فصلنامه گیاه پزشکی
سال چهل و هفتم شماره 4 (زمستان 1403)

Legumes are widely regarded as one of the most significant protein sources in human and animal food chains. The common bean is the primary legume crop, accounting for 85% of global bean production. The scientific community's primary priority is to develop innovative techniques to assure food security in addition to agricultural product safety, while simultaneously implementing realistic plans to reduce the usage of pesticides and artificial fertilizers. Among the investigated solutions, the utilization of beneficial microbes is one of the key components in establishing a green rotation in agricultural systems across the world. This study aimed to evaluate the endophytic role of native Beauveria species on the development and biochemical characteristics of common beans.

Spore suspension (1 × 108 ml-1) was produced after a 10-day culture of the species. The spore suspension was introduced to the soil after the seeds had been disinfected during planting. To assess the fungus's establishment in the plants, samples were collected up to 25 days following inoculation. The experiment was conducted in a completely randomized design with three replications for each treatment, and parameters such as dry and fresh root and shoot weight, plant height, root length, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, phenol, proline, and polyphenol oxidase enzyme were determined. SAS software was used to analyze the data, and Duncan's multiple range test was used to compare means at a P-value of <0.05.

Beauveria species injected with 1 × 108 ml-1 spores per milliliter were re-isolated by cultured bean root, stem, and leaf tissues in PDA culture media, confirming endophytic fungi. These two Beauveria species were capable of establishing systematic colonization in tissues from all bean organs. The study found that employing B. pseudobassiana and B. bassiana, as well as integrating these two species, raised bean plant height by 37.7, 20.2, and 41.4%, respectively, compared to the control treatment. Similarly, applying these treatments increased root length by 15.5, 24.5, and 32.7%, respectively, compared to the control treatment. According to the findings of this study, B. pseudobassiana, B. bassiana, and the mixture of these two fungal species increased the dry weight of the aerial sections of beans by 50.6, 36.9, and 72.6 percent, respectively. Furthermore, the use of B. bassiana, B. pseudobassiana, or a mixture of these two species elevated root dry weight by 44.1%, 39.5%, and 55.8%, respectively, in comparison with the control treatment. In general, all treatments produced more chlorophyll a, chlorophyll b, and total chlorophyll than the control treatment. The combination of two species resulted in the maximum number of features, which were 153.9%, 162.8%, and 156.9%, respectively, in comparison with the control treatment. The results indicated that the amount of Carotenoid, polyphenol oxidase enzyme, phenol, and proline rose considerably when two fungal species were used alone or in combination, compared to the control treatment.

Endophytic B. pseudobassiana has been the subject of no prior research, based on our findings. The fungal strains used in the current study were re-isolated from the roots and other parts of the plant, indicating that the inoculated strains colonized the studied bean plants systematically. Entomopathogenic fungi have recently attracted the attention of researchers for the profits they provide to their hosts, particularly in plant growth. The findings revealed that employing endophytic fungi and interacting with them might enhance the morpho-physiological properties of bean plants. As a result, we discovered that entomopathogenic fungi might act as both endophytic and plant growth boosters. In spite of the current proceedings, more study is required to investigate the endophytic nature of these native species in other hosts, their effect on pathogen and insect control, and their effect on metabolites, hormones, and micro-nutrients using various inoculation methods.

Cabbage aphid, Brevicoryne brassicae L. is one of the important pests of brassicaceous plants ‎worldwide, causing considerable damage to them. It not only damages host plants by directly ‎sucking the tissue sap and excreting honeydew, but also transmits some plant pathogenic viruses ‎and further weakens the host crops. In one hand, due to the adverse effects of irregular chemical ‎pesticide use on vegetables such as cabbage, and indecisive effects of biocontrol agents in pest ‎control, exploring alternative methods for cabbage aphid management such as botanical pesticide ‎application sounds appropriate and necessary. Therefore, in the present study, acute toxicity of the ‎botanical insecticide, BotanAphid was studied against cabbage aphid on white and red cabbages by ‎determining their corresponding LC50 values. Moreover, their sublethal (corresponding LC25 ‎values) effect was assessed on the fertility life table parameters of the pest in both white and red ‎cabbages.‎

