Journal of Soil and Plant Interactions

---

In order to study the effects of salinity stress on morphological traits, essential oil content and ion accumulation in basil (Ocimum basilicum) plant under hydroponic conditions, a factorial experiment based on completely randomized blocks design with three replications was conducted on three landraces (Jahrom, Banafsh and Isfahan) and five NaCl salinity levels (0, 40, 80, 120 and 160 mM) in controlled greenhouse conditions. The results indicated a significant reduction in plant height, shoot dry weight and root dry weight due to increasing salinity level. Among the landraces, Banafsh landrace had the highest biomass. Also, with the increase in salinity level, sodium ion content of shoot and root increased. However, Ca2+ and K+ contents and Ca2+/Na+ and K+/Na+ ratios of both shoot and root decreased. These ratios were higher in shoots, as compared to roots, of all three landraces. Essential oil content increased with the increase in stress level. However, this much increase in essential oil content is not important at high salinity levels due to high reduction in biomass. This could be important at moderate stress considering produced biomass. Among the studied landraces, Jahrom landrace contained the highest essential oil content.

---

In order to study the effects of mycorrhizal fungi on quantitative and qualitative traits of roots, shoots and flower of Lisianthus, the inoculation with two mycorrhizal fungi isolates (Glomus mosseae and G. intraradices) and their blend was experimented under different levels of phosphorus (10, 20 and 40 mg/kg soil) in a factorial trial, based on a randomized complete blocks design, under greenhouse conditions. The results indicated that inoculated Lisianthus plants had better growth and higher biomass compared to the non-mycorrhizal plants. Inoculation with arbuscular mycorrhizal fungi significantly reduced number of required days to flowering and increased flowering stem characteristics including length and number of flowering stems, number of flowers, mean flower diameter and fresh weight of flowers per plant. The results revealed that under optimum level of phosphorus, mixture of the two arbuscular mycorrhizal fungi performed better than either of them in increasing the efficiency of the studied indices.

---

In order to determine the critical period for weed control of greenhouse cucumber, an experiment was conducted in 2012 in a soil greenhouse located 25 km from Mashhad, as a randomized complete blocks design with three replications. The experiment consisted of two treatment series of weed interference. The first series consisted of weed-interference periods (including 14, 28, 42, 56, 70 and 84 days after emergence and the entire growth period of greenhouse cucumber) and the second series consisted of weed-free periods (including 14, 28, 42, 56, 70 and 84 days after emergence and the whole period of greenhouse cucumber growth). Results of this study showed that red root pigweed, common purslane, black nightshade, dwarf mallowand and common lambsquarters were the weeds with the highest density and biomass. Increasing or decreasing the weed-interference and weed-free periods led to changes in density, biomass, relative density and relative biomass of these plants. If 10, 5, and 1% of greenhouse cucumber yield loss are acceptable, then weed control must be carried out from 23 to 77 days (54 days), 18 to 94 days (76 days), and 16 to 107 days (91 days) after the greenhouse cucumber emerges, respectively. In general, the results of this experiment demonstrated that weed control in greenhouse cucumber production is necessary to achieve optimal yield.

---

Root exudates and morphological root traits play an important role in plant species’ response to drought. However, the functional consequences of these drought-induced changes for rhizosphere microbial communities are unknown. We hypothesized that drought-sensitive and -tolerant grass genotypes widely differ in the quality of root exudates, growth strategies, and root systems, which may affect rhizosphere microbial communities. Therefore, we examined microbial biomass carbon and nitrogen in the rhizosphere of drought-sensitive and -tolerant genotypes of Bromus inermis, Dactylis glomerata, and Festuca arundinacea species under four years water stress treatments at Lavark Farm of the Isfahan University of Technology. Responses of the rhizosphere microbial communities to the water stress varied by the plant genotypes. Water stress increased rhizosphere microbial biomass carbon in the drought-sensitive and -tolerant genotypes of Bromus inermis species. In contrast, water stress treatment significantly reduced microbial biomass in the rhizosphere of Dactylis glomerata genotypes. The effect of water stress on rhizosphere microbial biomass carbon was positive in the drought-sensitive genotypes of Festuca arundinacea species, while conversely, this effect was negative in the drought-tolerant genotypes. We found a similar pattern across two drought-sensitive and -tolerant genotypes of Bromus inermis species to the water stress, which could be an evolutionary strategy to overcome drought conditions through the stimulation of microbial biomass and activity and the subsequent mineralization of nutrients. Higher microbial biomass carbon in the rhizosphere soils relative to those in the control (bulk soil) were observed, regardless of the moisture treatment. Under the water stress, microbial biomass carbon were almost simillar in the rhizosphere of drought-sensitive and -tolerant genotypes but were higher in the drought-tolerant genotypes without the stress.
 

