Soil Drench Treatment Research Articles

Strigolactones GR-24 and Nijmegen Applications Result in Reduced Susceptibility of Tobacco and Grapevine Plantlets to Botrytis cinerea Infection.

Priming agents are plant defence-inducing compounds which can prompt a state of protection but may also aid in plant growth and interactions with beneficial microbes. The synthetic strigolactones (±)-GR24 and Nijmegen-1 were evaluated as potential priming agents for induced resistance against Botrytis cinerea in tobacco and grapevine plants. The growth and stress response profiles of B. cinerea to strigolactones were also investigated. Soil drench treatment with strigolactones induced resistance in greenhouse-grown tobacco plants and restricted lesion development. The mode of action appeared to function by priming redox-associated compounds to produce an anti-oxidant protective response for limiting the infection. The results obtained in the in vitro assays mirrored that of the greenhouse-grown plants. Exposure of B. cinerea to the strigolactones resulted in increased hyphal branching, with (±)-GR24 stimulating a stronger effect than Nijmegen-1 by affecting colony diameter and radial growth. An oxidative stress response was observed, with B. cinerea exhibiting increased ROS and SOD levels when grown with strigolactones. This study identified the application of strigolactones as potential priming agents to induce disease resistance in both tobacco and grapevine plants. In addition, strigolactones may alter the ROS homeostasis of B. cinerea, resulting in both morphological and physiological changes, thereby reducing virulence.

Effect of Cyanobacterial Combinations on Peanut Yield

The characteristics of two cyanobacterial strains, Anabaena oryzae and Nostoc muscorum, were studied in order to use them as biofertilizers in a field experiment conducted in the two winter seasons of 2021 and 2022 at the Ismailia Agricultural Research Center Station to study the effect of both strains on peanut plant in sandy soil. Cyanobacterial strains were used individually by coating seed, soil drench, and foliar applications, as well as mixed applications of two strains in various ways. Both cyanobacterial strains morphological examination revealed that they both have heterocysts, nitrogen, phosphorus, and potassium in their culture filtrate, and they were able to produce chlorophyll a and phosphatase enzymes. The results of an agricultural experiment showed that using Nostoc muscorum and Anabaena oryzae separately had a positive effect on peanut plants in a variety of applications, but combining both of these applications with 75% nitrogen increased the growth traits, nutrient contents, and soil biological activities in both peanut plants and their rhizosphere soil. The soil drench treatment with A. oryzae and Nostoc muscorum plus 75% nitrogen produced the highest growth results and peanut yields in a single application. The A. oryzae Soil Drench Application (S) + N. muscorum Foliar Application (F) with 75% N reported the best outcomes in mixed treatments. However, compared to single applications, all blended applications displayed better growth and yield characteristics. The results of the study suggest that employing cyanobacteria in a mixed application will enhance its advantages over a single use.

Root-knot nematode pathogen suppression in eggplant using antagonistic fungi

BackgroundMeloidogyne incognita (Kofoid and White) Chitwood is a major pest of eggplant in Pakistan. The second-stage juveniles (J2s) feed on the roots of eggplant. Damaged roots swell and the plant exhibits stunted growth. Mostly farmers rely on the use of broad-spectrum nematicides. However, due to hazardous effects on the environment and non-target species, its application is greatly criticized. Fungal biocontrol agents have been long used for curtailing root-knot nematode infections. The present study was conducted to determine the virulence of four fungal biocontrol agents against M. incognita under laboratory and greenhouse conditions.ResultsThe in vitro results revealed that Trichoderma harzianum significantly caused 77.60% egg inhibition, followed by Pochonia chlamydosporium (53.0%) at 1:1 concentration after 72 h. The maximum J2s mortality was achieved by T. harzianum (82.0%), followed by P. chlamydosporium (70.20%) at 1:1 concentration after 72 h. The in-planta examination carried out at a greenhouse demonstrated that the soil drench treatment of fungal biocontrol agents significantly suppressed M. incognita parameters and upraised the eggplant growth. The mean least number of galls (22.25) was in T. harzianum treated plants, while the control had (206.8) galls. Likewise, T. harzianum curtailed the least egg masses to 35.75 and swollen females to 21.12 than control negative (224.13 egg masses and 182.75 swollen females).ConclusionT. harzianum was the best agent to control M. incognita (J2s) effectively, followed by P. chlamydosporum. T. harzianum may be a contribution to the biological control of M. incognita in Pakistan.

