Changes in growth and nutrient concentrations of fenugreek (Trigonella foenum-graecum L.) in response to inoculation with different species of mycorrhizal fungi

Introduction: The use of bio-fertilizers along with the rational use of chemical fertilizers can be a good solution to reduce environmental pollution. Bio-fertilizers include microorganisms such as bacteria, fungi, cyanobacteria, etc., which improve the structure and quality of the soil and strengthen the soil in terms of nutrients. Mycorrhizal arbuscular fungi are present in many soils and coexist with the roots of most plant species (Wang et al. 2021). Due to the high importance of fenugreek in food and pharmaceutical industries and the need to reduce environmental pollution caused by the improper use of chemical fertilizers, in this study the effect of inoculation of ten species of mycorrhiza fungi of different genera on growth and some biochemical characteristics of fenugreek were investigated.
Materials and Methods: A pot experiment was conducted to investigate the inoculation effect of different species of mycorrhizal fungi on the growth and nutrient elements of fenugreek (Trigonella foenum-graceum) based on a completely randomized design with three replications in the research greenhouse of Ferdowsi University of Mashhad during 2020-2021. The treatments were included 10 species of mycorrhizal fungi Glomus mosseae, Glomus etunicatum, Glomus claroideum, Glomus caledonium, Glomus interaradices, Glomus fasiculatum, Acaulospora langula, Scutellospora castanea, Glomus versiforme, Gigaspora margarit and non-inoculation (control). The studied traits were morphological traits (plant height, number of branches, number of nodes, internode length, leaf length and width, fresh and dry weight of plant aerial parts, root length, fresh and dry weight of roots) and the content of macro and micro elements (N, P, K, Mg, Ca, Fe, Mn, B, Cu, Zn).
Results and discussion: The results of analysis variance showed that the effect of mycorrhizal fungi on growth and the content of nutrient elements was significant at the level of 1% probability. Mycorrhiza inoculation significantly increased the height of fenugreek plants. The lowest plant height was observed in the un-treated plants and the highest plant height was related to plants inoculated with R. castanea. The highest leaf length and width was recorded in plants inoculated with R. intraradicese, which were 7.06 and 31.63% higher than the control, respectively. The results showed that the highest fresh weight of plant aerial part was obtained in the inoculated plants with R. castanea, which was 111.66% (more than twice) higher than the un-inoculated plants. However, F. mosseae caused a decrease (30.88%) of fresh weight compared to the control treatment. The highest plant dry weight belonged to plants inoculated with R. castanea, A. langula and D. versiformis which were 133.58% higher than the un- inoculated plants. The lowest plant dry weight was obtained in the control treatment which was not significantly differed from the treatment of C. etunicatum. Comparison of the mean data showed that inoculation with mycorrhiza fungi effectively increased the root growth of fenugreek. Although inoculation of fenugreek with mycorrhiza fungi had a significant effect on improving the nutrient uptake, but the plant response varied depending on the studied fungus species and in some species reduction in nutrient contents was recorded. Literature survey showed that the inoculation with appropriate species of mycorrhizal fungi can effectively increase the growth and biomass of fenugreek by improving the plant physiological traits and absorption of nutrient elements (Latef and Chaoxing, 2011; Baghbani arani et al., 2017).
Conclusions: According to the obtained results, the response of fenugreek to inoculation was depended on the mycorrhizal fungi species therefore determining suitable species of fungi is necessary to improve the growth and yield of this plant. Generally inoculation of fenugreek with C. claroideum, R. castanea and R. intraradices can be suggested as a suitable alternative to chemical fertilizers to increase the yield of fenugreek under greenhouse and field condition.