---

To investigate the effect of sodium selenate (Na2SeO4) and sodium selenite (Na2SeO3) on some morphological characteristics and nutrients concentration in peppermint, an experiment was conducted in a completely randomized design with four replications. Different levels of sodium selenate and sodium selenite (0, 4, 8, and 12 mg l-1) were applied in soilless cultivation in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad. Then morphological traits and the concentrations of nutrients in the leaf were measured in the flowering stage. The results showed that the application of two forms of selenium at a concentration of 4 mg l-1 increased the growth traits in peppermint. The highest concentration of both salts decreased the plant growth. The results also showed that with increasing the concentration of selenite and sodium selenate, the selenium concentration increased, but the use of sodium selenate caused higher concentration of this element in the leaf. At a concentration of 4 mg l-1 selenium, the concentrations of macronutrients including nitrogen, phosphorus, potassium, calcium, and magnesium in the leaf increased by 43.7, 11.1, 3.2, 11.6, and 9.2%, respectively, compared to the control but were not significant. The highest nitrogen concentration was observed at the concentration of 4 mg l-1 sodium selenite 43.7% greater than the control. With increasing the concentration of selenium, except for molybdenum and manganese, the concentration of zinc, iron, boron, and copper increased. The highest concentrations of iron and boron were obtained at 12 mg l-1 sodium selenate, 60.2 and 25.7% greater compared to the control, respectively. The highest concentrations of zinc and copper measured at 12 mg l-1 sodium selenite were 63.3 and 40.6% greater than the control, respectively. In general, it is concluded that 4 mg l-1 of sodium selenate can be applied to improve the growth and nutritional condition of the peppermint.

---

Abstract
To investigate the effect of ten species of mycorrhizal fungi belonging to seven different genera (Racocetra, Rhizophagus, Claroideoglomus, Funneliformis, Diversispora, Acaulospora and Gigaspora) on some growth and biochemical traits of fenugreek (Trigonella foenum-groecum), a pot experiment based on a completely randomized design was conducted in the research greenhouse of Ferdowsi University of Mashhad. The changes of biomass, number and length of pods, weight of 1000 seeds, photosynthetic pigments, phenolic compounds, soluble carbohydrates, total protein, and antioxidant capacity in fenugreek plants in response to mycorrhizal inoculation were studied. The results of variance analysis of the data showed that the effect of mycorrhizal fungi on all studied traits was significant at the probability level of 1%. Based on the findings, the response of fenugreek plant to inoculation with different species of mycorrhizal fungi was variable. Inoculation with suitable species of mycorrhizal fungi through improving the growth condition and biochemical traits of treated plants increased the fenugreek growth based on plant fresh and dry weights. In the present study, mycorrhizal species, especially R. castanea, A. langula, R. intraradicese, and G. margarita enhanced the amount of chlorophyll and the activities of antioxidant enzymes of inoculated fenugreek plant compared to the control, which was accompanied by increasing the plant growth in terms of fresh and dry weights in these treatments. According to the obtained results, inoculation of fenugreek plant with C. claroideum, R. castanea, A. langula, G. margarita, R. fasciculatus, and F. caledonium fungi can be suggested as a suitable alternative for chemical fertilizers to increase the yield of this plant.

Background and Objective: In sustainable agriculture, organic and low input cultivation systems are the most important factors and the application of biofertilizers to reduce chemical fertilizers usage is the main step (1). Biofertilizers can improve physical, chemical and biological properties of soil and with minimum negative effects on the environment, could increase soil fertility (2). The application of useful microorganisms such as arbuscular mycorrhizal (AM) fungi as an important biofertilizer plays a key role in water and nutrient supply for plants (3). The purpose of this study was to investigate the effect inoculation with different mycorrhizal species on the growth and biochemical traits of fenugreek.

