Shade stress is a common problem encountered in turfgrass management situations worldwide. Shade reduces photosynthetic photon flux (PPF), alters light quality, reduces air movement, and may introduce tree root competition. As a species, Kentucky bluegrass (Poa pratensis L.) possesses relatively poor shade tolerance, which limits its use in reduced light environments. However, genetic alteration of the gibberellic acid enzyme pathway has shown promise in some plant species for improving growth in shade. The objective of this 2-year field study was to determine the comparative performance under reduced PPF and determine minimal daily light integral (DLI_m) requirements for acceptable quality of a conventional (CONV) Kentucky bluegrass (KBG) blend and gibberellic acid 2-oxidase (GA2ox) transformed “ProVista” (PV) KBG. A 2-year field study was conducted under neutral density shade treatments producing monthly daily light integrals averaging from ∼5.8 (90% shade) to 48 mol m⁻² day⁻¹ (full sun) for mid-June through October study periods. Based on nonlinear regression of mean monthly DLI during the study period versus turfgrass quality (TQ) at the end of each study period, DLI_m was found to range from 7.5 to 10 mol m⁻² day⁻¹ for PV and from 22.5 to 26.2 mol m⁻² day⁻¹ for CONV KBG. Improved TQ of PV under low light intensities may be associated with reduced rates of leaf elongation, greater stand density, higher chlorophyll concentrations, and darker green color compared to CONV KBG. Although shade duration did not exceed 4 months, the results suggest that GA2ox-transformed PV KBG possesses improved tolerance to reduced PPF compared to CONV KBG.

中文翻译：

---

GA2ox 转化和传统肯塔基早熟禾光合光子通量降低时的最低光照要求和性能

荫蔽压力是全世界草坪管理中遇到的常见问题。遮荫会降低光合光子通量 (PPF)、改变光质量、减少空气流动，并可能引入树根竞争。作为一个物种，早熟禾（Poa pratensis L.）的耐荫性相对较差，这限制了其在弱光环境中的使用。然而，赤霉酸酶途径的遗传改变在一些植物物种中显示出改善阴凉生长的希望。这项为期 2 年的实地研究的目的是确定在减少 PPF 的情况下的比较性能，并确定传统 (CONV) 肯塔基早熟禾 (KBG) 混合物和赤霉酸 2-氧化酶可接受质量的最低日光积分 (DLI m ₎要求(GA2ox) 改造了“ProVista”(PV) KBG。在中性密度遮荫处理下进行了为期 2 年的实地研究，从6 月中旬到 10 月的研究期间，每月每日光积分平均为 ∼5.8（90% 遮荫）到 48 mol m ^-2 day ^{-1 （全日照）。}根据研究期间平均每月 DLI 与每个研究期结束时草坪质量 (TQ) 的非线性回归，发现DLI _{m的 PV 范围为 7.5 至 10 mol m} ⁻² day ⁻¹，PV 范围为 22.5 至 26.2 CONV KBG 为mol m ⁻²天^{−1 。}与 CONV KBG 相比，低光强度下 PV 的 TQ 提高可能与叶片伸长率降低、林分密度更大、叶绿素浓度更高以及颜色更深有关。尽管遮荫持续时间不超过 4 个月，但结果表明，与 CONV KBG 相比，GA2ox 转化的 PV KBG 对减少的 PPF 具有更高的耐受性。