Evaluation of Diverse Cumin (Cuminum cyminum L.) Ecotypes for Seed Yield under Normal and Water Stress Condition

Cumin (Cuminum cyminum L.) is the second most popular spice in the world and one of the important medicinal plants in Iran. Cumin seed yield is highly affected by water stress, which is one of the most important abiotic stresses affecting seed yield. So far, drought tolerance studies in cumin have been done on limited cumin ecotypes. In the present investigation, forty-nine diverse cumin ecotypes were tested under normal and water stress conditions during 2013 and 2014. The experiment was conducted under two different irrigation regimes of normal irrigation and mid/late season water stress i.e., during flowering. Each of experiments was conducted in a simple lattice design with two replications. The combined analysis of variance showed significant differences among all sources of variation. Twelve drought tolerance indices were calculated based on seed yield under drought and irrigated conditions. Yield under stress and non-stress conditions was significantly and positively correlated with Geometric Mean Productivity Geometric Mean Productivity (GMP), Stress Tolerance Index (STI), Harmonic Mean (HM), Drought Resistance Index (DI), modified Stress Tolerance Index in normal irrigation (K1STI), modified Stress Tolerance Index in stress irrigation (K2STI), Stress Non-stress Production Index (SNPI) and Stress Tolerance Score (STS). PCA and cluster analysis were followed to reveal the relationship among different indices. To visualize the GE interaction effects on cumin seed yield, the data were subjected to GGE-Biplot analysis. Finding superior ecotypes in each environment was done using GGE-Biplot. Regarding mean yield and drought tolerance indices, ecotypes from Maneh (Northern Khorasan), Shahmirzad (Semnan), and Rafsanjan (Kerman) were identified as the most favorable candidates for further research in cumin breeding programs. GC/MS analyses of elite ecotype Kerman (Rafsanjan) was also done for both conditions, the main components of essential oil were found to be γ-terpinene, β-pinene, m-cymene, and cuminic aldehyde.