Application of different commercial biostimulants to enhance vine tolerance toward drought stress

BENYAHIA FADWA; GIOVANELLI, FRANCESCO; GONZALEZ, CARINA V.; ANDREOTTI, CARLO

Conegliano

Congreso; Convegno Nazionale di Viticoltura 2022; 2022

Although the rising interest in plant biostimulants’(PBs) implications in several crops for water stress tolerance, research about their efficacy in viticulture is partly missing and results are often inconsistent. In this study, we evaluated the effect of four different commercial biostimulants (arbuscular-mycorrhizal fungi (AMF), protein-hydrolysate (PH), seaweed extracts (SEA) and silicon (SI)) on growth and physiological behavior of potted grapevines (cv. Sauvignon blanc) upon water stress exposure. Fifty vines were transplanted in 6L pots filled with sand, perlite and peat (60:20:20 by volume). Vines were grown in controlled conditions under two water regimes: well-watered (WW) and water-stress (WS). Five biostimulants applications were performed through drenching (AMF) or foliar sprays (PH, SEA, SI) before imposing the water stress conditions. Vine growth performances, during and after the drought period, as affected by the different PBs applications were monitored every other day by measuring several physiological (plant water status, leaf gas exchange, chlorophyll fluorescence, chlorophyll content) and biometric parameters (shoot length, number of leaves, leaf area). At the end of trial, the biomass of the different organs was determined.During WS, midday stem water potential of AMF and SEA-treated plants showed a slower decrease (-0.2 MPa/day, corresponding to 36% less) than the untreated-WS vines. Moreover, the PBs pre-stress application accelerated the leaf gas exchange recovery to WW values. Upon rewatering, SI-WS-treated plants showed increments of leaf gas exchanges rates that were around 30% higher than those of the control-WS vines. As for the seasonal biomass accumulation, it resulted lower in WS-vines, independently of the PBs. Overall, the application of selected PBs before the water stress allowed to slow down the buildup of the drought stress in grapevine, therefore enhancing the possibility for the crop to overcome the negative physiological consequences of periods of water scarcity. Further evidence of PBs effectiveness is nevertheless needed especially under vineyard (open field) conditions.