Soil drenching and foliar spray with bioagents for reducing wheat leaf diseases under natural field conditions

Foliar diseases, like powdery mildew, septoria leaf blotch (SLB) and stem rust, affect wheat plants causing severe yield losses. Biofertilizers Pseudomonas fluorescens Migula (NRC2041) and Bacillus subtilis Ehrenberg (NRC313) or the arbuscular mycorrhizal fungi Glomus mosseae Tul. & C. Tul. (NRC212A) and G. fasciculatum Tul. & C. Tul. (NRC212B) were used for soil treatment followed by foliar spray with Trichoderma harzianum or P. fluorescens to manage severity of wheat foliar diseases under field conditions for two successive growing seasons. Under field conditions, at all soil drench and foliar application treatments, Sids 14 was the most sensitive cultivar for high disease severity followed by Misr 2 and Giza 168. Also, the obtained results showed that the most effective treatments were soil drench with mycorrhizae followed by foliar spray with either T. harzianum or P. fluorescens. Meanwhile, the fungicide Amistar showed a superior reduction in disease severity compared to other applied treatments. In addition, the increased yield was correlated to the decreased severity of the recorded diseases. The present study suggests using bioagents for reducing the severity of wheat leaf diseases and increasing the grain yield under field conditions.

Effects of an Ascophyllum nodosum seaweed extract application dose and method on growth, fruit yield, quality, and water productivity of tomato under water-deficit stress

• We evaluated the effect of Ascophyllum nodosum seaweed extract (ASE) formulation on tomato under drought stress. • Tomato yielded more when ASE was applied at 5 mL L –1 as a soil drench than as a foliar spray. • Water productivity was maximized at 5 mL L –1 for all soil moisture levels. • Soil or foliar application of ASE at 5 mL L −1 could be regarded as an optimum dose. • ASE at 5 mL L −1 as a soil drench is more effective than its application as a foliar spray. The scarcity of irrigation water is a major threat restricting growth and productivity of almost all agronomic and horticultural crops. The tomato ( Solanum lycopersicum L.) is no exception. Seaweed extracts are widely used as biostimulants for the improvement of plant growth and development. Two independent pot experiments were conducted to find out the best soil drench or foliar spray dose of a commercial Ascophyllum nodosum seaweed extract (ASE) formulation (Amino Seaweed, SV Group, Bangkok, Thailand) on growth, physiological and biochemical parameters, fruit yield, quality, and water productivity of tomato under water-deficit stress. The commercial ASE formulation was applied in five doses (0, 2.5, 5, 10, and 20 mL L −1 ) as a soil drench (Experiment 1) or as a foliar spray (Experiment 2) under three soil moisture levels (50, 75, and 100% field capacity [FC]). Severe soil moisture deficit of 50% FC caused a 67 and 52% reduction in fruit yield, 11 and 11% reduction in fruit length, 25 and 29% decrease in leaf relative water content, while total soluble solids content was increased by 38 and 49% compared with 100% FC in Experiments 1 and 2, respectively. Soil drench or foliar spray of the commercial ASE formulation at 5 mL L −1 was effective at all soil moisture levels. Soil drench of the commercial ASE formulation at 5 mL L −1 resulted in 225% higher fruit yield in comparison to the untreated plants at 50% FC, whereas its application as a foliar spray resulted in 271% higher fruit yield in comparison to the untreated plants subjected to severe water-deficit stress (50% FC). Water productivity was found lower for the untreated plants regardless of soil moisture levels in both application methods; however, it was maximized at 5 mL L –1 for all soil moisture levels. The beneficial effects of 5 mL L –1 ASE formulation dose was also evident in physiological/biochemical traits and fruit quality of tomato regardless of application methods. Tomato yielded more when the commercial ASE formulation was applied at 5 mL L –1 as a soil drench (523.3 g plant –1 fruit yield) rather than as a foliar spray treatment (397.1 g plant –1 fruit yield). The results indicate that (i) 5 mL L −1 could be regarded as an optimum dose of the commercial ASE formulation for tomato applied either as a soil drench or foliar spray and (ii) exogenous application of the commercial ASE formulation at 5 mL L −1 as a soil drench treatment is more efficient, especially in fruit yield improvement, compared with its application as a foliar spray and, therefore, this technique holds promise for tomato cultivation under moderate water-deficit stress.

