PATTERN OF ACCUMULATION OF INORGANIC ELEMENTS IN SUNFLOWER (HELIANTHUS ANNUUS L.) PLANTS SUBJECTED TO SALT STRESS AND EXOGENOUS APPLICATION OF 5-AMINOLEVULINIC ACID

Influence of a potential plant growth regulator, 5-aminolevulinic acid (5-ALA) on the pattern of accumulation of some key inorganic elements in salt-stressed sunflower plants was observed under greenhouse conditions. Two cultivars of sunflower viz., Hysun-33 and S-278 were grown under non-saline and saline (150 mM NaCl) regimes in sand culture. After two weeks of salt treatment, all plants were subjected to four (0 (no spray), 20, 50 and 80 mg L-1) levels of 5-ALA as a foliar spray for 14 days. Shoot fresh and dry matter of both sunflower cultivars was markedly reduced due to salt stress. Of different inorganic ions, Na+ and Cl- in leaf, stem and root tissues increased markedly while, K+, and Ca2+ in all these tissues reduced under the saline regime. However, salt stress did not alter the leaf, stem or root P as well as root K+/Na+ ratio. Foliar-applied ALA improved growth under normal (non-saline) and saline conditions, and 20 and 80 mg L-1 levels of 5-ALA were relatively more effective than the other levels used in this study. Of nutrient accumulation, 5-ALA altered only root Na+ and K+ and root K+/Na+ ratio e.g., root Na+ was lower at 50 mg L-1, while root K+ and K+/Na+ ratio were higher at 80 mg L-1. In contrast, accumulation of all other ions in plant organs remained unaffected. Overall, foliar-applied 5-ALA did not alter the accumulation of different nutrients in different plant parts except root Na+, K+ and K+/Na+ ratio in both sunflower cultivars.