Physiological responses of fava genotypes (Phaseolus lunatus L.) submitted to water stress cultivated in the state of Ceará

Abstract Among species of the genus Phaseolus, fava is the most tolerant to drought when compared to common beans. Despite its importance, it has been little studied, requiring applied research to the culture for a better understanding of the mechanisms involved in the response to the water deficit. This study evaluates the tolerance of four fava genotypes grown in Ceará on their resistance to water stress. The experiment was carried out in a completely randomized design, in the 4 x 3 factorial scheme in which the first factor was constituted by the cultivars: ‘Branca’, ‘Mulatinha’, ‘Preta’ and ‘Coquinho Laranja’; the second by three water regimes: irrigated, moderate deficit and severe deficit; with five replicates. (A), stomatal conductance (gs), Ci / Ca ratio, Transpiration (E), water use efficiency, efficiency in the use of intrinsic water (USA int), instantaneous carboxylation efficiency (EiC) and electron transfer rate (ETR). Without compromising its metabolism, the genotype Coquinho Laranja was more tolerant to the water deficit, evidencing higher photosynthetic productivity, associated with the high efficiency in the use of water by the closure of its stomata with reduction of transpiration.摘要：在菜豆属（Phaseolus）各物种中，相较于普通菜豆，fava菜豆对干旱的耐受性最强。尽管该作物具有重要的应用价值，但相关研究仍较为匮乏，亟需开展针对其栽培的应用研究，以深入解析其应对水分亏缺的内在生理机制。本研究针对种植于巴西塞阿拉州的4份fava菜豆基因型，评估其对水分胁迫的抗性表现。实验采用完全随机设计，设置4×3因子试验方案：第一因子为4个供试品种，即‘布兰卡（Branca）’、‘穆拉廷哈（Mulatinha）’、‘普雷塔（Preta）’与‘科金霍·拉兰哈（Coquinho Laranja）’；第二因子为3种水分处理模式，即正常灌溉、中度水分亏缺与重度水分亏缺，每组设置5次重复。本研究测定的指标包括：光合速率（A）、气孔导度（stomatal conductance, gs）、胞间CO₂浓度与大气CO₂浓度比值（Ci/Ca）、蒸腾速率（Transpiration, E）、水分利用效率、内在水分利用效率（USA int）、瞬时羧化效率（instantaneous carboxylation efficiency, EiC）以及电子传递速率（electron transfer rate, ETR）。基因型‘科金霍·拉兰哈（Coquinho Laranja）’在未损害自身代谢功能的前提下，对水分亏缺具有更强的耐受能力，其光合生产力更高，这与其通过关闭气孔以降低蒸腾速率、进而提升水分利用效率的调控机制密切相关。