Evaluation of Some Quantitative and Qualitative Traits of Shirazi Balangu (Lallemantia royleana) Medicinal Plant in Response to Salinity Stress and Mycorrhizal Fung

The medicinal plant of Balangu Shirazi (Lalemantia royleana Benth) to the Lamiaceae or Labiateae family. This medicinal plant is native to the tropical regions of Asia, India, Afghanistan and Pakistan. This plant is also found in various regions of the Middle East and Europe, especially Turkey, Iran and in the Siberian regions of Russia, i.e. in Western Siberia. Due to the presence of high mucilage content, Lallemantia royleana seeds quickly absorb water through the hydration process and produce a sticky, cloudy and tasteless liquid that can be used as a new source of hydrocolloid in food formulations as well. Soil salinity is a growing problem in agricultural ecosystems that endangers the growth and productivity of plants. Salinity causes ionic toxicity, nutritional imbalance, pigment destruction and inhibition of photosynthesis, oxidative and osmotic stress, limited release of CO2 in leaves, changes in metabolic pathways, cell deformation, premature aging and finally cell death in it becomes a plant. Therefore, effective solutions to deal with soil salinity under agricultural management systems can include all kinds of salt-resistant species and biotechnological approaches such as the use of beneficial microorganisms that are able to improve plant tolerance to salt. Mycorrhizal fungi, one of the common soil microbes, can occupy the roots of most terrestrial plant species. Notably, mycorrhizal fungi can improve host plant tolerance to salinity stress by a series of physiological and biochemical mechanisms, including higher water use efficiency, photosynthetic capacity, maintaining ion homeostasis, osmotic protection, maintaining cell ultrastructure and enhancing antioxidant metabolism. This study was conducted with the aim of investigating the role of three mycorrhizal fungi on seed yield, physiological characteristics and mineral elements (N, P and K) of the medicinal plant L. royleana under salt stress conditions.

This experiment was factorial based on a completely randomized design including the treatment of mycorrhizal fungi at three levels (R. irregularis, G. versiform, F. mosseae) with the number of spores 5 x 106 per milliliter of inoculum and salinity stress including four level (0, 2, 4, 6 and 8 dS/m of sodium chloride salt) was done in three repetitions. This experiment was carried out in 2018 in a greenhouse at Islamic Azad University, Mahabad Branch, day and night temperatures were 25 and 22 degrees Celsius, respectively, with two relative humidity levels of 60 (during the day) and 40 (at night). The percentage and amount of carbon dioxide was about (mMol.mol-1) 500-600. Shirazi Balangu seeds were obtained from Pakan Seed Company of Isfahan with 99% purity and 80% potency. Distilled water was used for zero treatment (control) and pure sodium chloride salt (Merck, Germany) was used to prepare solutions with electrical conductivity of 2, 4, 6 and 8 dS/m. Balango seeds were sown in the middle of Mehr in pots with an opening diameter of 20 cm and a length of 18 cm containing soil, sand and manure (2:1:1) at a depth of 0.5-1 cm. Three fungi G. versiform, R. irregularis and F. mosseae were used for mycorrhiza inoculation, and there were at least 50 live spores in each gram of soil. The ratio of the inoculant used to the soil was one to nine (by volume) and in layers. In order to prevent any deficiency of nutrients, 10 ml of Hoagland nutrient solution with half the concentration of phosphorus was added to all the pots every week. The traits under study encompassed the seed yield of a single plant, seed oil percentage, antioxidant capacity, proline content, as well as the leakage of ionic substances and nutrients such as nitrogen, phosphorus, and potassium. Analysis of variance (ANOVA) was conducted on the data using SAS 9.1 statistical software. Mean comparisons among traits were performed utilizing Duncan's test at a significance level of 5%.

The results showed that the traits evaluated in the present study were affected by mycorrhizal fungus treatments, salinity stress and the mutual effect of fungi in salinity stress. Seedlings inoculated with mycorrhizal fungus R. irregularis had the highest seed yield, percentage of oil, proline, antioxidant power and mineral elements compared to the other two strains of mycorrhizal fungus. Salinity stress increased the percentage of oil, proline, and antioxidant power of L. royleana medicinal plant leaves, and increasing the salinity stress from 0 to 8 dS/m decreased grain yield and mineral elements. According to the comparison results of the average effect of fungus interaction in salt stress, the highest amount of seed yield and mineral elements in plant inoculation with R. irregularis fungus was observed in the absence of salt stress, as well as the highest amount of traits of oil percentage, proline and antioxidant power. It was obtained in a tension of 8 dS/m. According to the results of the present research, the use of R. irregularis mushroom strain had the most positive effect on the quantitative and qualitative characteristics of L. royleana medicinal plant compared to the absence of mushroom inoculation.

In general, the results of this study showed that mycorrhizal inoculation had a positive and significant effect on seed yield, antioxidant capacity, oil percentage, proline content and the concentration of nitrogen, phosphorus and potassium elements in L. royleana plant. Also, the results indicated that the use of mycorrhiza in the cultivation of L. royleana can partially prevent the occurrence of element deficiency in saline soils and reduce the high consumption of chemical fertilizers. This assertion has been corroborated by research conducted by other scholars focusing on medicinal plants. Employing mycorrhizal symbiosis in saline soils has been shown to enhance plant resistance to salinity. Therefore, by employing a suitable mycorrhizal strain with salinity resistance, it becomes feasible to mitigate the departure of saline soils from the production cycle, thereby averting consumption-related issues. Furthermore, the excessive use of chemical fertilizers has led to numerous problems, highlighting the need for alternative approaches.