Management of Potato Bacterial Wilt Disease Using Abiotic Treatments

Bacterial wilt disease caused by Ralstonia solanacearum (Smith) Yabuuchi is one of the most important bacterial diseases in the world. This study aimed to test some chemical compounds such as bactericides that were applied to control bacterial wilt disease under artificial inoculation conditions and their effects on the yield of potatoes under greenhouse conditions.In vitro, tested chemical compounds (Cefalexin, Gentamycin, and Copper sulphate) inhibit the growth of R. solanacerum compared with control treatment. Copper sulphate was the most effective where the Inhibition zone diameter was 6.0 to7.4mm compared with cefalexin and gentamycin, 3.6 to 5.8mm respectively, but cefalexin was moderately effective 4.2 to 5.8mm and gentamycin was less effective 3.6 to 5.8mm against the pathogen. Inhibition zone diameter was increased with increasing concentrations of tested chemical compounds. Greenhouse experiments showed that the chemical compounds used reduced the severity of potato bacterial wilt disease and increased potato yield compared with control treatment. When using Cefalexin, the mean of wilted shoots was 20.5 and the severity of disease 16.3, while when using Gentamycin as an Abiotic, the mean of wilted shoots was 22.8 and severity of disease 17.6 which was the most effective compared with Copper sulphate treatment were wilted shoot was 31.8 and severity of disease 29.6. The application of tested chemical compounds as soil drench treatment led to a percentage of infection which ranged from16.4 to19.0 more effective than tuber treatment where the percentage of infection ranged from 18.4 to 20.1.

Sodium Selenate: An Environmental-Friendly Means to Control Tomato Bacterial Speck Disease

Selenium (Se) is a micronutrient which plays a beneficial role in plants. Its adsorption at low doses can stimulate plant growth and enhance the plant’s capacity to respond to abiotic stresses, such as salinity, drought, cold and hot temperature, probably due to its antioxidant properties. Here, the effect of selenium supplied in soil-drench treatments as sodium selenate (Na2SeO4) at the dose of 4 mg L−1 (21.17 µM) per plant was studied on tomato (Solanum lycopersicum L.; cv. Rio Grande) against Pseudomonas syringae pv. tomato (Pst), the causal agent of tomato bacterial speck. Sodium selenate treated tomato plants challenged with Pst showed a reduction in disease severity expressed as percentage of diseased area and number of lesions per leaf. Furthermore, Pst bacterial cells were unable to proliferate in treated tomato plants. The effect of sodium selenate against Pst was also assessed in vitro, demonstrating that the growth of the bacterium was affected in a dose-dependent manner (EC50 = 42 ppm). It is notable that in tomato plants treated with sodium selenate at the above reported dose, a marked callose deposition was observed as well as the expression of the salicylic-acid-responsive tomato ‘pathogenesis-related protein 1b1’ (PR1b1) but not of the jasmonate-mediated ‘proteinase inhibitor 2’ (PIN2) genes. Induced defence responses and direct antimicrobial activity protect treated tomato plants against Pst attacks, suggesting the potential of sodium selanate as an environmentally friendly and effective bacterial control means. Moreover, the increased Se content in treated tomatoes offers an effective approach to reduce Se deficiency problems in human diets.

