Nitrogen improves biomass production and chlorophyll synthesis in basil plants grown under salt stress

Basil ( Ocimum basilicum L.), a medicinal and aromatic plant extensively cultivated in the Northeast region of Brazil, encounters growth challenges attributed to the salinity of irrigation water and soil. Nitrogen (N) is a crucial macronutrient employed to mitigate salt stress in plants. Therefore, this study aimed to evaluate the production of phytomass and chlorophyll synthesis in purple basil plants grown under salinity stress and nitrogen fertilization. The experiment was conducted in 2021 under protected environmental conditions at the Center for Agricultural Sciences, Universidade Federal Para & iacute;ba, Areia -PB, Brazil. Five levels of salt stress (0.0, 0.80, 2.75, 4.70, and 5.50 dS m -1 ) and five doses of N (0.00, 58.58, 200.00, 341.42, and 400.00 mg L -1 ) applied via foliar were studied. The results revealed that foliar fertilization with N increases plant tolerance to salt stress, promoting root fresh and dry mass accumulation at 294.96 and 205.36 mg L -1 and under ECw of 1.14 and 0.5 dS m -1 , respectively. Applying 217.39 and 231.30 mg L -1 of N improves the production of stem dry biomass and the shoot/root ratio of basil plants subjected to salinity of 0.5 dS m -1 . The electrical conductivity of irrigation water above 0.8 dS m -1 adversely affects biomass production. The salinity at 3.8 to 4.0 dS m -1 stimulated chlorophyll synthesis in purple basil plants. However, the foliar application of N proves to be a strategic approach to counteract these effects, resulting in increased total dry mass production and chlorophyll contents.