Evaluating the Spectral and Physiological Responses of Grapevines (Vitis vinifera L.) to Heat and Water Stresses under Different Vineyard Cooling and Irrigation Strategies

Alessia Cogato,Vinay Pagay,Franco Meggio,Lihua Wu,Marco Sozzi,Shaikh Yassir Yousouf Jewan,Francesco Marinello

doi:10.3390/agronomy11101940

Abstract

Heat stress (HS) and water stress (WS) pose severe threats to viticulture, and effective management solutions to counter their effects on grapevine performance must be examined. In this study, we evaluated the physiological and spectral responses of Vitis vinifera L. cv. Sauvignon blanc to individual (HS) and combined (HS + WS) stress under four different cooling and irrigation strategies. The treatments were: standard drip irrigation (SI), extra drip irrigation (SI+), extra sprinklers irrigation (SPRI), and sustained deficit irrigation (SDI; 50% of SI). Compared to the other treatments, in the early stages after the occurrence of HS, the vine water status of SPRI and SI+ improved, with high stomatal conductance (gs) (SPRI) and stem water potential (Ψstem; SPRI and SI+). All the physiological indicators measured were significantly lower after the end of HS in the SDI treatment. We also identified the spectral response of grapevine to HS and combined HS and WS (resulting from SDI). Consistent with the physiological analysis, the proximal spectral responses of leaves identified SPRI and SI+ as putative cooling strategies to minimize vine HS. The vines undergoing combined stress (SDI) showed greenness amelioration 10 days after stress, as revealed by the greenness vegetation indices (VIs), i.e., Green Index (GI), Normalized Difference Greenness Vegetation Index (NDGI), and Visible Atmospherically Resistant Index (VARI). However, their physiological recovery was not achieved within this time, as shown by the Simple Ratio Index (SRI), Transformed Chlorophyll Absorption Ratio Index (TCARI), and TCARI/Optimized Soil-Adjusted Vegetation Index (TCARI/OSAVI). A three-step band selection process allowed the identification of the spectral traits’ responsive to HS and combined stress, i.e., 1336–1340 nm, 1967–1971 nm, and 600–604 nm.

Highlights

One of the consequences of climate change is the increased frequency, duration and intensity of heatwaves [1,2]
The results showed that sustained deficit irrigation (SDI) treatment suffered from heat stress (HS), because all the physiological indicators were significantly lower two days after the end of HS, and the stress condition persisted 10 days after the end of HS (Figure 3)
We analyzed the physiological behavior of Sauvignon blanc under conditions of individual HS and combined HS and water stress (WS)

Summary

Introduction

One of the consequences of climate change is the increased frequency, duration and intensity of heatwaves [1,2]. Current projections estimate that heatwaves will further increase by 2100 [9,10]. The effects of heat stress (HS) on grapevine physiology have been studied. The inhibition of net photosynthesis (Pn) caused by HS can lead to lower yield in several grapevine varieties [6,7]. Grape berry maturation may be delayed [11], with a consequent reduction in the size and fresh weight [7] and increased shriveling of berries [12,13]. A decoupling between anthocyanins and sugar was observed in Shiraz and Cabernet Franc under high-temperature conditions [14], and rotundone concentrations were reduced in Shiraz wines [15]

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Discussion

Conclusion