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

NUDRAT AISHA AKRAM¹ AND MUHAMMAD ASHRAF^1,2

Abstract: 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.

¹Department of Botany, University of Agriculture, Faisalabad, Pakistan

²Second affiliation: Department of Botany and Microbiology, King Saud University, Riyadh, Saudi Arabia