| چکیده انگلیسی مقاله |
Background and Objectives: Zataria multiflora Boiss. is an important medicinal plant species in the Lamiaceae family, native to Iran and some neighboring countries. Water scarcity is a significant limiting factor for crop growth and production. Reduced efficiency of chemical fertilizer uptake under drought conditions and their adverse environmental effects necessitates using sustainable agricultural practices. Mycorrhizal fungi, through their symbiotic with plants, provide essential nutrients to plants and mitigate the adverse effects of biotic and abiotic stresses on plants. This study investigates the influence of mycorrhizal symbiosis under drought stress and non-stress conditions on morpho-physiological characteristics of eight Z. multiflora ecotypes.
Methodology: This study was conducted on eight Z. multiflora ecotypes collected from Safashahr, Neyriz, Khanekhore, and Fasa (located in Fars province), Faridan, Baharestan, Kalat Ghazi (located in Isfahan province), and Qasreghand (located in Sistan and Baluchestan province). Two-year-old plants of these ecotypes were subjected to two levels of drought stress, consisting of 50% and 90% soil field capacity, representing drought stress and non-drought stress conditions, respectively. Mycorrhizal fungi were applied at two levels (with and without) in a factorial experiment based on the completely randomized design with three replications, conducted in a greenhouse of the Agriculture Faculty, Shahrekord University, Iran. Drought stress was applied through reduced watering, and arbuscular mycorrhizal fungi were inoculated in holes at a depth of 4-5 cm around the roots in the pots. The symbiosis was confirmed through root staining. Morpho-physiological traits, including plant length, width, crown area, leaf area, dry plant yield, and chlorophyll "a" and "b" content, were measured. After variance analysis, the means were compared using the LSD test. Pearson correlation coefficients were used to determine trait correlations, and stepwise regression was employed to identify traits affecting dry plant yield.
Results: The results of the analysis of variance showed that ecotype, drought stress, and mycorrhizal application had highly significant effects on plant length, plant width, crown area, leaf area, dry plant yield, and chlorophyll "a" and "b" content. The significance of the two- and three-way interaction effects of ecotypes with drought stress and mycorrhizal application in all studied traits indicates the different responses of ecotypes to drought stress and mycorrhizal fungus application. Comparing the means of the two drought stress levels indicated a significant reduction in all traits under stress conditions. Mycorrhizal application in non-stress conditions significantly increased the traits. Using mycorrhizal fungi under drought stress conditions compensated for part of the reduction caused by drought stress in the traits, resulting in an increase ranging from 14% (plant width) to 210% (dry plant yield) compared to drought stress conditions. The comparison of ecotypes in each combination of stress levels and mycorrhizal application levels suggests that plant length and width, crown area, leaf area, and plant dry yield increased. The intensity of response or change in these ecotypes to drought stress and mycorrhizal application varies. The correlation coefficients and stepwise regression results indicate the critical role of leaf area and plant length in dry plant yield under both non-drought and drought stress conditions.
Conclusion: In this restudy, high variability was observed in the evaluated traits such as plant length and width, canopy area, leaf area, plant dry yield, and chlorophyll "a" and "b" levels in the Z. multiflora ecotypes. On the other hand, the different reactions of these ecotypes to drought stress indicate the high genetic potential of this native plant in Iran. Therefore, it can be used to select superior genotypes. Considering the increasing and significant effect of most of the characteristics studied, including yield due to the application of mycorrhizal fungus, this fungus can be used in producing Z. multiflora under standard cultivation conditions and drought stress. |