Abstract
Background and objectives: Black cumin is a dicot herbs, herbaceous annual that belongs to the Buttercup family. It has been reported that this plant is native to West Asia, with Middle East and the India subcontinent origin. Previous studies in black cumin showed that seed yield had positive significant correlation with biomass, seeds per follicle, seed per plant, plant height,1000 seed weight, number of stem branch and harvest index. Variation in black cumin ecotypes is a good source for study of the relationships among yield and its components and breeding program. This study aimed to investigate grain yield potential in different Iranian black cumin ecotypes, the relationship between yield and its components, and to determine the most effective traits on yield.
Materials and methods: In order to study the diversity, correlation coefficients and path analysis of traits related to yield, 16 Iranian black cumin ecotypes were collected form Ahvaz, Bojnoord, Dasthe moghan, Gonbad, Gorgan, Jovian, Kashmar, Kerman, Marivan, Mashhad, Oromieh, Sabzevar, Saravan, Shirvan, Zabol and Zahedan. These ecotypes were cultivated in randomized complete block design with three replications in the field of Agricultural University of Shirvan. Day to begin of flowering, 50% of flowering, end of flowering, height, number of stem branches, number of follicles per plant, weight of follicle, number of seeds per follicle, 1000 seed weight, biological yield, harvest index and seed yield were evaluated. Means of treatments were compared using Duncan’s multiple range tests in 0.01 percent level. Path analysis was performed for seed yield performance based on selected characters by stepwise multivariate regression method. For data analysis software R, Statistica V8 and JMP V4 were used.
Results: Based on the analysis of variance, ecotype effect was significant for all traits. Mashhad and Zahedan ecotypes had the highest and Oromieh ecotype had the lowest days to flowering. Mashhad and Gorgan had the highest seed yield with 1131 and 272.7 kg/ha respectively. The correlation of seed yield with the number of follicles per plant, biomass plant, weight of follicle, number of branches and harvest index were positive and significant. Cluster analysis of ecotypes of different regions in different categories showed that there is not a good match between genetic diversity and geographic diversity. Stepwise regression analysis showed that about 68.5% of the seed yield variation explained by number of capsules per plant. Then the biomass, 1000 seed weight and day to 50% flowering, which were entered into the model, which explained 4, 6.2 and 1.2% of the seed yield variation, respectively. In path analysis, the number of capsules per plant had the highest direct effect on seed yield(0.59**) and the highest indirect effect of biomass effected by the number of capsules per plant(0.395).
Conclusion: Results showed that there was high genetic diversity among black cumin ecotypes for use in breeding programs, so they can be used to select the desired agronomic characteristics for developing new cultivar. In black cumin, the number of capsules per plant and seed weight had major contributions on yield and hence selection for these traits can possibly lead to improvement in yield of black cumin.