Biochar impacts on NH3-volatilization kinetics and growth of sweet basil (Ocimum basilicum L.) under saline conditions

Abstract Sweet basil (Ocimum basilicum var. Genovese) is an important medicinal herb and is considered to be a moderately salt-tolerant plant. However, little is known about the effect of biochar on enhancing its salinity tolerance. The response of basil plant to water salinity (8 dS m−1, NaCl salinity) and three levels of biochar i. e., C, BC1, and BC2 (0, 1, and 2 % by weight) was investigated, as was the effect of biochar on NH3 volatilization kinetics. Irrigation of basil plants with saline water reduced the plant height, fresh weight, and dry weight by 27 %, 18 %, and 17 % in comparison to tap water. The application of biochar to saline irrigated basil caused remarkable increases in all the recorded growth parameters. Water salinity reduced N, P, and K availability and shoot concentrations. When applied, BC1 and BC2 under saline conditions increased shoot concentrations of N by 42 % and 67 %; P by 40 % and 70 % and K by 15 % and 50 %. Water salinity increased the concentrations of proline and phenolic compounds by 15 and 70 %, respectively; moreover, it reduced the total chlorophyll by 10 %. Water salinity reduced the oil yield by 15 %. The overall oil yield was increased by 18 and 38 % as a result of BC1 and BC2 application. The salinity of irrigation water increased the NH3 volatilization and reduced its half-life by 34 %. On the other hand, biochar reduced NH3 volatilization and increased its half-life. Biochar improved the growth and yield of basil plants by improving the efficiency of photosynthesis and the absorption of essential nutrients. It also had a role in reducing the concentrations of biochemical substances produced under salt stress. Therefore, using biochar is a good strategy for reducing NH3 volatilization and enhancing soil quality and plant productivity under saline irrigation.