Expanding eco-friendly approaches to improve plant growth and crop productivity is of great important for sustainable agriculture. Therefore, a field experiment was carried out at the Faculty of Agriculture Farm, Mansoura University, Egypt during the 2018 and 2019 growing seasons to study the effects of different bio- and organic fertilizers and their combination on hybrid maize growth, yield, and grain quality. Seeds were treated with Azotobacter chrocoocum, arbuscular mycorrhizal fungi (AMF), Bacillus circulans, biogas slurry, humic acid (HA), and their combination aiming to increase the growth and yield of maize and to reduce the need for chemical fertilizers. The results showed that combined application of the biofertilizer mixture (Azotobacter chrocoocum, AMF, and Bacillus circulans) with organic fertilizers enhanced maize growth, yield, and nutrient uptake. Moreover, the bio-organic fertilization has improved the soluble sugars, starch, carbohydrates, protein, and amino acid contents in maize seeds. Additionally, the bio-organic fertilization caused an obvious increase in the microbial activity by enhancing acid phosphatase and dehydrogenase enzymes, bacterial count, and mycorrhizal colonization levels in maize rhizosphere as compared with the chemical fertilization. Additionally, the bio-organic fertilizers has improved α-amylase and gibberellins (GA) activities and their transcript levels, as well as decreased the abscisic acid (ABA) level in the seeds as compared to the chemical fertilizers. The obtained results of bio-organic fertilization on the growth parameters and yield of maize recommend their use as an alternative tool to reduce chemical fertilizers.

Guar is an economically important legume crop that is used for gum production. The clean and sustainable production of guar, especially in newly reclaimed lands, requires biofertilizers that can reduce the use of mineral fertilizers, which have harmful effects on human health and the environment. The present study was conducted to investigate the effects of biofertilizers produced from Bradyrhizobium sp., Bacillus subtilis, and arbuscular mycorrhizal fungi (AMF), individually or in combinations, on microbial activity, and nutrients of the soils and the guar growth and seed quality and yield. The application of biofertilizers improved shoot length, root length, number of branches, plant dry weight, leaf area index (LAI), chlorophyll content, and nutrient uptake of guar plants compared with the control plants. Moreover, the application with biofertilizers resulted in an obvious increase in seed yield and has improved the total proteins, carbohydrates, fats, starch, and guaran contents in the seeds. Additionally, biofertilizer treatments have improved the soil microbial activity by increasing dehydrogenase, phosphatase, protease, and invertase enzymes. Soil inoculation with the optimized doses of biofertilizers saved about 25% of the chemical fertilizers required for the entire guar growth stages. Our results could serve as a practical strategy for further research into integrated plant-microbe interaction in agriculture.

Thirty bacterial isolates were tested on three different media for Poly-ß-hydroxybutyrate (PHB) production. The best bacterial isolates for producing PHB were screened and identified based on molecular biology; then, using three different alternative carbon sources (dried whey, sugar beet molasses and date molasses), physical properties were evaluated by Infrared (IR) spectrometry and Gas chromatography–mass spectrometry (GC-MS/MS) analysis. Our results showed that the best isolates identified based on molecular biology were Bacillus paramycoides MCCC 1A04098, Azotobacter salinestris NBRC 102611 and Brevundimonas naejangsanensis BIO-TAS2-2. The addition of sugar beet molasses to the medium of A. salinestris increased the cell dry weight (CDW), PHB concentration, PHB% and conversion coefficient (4.97 g/L, 1.56 g/L, 31.38% and 23.92%, respectively). The correlation coefficient values between PHB g/L and CDW g/L varied between very strong and moderate positive correlation. IR of the produced PHB from B. paramycoides and A. salinestris showed similar bands which confirmed the presence of PHB; however, B. naejangsanensis showed weak bands, indicating lower PHB concentration. The chemical composition obtained showed that the GC-MS of the PHB extracted represents 2, 4-ditert-butylphenol for B. paramycoides and isopropyl ester of 2-butenoic acid for both of A. salinestris and Brevundimonas naejangsanensis. Therefore, PHB produced by microorganisms can be considered a biodegradable polyester, and represents a promising technique for the development of eco-friendly and fully biodegradable plastics.

Using Bacillus species as bioagents for environmentally sustainable and economically viable plant disease management is a viable strategy. Thus, it is important to promote their use in agriculture. In this study, two Bacillus species were isolated from the rhizosphere of tomato plants, while three fungal species were isolated from samples of tomato plants that were infected with damping-off disease. The Bacillus strains were tested in vitro for their antagonistic activity against fungal species using a dual culture technique. In a greenhouse experiment, the effectiveness of applying antagonistic bacteria with soilborne fungal disease on induced damping-off of tomato (cv. Super Strain B) plants, their physiological attributes, antioxidant enzymes, mineral content, and yield under greenhouse conditions during the 2022 and 2023 seasons were determined. The fungal isolates were identified as Fusarium oxysporum KT224063, Pythium debaryanum OP823136, and Rhizoctonia solani OP823124, while the Bacillus isolates were identified as B. subtilis OP823140 and B. amyloliquefaciens OP823147 on the basis of the rRNA gene sequences. The dual culture test revealed that B. subtilis outperformed B. amyloliquefaciens in resistance to R. solani and F. oxysporum, which were recorded as 28.33 and 33.00 mm, respectivley. In contrast, B. amyloliquefaciens caused the highest antagonistic effect against tested P. debaryanum fungus. Additionally, in a greenhouse experiment, tomato plants treated with each of these antagonistic Bacillus strains significantly suppressed fungal disease, displayed improved plant growth parameters, had an increased content of photosynthetic pigments, antioxidants enzymes, and total phenols, and an increased macronutrient content and yield during the two growing seasons. In conclusion, effective applications of B. subtilis and B. amyloliquefaciens had the potential to mitigate damping-off disease, which is caused by F. oxysporum, P. debaryanum, and R. solani in tomato plants, while simultaneously promoting growth dynamics.

An experiment was carried out in Sakha Research Station, Kafrelsheikh governorate, Egypt during the 2018-2019 seasons to isolate the cyanobacteria dominated in the soil samples of rice fields polluted by two pesticides (carbofuran and penoxsulam). These cyanobacterial isolates were identified and the best isolates, regarding growth activities and nitrogen (N2) fixation capacities, were chosen and further applied to the rice field to study their effect on rice yield under different urea concentrations (0, 35 and 69 kg N2/fed). Data revealed that nine cyanobacterial isolates were successfully obtained and purified. A growth curve experiment was conducted on these isolates and revealed that three isolates (Nostoc muscorum, Anabaena cylindrica, and Anabaena variabilis) had the best growth activities and capacities for N2 fixation. Within limit, both pesticides showed stimulation of both cell growth and N2 fixation. With higher concentrations, these values tended to decline due to the possible inhibitory or toxic effect of these pesticides. Generally, cyanobacterial isolates were less tolerant to penoxsulam and were inhibited at lower concentrations compared to carbofuran. With carbofuran application on rice field (Egyptian hybrid rice 1 variety), the interaction between cyanobacteria and urea resulted in the highest grain yield with the recommended dose of urea (69 kg N2/fed), while the highest 1000-grain weight was obtained with half the recommended dose of urea (35 kg N2/fed). Moreover, the use of a mixture of cyanobacterial species rather than a single one resulted in more satisfactory results.