Dissipation and transformation of the diamide insecticide cyantraniliprole in ornamental snapdragon (Antirrhinum majus)

Dissipation and transformation of cyantraniliprole, a new diamide class of insecticides, were investigated under greenhouse conditions, using snapdragon (Antirrhinum majus) as the model plant. Dissipation of cyantraniliprole in treated leaves was found to be dependent upon application methods (foliar spray versus soil drench) and doses (high versus low dose), with the parent insecticide being the major residue at various sampling points. A high-dose foliar application resulted in pesticide residue of 6.7–23.8 μg/g foliar fresh weight over 8 weeks of treatments, while in soil drench treatment the residue varied from 0.8 to 1.4 μg/g. However, the residue contents were similar between the two application methods at a low application dose. The transformation pathways of cyantraniliprole were primarily intramolecular rearrangements, with IN-J9Z38 being the major metabolite across treatments. Several other metabolites were also identified, some of which were unique to the application methods. Out of total 26 metabolites tentatively identified in this study, 10 metabolites were unique to foliar application, while six metabolites were unique to soil drench. In addition to plant-mediated biotransformation, photodegradation of the parent compound was identified as a potential mechanism in foliar application.

Effect of Silicic Acid Formulation (Silicon 0.8%) on Two Major Insect Pests of Tomato under Greenhouse Conditions

Tomato (Solanum lycopersicum L.) is an important vegetable crop in Iraq. This horticultural crop is attacked by several insect pest species. Among them, the whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and the tomato leaf miner Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) are the major threat of greenhouse tomatoes in Basrah province in southern Iraq. The management of these pests is heavily based on application of chemical pesticides. Vast application of pesticides caused harmful damage to the environment, human health and may increasing the risk of pest resistance on insect populations. One of the promising strategies which are compatible with organic farming is application of silicon for enhancing plant vigor and resistance to pest damage on various agricultural crops. Due to these facts, the experiments have been carried out at Basrah University to evaluate the effects of silicon (Si) fertilization on tomato plants for reducing damage of these two major pests. Treatments comprised two type of Si applications (Soil drench treatment and foliar spraying) with four Si concentrations (0, 0.5, 1 and 2%) of AB Yellow ® silicic acid formulation. The population density of B. tabaci and T. absoluta were studied weekly during the growth season. The results clearly demonstrated that Silicon applications significantly decreased the population of immature of both whiteflies and tomato leaf miner on tomato crop in the greenhouse; Si-Foliar spraying was more effective in reducing the population density of these key pests compared to Si- soil drench application.

Natural uptake of anti-oomycetes Trichoderma produced secondary metabolites from pearl millet seedlings – A new mechanism of biological control of downy mildew disease

The present study aims to analyze the pearl millet (PM) seedlings ability to uptake anti-oomycetes secondary metabolites (SMs) produced by Trichoderma and their subsequent involvement in downy mildew (DM) disease suppression. SMs from potent Trichoderma spp. were extracted and studied for their anti-mildew and zoosporangiosporicidal properties in PM infected with Sclerospora graminicola. Varying degree of inhibition was recorded against sporangiophore development on the infected abaxial leaf surface and zoosporangiosporicidal activity by SMs. T. asperellum (DL-81) recorded higher anti-mildew activity and 83% of zoosporangiosporicidal activity. Xylem exudates collected from decapitated PM seedlings pretreated with SMs as soil drench also recorded similar activities. Similarly, xylem exudates collected from T. atroviride (MH-50), T. asperellum (DL-81), T. virens (MP-60) and treated seedlings recorded 42%, 40% and 36% of zoosporangiospricidal activity, respectively. Under greenhouse conditions, seed, soil drench and foliar spray treatment with crude SMs showed the reduction in diseases incidence. Least disease incidence of 14.6% was recorded with T. asperellum (DL-81)-SMs soil drench followed by T. virens (MP-60)-SMs soil drench treatment (15.5%). Supporting to our laboratory and greenhouse studies, UPLC-MS/MS analysis of SMs from culture filtrates and xylem exudates of selected Trichoderma revealed the presence of several compounds, which were previously reported as antimicrobial in nature. A novel biocontrol mechanism through which the PM can uptake some anti-oomycetes compounds from rhizosphere and suppress the DM severity is discussed in this study.

