Abstract Intensively managed poplar plantations (Populus spp. and their hybrids) have the potential to provide large quantities of renewable biomass for bioenergy. Identifying clonal varieties that are productive on water-limited, marginal agricultural land unsuitable for food production with low land costs is key to realizing that potential. Carbon isotope discrimination (Δ13C) is the current method of choice for selecting varieties able to maintain higher levels of production under moderate drought stress (drought resistance). However, other physiological and morphological traits may be effective as selection criteria for drought stress and cost less to collect and analyze. The objective of this study was to test the efficacy of Δ13C, along with alternative physiological and morphological traits, in predicting drought resistance of hybrid poplar varieties. The other traits considered were leaf mass per area (LMA), petiole diameter (PD), petiole length (PL), individual leaf area (LA), adaxial stomatal density (ADAX), abaxial stomatal density (ABAX), minor vein density (MVD) and chlorophyll content (CHLOR). We found that Δ13C was a poor indicator of drought resistance and ABAX was the only single trait that was a statistically significant predictor of varietal performance under drought stress. The best indicator of drought stress was a composite of all nine variables.

中文翻译：

---

指示杂交杨树抗旱性的叶片性状

摘要 集约化管理的杨树人工林（杨树属及其杂交种）具有为生物能源提供大量可再生生物质的潜力。确定在水资源有限、土地成本低、不适合粮食生产的边际农业土地上生产的克隆品种是实现这一潜力的关键。碳同位素鉴别 (Δ13C) 是目前选择能够在中等干旱胁迫（抗旱性）下保持较高产量水平的品种的首选方法。然而，其他生理和形态特征可能是有效的干旱胁迫选择标准，并且收集和分析成本较低。本研究的目的是测试 Δ13C 的功效，以及其他生理和形态特征，预测杂交杨树品种的抗旱性。考虑的其他性状是单位面积叶质量 (LMA)、叶柄直径 (PD)、叶柄长度 (PL)、单叶面积 (LA)、正面气孔密度 (ADAX)、背面气孔密度 (ABAX)、小脉密度 ( MVD) 和叶绿素含量 (CHLOR)。我们发现 Δ13C 是一个较差的抗旱性指标，而 ABAX 是唯一在干旱胁迫下对品种表现具有统计学意义的预测指标的单一性状。干旱胁迫的最佳指标是所有九个变量的综合。我们发现 Δ13C 是一个较差的抗旱性指标，而 ABAX 是唯一在干旱胁迫下对品种表现具有统计学意义的预测指标的单一性状。干旱胁迫的最佳指标是所有九个变量的综合。我们发现 Δ13C 是一个较差的抗旱性指标，而 ABAX 是唯一在干旱胁迫下对品种表现具有统计学意义的预测指标的单一性状。干旱胁迫的最佳指标是所有九个变量的综合。