Effects of Different Zinc Levels on Vegetative Growth and Essential Oil Contents of some Iranian and Turkish Cumin ( Cumin cyminum L.) Genotypes.

Cumin (Cuminum cyminumL.), originated from East Mediterranean country of Egypt, is widely cultivated in Middle Eastern, Asia minor and South East Asian countries. Zn is an essential factor in tryptophan metabolism and affects auxin contents in plants. In order to evaluate effects of Zn on vegetative growth, grain yield and its components on cumin genotypes, a field experiment was carried out at the department of field crops Ankara University; Turkey using randomized complete blocks split plot design with four replications during 2011 growing season. Four amounts of Zn (0, 1.5, 3 and 4.5 kg ha-1) in the form of soil application, were allocated at main plots and six genotypes [Kashmar, Bardskan, Mashhad (Iranian-origin)], [Haymana, Turkman and Egebin, (Turkish-origin)] were assigned to sub plots. Analysis of variance results showed significant interaction of zinc levels and genotypes for traits like root heights, grain yield, total dry matter, number of branches per plant and grain essential oil (p<0.01). Applications of different Zn levels was better than control in grain yield and its components. The highest amount of grain yield and essential oil (3.64%) was recorded using 3kg ha-1Zn application. Grain yield had significant and positive correlation with plant height (r=0.95**) and root length (r=0.95**). Root length (3.59) and total dry maater (2.71), had the most positive direct effects and incontrast plant height (-1.63), number of branches per plant (-2.33) had negative direct effect on grain yield. At the regression model based on grain yield as a dependent variable, traits of plant height, root length, total dry matter, number of branches per plant and oil yield remained at the final model. Concerning essential oil constituents, β-terpinene was the major compound followed by p-cymene and β-pinene. Highest γ-terpinene content (49.14%) was recorded in Kashmar genotype using 3 kg ha-1Zn. [ABSTRACT FROM AUTHOR]