Abstract

Ameliorative impact of salicylic acid (SA) on Vigna unguiculata L. (cowpea) cultivar IT93k-452-1 during water deficit stress was investigated. Plants were subjected to water deficit stress (WD) for 7 days at either the vegetative stage (DVS) or the reproductive stage (DRS) and the leaf water potentials (ψ_w) of -1.9 MPa and -2.01 MPa were obtained, respectively. Stress caused reductions in almost all parameters studied. 3 and 5 mM SA foliar treatment caused increases of 27% in leaf ψ_w, 94% in chlorophyll content, 75% in plant biomass, 7% in nitrate reductase activity and 38% in proline content in DVS plants while the impact was much lower in DRS plants. Stress stimulated almost 3-fold increase in antioxidant vitamin B₁₂ in DVS plants and 40% increase in vitamin C in DRS plants and SA (3 mM) further increased the latter by 14%. Overall, SA had a protective influence on the water potential and growth of stressed plants accompanied by an increase in production of osmolyte proline and antioxidant vitamin C.  

Key words: Antioxidants, growth, salicylic acid, water stress.

Abbreviation

SA, Salicylic acid; NRA, nitrate reductase activity; DVS, vegetative stages; DRS, reproductive stages; HPLC, high performance liquid chromatography;ABA, abscisic acid; P5CS, D’-pyroline-5-carboxylate synthetase; ASC, ascorbate;SOD, superoxide dismutase; APX, ascorbate peroxidase; GR, glutathione reductase;WD, water deficit.