Quantitive changes of enzyme activity in wheat induced by Streptomyces sp. Strain HU2014

Biocontrol microorganism have a diverse range of activities and they have been focused on potential biocontrol agents in agriculture. They can induce plant defensed response and enhance plant disease resistance. Streptomyces sp. produce active metabolites that can inhibit the growth of phytopathogens. Induced resistance is usually indicated by the activity of Peroxidase (POD), Polyphenoloxidase (PPO), and Phenylalanine ammonia-lyase (PAL) or other defense enzymes. The related reports mainly focused on disease control or promoting growth of cash crops or vegetables, but less on wheat presently. Moreover, the information about the concentration of fermentation broth and mycelia of Streptomyces affected the quantitative changes of defensed enzyme activities is limited. In this study, we started from isolating a Streptomyces strain, named S. sp. strain HU2014, and demonstrated (POD), (PPO), (PAL) enzymes in different concentration of the mycelia (M) and extracellular filtrate (EF) of the strain with the application of soil drench treatment. The enzyme activities were determined by visible spectrophotometry. The results showed that the activities of POD and PAL at the concentration of 103-fold dilution of the EF increased significantly to some extent in comparison with untreated control, by 173.86 % (P < 0.05) and 71.92 % (P < 0.05), respectively. In the range of different concentration of the M, POD and PPO activities were enhanced with the increasing of dilution ratio, but the difference was not significant. It is expected to be an excellent resource for the development of new biological preparations.

Impact of Imidacloprid Soil Drenching on Survival, Longevity, and Reproduction of the Zoophytophagous Predator Podisus maculiventris (Hemiptera: Pentatomidae: Asopinae)

Systemic insecticides when applied as seed treatments or soil drenches are often more toxicologically selective for natural enemies than target pests. This may not be the case, however, for omnivorous predators, which are at risk of extended exposure to systemically applied pesticides through ingestion while feeding on treated plants for nutrients or water. Such exposure may kill or have sublethal consequences for these natural enemies, compromising their role as biocontrol agents of agricultural pest species. The spined soldier bug, Podisus maculiventris (Say) (Hemiptera: Pentatomidae: Asopinae), is an important zoophytophagous biocontrol agent (i.e., able to substitute zoophagy by phytophagy for survival) that may be exposed to systemic insecticides in many agricultural systems. We, therefore, examined effects on P. maculiventris following exposure to cabbage plants subject to soil-drench treatments with imidacloprid, a systemic neonicotinoid insecticide. Predator survival, development, body weight, and reproduction were recorded. Imidacloprid significantly affected nymph survival and adult emergence, but not duration of the nymphal period or adult body weight. At one-twentieth the recommended field rate for whitefly and aphid management, imidacloprid treatments reduced longevity, fecundity, and fertility of female predators. These findings demonstrate that soil treatments with systemic insecticide can negatively impact zoophytophagous natural enemies.

Interaction between Biotic and Abiotic Agents to Control of Potato Bacterial Wilt Disease

