Iranian Journal of Plant Physiology
Volume:15 Issue: 1, Winter 2025

Water stress is one of the major limitations in crop production and performance stability. This study aimed to investigate the effect of biological stimulants on the quantitative and qualitative performance of sugar beet under drought stress. A field experiment was conducted to evaluate the effect of irrigation regimes (irrigation after 80, 160, 240, and 320 mm of water evaporation from the class A pan) and the application of biological stimulants at 5 levels (control, seaweed extract at 3 and 6 kg ha⁻¹, humic acid at 3 and 6 kg ha⁻¹). The results showed that the highest gross sugar (15.99%), extraction coefficient (77.31%), and pure sugar (12.37%) were obtained under irrigation conditions after 240 mm of water evaporation, while the highest levels of sodium (16.4%) and nitrogen (3%) were ob tained under irrigation conditions after 320 mm of water evaporation. The use of biological stimulants caused a significant increase in gross sugar and pure sugar and a reduction in sodium and nitrogen compared with the control treatment. The maximum root yield (74.06 t ha⁻¹) and pure sugar yield (8.42 t ha⁻¹) were obtained in the foliar application of 6 kg ha⁻¹ of humic acid under irrigation conditions after 80 mm of water evaporation. In general, 6 kg ha⁻¹ of seaweed extract and 3 kg ha⁻¹ of humic acid under moisture stress conditions reduced sugar beet root impurities such as sodium and harmful nitrogen. As a result, the efficiency of root sugar extraction was significantly improved, and the sugar percentage of molasses was reduced.

Fungi are the largest organisms found on Earth; hence, it is important to understand the factors influencing their distribution. In the present study, samples were collected in three stages of rice planting: before planting, during cultivation, and after cultivation from paddy fields in Najaf city. These samples were then cultured using potato dextrose agar medium. The BLAST tool (Basic Local Alignment Search Tool) was used for the identification of the fungi, and their counts were determined using a microscope.The results showed that the identified fungi belonged to genera such as Aspergillus, Achroiostachys, Actinomucor, Cladosporium, Curvularia, Fusarium, Penicillium, Proteus, and Talaromyces. The most frequently identified fungi were Fusarium humuli, Aspergillus niger, Alternaria alternata, Penicillium oxalicum, Aspergillus terreus, and Penicillium griseofulvum, respectively. The highest number of colonies and most significant environmental effects were observed before planting and after the agricultural stages. Species distribution was significantly correlated with environmental factors. Additionall y, principal component analysis revealed that the greatest impact of environmental parameters on species distribution was explained by the first and second components, which accounted for 46.05% and 30.20% of the variation, respectively.

Taxus baccata plant is one of the most important sources of the anti-cancer drug Taxol. This plant is among the endangered species due to its low growth and reproduction, as well as excessive harvesting from nature. The amount of this valuable drug in the plant is very low. Therefore, by using the tissue culture technique, the approach of exploiting this valuable plant to produce Taxol can be changed from natural areas to controlled conditions, thus saving it from the danger of extinction and allowing for the extraction of more of this medicine from the plant. In this research, four different types of yew tissue (stem, leaf, shoot tip, and leaf + node) were investigated. For the induction of callus, four types of explants were placed in Gamborg culture medium with 6 mg/L 2,4-D, 0.5 mg/L kinetin, and 30 g/L sucrose. After four weeks, callus fresh and dry weight, callus formation rate, callus browning rate, and callus size were investigated. The results showed that the highest fresh and dry weight of callus belonged to the shoot tip tissue, and the lowest fresh and dry weight of callus belonged to the leaf tissue. Also, stem tissue and leaf + node tissue showed the highest percentage of callus formation (100%). The results of callus browning showed that the stem tissue browned more than other tissues. Examination of the callus size showed that the shoot tip tissue had the largest callus size compared to other tissues.

Falcaria vulgaris has not been domesticated or cultivated so far. The natural habitats of the medicinal plant F. vulgaris are endangered due to the use of herbicides and excessive harvesting by local people. Also, due to its therapeutic and food applications, there is a need for protocols for the propagation of F. vulgaris. To address this need, the experiment was performed as a two-factor factorial based on a completely randomized design with expe rimental factors being the type of rhizome (whole rhizome, proximal end of rhizome, and distal end of rhizome) and the period of cold stratification (one week, two weeks, and three weeks). The survival rate, number of days to emergence, fresh and dry weight, and the number of leaves, leaf length, leaf area, and crown diameter were measured as growth parameters. The best overall yield, in terms of survival rate, number of days to emergence, fresh and dry weight, number of leaves, leaf length, leaf area, and crown diameter, was observed in the proximal end of the rhizome (8 cm) and the whole rhizome propagules subjected to three weeks of cold stratification.

The effect of nanoparticles on living organisms is not well understood yet. The physicochemical properties of nanoparticles enhance the use of nanotechnology in various fields. In this study, the effect of different concentrations of nano and bulk nickel oxide (0, 10, 20, 50, 100, 200, 400, 600, 800, and 1000 ppm) on fennel seed germination and growth was tested in a randomized complete design with four replications. After 14 days of seed treatment, germination factors (germination percent, relative germination percent, mean germination time, germination rate, germination index, and weight germination index) were measured. In general, low nano concentrations and medium bulk concentrations on fennel seed growth showed stimulating effects, while high nano and bulk concentrations showed toxic effects. Therefore, exposure of fennel seeds to low concentrations of NiO nanoparticles and medium concentrations of bulk NiO stimulated seed germination. These concentrations can be used as a new approach to overcome seed germination problems of some plant species, especially medicinal plants such as fennel.

