STUDIES ON THE EFFECT OF SALT STRESS ON GERMINATION AND SEEDLING GROWTH OF Vigna unguiculata (L.) Walp

ABSTRACT

Salt stress is a major abiotic stress factor influencing plant growth, development and crop yield. This study investigated the effect of salt stress on germination and seedling growth of Cowpea (Vigna unguiculata (L.) Walp.) which is known for its tolerance to drought and is widely cultivated for its nutritional and economic value. This experiment was carried out using petri dishes. Seeds of V. unguiculata were exposed to five concentrations of NaCl and replicated three times. The effect of the various concentrations of NaCl namely - R2 (0.2g/l), R3 (2g/l), R4 (5g/l) and R5 (10g/l) and distilled water as R1 (control) - on the germination (%) of V. unguiculata seeds and other growth parameters (shoot length, root length, number of root hairs, stem girth, number of leaves, leaf area) were recorded. Germination was observed on the third day for R1, R2, R3 and R4 with R1 having the highest germination (100±0.00%), followed by R2 with 86.66±6.66%. The R3 seeds recorded moderate germination (66.66±6.66%) while R5 had no germination. The adverse effect of the salt treatment increased along the concentration gradient. Shoot length (11.17±3.93cm) and root length (5.17±1.87cm) were significantly higher in R2 by day 8, performing better than other treatments. Number of roots were also higher in R1 and R2 while R4 and R5 had no roots. The R2 plants recorded the highest leaf area (2.52±1.26cm2 ). Analysis of Variance (ANOVA) showed that there was significant difference between R1, R2 and R3. The results suggested that R2 with moderate salinity enhanced growth whereas higher salinity R5 inhibited germination and growth indicating an adverse effect of salt stress on Vigna unguiculata L.