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Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UC Davis Electronic Theses and Dissertations (2021)

Chloride-induced grapevine toxicity is a leading contributor to abiotic stress in viticultural regions characterized by aridity and limited water availability. Although an essential element for plants, in large enough quantity chloride can reduce net photosynthesis, leaf area, and water uptake in grapevines. Furthermore, the scarcity of water for irrigation has promoted the use of water use efficient irrigation methods such as dripline application, which can limit leaching of nutrients and toxins, and a build-up of salts on the periphery of the wetting-zone. Deficit irrigation practices can also be utilized to improve fruit quality. This dissertation explores the range of tolerance to toxic soil-chloride concentrations in genus Vitis, limitations and thresholds for chloride tolerance in grapevines, and the potential for breeding chloride tolerant grapevine rootstocks. Each topic is expanded in chapters 1, 2, and 3 of this dissertation, respectively. The historic threat of Grapevine Phylloxera in vineyards has resulted in the proliferation of grapevine rootstock cultivars to address this pest and other stressors. Relative to many other perennial crops, grapes have a wide selection of stock to choose from. However, there are innumerable, untested, and often undiscovered species and landraces undisturbed in their native habitats of the Americas that may hold further benefits to vineyards worldwide. To better define the range of chloride tolerance in Vitis germplasm, we examined the resistance to chloride toxicity in six species of wild grapevine collected from the south and southwestern United States alongside several cultivated and widely utilized rootstock cultivars. Presented in chapter 1, results from this survey suggest untapped potential for quasi-halophytic properties in some wild grapevine species such as V. acerifolia and V. doaniana. In chapter 2 common varieties were tested against a gradient of applied sodium chloride ranging from 0 – 100 mM NaCl to better define the chloride concentration threshold at which photosynthetic function begins to decline in commercial rootstock cultivars and chloride becomes toxic. Chapter 2 establishes a range of NaCl exposure between 25-75 mM NaCl in which photosynthetic function begins to break down in many rootstock varieties. Finally, chapter 3 crosses a highly tolerant and highly susceptible parent to explore the breeding potential of chloride tolerance phenotypes in grapevine offspring. Throughout the 77 tested offspring we observed a wide range of continuous increments of foliar chloride accumulation, suggesting possible heritability of chloride-excluding phenotypes. These experiments suggest an untapped source of chloride tolerance in grapevines exists, the range at which these semi-tolerant varieties have the highest efficacy and support the heritability of chloride-excluding phenotypes in subsequent generations. Taken together, this project increases the likelihood a breeding program can introduce chloride-tolerant grapevine rootstock phenotypes that could be successful.

    Cover page: Exploration of Grapevine Rootstocks to Combat Chloride-Induced Toxicity
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2020)
    Rising temperatures in most agricultural regions of the world are associated with a higher incidence of extreme weather events such as heat waves. We performed an experiment to mitigate the impact of heat waves and exposure of berries in grapevine (Vitis vinifera cv. "Cabernet Sauvignon") with untreated vines (Exposed) or with fruit-zone partial shading (Shaded) under 40 and 80% replacement of crop evapotranspiration (ET c ) with sustained deficit irrigation in a factorially arranged experiment. The trial was performed in a vineyard with vertically shoot positioned trellis with a row orientation that concentrated solar radiation exposure on the southwest aspect of the fruit zone. Leaf stomatal conductance (g s ) and net carbon assimilation (A N ) were significantly lower in shaded leaves under partial fruit-zone shading that resulted in lower pruning mass for Shaded treatments. Stem water potential (Ψ stem ) responded to a large extent to increased irrigation. However, grapevines with partial fruit-zone shading had transiently better water status under 40% ET c . Cluster maximum temperatures were 3.9°C greater in Exposed grapevines. Exposed clusters had transiently lower acidity and higher pH. However, Exposed clusters on 40% ET c had higher total soluble solids (TSS). The experimental vineyard suffered a 4-day heat wave 21 days before harvest, resulting in 25% of the clusters being damaged in Exposed treatment, regardless of irrigation amount. Furthermore, berries in Exposed treatments suffered a great loss of anthocyanins and flavonols even if they were not damaged by direct solar exposure. The pre-planting decision of using a vertically shoot positioned trellis that concentrated solar radiation on the Southwest aspect offered mild protection in a hot climate region with a sunny growing season with extreme heat events during the execution of study. The extreme conditions under which this study was conducted are not unusual, and have become more expected. Our work provided evidence of the vulnerability of grape berry to heat waves and exposure during heat wave events and possible protection methods to mitigate these effects in situ in context of climate change.
      Cover page: Mitigating Heat Wave and Exposure Damage to “Cabernet Sauvignon” Wine Grape With Partial Shading Under Two Irrigation Amounts
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2022)

      Background

      Soil salinity, in both natural and managed environments, is highly heterogeneous, and understanding how plants respond to this spatiotemporal heterogeneity is increasingly important for sustainable agriculture in the era of global climate change. While the vast majority of research on crop response to salinity utilizes homogeneous saline conditions, a much smaller, but important, effort has been made in the past decade to understand plant molecular and physiological responses to heterogeneous salinity mainly by using split-root studies. These studies have begun to unravel how plants compensate for water/nutrient deprivation and limit salt stress by optimizing root-foraging in the most favourable parts of the soil.

      Scope

      This paper provides an overview of the patterns of salinity heterogeneity in rain-fed and irrigated systems. We then discuss results from split-root studies and the recent progress in understanding the physiological and molecular mechanisms regulating plant responses to heterogeneous root-zone salinity and nutrient conditions. We focus on mechanisms by which plants (salt/nutrient sensing, root-shoot signalling and water uptake) could optimize the use of less-saline patches within the root-zone, thereby enhancing growth under heterogeneous soil salinity conditions. Finally, we place these findings in the context of defining future research priorities, possible irrigation management and crop breeding opportunities to improve productivity from salt-affected lands.
        Cover page: Plant responses to heterogeneous salinity: agronomic relevance and research priorities
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