COMPARATIVE ANALYSIS OF SALT AND HEAVY METAL STRESS RESPONSES IN CITRULLUS COLOCYNTHIS (L.) SCHRAD AND CUCUMIS MELO SUBSPECIES AGRESTIS (NAUD) FOR PHYTOREMEDIATION APPLICATIONS.

The pursuit of resistant plant varieties is indispensable for phytoremediation against salt and heavy metal stresses. Citrullus colocynthis (L.) Schrad and Cucumis melo subspecies agrestis are cucurbit weeds used as raw material in for medicines, papers and artificial cotton. Abiotic stresses like salt and heavy metal hassles are prodigious deterrents to early growth of plants. Nickel (Ni), in petite is a decisive micronutrient of plants but disturbs the proficiency of the plants under higher levels. However, response of various plant ecotypes varies under various concentrations of salinity and heavy metals. Germination, morphology, biochemistry and physiological properties are key to determining the fate of the plant. The present objective was to compare the impact of independent stresses by varying concentrations of salt (100, 200 and 400 mM NaCl) and heavy metal (50, 100 and 200 µM NiCl₂) on morphophysiological and biochemical parameters of Citrullus colocynthis (L.) Schrad and Cucumis melo subspecies agrestis from desert and agricultural ecotypes. It was a four-replica CRD trial. Germination percentage, radicle and plumule length, seedling fresh and dry weight, K⁺, Ca⁺⁺, chlorophylls a and b showed a significat increase ( p ≤ 0.05) at lower level of stress (100 mM NaCl and 50 µM NiCl₂), slight decrease at moderate level of stress (200 mM NaCl and 100 µM NiCl₂) while significant decrease under higher stress levels (400 mM NaCl and 200 µM NiCl₂). An increase of Na⁺, Cl^-, Ni⁺ and secondary metabolites (total soluble sugars, total soluble proteins, catalase, superoxide dismutase and proline) with increasing stress levels was perceived. Citrullus colocynthis (L.) Schrad and Cucumis melo subspecies agrestis are adaptive to salt and heavy metal levels.Tolerance of salts and heavy metal metals in sequence C. colocynthis (L.) desert > C. colocynthis (L) cultivated > C. melo (L) agrestis desert > C. melo (L) agrestis agricultural was recorded and can be recommended for phytoremediation. [ABSTRACT FROM AUTHOR]