing of ABA applications. Two application methods were tested - spray application to buds or soil application. Spray application of ABA solutions to unopened buds increased the number of days to budburst by 3.5 days in one of four laboratory trials on single-bud cuttings, and delayed budburst by one day in established field-grown vines in one of two years. Further study to enhance the efficacy of ABA spray applications should examine materials or methods to improve penetration of ABA through bud scales. Soil applications of ABA to container-grown vines provided the greatest delay in budburst (up to 7 days) and gave the most consistent response. Soil application of ABA to established field-grown vines, however, produced no response and this may not be a practical or economical application method for commercial vineyards.