Bacterial wilt disease caused by Ralstonia solanacearum (Smith) Yabuuchi, et al. (1995) is one of the most important bacterial diseases over the world. This study was planned to control the disease using interaction between biotic and abiotic agents, under greenhouse experiment. In vitro, tested bactericides (gentamycin, ceflaxcin and copper sulphate) were decreased growth of R. solanacerum compared with control treatment. Copper sulphate was the most effective compared with ceflaxcin and gentamycin, but ceflaxcin was moderately effective and gentamycin was less effective against the pathogen. Inhibition zone diameter was increased with increasing concentrations of tested bactericides. Application of different bio-agent isolates (Pseudomonas fluorescence, Bacillus subtitlis, Bacillus megaterium and Serratia mareacescne) were reduced the growth of the pathogen compared with control treatment. B. subtilis isolate was the most effective, but isolates of Ps. fluorescens and B. megaterium were moderately effective and S. marescences isolate was less effective against the pathogen. Greenhouse experiments, disease severity were decreased and potato yield were increased with interaction between bio-agents (Bacillus subtilis, and Pseudomonas fluorescence isolates) and bactericides (gentamycin and ceflaxcin), or bio-agents and resistance inducers factors (salicylic acid and jasmonic acid) or bactericides and resistance inducers factors compared with control treatment. However, interaction between bio-agents as tuber treatment and bactericides as soil drench treatment or interactions between bactericides as soil drench treatment and resistance inducers as foliar treatment were the most effective against the disease and the yield. But, interactions between bio-agents as soil drench treatment and resistance inducers as foliar treatment were moderately effective to control the disease and the yield. But, interaction between ceflaxcin as bactericide and Ps. fluorescens isolate as bio-agent or salicylic acid as resistance inducer were the most effective on disease severity and the yield compared with other treatments, but interaction between B. subtilis isolate as bio-agent and jasmonic acid as resistance inducer were less effective compared with other treatment.

Management of Lettuce Bacterial Soft Rot Disease Using Biotic and Abiotic Agents under Field Conditions

The current investigation was planned to apply some biotic and abiotic treatments singlely and/or combined to control bacterial soft rot diseases of lettuce under field conditions in Qaha region, Qalyubia Governorate, Egypt. The application of resistance inducers (jasmonic acid and salicylic acid), antibiotics (norfloxacin and tetracycline) and bio-agents (isolates of B. subtilis and Ps. fluorescens) significantly reduced the disease severity as a single treatment compared to the control treatment. Obtained results indicated that resistance inducers appeared to be most effective against bacterial soft rot disease of lettuce compared with other treatments, while antibiotics were less effective at controlling the disease. However, the interaction between bio-agents as soil drench treatment, antibiotics, or resistance inducers as foliar treatment significantly reduced the severity of lettuce bacterial soft rot disease compared with the control treatment. Furthermore, the interaction between disease severity was more reducted with interaction treatments between Ps. fluorescens isolate rather than interact with treatments between B. subtilis isolate and other treatments. However, the interaction between the isolate of Ps. fluorescens as bio-agent treatment or norfloxacin as antibiotic or salicylic acid as a plant resistance inducer, were the most effective methods to control the disease compared with other treatments. Meanwhile, the interaction between resistance inducers and antibiotics as foliar treatments were significantly reduced from the severity of lettuce bacterial soft rot disease compared with the control treatment. Disease severity was more reduced with the application of interaction between norfloxacin and resistance inducers than the interaction between tetracycline and resistance inducers. Meanwhile, the severity of the disease decreased more with the application of interaction between salicylic acid and antibiotics than the interaction between jasmonic acid and antibiotics. Generally, all combination treatments were more efficient than single treatments alone to significantly manage the spread and the infection of the disease compared to the untreated control.

Evaluating different approaches in the application of phosphonates for the control of apple root diseases

Phosphonate fungicides are registered on various tree crops in South Africa for the management of oomycete root rot pathogens, but not on apple trees. The study investigated several phosphonate treatments previously evaluated independently by technical advisors in South Africa. A replicated orchard trial was conducted in non-bearing asymptomatic orchards; tree roots were infected by oomycetes but foliar symptoms were absent. Phosphonate foliar-, trunk paint- and soil drench treatments were equally effective, and consistently resulted in a significant reduction in Phytophthora cactorum and Pythium irregulare root DNA quantities relative to the non-treated control. The latter was not always true for phosphonate trunk spray treatments. Trunk paint applications applied at an annual dosage of 40 g phosphorous acid/tree yielded significantly higher root phosphite (breakdown product of phosphonates) concentrations than the soil drench and trunk spray applications; the latter were applied at lower annual dosages of 7.5 g a.i./tree and 20 g a.i./tree, respectively. Foliar sprays applied at a low annual dosage (1.8 to 3.0 g a.i./tree) often outperformed the soil drench and trunk spray treatments in root phosphite concentrations. No clear association was evident between root phosphite concentrations and pathogen suppression. Root phosphite typically peaked at 8-weeks post-treatment for winter applications, and between 2- to 4-weeks for summer applications. A rapid decline in root phosphite was evident over the 12-week summer period, but not for winter applications. Monitoring root growth in the untreated control plots showed that root growth was continuous but that it peaked in summer, with reduced growth in winter.