After preliminary bioassays based on recommended concentration (2 % for cotton aphid) in both ‎plant cultivars, five concentrations were estimated by logarithmic intervals in white (0.45, 0.81, ‎‎1.48, 2.69 and 4.9 percent) and red (0.5, 0.89, 1.58, 2.82 and 5.01 percent) cabbages. Control ‎aphids were treated with distilled water containing 0.05% citowett as surfactant. Thirty newly ‎emerged adult aphids were randomly selected for each treatment. Ten insects were placed on each ‎leaf disc and treated uniformly by a hand sprayer. After drying, insects were placed within Petri ‎dish with ventilation. The number of dead insects were counted after 24 h. Bioassay data were ‎analyzed by probit analysis using SAS 24.0. To study the sublethal effects of BotanAphid on ‎fertility life table parameters of B. brassicae, the calculated LC25 values (0.675 and 0.765 percents ‎respectively for white and red cabbage cultivars) of BotanAphid were used. For each treatment and ‎control, 50 adult aphids were treated similar to bioassays. All treated insects were removed after 24 ‎h and the number of 50 newly emerged first instar nymphs from treated adults were randomly ‎selected and kept individually. The number of dead insects and produced nymphs were recorded ‎daily and removed from experimental units. Life table data were analyzed using Twosex-MsChart ‎program and the means and standard errors of parameters were calculated by bootstrap method ‎using 100000 replicates.‎

According to the bioassays, the mean lethal concentrations (LC50 values) of this pesticide on ‎cabbage aphid were 1.552 and 1.704 percents respectively in white and red cabbages. In life table ‎study with LC25 values of aphicide, the lowest fertility and reproduction period of B. brassicae ‎were remarkably decreased on BotanAphid treatment in both white and red cabbages compared to ‎corresponding control (insecticide-free) units. Furthermore, pre-adult duration was prolonged and ‎survival of treated aphids was decreased considerably when compared to control. In addition, ‎insecticide treatment caused intrinsic rate of increase (r), as the most important population growth ‎parameter, of the cabbage aphids to be lowered significantly compared to corresponding control ‎insects. Also, BotanAphid sublethal concentration resulted in considerable decrease in other life ‎table parameters when compared to appropriate control insects in both cabbage cultivars. ‎Reproduction values and life expectancies were the highest in control aphids and the lowest in ‎LC25-treated insects.‎

Our results revealed that B. brassicae suffered considerable mortality from BotanAphid, as a ‎botanical insecticide in nearly recommended concentrations (2 %). Comparison of LC50 confidence ‎intervals (95%) showed that susceptibility of the pest was not statistically different in treated aphids ‎on white and red cultivars. This showed that the plant cultivar did not impose significant impact on ‎aphid mortality. Given that the chemical content of sap and nutritional quality of two cultivars are ‎varying in different cultivars, these did not affect adult aphids’ mortality encountering BotanAphid. ‎Using LC25 value in each cultivar for analyzing life table parameters demonstrated the its negative ‎influence on all parameters compared to control insects in both cultivars. Besides these results, due ‎to botanical nature of BotanAphid and its low risk for non-target organisms especially human, this ‎pesticide application is recommendable on fresh-consuming vegetables such as different cabbage ‎cultivars.‎

Septoriosis is one of the important diseases of wheat in the world and Iran too. Considering the high cultivated area of wheat and the economic importance of this crop in Ilam province, the present study done with the aim of investigating the combined effects of Trichoderma fungus and epiphyte bacteria to reduce the damage caused by Septoria tritici on two Mehregan and Tajan varieties of wheat in vitro and under greenhouse conditions.

Materials and Methodes:

