Open Access
Site characteristics determine the effectiveness of tillage and cover crops on the net ecosystem carbon balance in California vineyard agroecosystems
(Frontiers Media, 2022) Zumkeller, María; Yu, Runze; Torres Molina, Nazareth; Marigliano, Lauren E.; Zaccaria, Daniele; Kurtural, Sahap Kaan; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Globally, wine grape vineyards cover approximately 7.4 M ha. The potential for carbon (C) storage in vineyards is of great interest to offset greenhouse gas emissions and mitigate the effects of climate change. Sustainable soil management practices such as cover crop adoption and reduced tillage may contribute to soil organic carbon (SOC) sequestration. However, site-specific factors such as soil texture, other soil physicochemical properties, and climate largely influence the range and rate to which SOC may be stored. To measure the potential for C storage in vineyards under varying sustainable soil management practices, we calculated the net ecosystem carbon balance (NECB) of three cover crops [perennial grass (Poa bulbosa hybrid cv. Oakville Blue); annual grass (barley, Hordeum vulgare); resident vegetation (natural weed population)] under conventional tillage (CT) and no-till (NT) management. Results provided evidence that vineyards served as C sinks. In sandy soils, the type of cover crop and tillage may be of little influence on the NECB. While in finer-textured soils, tillage reduced the NECB and higher biomass-producing cover crops enhanced the overall C storage potential of the vineyard agroecosystem. Overall, our results revealed that site characteristics, namely, soil texture and climate, were key determinants of the C storage potential of vineyards in Mediterranean climates such as those found in coastal and inland California wine grape production regions.
Open Access
Adapting wine grape production to climate change through canopy architecture manipulation and irrigation in warm climates
(Frontiers Media, 2022) Yu, Runze; Torres Molina, Nazareth; Tanner, Justin D.; Kacur, Sean M.; Marigliano, Lauren E.; Zumkeller, María; Gilmer, Joseph Chris; Gambetta, Gregory A.; Kurtural, Sahap Kaan; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Grape growing regions are facing constant warming of the growing season temperature as well as limitations on ground water pumping used for irrigating to overcome water deficits. Trellis systems are utilized to optimize grapevine production, physiology, and berry chemistry. This study aimed to compare 6 trellis systems with 3 levels of applied water amounts based on different replacements of crop evapotranspiration (ETc) in two consecutive seasons. The treatments included a vertical shoot position (VSP), two modified VSPs (VSP60 and VSP80), a single high wire (SH), a high quadrilateral (HQ), and a Guyot pruned VSP (GY) combined with 25%, 50%, and 100% ETc water replacement. The SH had greater yields, whereas HQ was slower to reach full production potential. At harvest in both years, the accumulation of anthocyanin derivatives was enhanced in SH, whereas VSPs decreased them. As crown porosity increased (mostly VSPs), berry flavonol concentration and likewise molar % of quercetin in berries increased. Conversely, as leaf area increased, total flavonol concentration and molar % of quercetin decreased, indicating a preferential arrangement of leaf area along the canopy for overexposure of grape berry with VSP types. The irrigation treatments revealed linear trends for components of yield, where greater applied water resulted in larger berry size and likewise greater yield. 25% ETc was able to increase berry anthocyanin and flavonol concentrations. Overall, this study evidenced the efficiency of trellis systems for optimizing production and berry composition in Californian climate, also, the feasibility of using flavonols as the indicator of canopy architecture.
