Salinity-induced structural and functional changes in 3 cultivars of Alternanthera bettzickiana (Regel) G.Nicholson

Three cultivars of Alternanthera bettzickiana (Regel) G. Nicholson have been evaluated for their tolerance and adaptability potential to salt stress. During the experiment, 5 salt regimes were maintained: 18 (control), 50, 100, 150, and 200 mM NaCl. Salinity adversely affected all growth shoot length and leaves per plant. Root fresh and dry weight decreased with an increase in salinity levels in all 3 cultivars. A. bettzickiana 'Green' was the most tolerant among the cultivars under study, with relatively lower ion leakage through roots, larger vascular region area, and wide metaxylem vessel in roots and stems recorded. Also observed were greater phloem and pith cell area in stems that increased midrib thickness, cortical cell area, vascular bundle area, and metaxylem area in leaves with increase in salinity level. Moreover, the vascular region area in roots, cortical cell area, vascular region thickness, metaxylem area, phloem cell area and pith cell area in stems, leaf thickness, epidermal thickness, cortical cell area, vascular bundle area, and metaxylem area in leaves were recorded in this cultivar with an increase in salinity levels. All cultivars showed increased Na+ and Cl- content and decreased K+ and Ca2+ with an increase in the salt level of the medium.