Combined effects of water status and iron deficiency chlorosis on grape composition in non-irrigated vineyards

ABSTRACT: Although water deficit and iron deficiency chlorosis are common environmental stresses in the Mediterranean area, few data are reported in the literature on their effects on vineyards, when acting simultaneously. The main objective of this research was to study the combined effects of iron deficiency and water status on vigor, yield and fruit composition in rainfed vineyards. Moreover, the investigation aimed to evaluate the feasibility of using foliar chlorophyll content (Chl) and predawn leaf water potential (LWP), measured at veraison, to assess potential quality of grapes in the framework of precision viticulture. For this, 24 non-irrigated ‘Tempranillo’ vineyard subzones were monitored in Ribera del Duero (North-Central Spain) during three consecutive seasons (2011-2013). The analysis of variance and principal component analysis showed that malic acid concentrations of the must were impacted only by Chl, whereas total soluble solids and total acidity were mainly modified by LWP. Both water and iron status reduced yield and berry weight and had additive effects on extractable anthocyanin content in grapes, total polyphenol index and color density of the must. In all seasons, the ratio Chl/LWP had a better predicting value for quality parameters of these grapes than leaf area index, Chl or LWP individually. The present work demonstrates the potential interest of physiological indexes combining water status and foliar chlorosis as indicators of grape phenolic potential in rainfed vineyards affected by iron deficiency.

摘要：尽管水分亏缺与缺铁性失绿是地中海地区常见的环境胁迫，但目前文献中鲜有关于二者同时作用对葡萄园产生的影响的相关报道。本研究的核心目标为探究水分状况与缺铁胁迫的复合效应，及其对雨养葡萄园的树势、产量及果实品质组成的影响。此外，本研究旨在评估在精准葡萄栽培（precision viticulture）框架下，利用转色期测定的叶片叶绿素含量（Chl）与黎明前叶水势（LWP）预判葡萄潜在品质的可行性。为此，研究团队于2011至2013年连续三个生长季，在西班牙中北部的杜罗河产区（Ribera del Duero）对24个非灌溉丹魄（Tempranillo）葡萄园亚区进行了监测。方差分析与主成分分析结果显示，葡萄汁中的苹果酸浓度仅受叶绿素含量影响，而总可溶性固形物与总酸度则主要受黎明前叶水势调控。水分与铁营养状况均会降低产量与浆果重量，且对葡萄可提取花青素含量、总多酚指数及葡萄汁色泽密度存在加性效应。在所有三个生长季中，相较于单独使用叶面积指数、叶绿素含量或黎明前叶水势，Chl/LWP比值对葡萄品质参数的预测效果更佳。本研究证实，将水分状况与叶片失绿情况相结合的生理指标，可作为受缺铁胁迫的雨养葡萄园葡萄酚类物质潜力的评价指标，具备潜在应用价值。