Seasonal grapevine crop coefficients (K_c) were estimated from the shaded area (SA) beneath grapevine canopies at solar noon in vineyards with different trellises and row spacings. The trellises included the vertical shoot positioning (VSP) trellis, Lyre trellis, single and double curtains, cross-arms of varying lengths, and sprawl systems (shoots not positioned). Measurements were taken throughout the grape growing regions of California. The percent shaded area (PSA) was multiplied by 0.017, slope of the relationship between PSA and K_c, to calculate the K_c. Vines used to measure SA were not stressed for water as midday leaf water potential was ≥ −1.0 MPa. The seasonal increase in SA was significantly correlated with the accumulation of degree-days (DDs; base 10°C from the approximate date of budbreak) across locations and years. The PSA was a significant function of trellis – wider trellises spread the canopy and increased SA more than narrower trellises, thus having greater K_c values. The mid-season K_c (K_{c mid}) for the Lyre and VSP trellises on a 2.74 m row spacing were 0.96 and 0.49, respectively. In addition, K_{c mid} was inversely correlated with vineyard row spacing – the closer the row spacing for a particular trellis, the greater the K_{c mid}. The K_{c mid} for a VSP trellis on 1.83 and 3.05 m row spacings were 0.87 and 0.52, respectively. In contrast, the effects of vineyard row direction and location were minor. The seasonal K_c values developed here do not decrease from mid-season, even after harvest, with a few exceptions. Equations given herein express the seasonal K_c as a function of degree-days, trellis type, and row spacing, thus providing useful estimates of seasonal K_c values for use in California or elsewhere in vineyards with trellises like those in this study.

季节性葡萄作物系数 (K _c ) 是从具有不同棚架和行距的葡萄园在太阳正午时葡萄树冠下的阴影面积 (SA) 估算的。格架包括垂直射击定位 (VSP) 格架、Lyre 格架、单帘和双帘、不同长度的横臂和蔓延系统（未定位的射击）。在加利福尼亚的整个葡萄种植区进行了测量。阴影面积百分比 (PSA) 乘以 0.017，即 PSA 和 K _c之间关系的斜率，以计算 K _c. 由于正午叶片水势≥ -1.0 MPa，因此用于测量 SA 的葡萄藤没有受水压力。SA 的季节性增加与不同地点和年份的度日（DDs；从大约发芽日期起基准 10°C）的累积显着相关。PSA 是格子的一个重要功能——较宽的格子扩展了树冠，并且比较窄的格子增加了更多的 SA，因此具有更大的 K _c值。Lyre 和 VSP 格子在 2.74 m 行距上的季中 K _c (K _{c mid ) 分别为 0.96 和 0.49。}此外，K _{c mid}与葡萄园行距呈负相关——特定格子的行距越近，K _{c mid}越大。ķ行距为 1.83 和 3.05 m 的 VSP 格子的_{c 中值分别为 0.87 和 0.52。}相比之下，葡萄园行方向和位置的影响较小。这里开发的季节性 K _c值不会从季节中期开始下降，即使是在收获之后，也有一些例外。本文给出的公式将季节性 K _c表达为度日、格子类型和行距的函数，因此提供了有用的季节性 K _c值估计值，可用于加利福尼亚或其他地方的葡萄园中与本研究中类似的格子。