Understanding morphological, physiological and biochemical characteristics of faba bean (Vicia faba L.) under drought condition

Abstract

Drought stress is one of the most important limiting factors for the sustainable production of faba bean (Vicia faba L). This study covered the characterization of physiological, biochemical and morphological traits that are enhancing the drought tolerance of faba bean by assessing key traits under the field and controlled environments. The investigations utilised a range of plant tissues, i.e. leaf, flower, root and grain tissue’s response under water deficit (WD) conditions. Carbon isotope discrimination was found as a suitable trait as well as predict grain yield. Large genotypic variation (16.84‰ ~ 21.96‰) among genotypes made it a potential selection tool for breeding programs. Among yield contributing characters, plant height and 100 seed weight were the most important contributors (0.60**). Hydroponic assay showed great promise and results from hydroponic assays were confirmed through a subsequent sand culture study and suggested as an effective screening platform as genotypes had a similar response under both conditions. Leaf chemistry of faba bean genotypes showed the presence of increased myo-inositol and sucrose in irrigated treatments. Comparison of water use efficiency prediction through leaf-level carbon isotope abundance and gas exchange suggested the former would be a suitable tool as a drought tolerance screening tool. The relatively small differences in carbon isotope abundance between leaf and grain suggest that either tissue are appropriate for inclusion in breeding programs. Pod formation during stress was primarily governed by the pistil. Reciprocal crosses between WD and well-watered (WW) plants showed pistil were more sensitive to drought than stamen. Finally, the grain quality of faba bean tends to be resilient and not affected by WD. Quantification of essential amino acids and major mineral nutrients in grains collected from WW and WD plants that showed no significant effect between treatments.