Arbuscular Mycrorrhizal Fungi Inoculation and Applied Water Amounts Modulate the Response of Young Grapevines to Mild Water Stress in a Hyper-Arid Season

Abstract

Several factors may affect the success of a replanting vineyard. Given the current environmental conditions, an optimized irrigation schedule would still be one of the most desirable tools to improve crop productivity and fruit quality. On the other hand, the symbiosis of grapevines with arbuscular mycorrhizal fungi (AMF) is a key component of the vineyard production systems improving the vine growth, nutrient uptake, and berry quality. The aim of this study was to characterize the response of Merlot grapevines to AMF inoculation and two different irrigation amounts in their first productive year. The experiment was conducted on 2-year Merlot grapevines inoculated with AMF (I) or not-inoculated (NI) and subjected to two irrigation amounts, full irrigated (FI), where the amount of water was enough to maintain expansive growth and half irrigated (HI) where plants received the half of the amount of water of FI plants. Water status, gas exchange parameters, growth, mineral content, berry composition, and mycorrhizal colonization were monitored through the season. AMF inoculation improved the grapevine vegetative growth, water status, and photosynthetic activity, especially when vines were subjected to HI irrigation; however, no effect was observed on the leaf mineral content, must pH, total soluble solids, or total acidity. The main effects were observed on the flavonoid composition of berry skins at harvest. Irrigation amounts and mycorrhizal inoculation modified cyanidin and peonidin derivatives whereas flavonol composition was mainly affected by irrigation treatments. A strong relationship between the mycorrhizal colonization rate of roots and total quercetins, cyanidins, and peonidins was found. Findings support the use of a mycorrhizal inoculum and a better water management in a hyper-arid growing season; however, these results may be affected by edaphoclimatic characteristics and living microbiota in vineyard soils, which should be taken into account before making the decision of inoculating the vineyard.

Effects of Irrigation at Different Fractions of Crop Evapotranspiration on Water Productivity and Flavonoid Composition of Cabernet Sauvignon Grapevine

“…Previous research suggested that these effects might be related to the altered regulation of nutrient transport, cell wall-related, phenylpropanoid, and stilbene biosynthesis genes driven by AMF colonization (Bruisson et al, 2016 ; Balestrini et al, 2017 ). Additionally, it was recently reported that AMF may enhance the content of flavonoids in berries (Torres et al, 2019 , 2021a ), leading to improved berry composition and antioxidant properties in spite of the lack of effect on petiole nutrient contents (Torres et al, 2021a ). However, vineyard management practices may affect the soil structure and the composition of the rhizosphere-living microbiota (Coller et al, 2019 ; Vink et al, 2021 ), as well as the microbiota associated with grapevine roots, which is mainly composed by Rhizophagus and Glomus genus (Schreiner, 2020 ), likely affecting the effectiveness of the symbiosis.…”

“…Root samples were cleaned, cleared, and stained according to methods described in Koske and Gemma (1989). Fifty root segments per replicate (∼1 cm each) were examined under the microscope to determine intraradical AMF colonization as previously described in Torres et al (2016Torres et al ( , 2021a. Briefly, the extension of mycorrhizal colonization was determined by estimating its product in width and length according to a scale range between 0 and 10, where 0 is the complete absence of fungal structures.…”

“…The other aim in applying water deficits was to maintain or improve grape berry composition (Terry and Kurtural, 2011 ). Deficit irrigation methods apply a predetermined fraction of the crop evapotranspiration (ET c ), during a portion of the growing season (Torres et al, 2021a ). A large and growing body of literature investigated how these strategies, including various timing, duration, and severity, affected grapevine physiology and consequently, berry composition regarding sugar and anthocyanin accumulation and the subsequent chemical composition in wines (Chaves et al, 2010 , Intrigliolo and Castel, 2008 ; Keller et al, 2016 ; da Silva et al, 2018 ; Torres et al, 2021b ).…”

“…In addition, previous studies demonstrated that management practices strongly shaped bacterial and fungal communities in vineyard soils (Coller et al, 2019 ; Vink et al, 2021 ), which may modulate grapevine responses to environmental stresses. Under controlled conditions, the association of grapevines with AMF enhanced berry quality (i.e., increased phenolic content) when potted grapevines were subjected to deficit irrigation and elevated temperature (Torres et al, 2018b , c ), whereas berry flavonoid metabolism was upregulated in AMF-inoculated grapevines in vineyards (Torres et al, 2021a ).…”

Arbuscular Mycorrhizal Fungi Improve Growth, Photosynthetic Activity, and Chlorophyll Fluorescence of Vitis vinifera L. cv. Ecolly under Drought Stress

“…A positive effect on plant biomass, osmolytes, and antioxidant enzyme activity under drought was noted in Zenia insignis [11], while alleviating the effect of AMF on Knautia arvensis drought stress was supported by lower proline accumulation [12]. Higher water-use efficiency in mycorrhizal wheat was also noted [13], and a few pieces of research have reported that AMF symbiosis increased grapevine tolerance to water stress and increased water-use efficiency [2,18].…”