THE DEFENSIVE ROLE OF AMINO ACID IN GUAR {CYAM OPSIS TETRAGONOLOBA (L.) TAUB.) AGAINST STRESS CONDITION INDUCED BY DROUGHT

摘要

Plant growth and crop production are significantly negatively affected by drought. Herein, guar was grown under varying drought conditions, as C (field capacity-control of 100%), D1 (75% depletion of the available water holding capacity (AW HC)), D2 (50% depletion of the AW HC), D3 (depletion of 25% the AW HC), D4 (no irrigation water applied) and investigated with regards to the enzymatic, morphological, and physiological activity resulting from the application of amino acid (AA) at a dose of 600 mg L-1 (D1+AA; D2+AA; D3+AA; D4+AA). Remarkable increases have been observed in both the shoot weight (fresh and dry) and length from the application of amino acids and number of leaves and area of the guar plants when a comparison was made with the drought-stressed treatments alone. Additionally, after the procedures mentioned above, significant increases were observed in the flavonoid, total phenolic, and relative water contents, ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) activity. Moreover, significantly decreased malondialdehyde (M DA) content was observed. Therefore, the application of AA, which increased the defense system of the guar plant, was supported by the results, allowing the plant to better tolerate the negative effects caused by drought stress.