Genetic variation in essential oil constituents of ajwain (Trachyspermum ammi L. Sprague) varieties at varying nitrogen levels under semiarid tropics of Northern Karnataka, India

Abstract

Essential oil of five varieties of ajwain was extracted and their constituents were analyzed by GC-MS. All the varieties showed a significant difference in essential oil content which ranged from 4.17 % in variety Ajmer Ajwain-1 to 5.17 % in Local cultivar. In all the varieties five major compounds including thymol, cymene, γ-terpinene, α-pinene, and β-pinene were detected. Thymol was the most abundant compound in all the varieties, the content of which varied from 53.79 % in variety Ajmer Ajwain-93 to 67.79 % in variety Ajmer Ajwain-1. The γ-terpinene content was the second most important constituent recorded 25.39 % in variety Ajmer Ajwain-93. Cymene was the other important content that showed large variation from 14.77 % in variety Ajmer Ajwain-1 to 21.61 % in Local cultivar. α-Pinene and β-pinene were other constituents that showed significant variation in varieties. Studied varieties showed significant genetic variation in essential oil constituents. However, no significant effect on essential oil constituents was observed due to varying levels of nitrogen