Salt stress negatively affects the growth, development, and yield of horticultural crops. Nitric oxide (NO) is considered a signaling molecule that plays a key role in the plant defense system under salt stress. This study investigated the impact of exogenous application of 0.2 mM of sodium nitroprusside (SNP, an NO donor) on the salt tolerance and physiological and morphological characteristics of lettuce (Lactuca sativa L.) under salt stress (25, 50, 75, and 100 mM). Salt stress caused a marked decrease in growth, yield, carotenoids and photosynthetic pigments in stressed plants as compared to control ones. Results showed that salt stress significantly affected the oxidative compounds (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX)) and non-oxidative compounds (ascorbic acid, total phenols, malondialdehyde (MDA), proline, and H₂O₂) in lettuce. Moreover, salt stress decreased nitrogen (N), phosphorous (P), and potassium ions (K⁺) while increasing Na ions (Na⁺) in the leaves of lettuce under salt stress. The exogenous application of NO increased ascorbic acid, total phenols, antioxidant enzymes (SOD, POD, CAT, and APX) and MDA content in the leaves of lettuce under salt stress. In addition, the exogenous application of NO decreased H₂O₂ content in plants under salt stress. Moreover, the exogenous application of NO increased leaf N in control, and leaf P and leaf and root K⁺ content in all treatments while decreasing leaf Na⁺ in salt-stressed lettuce plants. These results provide evidence that the exogenous application of NO on lettuce helps mitigate salt stress effects.

Pea is an important legume crop because of its higher bioactive compounds, and its seeds are famous as functional foods. However, the yield of pea is still limited because of multiple biotic and abiotic stresses which prevailed during the growth period. Saline conditions significantly hamper pea growth, yield, and quality among abiotic stresses. Salicylic acid is effective for the activation of oxidative, non-oxidative, osmolytes, and metabolites. Hence, the present study was conducted at exogenous application of salicylic acid (control, 1 µM, 2 µM, and 3 µM) to mitigate the adverse effects of salt stress (control, 25 mM, 50 mM, and 100 mM NaCl) in pea plants grown in the year 2019–2020. The aim of the present study was to evaluate pea performance under saline conditions by salicylic acid sprays. Pea growth and yield were significantly decreased at 100 mM NaCl compared with the control and other salinity levels. Moreover, the growth and yield of pea were improved under exogenous application of salicylic acid treatment at 3 µM than others. Quality traits, i.e., carotenoids, ascorbic acid, and phenolic content, were decreased at 100 mM NaCl, and these quality traits were significantly improved under salicylic acid treatment of 3 µM. Chlorophyll a, chlorophyll b, total chlorophyll, photosynthesis, and stomatal conductance were reduced at 100 mM NaCl. In contrast, photosynthetic pigments, photosynthesis, and stomatal conductance were enhanced at 3 µM salicylic acid. The increases in SOD, CAT, POD, and APX were observed at 100 mM NaCl and 3 µM salicylic acid. The current study proved that exogenous application of salicylic acid concentrations had the potential to mitigate the salinity’s adverse effects by maintaining the physiological and metabolic activities of pea plants.

Sewage wastewater is one of the richest sources of mineral nutrients contributing toward plant growth and yield. However, the accumulation of heavy metals in the edible parts of vegetables and fruits can be dangerous to life. The current research aimed to evaluate the performance of a sand column filter for the elimination of heavy metals from sewage wastewater applied to selected vegetables. The contents of heavy metals, i.e., Pb⁺², Ni⁺², Cu⁺², and Fe⁺², were estimated to be higher in untreated sewage wastewater than in treated water. The number of leaves, fresh and dry weights of leaves, roots, and total biomass of lettuce, carrot, and cauliflower were improved due to the irrigation of unfiltered sewage wastewater compared to sewage wastewater. The curd diameter, fresh and dry weights of curd, stem fresh weight of cauliflower, and the root length and diameter of carrot increased after irrigation with the unfiltered sewage wastewater in comparison to the treated sewage wastewater. The accumulation of heavy metals, i.e., Pb⁺², Ni⁺², Cu⁺², and Fe⁺², was higher in the roots, leaves, and edible parts of the selected vegetables. In the present study, the Cd⁺² and Cr⁺² concentrations were not affected by the filtration process through a sand column filter. Conclusively, filtration through a sand column filter is effective for the removal of heavy metals from sewage wastewater used to irrigate agricultural land.

Agricultural waste disposal is one of the main concerns in today's world that can cause environmental pollution. Utilisation of agro-waste materials to grow mushrooms is an eco-friendly method to reduce pollution. Therefore, various agricultural waste materials, such as wheat straw, rice straw and cotton waste, were utilised for the production of milky mushroom. Among the substrates used in this study wheat straw showed superior substrate for the production of milky mushroom. The agronomic traits studied such as total yield, number of fruiting bodies, the maximum diameter of pileus and stalk length, biological efficiency, protein contents, phosphorous and potassium contents were observed on wheat straw substrate. Peat moss, loam soil and spent mushroom substrate were used as casing materials. Among the casing materials used, the highest yield and biological efficiency were observed on peat moss. The results also indicated that the addition of supplements with the substrate improved yield and yield contributing characteristics. Among the tested supplements (wheat bran and rice bran), wheat bran was the best supplement for wheat straw substrate to cultivate milky white mushroom.