Effect of Irrigation CutOff on Flowering Stage and Foliar Application of Spermidine on Some Quantitative and Qualitative Characteristics of Various Ecotypes of Cumin

Medicinal plants play major roles in human health. . Cumin (Cuminum cyminum L.) is an annual plant that commonly cultivated in arid and semiarid regions of Iran. The crop has a wide range of uses including medicinal, cosmetic and food industry. Cumin occupies about 26% of the total area devoted to medicinal plants in Iran. However, cumin is seriously affected by the Fusarium wilt and blight diseases. The diseases usually increase under warm and wet conditions. It was demonstrated that the peak of the disease incidence is occurring at the flowering stage and irrigation cutoff at this time may be reduced the diseases density.
In order to evaluate the effects of irrigation cutoff in flowering stage and foliar application of spermidine on some characteristics of various ecotype of cumin, an experiment was conducted in a split-split-plot arrangement in randomized complete block design with three replications at the research farm of Shahid Bahonar University of Kerman at 2014. The experimental treatments were irrigation in two levels (complete irrigation and cutoff the irrigation in flowering stage) assigned to main plots, foliar application of spermidine in three levels (0, 1 and 2 Mm) as a subplot and cumin ecotypes in three levels (Kerman, Khorasan and Esfahan) that was randomized in sub-subplot. Plots size under the trial was 4 m × 3 m so as to get 50 cm inter row spacing in six rows. The ideal density of the crops was considered as 120 plant m-2. As soon as the seeds were sown, irrigation was applied every 10 days. Foliar application of spermidine was done at three stages (after thinning, before flowering stage and in the middle of flowering stage). No herbicides and chemical fertilizers were applied during the expriments.
In this study the number of branches, umbels per plant, 1000-seed weight, seed yield per plant and hectare, harvest index, essential oil percentage and yield, infected plants and proline contents were assessed. The results showed that irrigation treatment had a significant effect on all the studied traits except number of branches and umbels per plant. The irrigation cutoff at flowering stage caused a significant increase in seeds per umbel, infected plants and seed yield per plant and hectare Whereas harvest index, essential oil percentage and yield and proline contents were higher in irrigation cutoff treatment compared to completely irrigated treatment. The value of decrease in seed yield per hectare as affected by irrigation cutoff was so lower than that per plant; because more infected plants were observed in completely irrigatedtreatment in comparison with cutoff irrigated treatment. Decreasing the value of the seed yield per plant and hectare affected by irrigation cut-off were 58 and 15%, respectively. Proline contents in irrigation cut-off treatment were about two times more than completely irrigatedtreatment. Khorasan and Kerman ecotypes had higher value in comparison with Esfahan in all studied traits.. Seed yield per hectare for Kerman, Khorasan and Esfahan ecotypes were 525, 306 and 525 kg, respectively. The highest essential oil yield (14.92 kg ha-1) was gained in 1 Mm spermidine for Khorasan ecotype and the lowest (6.87 kg ha-1) was observed in 0 Mm spermidine for Esfahan ecotype. There was no significant difference between foliar application levels in terms of the studied traits such as….
Irrigation cutoff at flowering stage caused a significant increase in seeds per umbel, infected plants and seed yield per plant and hectare Whereas harvest index, essential oil percentage and yield and proline contents were higher in irrigation cutoff treatment compared to completely irrigated treatment. Khorasan and Kerman ecotypes achieved higher potential for cultivation in Kerman climate condition compared to Esfahan ecotype.