Citric Acid Alleviated Salt Stress by Modulating Photosynthetic Pigments, Plant Water Status, Yield and Nutritional Quality of Black gram [Vigna mungo (L.) Hepper]

Background: Salt stress (SS) has seriously threatened the productivity of pulses including black gram in modern input-intensive farming systems which necessitates finding biologically viable, pro-farmer and environmentally friendly SS ameliorating strategies. Methods: An experiment was conducted to assess three levels of both SS (0, 50 and 100 mM NaCl) and citric acid (CA, 0, 50 and 100 µM) applied as a foliar spray to ameliorate the deleterious effects of SS on black gram (cv. BARI Mash-3). The response variables included plant growth traits like plant height (PH), leaf number (BLPP) and root dry weight (RDW) along with chlorophyll contents (chl a, chl b and tchl), plant water status (relative water content RWC and water retention capacity WRC), grain yield (GY), stover yield (SY), biological yield (BY)) and harvest index (HI) along with nitrogen (N) and protein (P) content of black gram. Result: The results revealed that CA (100 µM) remained unmatched by increasing PH (76.25%), NLPP (37.52%), RDW (83.67%), Chl a (17.80%), Chl b (11.59%), tChl (15.51%), RWC (9.81%) and WRC (26.64%) under highest level of induced SS. The same treatment also surpassed the rest of the doses in terms of grains number per pod (23.89%), 100 grains weight (59.74%), GY (82.86%), SY (59.66%), BY (64.94%) and HI. Moreover, CA accumulated N and P content (29.9%) in the grain under SS conditions. These results indicated that application CA alleviated the adverse effects of SS by triggering the growth, yield and nutritional quality which might be developed as a potent strategy to cope with the declining productivity of black gram in saline environment.