Response of Basil Species to Soil Sodicity Stress

Abstract

Growth, yield, essential oil composition, and cation accumulation of two species of Ocimum (viz., O. basilicum and O. sanctum) in response to soil sodicity was studied in pot experiments. The herb yield of O. basilicum significantly decreased with increases in soil exchangeable sodium percentage (ESP). The oil yield of O. basilicum significantly increased with increase in soil ESP from 4.0 (control) to 16.0, and further increases in soil ESP decreased the yield. The decrease in the yield of O. basilicum was 4.7, 13.1, 13.6, 23.7, and 24.3% in herb and 3.8, 11.5, 15.4, 23.0, and 26.9% in oil yield the over the control (ESP 4.0) at soil ESP values of 24.0, 32.5, 36.0, 45.0, and 50.0, respectively. The herb and oil yield of O. sanctum significantly increased with an increase in the soil ESP from 4.0 (control) to 24.0, and further increases in soil ESP decreased the yield. The maximum increase in the herb and oil yield of O. sanctum was 18.2% over the control (ESP 4.0) at the soil ESP of 24.0. At high sodicity, the decrease in yield of O. sanctum was 12.4 and 23.2% in the herb and 12.7 and 20.9% in the oil yield over control (ESP 4.0) at soil ESP values of 45.0 and 50.0, respectively. The concentration of methyl chavicol in the essential oil of O. basilicum and that of eugenol in the essential oil of O. sanctum was significantly higher at moderate soil sodicity levels as compared to the control (ESP 4.0). Increases in soil ESP enhanced the concentration of sodium (Na) and decreased that of calcium (Ca) and magnesium (Mg) in shoot tissues of both the Ocimum species. The concentration of potassium (K) in shoot tissues of O. sanctum gradually decreased with increase in soil ESP, and that of K in the O. basilicum increased with increase in soil ESP from 4.0 (control) to 36.0. Further increases in soil ESP decreased the K content. These results indicate that both these Ocimum species are highly tolerant to soil sodicity stress.