Legume Research- An International Journal 2068 RESEARCH ARTICLE Legume Research- An International Journal, Volume 47 Issue 12: 2068-2076 (December 2024) Citric Acid Alleviated Salt Stress by Modulating Photosynthetic Pigments, Plant Water Status, Yield and Nutritional Quality of Black gram [Vigna mungo (L.) Hepper] Md. Aktaru Hossain 1 , Mst. Smrity Khatun 1 , Mottaleb Hosen 1 , Zakariya Ibne Sayed 1 , Md. Rafiqul Islam 2 , Md. Kaium Chowdhury 3 , Muhammad Aamir Iqbal 4 , Ibrahim Al-Ashkar 5 , Zeki Erden 6 , Cagdas Can Toprak 6 , Ayman El Sabagh 6,7 , Mohammad Sohidul Islam 1 10.18805/LRF-820 ABSTRACT 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. Key words: Grain legumes, Mash, Organic acid, Salt stress, Water status. 1 Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh. 2 Department of Agronomy, Regional Agricultural Research Station (Bangladesh Agricultural Research Institute), Ishurdi, Pabna, Bangladesh. 3 Department of Agricultural Extension, Agricultural Training Institute, Gaibandha 5700, Bangladesh. 4 Department of Chemical Engineering, Louisiana Tech University, Ruston LA 71270, United States. 5 Department of Plant Production, College of Food and Agricultural Sciences, King Saud University, P.O. Box. 2460, Riyadh 11451, Saudi Arabia. 6 Department of Field Crops, Faculty of Agriculture, Siirt University, Turkey. 7 Department of Agronomy, Faculty of Agriculture, Kafrelsheikh University, Kafr El-Shaikh 33516, Egypt. Corresponding Author: Muhammad Aamir Iqbal, Department of Chemical Engineering, Louisiana Tech University, Ruston LA 71270, United States. Email: muhammadaamir.iqbal@fulbrightmail.org How to cite this article: Hossain, M.A., Khatun, M.S., Hosen, M., Sayed, Z.I., Islam, M.R., Chowdhury, M.K., Iqbal, M.A., Al-Ashkar, I., Erden, Z., Toprak, C.C., Sabagh, A.E. and Islam, M.S. (2024). Citric Acid Alleviated Salt Stress by Modulating Photosynthetic Pigments, Plant Water Status, Yield and Nutritional Quality of Black gram [Vigna mungo (L.) Hepper]. Legume Research. 47(12): 2068- 2076. doi: 10.18805/LRF-820. Submitted: 07-06-2024 Accepted: 22-07-2024 Online: 09-08-2024 INTRODUCTION Grain legumes are a vital source of protein, a wide range of minerals and numerous vitamins which are essential for robust human health (Iqbal et al., 2019). These are the cheapest source of protein and hence referred to as poor man’s meat (Abbas et al., 2021; Iqbal et al., 2018). Among pulses, black gram [Vigna mungo (L.) Hepper] has attained strategic pertinence in ensuring the food and nutritional security of a rapidly increasing population (Iqbal et al., 2024; Ramamoorthy and Ariraman, 2023). Various traits including self-pollination, well-grown root network, drought tolerance, short life cycle (Hema et al., 2024) and unprecedented adaptability under varying agro-climatic conditions favor its cultivation (Sadiq et al., 2023). Despite significant genetic improvement of field crops using genetic engineering approaches (Li and Iqbal, 2024), legumes yield has remained stagnant owing to frequent incidence of abiotic stresses (soil salinity, heat stress, drought, etc.) (Iqbal and Iqbal, 2015) and biotic stresses (Arthanari, 2024). Recently, soil salinity (SS) has emerged as one of the most challenging abiotic stresses for sustainable production of field crops including black gram (Ahmad et al., 2023). The SS directly imposes physiological disruptions of vital metabolic processes like photosynthesis in crop plants, which eventually causes stunted growth