Genotypic Differences in Photosynthesis and Partitioning of Biomass and Ions in Salinized Faba Bean

Vicia faba (L.) is a valuable grain legume, rich in nutrients and bioactive constituents with large genotypic variability in resistance to abiotic stress. Growth and performance of two hydroponically-grown V. faba cultivars (Nubaria 1 and Nubaria 2) were investigated under the impact of 0, 20, 50, 100 and 175 mmol/L NaCl. Shoot growth of the two cultivars was moderately reduced by NaCl salinity; but root growth was robust, at the expense of either leaves in the salt-resistant Nubaria 1 or stem in Nubaria 2. Nubaria 1 showed better vigor and greater leafiness but lesser content of photosynthetic pigments with higher carotenoid content than Nubaria 2. Rates of transpiration and photosynthesis were higher in Nubaria 2 than Nubaria 1, with more adverse effect of salinity on transpiration than on photosynthesis. The reduced K+ and Ca2+ uptake and the enhanced Na+ uptake under salinity was associated with restriction of ion transport to the foliage, particularly the leaves. The role of stem in providing K+ and Ca2+ to and retention of Na+ away from the leaves and root under salinity stress was more evident in Nubaria 1 than Nubaria 2. Key words: Vicia faba, gas exchange, genotype, minerals, salinity