Salinity is a severe environmental factor that has limited the growth and productivity of crops. External application of regulating substances is a useful strategy to minimize the inhibitory effects of salinity on seedling growth. A controlled study was conducted to assess the interactive effects of exogenous gibberellic acid (GA3) addition and salinity on plant growth and antioxidant enzymes of castor bean (Ricinus communis L.) plants. The 50 mM level did not negatively affect the early growth of castor seedlings. At the 100 mM salinity level, however, seedling growth and physiological parameters were severely affected. Plant height, leaf area, and the weight of root, stem, leaf, and the whole plant was reduced by up to 21.7, 27.9, 33.3, 37.5, 33.2, and 34.5%, respectively. The activity of superoxide dismutase (SOD), peroxidases (POD), catalases (CAT), and proline content were also decreased by up to 32.0, 34.3, 53.6, and 212.4% at such a high salinity level. Presoaking seeds with 250 uM GA3 increased plant height, stem diameter, and the weight of leaf and the whole plant by up to 13.3, 7.4, 66.7, and 39.1%, respectively. The activity of SOD and POD and the content of proline and soluble protein were also significantly increased when GA3 was applied at 250 uM. This study indicated that exogenous addition of GA3 at appropriate concentrations can be a useful strategy to promote early seedling growth of castor bean plants grown under saline conditions.

Salinity stress is one of the most prevalent environmental factors that severely affect seed germination, early growth stages, and crop production. The present study was carried out to evaluate the protective role of β-aminobutyric acid (BABA) in alleviating salt stress in chickpea (Cicer arietinum L.) varieties (Jabel Marra, Porgeg and Shendi) under four concentrations of NaCl solutions (0, 50, 100, and 150 mM NaCl). Three levels of β-aminobutyric acid (0, 0.25, and 0.50 mM) were applied. Germination and seedling attributes were measured. A high level of salinity (150 mM NaCl) increased mean germination time by 10.0% and decreased the coefficient velocity of germination and root dry weight by 12.1% and 96.2%, respectively, compared with the control. 'Jabel Marra' significantly surpassed other studied varieties in germination characters, while at seedling growth, 'Shendi' outperformed other varieties in root and shoot length, fresh, and dry weights. Seeds treated with 0.25 mM BABA caused increment on water uptake by 18.1% compared with 0.0 mM BABA. At 150 mM NaCl, seeds primed with 0.50 mM BABA increased the germination percentage of 'Jabel Marra' and 'Porgeg' by 6.3% and 11.9% as compared with 0.0 mM BABA. Under 50 mM NaCl and 0.50 mM BABA, root length, shoot length, shoot fresh weight, and root dry weight were increased by 170.6%, 44.8%, 80%, and 49.3%, respectively, relative to 0.0 mM BABA. The present study results suggested that seed priming by BABA could be useful to alleviate the salinity stress of chickpea at germination and early seedling growth.