Department of Viticulture and Enology, University of California Davis , 1 Shields Avenue, Davis, California 95616, United States.
E. J. Gallo Winery, 1541 Cummins Drive, Modesto, California 95358, United States.
J Agric Food Chem. 2017 Jul 5;65(26):5255-5265. doi: 10.1021/acs.jafc.7b01749. Epub 2017 Jun 26.
Plant water stress affects grape (Vitis vinifera L. cv. Cabernet Sauvignon) berry composition and is variable in space due to variations in the physical environment at the growing site. We monitored the natural variability of grapevine water stress by stem water potential (Ψ) and leaf gas exchange in an equi-distant grid in a commercial vineyard. Spatial differences were measured and related to topographical variation by modeling. Geospatial analysis and clustering allowed researchers to differentiate the vineyard block into two distinct zones having severe and moderate water stress where it varied by 0.2 MPa. Differences in stem water potential affected stomatal conductance, net carbon assimilation, and intrinsic water use efficiency that were different in all measurement dates. The two zones were selectively sampled at harvest for measurements of berry chemistry. The water status zones did not affect berry mass or yield per vine. Significant difference in total soluble solids was observed (3.56 Brix), and in titratable acidity, thus indicating a direct effect of water stress on ripening acceleration. Berry skin flavonol and anthocyanin composition and concentration were measured by C18 reversed-phased high-performance liquid chromatography (HPLC). The anthocyanins were most affected by the two water stress zones. The dihydroxylated anthocyanins were more affected than trihydroxylated; therefore, the ratio of the two forms increased. Flavonols were different in total amounts, but hydroxylation patterns were not affected. Proanthocyanidin isolates were characterized by acid catalysis in the presence of excess phloroglucinol followed by reversed-phase HPLC. Proanthocyanidins showed the least significant difference, although (+)-catechin terminal subunits were important predictors in a partial least square model used to summarize the multivariate relationships, predicting Ψ or the management zone. The results provide fundamental information on vineyard water status to discriminate harvest or direction to vineyard operators to modify irrigation management to equilibrate berry composition at harvest.
植物水分胁迫会影响葡萄（Vitis vinifera L. cv. Cabernet Sauvignon）浆果的成分，并且由于生长地点的物理环境的变化，在空间上具有变异性。我们通过茎水势（Ψ）和叶片气体交换在商业葡萄园的等距网格中监测葡萄水分胁迫的自然变化。通过建模测量了空间差异，并与地形变化相关联。地理空间分析和聚类使研究人员能够将葡萄园块分为两个具有严重和中度水分胁迫的不同区域，其差异为 0.2 MPa。茎水势的差异影响气孔导度、净碳同化和内在水分利用效率，这些在所有测量日期都不同。在收获时对两个区进行选择性采样，以测量浆果化学特性。水分状况区不影响浆果质量或每株葡萄的产量。在总可溶固形物方面观察到显著差异（3.56 度），以及可滴定酸度，这表明水分胁迫对成熟加速有直接影响。通过 C18 反相高效液相色谱（HPLC）测量浆果果皮类黄酮和花色苷的组成和浓度。花青素受两个水分胁迫区的影响最大。二羟基化的花青素比三羟基化的花青素受影响更大；因此，两种形式的比例增加。类黄酮的总量不同，但羟基化模式不受影响。在存在过量根皮苷的情况下通过酸催化并随后通过反相 HPLC 对原花青素分离物进行了表征。原花青素表现出最小的差异，尽管（+）-儿茶素末端亚基是用于总结多变量关系的偏最小二乘模型中的重要预测因子，可预测 Ψ 或管理区。这些结果为葡萄园水分状况提供了基本信息，以便区分收获或为葡萄园经营者提供方向，以修改灌溉管理，在收获时使浆果成分达到平衡。
