Effects of an early-summer drought stress on leaf photosynthesis, growth and yields of grapevine in mountain conditions
MetadataShow full item record
Climate change scenarios for alpine areas predict increasing temperatures and more variable precipitation distribution during the year. The eco-physiological responses of grapevines to modified conditions, and in particular to water stress, depend on complex interactions of edaphic and climatic factors. In the present research we examined the vine responses to increasing levels of drought stress in an early stage of berry development. The trial was conducted in a drip irrigated vineyard ('Sauvignon B.' on SO4 rootstock) in South Tyrol (northern Italy). Three treatments were established: i) standard farm irrigation (FI); ii) deficit irrigation (DI), corresponding to the 50% of the FI irrigation volume; iii) no irrigation, rainfed (RF). The growing season 2014 showed a short drought period during the early phase of berry growth (end of May-beginning of June) and an atypically high precipitation level during the remaining part of the summer. During the drought period, predawn leaf water potential (ΨPD) reached -0.7 MPa in RF vines. Transient loss of turgidity and shoot growth reduction were also observed. The drought effect was observable also later in the season when it caused delay of berry development, a long lasting reduction of the leaf photosynthetic capacity and a yield reduction of approximately 35% in DI and 63% in RF, compared to the FI treatment. Berry size was significantly reduced in RF treatment only. A shoot re-growth was observed in RF thesis after the high summer precipitation, highlighting the capacity of grapevines to react even within the same growing season to enhanced soil water availability.