The use of plant growth-promoting bacteria (PGPRs) to modulate salinity is of utmost importance for enhancing plant growth and adaptation in saline environments. This study aimed to investigate the effects of Azotobacter chroococcum and Pseudomonas putida on the growth and biochemical characteristics of rose-scented geranium under salinity stress. The experiment was conducted using a factorial design with four levels of PGPR treatment (control, Azotobacter, Pseudomonas, and Azotobacter + Pseudomonas) and three levels of salt at 0, 60, and 120 mM NaCl. The results indicate that salinity stress resulted in a decrease in plant yield, with the high est reduction observed at 120 mM salinity. This led to reductions in plant weight (31%), root weight (37%), total chlorophyll (33%), relative water content (RWC, 19%), essential oil yield (25%), as well as increases in malondialdehyde (MDA, 45%), catalase activity (179%), and superoxide dismutase activity (100%). However, the inoculation of geranium plants with PGPRs, particularly the simultaneous application of Azotobacter and Pseudomonas, resulted in stress mitigation. This was evident through an increase in biomass, photosynthetic rate, RWC, as well as a reduction in the activity of antioxidant enzymes and MDA in the leaves. Among the different treatments, the combined application of Azotobacter and Pseudomonas, along with a salinity stress level of 60 mM, resulted in the highest production of secondary metabolites, including total phenols, flavonoids, and essential oil content. In conclusion, the combined treatment of Azotobacter and Pseudomonas is recommended as an effective approach to mitigate salinity stress and increase plant yield in rose-scented geranium.

Prolonged water stress can have detrimental effects on most plants, including Vicia faba L. (broad bean), which is an important legume. The use of exogenous coarse or nano-structured silicon on various plants has yielded conflicting results in terms of improving plant water relations and alleviating drought stress. Therefore, the objective of this study was to examine the effects of exogenously applied silicon and nano-silicon on the morpho-physiological responses of three recently introduced Vicia faba genotypes during the vegetative growth stage under water deficit stress. In a greenhouse experiment, three genotypes, two levels of irrigation regimes, and three levels of silicon were arranged in a completely randomized factorial design, with five replications. The results indicated that water deficit stress significantly reduced shoot height, as well as shoot and root fresh and dry weights, while also decreasing relative water content in all three genotypes. Conversely, chlorophyll, carotenoid, malondialdehyde (MDA) content, and soluble guaiacol peroxidase activity increased in response to water stress. Notably, the G62 genotype exhibited greater sensitivity to water stress compared to G20 and G61, based on guaiacol peroxidase activity and MDA content. Furthermore, the effects of silicon and nano-silicon on the morpho-physiological characteristics of the plants were found to be minimal, but were significantly influenced by the genotype and experimental conditions. These findings suggest that before the wide application of exogenous silicon in field trials, particularly in mitigating the adverse effects of water deficit during the vegetative stage of Vicia faba, prior testing of genotype-specific responses is necessary.

This study investigated the role of arbuscular mycorrhizal fungi (AMF) in mitigating salinity stress in Pistacia vera L. cv. Ohadi. A greenhouse pot experiment was conducted using a randomized complete block design with two factors: Glomus mosseae inoculation (inoculated or non-inoculated) and salinity (control or 12 dS m⁻¹ NaCl). While salinity reduced AMF colonization from 67% to 43%, AMF-inoculated plants consistently exhibited superior performance compared to non-mycorrhizal plants. Salinity stress significantly decreased shoot and root biomass, total chlorophyll content, and net photosynthetic rate (Pn) in both groups. However, AMF symbiosis significantly ameliorated these negative effects, resulting in higher biomass, chlorophyll content, and a notably higher Pn (38.8% increase) under saline conditions. Furthermore, AMF inoculation altered the chlorophyll a/b ratio under salinity, suggesting an adaptive response in light-harvesting. Molecular analysis revealed that while salinity downregulated psbA, psbD, rbcL, and rbcS expression, AMF differentially upregulated psbA (under both conditions), psbD (specifically under salinity), and rbcL (under both conditions). Additionally, AMF improved shoot potassium (K) content and upregulated the expression of the SKOR gene, involved in K+ transport, under both control and saline conditions. These findings demonstrate that AMF symbiosis enhances salinity tolerance in pistachio by improving K nutrition, modulating photosynthetic gene expression, and consequently, maintaining photosynthetic efficiency under stress.

Plant growth and yield are affected by salinity. Symbiotic interactions between plants and endophytic fungi are a promising approach to promoting crop growth under salt-stress conditions. Here, the tolerance of the endophytic fungus Pleosporaceae sp. was verified under diverse NaCl levels (0, 50, 100, 150, and 200 mM). Subsequently, Pleosporaceae sp. production of indole acetic acid (IAA) was assessed in vitro at various salinity levels (0, 50, 100, 150, and 200 mM). Additionally, the effect of Pleosporaceae sp. inoculation on germination, growth, and biochemical characteristics of tomato (Solanum lycopersicum L.) under five levels of salinity (0, 20, 50, 100, 150, and 200 mM NaCl) was investigated. The results indicated that Pleosporaceae sp. exhibited strong salt tolerance and produced approximately 138.6 ± 0.7 μg/ml of IAA under 100 mM NaCl. Moreover, the results showed that this symbiotic fungus significantly enhanced germination and growth under salinity. Pleosporaceae sp. also significantly improved proline and sugar accumulation under salt treatment. This study suggests that the endophytic fungus Pleosporaceae sp. can be employed to mitigate sodium chloride-induced stress in plants, thereby improving plant growth and productivity.