Cover crop and deficit irrigation to maximize control of vineyard water availability in humid climate

Doctoral thesis abstract

Abstract

The objective of the study is to improve the quality and regularity of Tannat wine, through soil management aimed at increasing the potential control of vine water availability. We propose a change in the current grape growing paradigm, where the strategy in non-irrigated vineyards is to avoid competition with the cover crops through herbicide applications and accept unpredictable periods of water deficit or excess. A "new logic" instead, is based on the assumption that it is posible with under trellis cover crops (UTCC) limits water availability during periods of excess and avoid excesive vine water stress, during deficit periods with irrigation. Due to the interaction with other cultural practices will determine the balance between eco-systemic services and desservices of cover crops in vineyards, this strategy was evaluated in combination with other management practices (plantation density, trellis systems, nitrogen fertilization and irrigation strategies) from 2011 to 2015 in the south of Uruguay. UTCC was an effective tool to restrict the excessive vine vegetative growth, being water availability during post-bloom period the key driver for vegetative growth. UTCC increased grapes Brix and anthocyanins concentration, as well as enhance the aromatic and sensory profile of Tannat wines. Depending on the level and period in which water deficit occurs, UTCC could excessive restrict vine vegetative growth and yield, being a practice not recomended to apply in dry land. Conversely, with supplemental irrigation, it is an economically and environmentally sustainable alternative to consistently produce high quality wines in humid environments. The novelty of our results is the significant reduction of bunch rot incidence observed in UTCC compered to H treatment, independently of vegetative growth.