Methods: A pot experiment was conducted to investigate the inoculation effect of different species of mycorrhizal fungi on the growth, physiological and biochemical characteristics 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 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 included plant fresh and dry weights, number of pods, 1000-seeds weight, photosynthesis pigments, soluble carbohydrate, total phenol, flavonoids, total protein, and antioxidant activity. Minitab17 software was used to analyze the data and the mean comparison was performed based on Bonferoni test at 1% probability level.

Results: The results of variance analysis showed that the effect of mycorrhizal fungi on all studied traits was significant at the 1% probability level. According to the obtained results, the response of fenugreek to inoculation depended on the mycorrhizal fungi species. Among the studied mycorrhizal species, the S. castanea had the greatest effect on improving the plant biomass and photosynthesis pigments. The highest pod number and 1000-seeds weight were obtained in the plants inoculated with G. claroideum. In the plants inoculated with F. mosseae and C. claroideum, the total phenolic compounds were higher than in the other treatments. Also, the highest activities of guaiacol peroxidase and polyphenol oxidase were recorded in the plants treated with R. fasciculatus.

Conclusions: Inoculation with appropriate species of mycorrhizal fungi could effectively increase the growth and biomass of fenugreek by improving the plant physiological traits. According to the results of this study, inoculation of fenugreek with C. claroideum, R. castanea, A. langula, G. margarita, R. fasciculatus, and F. caledonium can be suggested as a suitable alternative for chemical fertilizers to increase the yield of fenugreek under the greenhouse conditions.

References:
1. Rahimi, A., Dovlati, B., Amirnia, R., Heydarzade, S., 2019. Effect of application of mycorrhizal fungus and Azotobacter on physiological characteristics of Trigonella foenum-graecum L. under water stress conditions. Iranian Journal of Plant Biology 11(4): 1-18. (In Persian with English abstract)
2. Rezazadeh Roghani, Sh., Aminian, R., Maffakheri, S., Asghari, B., 2019. The effect of biological fertilizers on the morphological traits of fenugreek (Terigonella foenum.graecum) in different humidity conditions. Horticultural Plant Nutrition 2(1): 145-163. (In Persian with English abstract)
3. Siavash Moghadam, S., Rahimi, A., Heydarzadeh, S., Moradzadeh, S., Hasanlu, M., 2017. The effect of mycorrhizal fungus symbiosis on the yield and biochemical characteristics of the medicinal plant fenugreek. Biotechnology of Medicinal Plants 3(1): 40-52. (In Persian with English abstract)

---

Abstract
Melatonin has been introduced as a strong antioxidant that has a protective role in stressful conditions and acts as an osmotic regulator and metabolic modifier when different stresses occur. In order to investigate the effect of melatonin pretreatment on improving the morphophysiological traits of Calendula officinalis L., a factorial completely randomized design with three replications was conducted. Melatonin at three levels (0, 100 and 150 µM) and sodium chloride at four levels (0, 30, 60 and 90 mM) were considered as the treatments. Based on the obtained results, the highest plant height, the highest number of leaves and the longest root length were obtained in 150 μM melatonin without sodium chloride treatment. On the other hand, at 90 mM salinity and without the presence of melatonin, the lowest number of leaves and plant height were observed. The fresh weight of the root, at different levels of salinity, showed a decreasing trend with increasing salinity concentration, so that its lowest value was observed in the concentration of 90 mM salt without melatonin. The fresh weight of the root increased with the increase in melatonin concentration. The highest relative water content and potassium percentage of leaves were observed in 150 μM melatonin treatment. As the salt concentration increased, the relative water content and potassium concentration decreased. The highest amount of soluble sugar related to 60 mM salinity in combination with 100 µM melatonin and the highest amount of proline was observed in 60 mM salinity + 150 µM melatonin. The results indicated that melatonin pretreatment was effective on the vegetative and physiological traits of marigold under salinity stress and was able to reduce the effect of salinity, especially in the concentrations of 30 and 60 mM sodium chloride.