Impact of Soil Drench and Foliar Spray of 24-Epibrassinolide on the Growth, Yield, and Quality of Field-Grown Moringa oleifera in Southwest China

The effects of soil drench (SD) (0.4 and 0.8 mg plant−1) and foliar spray (FS) (0.02, 0.04, and 0.08 ppm) of 24-epibrassinolide on the growth, yield, and quality of field-grown Moringa oleifera were evaluated. The results showed that all of the SD and FS treatments enhanced the net photosynthetic rate, stomatal conductance, transpiration rate, total chlorophyll content, and nitrate reductase activity in Moringa leaves. Both SD and FS promoted vegetative and reproductive growth of Moringa, but FS at an excessive concentration could suppress reproductive growth. Within a certain concentration range, the effect of FS on the reproductive growth was superior to that of SD, whereas the effect of SD on vegetative growth was better than that of FS. All of the 24-epibrassinolide treatments except for FS 0.08 ppm increased the number of seeds per fruit pod, the yield of fruit pods per tree, and the yield of seeds per tree, but the yield of the plants treated with SD was lower compared with FS. The FS 0.04 ppm treatment significantly increased the contents of oleic acid and eicosenoic acid and reduced the content of stearic acid in the seeds. All of the SD and FS treatments increased crude protein content in the leaf powder and seeds of Moringa as well as vitamin C in the leaves. Our results showed that the optimal concentration of 24-epibrassinolide for FS was 0.04 ppm, and the optimal concentration for SD was inferred to be higher than 0.8 mg plant−1.

Application of endophytic bacteria for the biocontrol of Rhizoctonia solani (Cantharellales: ceratobasidiaceae) damping-off disease in cotton seedlings

ABSTRACTThe antifungal potentialities of three endophytic bacterial strains, Stenotrophomonas maltophila H8 (Xanthomonadales: Xanthomonadaceae), Pseudomonas aeruginosa H40 (Pseudomonadales: Pseudomonadaceae) and Bacillus subtilis H18 (Bacillales: Bacillaceae) were evaluated against the phytopathogenic fungus Rhizoctonia solani in cotton seedlings under greenhouse conditions. The bacterial strains were applied as a soil drench or talc-based bioformulation in R. solani-infested soil and non-infested soil. Results indicated that the soil drench treatment was more efficient than talc-based bioformulation. A significant increase of seed emergence and seedling survival with a clear reduction of disease severity was achieved with the endophytic bacterial treatments. At the same time, the fresh weight, dry weight, shoot length and root length of the treated plants were markedly enhanced. Moreover, there was an apparent induction of the antioxidant enzymes (peroxidase, polyphenol oxidase and catalase) of the treated seedlings. Gas chromatography–mass spectrometry revealed the presence of various bioactive compounds in the bacterial supernatant. The antagonistic activity of the bacterial strains against R. solani was attributed to their capability to produce a broad spectrum of antifungal compounds in addition to bioactive molecules that can trigger the systemic resistance in the infected seedlings.