Open Access
Photoselective shade films mitigate heat wave damage by reducing anthocyanin and flavonol degradation in grapevine (vitis vinifera L.) berries
(Frontiers Media, 2022) Marigliano, Lauren E.; Yu, Runze; Torres Molina, Nazareth; Tanner, Justin D.; Battany, Mark; Kurtural, Sahap Kaan; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Wine grape production is challenged by forecasted increases in air temperature and droughts due to climate change and photoselective overhead shade films are promising tools in hot viticulture areas to overcome climate change related factors. The aim of this study was to evaluate the vulnerability of ‘Cabernet Sauvignon’ grape berries to solar radiation overexposure, optimize shade film use for preserving berry composition. An experiment was conducted for two years with four shade films (D1, D3, D4, D5) with differing solar radiation spectra transmittance and compared to an uncovered control (C0). Integrals for leaf gas exchange and mid-day stem water potential were unaffected by the shade films in both years. At harvest, berry primary metabolites were not affected by treatments applied in either year. Despite precipitation exclusion during the dormant seasons in shaded treatments, and cluster zone temperatures reaching 58°C in C0, yield was not affected. Berry skin anthocyanin and flavonol composition and content were measured by C18 reversed-phase HPLC. In 2020, total skin anthocyanins (mg·berry-1) in the shaded treatments were 27% greater than C0 during berry ripening and at harvest. Conversely, flavonol content in 2020 decreased in partially shaded grapevines compared to C0. Berry flavonoid content in 2021 increased until harvest while flavonol degradation was apparent from veraison to harvest in 2020 across partially shaded and control grapevines. Untreated control showed lower di- to tri-hydroxylated flavonol ratios closer to harvest. Our results provided evidence that overhead partial shading of vineyards mitigate anthocyanin degradation by reducing cluster zone temperatures and is a useful tool in combatting climate change in hot climate regions.
Open Access
Arbuscular mycrorrhizal fungi inoculation and applied water amounts modulate the response of young grapevines to mild water stress in a hyper-arid season
(Frontiers Media, 2021-01-14) Torres Molina, Nazareth; Yu, Runze; Kurtural, Sahap Kaan; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
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.
Open Access
Impacts of leaf removal and shoot thinning on cumulative daily light intensity and thermal time and their cascading effects of grapevine (vitis vinifera L.) berry and wine chemistry in warm climates
(Elsevier, 2020-10-23) Torres Molina, Nazareth; Martínez-Lüscher, Johann; Porte, Etienne; Yu, Runze; Kurtural, Sahap Kaan; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Leaf removal (LR), shoot thinning (ST) and their combination (LRST) are known to increase berry solar exposure affecting berry composition and consequently improving wine quality and antioxidant properties. We hypothesized that LR, ST or their combination (LRST) would affect flavonoid content during berry ripening by means of changes of the berry microclimate (light and temperature) as well as wine composition, quality, and antioxidant properties. Thermal time and sum of light intensity thresholds were different to achieve the maximum berry anthocyanin and flavonol contents. ST mostly affected wine characteristics by increasing alcoholic content, acidity, hue and phenolic substances. Wine antioxidant capacity decreased in ST wines likely by decreases in catechin and quercetin contents. ST and LRST increased proanthocyanidin polymerization and decreased monomeric flavan-3-ols, which may reduce wine bitterness and enhance astringency. Therefore, the management of canopy should take into account the warming trends in viticulture regions, rather than being applied preemptively.
Open Access
Effects of irrigation at different fractions of crop evapotranspiration on water productivity and flavonoid composition of Cabernet Sauvignon grapevine
(Frontiers Media, 2021) Torres Molina, Nazareth; Yu, Runze; Martínez-Lüscher, Johann; Kostaki, Evmorfia; Kurtural, Sahap Kaan; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Climate change models predict lower precipitation and higher air temperatures that will negatively affect viticultural regions. Irrigation of vineyards will be crucial for mitigating abiotic stress during the growing season. However, the environmental impact of irrigation requires consideration for ensuring its sustainability in the future. We evaluated the standard irrigation practices on grapevine water use efficiency, berry flavonoid composition, vineyard water footprint, and arbuscular mycorrhizal fungi-grapevine symbiosis in two seasons with contrasting amounts of precipitation. The irrigation treatments consisted of weekly replacement of 25, 50, and 100% of crop evapotranspiration (ETc) during two growing seasons. Irrigation in grapevine vineyards mitigated the water scarcity when precipitation during the dormant season was not sufficient. The results provided field data supporting that despite the low rainfall recorded in one of the seasons, increasing the amount of irrigation was not advised, and replacing 50% ETc was sufficient. In this treatment, berry composition was improved with increased contents of total soluble solids, anthocyanins, and flavonols, and a stable flavonoid profile without an economic decrease in yield. In addition, with 50% ETc, the mycorrhizal symbiosis was not compromised and water resources were not highly impacted. Altogether, our results provide fundamental knowledge for viticulturists to design an appropriate irrigation schedule under the future warming scenarios with minimal environmental impact in semi-arid regions facing warming trends.