Improvement in plant water relation and photosynthetic activity of mungbean (Vigna radiata L.) in response to salicylic acid under salinity stress

The study was conducted to determine whether exogenous application of salicylic acid (SA) through foliar spray could modulate the plant water relations, membrane stability and photosynthetic activity in mungbean (Vigna radiata L.) under two levels of salinity. After seed germination chloride dominated (Cl: SO₄ ratio 7:3) salinity was maintained in earthen pots at 4 and 6 dS m⁻¹ levels. At flower initiation, two concentration of salicylic acid viz 0.25 and 0.50 mM were applied as foliar spray on both non-saline and saline plants and observations were recorded at 2 and 6 days after spray of salicylic acid. Increasing salt stress reduced the plant water status and membrane stability. The salicylic acid application increased the water relations parameters and their response was more at 6 days after spray of 0.5 mM salicylic acid. The relative membrane injury and lipid peroxidation (MDA content) was also reduced with salicylic acid treatments in both saline as well as non-saline plants. The salicylic acid application increased the chlorophyll content and gaseous exchange related parameters in saline condition. The improvement in plant water status, membrane stability and chlorophyll content due to salicylic acid application was associated with photosynthetic activities in salt stressed plants. At higher salinity level recovery in photosynthesis was more pronounced at both levels of salicylic acid and times of observation. The present study suggests that salicylic acid application can ameliorate the deleterious effect of salinity stress in mungbean crop.