Evaluation of bacterial biological control agents for control of root-knot nematode disease on tomato

Among 19 bacterial strains isolated in Yunnan from rhizosphere soils and plant tissues, Bacillus methylotrophicus strain R2-2 and Lysobacter antibioticus strain 13-6 exhibited the highest antagonistic activity against the tomato root-knot nematode Meloidogyne incognita in plate and greenhouse pot experiments. The two strains, when applied as soil drenches or seed treatments in greenhouse experiments, reduced root-knot severity and incidence on tomato compared to no-bacteria controls. In tomato field trials conducted in separate years, soil drench treatment with either strain reduced root-knot disease levels and increased yields compared to the control. Levels of disease control and yield enhancement provided by the strains were higher than those using the chemicals abamectin and carbofuran. This is the first report of B. methylotrophicus being used as a biocontrol agent against a plant parasitic nematode and the first demonstration that B. methylotrophicus and L. antibioticus can suppress disease caused by root-knot nematodes in the field.

Evaluation of some Commercial Bio-Products on Damping-Off and the Yield of Bean Crop

Damping-off and root-rot diseases have significant impact on bean production and geographically wide spread and when being severe can completely destroy the legume crop. In this study, certain commercial products i.e., Bio-Cure B, Bio-Cure F, Bio-Healthy, Rhizo-N, Symbion-N, Symbion-NG and Symbion-NR, were evaluated for their efficacy to control damping-off disease and their effect on the yield of bean, under naturally infested field conditions during growingseasons of 2012-2015. Three pathogenic fungi i.e., Rhizoctonia solani, Fusarium solani and Pythium ultimum, were isolated from diseased bean seedlings showing damping-off symptoms collected from Qaha region, Qaluibiya Governorate. Disease incidence was decreased with application of commercial bio-products as seed or soil drench treatments. Application of the tested bio-products as soil drench treatment was more effective against damping-off disease andincreasing nodule production and the yield than their application as seed treatment. Rhizo-N was the most effective to control the disease, but Bio-Health was the lowest effective and Bio-Cure B, Bio-Cure F, Symbion-N, Symbion-NG and Symbion-NR recorded moderate effects. Meantime, nodule production and yield of bean were increased with application of the tested bio-products compared to the check treatment. Nitrogen fixation bacterial products i.e., Symbion-N,Symbion-NG and Symbion-NR, were the most effective to increase the yield and nodule formation compared to the tested bio-control products i.e., Bio-Cure B, Bio-Cure F, Bio-Health and Rhizo-N, which gave moderate effects. Application of Bio-Cure F or Rhizo-N or Symbion-NR for three times as soil drench treatment were more effective to control the disease and to increase the yield and nodule formation than when applied one time, during 2015 growing season.

Effect of bio-agents on pathogenic fungi associated with roots of some deciduous fruit transplants and growth parameters in New Valley Governorate, Egypt

Abstract Root rot and wilt disease complex was detected in several fig (Ficus carica L.), grapevine (Vitis vinifera L.), and pomegranate (Punica granatum L.) transplants in nurseries and new orchards of the El-Kharga, Baris, Balate, El-Dakhla, and El-Farafrah districts, of the New Valley governorate, Egypt. The percentage of root rot/wilt incidence and severity on fig, grapevine, and pomegranate transplants in the surveyed districts differed. The average percentages of root rot/wilt incidence and severity, in the surveyed districts, were 41.26, 31.42% in fig, 38.2, 29.5% in grapevine, and 32.1, 23.7% in pomegranate transplants, respectively. The most frequently isolated fungi from rotted roots of fig, grapevine, and pomegranate transplants were Fusarium oxysporum, Rhizoctonia solani, and Macrophomena phaseolina. In pathogenicity tests, all the tested fungi were pathogenic to fig, grapevine, and pomegranate transplants. Under laboratory conditions, all of the following tested bio-agents: Azotobacter sp., Bacillus cereus, B. megaterium, and B. subtilis, were able to inhibit growth of the causal pathogens to different degrees. The effect of these bio-agents individually and/or mixed, when used as a soil drench treatment, were varied in reducing the incidence and severity of root rot/wilt diseases in fig, grapevine, and pomegranate transplants under greenhouse conditions. The mixed bio-agents gave the highest protection against root rot/wilt diseases compared with the individually used of bio-agents. All treatments significantly increased plant height, number of leaves/transplant, leaf area, fresh and dry weight/transplant compared with the control treatment.