Shade is a major problem facing turf managers worldwide. Availability of low-cost devices and methods for quantifying daily light integral (DLI) offer the turf manager the ability to more precisely determine DLI levels in shade, yet minimal DLI requirements for acceptable turf quality (DLI_m) for many commonly used warm-season turf cultivars grown under longer-term chronic shade stress have not been extensively tested. The objectives of this 2-yr field shade study were to (a) determine effects of growth regulator trinexapac-ethyl (TE) and season (summer or fall) on DLI_m of nine commercially available bermudagrass (Cynodon spp.) and zoysiagrass (Zoysia spp.) cultivars; (b) determine effects of shade level and TE on summer percent green cover and root growth; and (c) determine effects of shade treatments on soil temperatures across the growing season. Significantly higher DLI_m were noted during summer compared to fall for all cultivars in the study. The DLI_m were generally higher for bermudagrass than zoysiagrass cultivars. ‘Tifway’ required the highest DLI_m (ranging from 23.5 to 27.2 mol m⁻² d⁻¹) of the bermudagrasses. ‘TifGrand’, ‘Celebration’, and ‘Latitude 36’ showed comparable DLI_m during summer and fall. Fewer consistent differences were detected between zoysiagrasses, with ‘Zorro’ and ‘Zeon’ showing the lowest summer DLI_m (18.1 and 19.1 mol m⁻² d⁻¹, respectively) and ‘Geo’ showing the lowest fall DLI_m (11.7 mol m⁻² d⁻¹). Trinexapac-ethyl reduced DLI_m only in Zorro, ‘Palisades’, and ‘JaMur’ zoysiagrass, but had no effect on bermudagrass DLI_m. The DLI_m for a number of cultivars were higher than those previously reported in the literature, which may be attributed to lower mowing heights and/or use of permanent shade structures that were not removed for the duration of the 27-mo study. The findings should benefit turf managers by guiding data-driven, seasonal-based, warm-season turfgrass cultivar selection for shaded environments.

中文翻译：

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百慕大和结缕草栽培品种的每日光照综合要求：季节和敌百虫的影响

阴影是全球草坪管理者面临的主要问题。用于量化日光积分 (DLI) 的低成本设备和方法的可用性使草坪管理者能够更精确地确定阴影中的 DLI 水平，但对于许多常用的暖季草皮质量 (DLI _m ) 的DLI 要求最低在长期慢性阴凉胁迫下生长的草坪栽培品种尚未经过广泛测试。这项为期 2 年的田间遮荫研究的目标是 (a) 确定生长调节剂 trinexapac-ethyl (TE) 和季节（夏季或秋季）对九种市售百慕大 ( Cynodon spp.) 和结缕草 ( Zoysia ) 的 DLI _m的影响spp.) 栽培品种；(b) 确定遮荫程度和 TE 对夏季绿化覆盖率和根系生长的影响；(c) 确定遮荫处理对整个生长季节土壤温度的影响。与研究中的所有栽培品种相比，夏季的DLI _m显着高于秋季。百慕大的 DLI _m通常高于结缕草栽培品种。'Tifway' 需要百慕大草的最高 DLI _m（范围从 23.5 到 27.2 mol m ^-2 d ^-1）。'TifGrand'、'Celebration' 和 'Latitude 36'在夏季和秋季显示出可比的 DLI _m。结缕草之间检测到的一致差异较少，“佐罗”和“吉翁”显示出最低的夏季 DLI_m（分别为 18.1 和 19.1 mol m ^-2 d ^-1）和“Geo”显示最低下降 DLI _m（11.7 mol m ^-2 d ^-1）。抗倒酯降低DLI_米仅在佐罗“帕利塞德”和“JaMur”结缕草，但对狗牙根DLI没有影响_米。许多品种的 DLI _m高于之前文献中报道的那些，这可能是由于较低的割草高度和/或使用了在 27 个月研究期间未移除的永久性遮荫结构。通过指导数据驱动的、基于季节的、暖季型草坪草品种在阴凉环境中的选择，这些发现将使草坪管理者受益。