Interactive effects of salinity and water stress on growth, leaf water relations, and gas exchange in amaranth (Amaranthus spp.)

Abstract Amaranth (Amaranthus spp.) is a promising vegetable species often grown under semi‐arid conditions prone to both drought and salinity. This study was initiated to evaluate the effects of water and salinity stresses, both individually and in combination, on plant growth/leaf water relations and gas exchange of two amaranth genotypes— Amaranthus tricolor and A. cruentus. Plants were grown in a greenhouse in plastic pots filled with a sand/vermiculite mixture and exposed to 8 days of drought and/or salinity stress, a recovery period of 8 days, followed by a final 2 weeks of stress. The treatments consisted of: (1) unstressed control; (2) 100 mM Nad (salt stress); (3) PEG (polyethylene glycol Mw 6000) iso‐osmotic to 100 mMNaCl (water stress); and (4) 50 mM NaQ + PEG iso‐osmotic to 50 mM NaCl (salt + water stress). Plant growth (leaf, stem, root dry mass, root: shoot ratio, leaf area) were reduced by stress treatments. The reduction in shoot growth was greater in plants subjected to PEG‐induced water ...