Investigations of the relationship between Cuminum cyminum L. traits under normal irrigation and drought stress

In order to investigate the relationship between different agronomic traits of cummin plant, an experiment was done in the form of a randomized complete block design under normal irrigation (irrigation at ۱۰۰% of field capacity) and drought stress (irrigation at ۵۰% of field capacity) in the greenhouse of Imam Khomeini International University. The studied traits included plant height, number of sub-branches, number of umbrellas per plant, number of umbrellas per umbel, number of seeds per umbel, ۱۰۰۰-seed weight, biological yield, grain yield, harvest index and essential oil percentage. The results of correlation analysis showed that in both normal irrigation and drought stress conditions, grain yield was positively correlated with height, number of branches, number of umbrellas per plant, number of umbrellas per umbel, number of seeds per umbrella, ۱۰۰۰-seed weight, biological yield, harvest index and essential oil percentage. Under normal irrigation conditions, the highest correlation between grain yield (۰.۹۵) was observed with the number of sub-branches, number of umbrellas per plant and essential oil percentage. Under drought stress, grain yield had the highest correlation with the number of umbrellas per plant. The highest correlation between essential oil percentage and number of umbrellas per plant (۰.۹۸) and number of seeds per umbrella (۰.۹۳) was observed under normal irrigation and drought stress conditions, respectively. The results of stepwise regression showed that under normal irrigation conditions the number of branches and ۱۰۰۰-seed weight had the greatest effect on grain yield and justified ۹۶% of the changes, while under stress conditions the number of umbrellas per plant and the percentage of essential oil had the greatest effect on grain yield and explained ۹۵.۸% of the changes. Under normal irrigation conditions, the number of umbrellas per plant and under stress conditions, the number of seeds per umbrella had the greatest effect on the percentage of essential oil and explained ۹۵.۶% and ۸۵.۷% of the changes, respectively.

Keywords:

Essential oil percentage , Correlation , Stepwise regression , Yield