Knowledge of the key physiological and biochemical traits related to genetic progress is essential to identify yield-limiting factors and guide future breeding strategies. The aim of this research was to determine the rate of genetic gain in grain yield and physiological and biochemical traits in Moroccan durum wheat cultivars released from 1984 to 2007. Plants were subjected to two water regimes (irrigated and rainfed) during three growing seasons in order to identify those physiological and biochemical traits associated with grain yield. Grain yield (GY) and diverse physiological and biochemical traits known to be linked to mild drought stress were evaluated at anthesis and postanthesis. Physiological traits included stomatal conductance (g_s), transpiration rate (E), chlorophyll fluorescence (F_v/F_m), chlorophyll content in flag leaf (SPAD), canopy temperature depression (CTD), and relative water content (RWC), whereas biochemical characteristics were leaf proline and water-soluble carbohydrates (WSC) content. Grain yield tends to increase linearly under irrigated conditions with a genetic gain of 1.75% yr⁻¹, in contrast, no significant change was observed under rainfed conditions. Traits that significantly increased over time were leaf proline content, g_s, E, CTD, and SPAD. The changes in GY under irrigated conditions were largely explained by increases in g_s during anthesis and postanthesis, CTD at postanthesis, and by leaf proline content at anthesis. Although genetic gains in GY under rainfed conditions could not be detected, leaf proline content and E were strongly associated to GY under these conditions, suggesting their usefulness as selection criteria for GY in water-limited environments.

中文翻译：

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1984-2007年摩洛哥硬粒小麦品种产量相关生理生化性状遗传进展

了解与遗传进展相关的关键生理和生化特征对于确定产量限制因素和指导未来的育种策略至关重要。本研究的目的是确定 1984 年至 2007 年发布的摩洛哥硬粒小麦品种的籽粒产量和生理生化性状的遗传增益率。植物在三个生长季节经历了两种水分状况（灌溉和雨育），以便识别与谷物产量相关的生理生化性状。在开花期和开花后评估了已知与轻度干旱胁迫相关的谷物产量 (GY) 和多种生理生化性状。生理性状包括气孔导度 (g _s )、蒸腾速率 (E)、叶绿素荧光 (F _v/F _m )、旗叶叶绿素含量 (SPAD)、冠层温度降低 (CTD) 和相对含水量 (RWC)，而生化特征是叶脯氨酸和水溶性碳水化合物 (WSC) 含量。在灌溉条件下谷物产量趋于线性增加，遗传增益为 1.75% yr ^-1，相比之下，在雨养条件下没有观察到显着变化。随时间显着增加的特征是叶脯氨酸含量、g _s、E、CTD 和SPAD。灌溉条件下 GY 的变化主要由 g _{s的增加来解释}在花期和花后，CTD 在花后，以及在花期叶脯氨酸含量。尽管无法检测到雨养条件下 GY 的遗传增益，但在这些条件下，叶脯氨酸含量和 E 与 GY 密切相关，表明它们可作为 GY 在缺水环境中的选择标准。