Background and Objectives: High NaCl levels, due to osmosis and ionization, can significantly diminish plant height, leaf area, and the fresh and dry weights of shoots and roots. Melatonin, a ubiquitous molecule produced in plants, acts as a growth regulator similar to indole acetic acid (IAA), which promotes cell expansion and growth. Under NaCl stress, plants close the stomata to prevent water loss, and this can result in decreased stomatal conductance and photosynthesis activity. However, it has been shown that the application of melatonin makes the stressful conditions tolerable for plants and leads to the opening of stomata, which has been reported to improve the photosynthetic machinery in sunflower and citrus plants (Brugnoli and Lauteri, 1991; Meloni et al., 2003; Ye et al., 2016). The aim of the present study was to investigate the role of melatonin in marigold, in order to improve vegetative and physiological traits.

Methods: A factorial experiment in a completely randomized design with two factors and three replications was conducted in greenhouse conditions at Sari Agricultural Sciences and Natural Resources University. Melatonin at three levels (0, 100 and 150 µM) and salinity at four levels (0, 30, 60 and 90 mM) were considered as the first and second factors, respectively. Marigold seedlings were sprayed three times every ten days. One week after the last melatonin treatment, irrigation with sodium chloride was applied every 7 days for 35 days. One week after the last application of sodium chloride, some traits such as plant height, number of leaves, flower diameter, root length, root fresh and dry weights, leaf relative water content, soluble sugar, proline, ion leakage, and sodium and potassium contents were measured.

Results: The interaction between salinity and melatonin affected the plant height, number of leaves, and root length, volume and dry weight. The highest plant height (i.e., 17 cm), the number of leaves (i.e., 34) and the root length (i.e., 18.83 cm) were obtained in the 150 μM melatonin treatment without salt. The highest root volume and dry weight were observed in 100 μM melatonin treatment without salt. The highest leaf relative water content and potassium content were obtained in 150 μM melatonin treatment. The highest amounts of soluble sugar and proline were recorded in 60 mM sodium chloride + 100 μM melatonin, and 60 mM sodium chloride + 150 μM melatonin, respectively. At 30 mM salinity without the use of melatonin, the lowest proline was recorded. The highest sodium content was recorded at 60 mM sodium chloride. At the concentration of 150 μM melatonin, the sodium content in the leaf decreased. With the increase of salt concentration, ion leakage increased and it was the highest at 90 mM salinity. At the concentration of 150 μM melatonin compared to the control, a decrease in ion leakage was observed.

Conclusions: The results showed that salinity stress reduced the vegetative traits of marigold, but the use of melatonin reduced the damage under salinity stress conditions. Melatonin, by protecting the membrane and structure of plant cells, maintaining the antioxidant system and helping to absorb potassium and reducing sodium absorption, could increase the resistance of marigold against salt stress. As a result, the use of melatonin moderated the effects of salinity and improved plant growth in saline conditions. Therefore, it is recommended to use 100 and 150 μM concentrations of melatonin for improving vegetative and physiological characteristics of marigold under salinity stress conditions.

References:
1. Brugnoli, E., Lauteri, M., 1991. Effects of salinity on stomatal conductance, photosynthetic capacity, and carbon isotope discrimination of salt-tolerant (Gossypium hirsutum L.) and salt-sensitive (Phaseolus vulgaris L.) C₃ non-halophytes. Plant Physiol. 95(2), 628–635.  https://doi.org/10.1104/pp.95.2.628.
2. Meloni, D.A., Oliva, M.A., Martinez, C.A., Cambraia, J., 2003. Photosynthesis and activity of superoxide dismutase, peroxidase and glutathione reductase in cotton under salt stress. Environ. Exp. Bot. 49(1) 69–76. https://doi.org/10.1016/S0098-8472(02)00058-8.
3. Ye, J., Wang, S., Deng, X., Yin, L., Xiong, B., Wang, X., 2016. Melatonin increased maize (Zea mays L.) seedling drought tolerance by alleviating drought-induced photosynthetic inhibition and oxidative damage. Acta Phys. Planta. 38(2), 48. https://doi.org/10.1007/s11738-015-2045-y.