Investigating the effects of inoculation of mycorrhizal fungi on yield and yield components of different ecotypes of black seed

The application of bio-fertilizers, especially mycorrhizal fungi, is known as one of the most important nutritional approaches in sustainable agriculture and agricultural ecosystem management. Among the numerous microorganisms in the rhizosphere, some have positive effects on plant growth promotion. These microorganisms are bio fertilizers such as plant-growth-promoting rhizobacteria, which colonize the rhizosphere and roots of many plant species and confer beneficial effects to plants. Therefore, the present study aimed to investigate the effects of two species of arbuscular mycorrhizal funguswas assessed on yield and yield components of three Iranian ecotypes of black seed medicinal plant.

To determine the inoculation of mycorrhizal fungi on yield and yield components of different ecotypes of black seed, a factorial experiment in randomized complete block design with three replications was conducted. The experiment was conducted as factorial in Sarayan faculty of agriculture at 2018, with two factors, the Rhizophagus fasciculatum and Rhizophagus mosseae species of mycorrhizal as first factor, Sarayan, Hamedan, and Shahrekord ecotypes of black seed as second factor, in three replications. The traits studied in this research were plant height, stem diameter, number of branches, the average height of the first branch, root length, total chlorophyll, number of flowering branches, the average height of the first capsule, capsule length, capsule diameter, number of capsules per plant, number of seeds per capsules, 1000-seed weight, grain yield, biological yield, harvest index, and straw yield.

The analysis of variance showed significant differences among investigated ecotypes of black seed for all traits. However, none of the above traits were affected by the interaction of Ecotype × mycorrhiza. In addition, the highest values of plant height (19.85 cm), the average height of the first branch (8.99 cm), root length (13.63 cm), the average height of the first capsule (19.16 cm), and capsule length (8.38 cm) for Hamadan ecotype, the highest values of the number of seeds per capsule (53.31 grains), biological yield (75.8 g.m-2), grain yield (26.16 g.m-2), and straw yield (49.64 g.m-2) for Shahrekord ecotype, and the highest 1000-seed weight (2.34 g) and harvest index (42.67%) for Sarayan cultivar were obtained. In other hand, the means of pod diameter, pod length, and number of flowering branches were increased in plants treated with both species of mycorrhizal bio-fertilizer than the control treatment so that the highest values in the number of flowering branches (8.24 cm) and capsule length (8.18 cm) were obtained under the application of Rhizophagus mosseae, and the thickest capsules (8.24 cm) were achieved under the application of frtilizers contained Rhizophagus fasciculatum. The results of simple correlation analysis showed the positive and significant correlation of seed yield trait with root length, number of secondary branches, number of flowering branches, number of pods per plants, and number of seeds per pod, at 5% probability level, and with biological yield and straw yield traits at 1% probability level. Results of path analysis showed positive direct effect of number of flowering branches and biological yield traits on grain yield and the highest positive direct effect was recorded for biological yield. In contrast, the highest negative direct effect on the grain yield of investigated ecotypes was obtained for the straw yield.

It was shown that there was a significant difference between the three black seed ecotypes in morphological and functional traits, so that Shahrekord and Hamedan ecotypes were superior in all traits (except thousand seed weight and harvest index) compared to Sarayan ecotype. In general, our findings demonstrated the relationship between morphological traits and yield components of black seed ecotypes under the inoculation of mycorrhiza strains, which can be employed in black seed breeding programs as a reference. Also, it is suggested that ecotypes/genotypes that are better in biological and straw yield traits were used for cretia selection traits in future.