The inhibition ability of 12 isolates of Trichoderma isolates was evaluated in vitro by duel culture and production of volatile metabolites. In addition, the inhibition effect of 207 epiphyte bacteria strains obtained from wheat leaves was examined with three tests including; antibiotic, volatile metabolite and siderophore production.Preparation of Trichoderma inoculum was done according to the method of Stocco et al. (2016). Fungal suspension was prepared and the concentration of spores in the resulting suspension was determined using a hemocytometer slide, 1 x 108 conidiaper ml for each Trichoderma isolate. Then, ten milliliters of the suspension prepared from each isolate was mixed with 90 milliliters of 0.25% agar water.The seeds of Tajen and Mehrgan cultivars were added to the above suspension. The seeds coated with Trichoderma were dried in the dark at room temperature and after 24 hours, they were planted in 2 kg sterile pots. 5-7 seeds were used in each pot.In order to prepare the inoculum of epiphyte bacteria, 24-hour culture of bacteria on NA culture medium was used and a suspension of bacteria was prepared in sterile distilled water and optical absorption of 0.1 at wavelength of 600 nm was done using a spectrophotometer. Inoculation of the bacterial inoculum was done using a manual spore sprayer and 24 hours before the inoculation of the pathogenic fungus.After preparing the pathogenic fungus spore suspension, two-leaf seedlings (14 days old) were inoculated. The pots were covered with plastic bags for 72 hours and kept in the dark for 24 hours. During this period, the environment of the pots was kept moist by using a hand sprinkler. After the mentioned period, the plastic bags were removed from the surface of the pots and kept for another 21 days at a temperature of 23 degrees Celsius and in a humidity condition higher than 70%.Under greenhouse conditions, growth characteristics of wheat including; fresh and dry weight root (g), fresh and dry weight shoot (g) and plant height (cm) were evaluated in the presence of pathogenic fungus and biocontrol agents. The data analysis ANOVA (Analysis of variance) was conducted using of the SAS software version 9.6 as a factorial test in completely randomized design (CRD) with three replicates.

The results showed two fungal isolates T6 (T. Longibrachiatum) and T1 (T. harzianum) and three bacterial strains C1d (S. saprophyticus), Dr1b (P. agglomerans), B2b (E. cloacae) had the ability to inhibit of the growth of S. tritici in vitro, which the mentioned isolates were selected for the greenhouse test.The greenhouse results showed the strong effect of combined treatment of fungus-bacterial T6+C1d (T. longibrachiatum+S saprophyticus) in increasing all functional traits of wheat and T1+B2b treatment (T. harzianum+E. cloacae ) had the lowest effect on plant functional traits.The t-test results between Mehregan and Tajan cultivars showed the highest fresh and dry weight root, fresh and dry weight shoot and plant height were obtained for Tajen variety. Generally the results showed the positive effect of various fungal and bacterial isolates in reducing the pathogenicity and damage caused by the septoriosis disease.

The results of antagonistic ability of fungal isolates and epiphytic bacteria in vitro and greenhouse showed there is a good correlation between two conditions. So the results showed a positive effect of the fungal and bacteria isolates in reducing Septoria damages. Finally, isolates T6 (T. Longibrachiatum) and T1 (T. harzianum) and three bacterial strains C1d (S. saprophyticus), Dr1b (P. agglomerans), B2b (E. cloacae) were intreroduced as the strongest antagonistic agents in control of this fungus. The possible main effects of T. longibrachiatum is related to induced resistance in the plant and the produce of volatile metabolites and antibiotics, and in bacteria are related to produce of volatile metebolites, antibiotics and siderophore.

Pistachio psylla Agonoscena pistaciae Burckhardt & Lauterer is Iran's most important pest of pistachio trees. Due to the negative effects of excessive use of chemical insecticides, alternative strategies are necessary to control this pest. In this research, some resistance-inducing compounds, including chitosan, gamma-aminobutyric acid (GABA), and potassium silicate in pistachio trees, were studied on the percentage of population growth and detoxifying enzymes of this psyllid. Based on the results obtained, 7 days after spraying, the lowest and highest population growth of pistachio psyllid nymphs were observed in chitosan treatment and control, respectively. Also, the average growth percentage of the nymph population after 14 days did not show a significant difference among GABA, chitosan and potassium silicate, but it significantly decreased on these treatments compared to the control. In this study, the highest and lowest activity levels of esterase enzyme in psyllid nymphs were achieved in the control and chitosan treatments, respectively.On the other hand, the highest level of glutathione S-transferase activity was obtained in chitosan and potassium silicate treatments, and the lowest one was found in the control. The study results revealed that the different inducers could reduce the A. pistaciae population growth by generating physiological changes in the host plant and, subsequently the pest insect. Therefore, these compounds could be considered in the integrated management of this pest.

Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is one of the most effective predators in controlling various pest species in greenhouses. Cold storage is a common method for preserving natural enemies in insectariums long-term. This study used different food materials (wheat bran, pumice, hollow oat, corn pollen sheath, date pollen sheath, sawdust, and rubber) to store N. californicus to examine its survival and predation. In each container, 20 female mated predatory mites (3-4 days old) were placed and kept for 1, 5, 10, and 15 days at four different temperatures (0, 5, 10, and 15°C with 60% relative humidity). The percentage of survival and lifespan were determined and the efficiency of the stored predatory mites (fecundity rate and predatory rate) was also compared with the main colony individuals (as a control treatment). The survival rate in the materials, including corn and date pollen sheaths, was higher than the other materials. The survival rate of individuals 1, 10, 15, and 20 days after storing predatory mites in corn pollen sheaths was 81, 70.62, 54.87, and 37.75%, respectively. Five or 10 °C was the best temperature for storing predatory mites. The efficiency of the predatory mite kept with corn pollen sheaths at 5°C was not significantly different from the control. Therefore, storing and transporting N. californicus to the market with corn and date pollen sheaths for a maximum period of 10 days at 5 °C is recommended.

Potato (Solanum tuberosum L.) is a vital crop of great global importance. Common scab is one of the most destructive diseases affecting the quality and yield of potatoes. Effective disease management strategies for potatoes include crop management, crop rotation, seed certification, natural and chemical pesticides, disease prediction models, germplasm screening, and the development of resistant varieties. Sulfur fertilization improves potato resistance to common scab, possibly by decreasing the soil pH. Applying sulfur and Thiobacillus bacteria in alkaline and calcareous soils has improved nutrient solubility and reduced damage caused by common potato scab disease.

An experiment was conducted to investigate the effects of sulfur and Thiobacillus on tuber yield and the common scab disease index under field conditions. The farm had a history of natural and uniform infection with potato scab disease. The treatments included: 1- control (no use of Thiobacillus and sulfur), 2- application of Thiobacillus, 3- granular sulfur, 4- liquid sulfur, 5- Thiobacillus+granular sulfur, and 6- Thiobacillus+granular sulfur+liquid sulfur. The experiment was conducted using a randomized complete block design with four replications.

Analysis of variance indicated that the application of sulfur and Thiobacillus significantly affected tuber yield and the common scab disease index. However, there was no significant difference in the mean number of plants among the experimental treatments. Regarding the mean number of tubers, the count increased from 104 in the control group to 135.75 in the treatment with granular sulfur+liquid sulfur+Thiobacillus treatment. This combination significantly increased tuber weight by approximately 4 kg compared to the control. Regarding the average number of tubers per plant, the treatments of granular sulfur+liquid sulfur+Thiobacillus and granular sulfur+Thiobacillus showed a significant difference compared to the control, increasing the number of tubers by 13.06% and 8.10%, respectively. Both treatments also significantly increased the mean tuber weight per plant by 19.69% and 16.21%, respectively, compared to the control. The percentage and disease index varied under the influence of the experimental treatments. The lowest disease index on potato tubers was associated with the simultaneous application of granular sulfur+liquid sulfur+Thiobacillus, followed by liquid sulfur alone. The decrease in the disease index on potato tubers can be attributed to the reduction in pH resulting from sulfur application. This study demonstrated that the simultaneous application of sulfur and Thiobacillus can effectively lower soil pH.

In conclusion, the application of sulfur and Thiobacillus bacteria enhances the yield and quality of potato tubers by improving soil conditions and plant nutrition. The forms of sulfur used played a crucial role in disease management; liquid sulfur, either alone or in combination with other treatments, significantly reduced disease severity. Liquid sulfur contains sulfate forms and has a pH of approximately one. Additionally, its liquid form allows for better penetration into soil pores and does not require soil microbial processes to alter pH. In contrast, powdered and granular forms of sulfur must be converted to sulfate forms by sulfur-oxidizing bacteria such as Thiobacillus. This conversion process is lengthy and gradually reduces soil pH over time. In the present study, various forms of sulfur, especially the liquid form, effectively reduced soil pH, although it did not lower it enough to classify the soil as acidic. It is important to note that the study's soil was calcareous, which has buffering properties that prevent drastic pH changes. Moreover, the effect of sulfur is not solely dependent on pH; even low amounts or specific forms of sulfur can significantly reduce common potato scabs without altering soil pH. This phenomenon may be due to the conversion of sulfur into toxic forms for microbes, such as hydrogen sulfide (H2S).