CO2 enrichment changed N metabolism of tomatoes under salinity stress

Abstract

• Elevated CO 2 reduced the negative effect of salinity stress in tomato. • Photosynthesis and transpiration improved in 50/50 v/v NO 3 : NH 4 but growth parameter was improved in 100/0 NO 3 : NH 4 in salinity stress in tomato. • The rate of reduction of vegetative traits due to salinity stress was significantly reduced by increasing the nitrate in the ratio of NO 3 : NH 4 in salinity stress in tomato. • Carbon dioxide enrichment was significant on protein and nitrate concentration. Salinity is a worldwide concern. The effects of CO 2 enrichment and N sources under salinity on the vegetative, photosynthetic, and biochemical parameters of tomato was explored. The tomato plants are cultivated in two climate-controlled greenhouses with two CO 2 levels: 300 (C1) and 700 (C2) ppm. Five NO 3 :NH 4 ratios (25/75(N1), 50/50(N2), 75/25(N3), and 100/0 (N4)) were used to fertilize plants in two salinity conditions (0 (S1) and 50 mM (S2)). When NH4 was raised, vegetative, yield and biochemical characteristics were seen to decline. By increasing nitrate, yield, and desirable tomato characteristics such as fresh weight of shoot, root, and fruit, dry weight of shoot and fruit, and the number of fruits per plant, photosynthesis, and water content of shoot were enhanced. Increased CO 2 mitigated the detrimental effects of salt stress. By increasing the nitrate in the ratio of NO 3 :NH 4 , notably in the S2N4 treatment, the rate of decrease of vegetative characteristics caused by salinity stress was greatly slowed. Under the detrimental influence of salinity stress, photosynthesis and transpiration improved in NO 3 :NH 4 , 50/50 (S2N2 treatment). In general, when the amount of ammonium was greater than nitrate (NO 3 :NH 4 ratio of 25/75) in both saline and non-saline conditions, the examined attributes did not demonstrate a favorable influence on all features.