Nest refuse of Acromyrmex balzani (Hymenoptera: Formicidae) increases the plant vigor in Turnera subulata (Turneraceae)

Some studies report the positive effect of organic residues from ant nests on soil properties and on the structure of the adjacent plant community in field experiments, but there is a gap about the effect on individual species. The purpose of the present study was to compare the soil nutrient content and the development of Turnera subulata Smith, an ornamental species, in the presence of the nest refuse (basically composed of fragments of grass leaves and the symbiotic fungus) produced by the leaf-cutting ant Acromyrmex balzani (Emery, 1890) or in control soil through a greenhouse pot experiment. The experiment was carried out with two treatments: control soil and soil with 25% of nest refuse. The plants were kept in 1L pots for 90 days. We evaluated the parameters: plant height, stem diameter, root length, number of leaves, dry weight of the root, dry and fresh aboveground biomass. Additionally, the relative chlorophyll content and leaf nutrients were used as nutritional parameters. As a result, plants that grew in the soil with nest refuse showed significant higher values of all parameters evaluated when compared to the control treatment (p < 0.001). We conclude that this biofertilizer contributed to the production of more vigorous plants, being able to act on the local dynamics of nutrients in the ecosystems where A. balzani occurs. As it is relatively abundant and easy to collect, the refuse of A. balzani has the potential to be used as an alternative substrate in the production of shortlife cycle plants.

Effect of Soil-Applied L-tryptophan on the Amount of Biomass and Nitrogen and Sulfur Utilization by Maize

As natural plant growth stimulators, amino acids are widely used to improve crop yield and quality. There are numerous studies documenting the influence of amino acids on plants, which is not always positive. This study was conducted to determine the effect of soil-applied L-tryptophan (L-TRP) on the accumulation and utilization of nitrogen and sulfur by maize. The study was carried out under the conditions of a pot experiment. The experimental design included three treatments: soil without fertilization (control), soil with mineral fertilization (NPKS), and soil with mineral fertilization and L-tryptophan addition (NPKS + L-TRP). The application of tryptophan to the soil, supported by mineral fertilization, caused a significant increase in maize biomass. Although no significant differences in nitrogen and sulfur contents in maize biomass were found between treatments without and with the addition of L-tryptophan, significantly higher intakes of both elements were observed in the NPKS + L-TRP treatment. The application of L-tryptophan increased the biosynthesis of Chlorophyll a. Utilization of nitrogen and sulfur by maize in the NPKS + L-TRP treatment was more than 27% and 17% higher, respectively, compared to the NPKS treatment. Maintaining the recommended contents of individual nutrients in the rhizosphere is not a guarantee of optimal quantitative and qualitative intake of nutrients. Problems with maintaining optimal relationships between individual nutrients may be compounded by soil properties.

The Influence of Basalt Powder on the Physicochemical Properties of Impoverished Oxisoils from Ngaoundéré (Adamawa - Cameroon)

The present study aims at assessing the fertilizing potential of basalts on impoverished oxisoils from Ngaoundéré (Adamawa, Cameroon). This specifically involves the application of finely ground basalts on impoverished oxisoils and monitoring changes in physicochemical properties during six months. An experimental design which consisted in a randomized complete block design is constituted of three series of four treatments each one: the control (ST), the control soil mixed with 100 g of finely ground basalt (T0 + BA_10), the control soil mixed with 200 g of finely ground basalt (T0 + BA_20), the control soil mixed with 300 g of finely ground basalt (T0 + BA_30). Each treatment was replicated ten times in every serie. The control treatment is only soils of Ng, collected at the top soil and without any basalt application. They are clayey, acid and display an average CEC. The basalt is rich in silica (47.52%), Calcium (8.22%), Magnesium (4.03%), sodium (4.01%), potassium (2.42%) and displays average content in alumina (16.54%) and iron (11.1%). The experiment was carried out in pots, and the incubated soil samples were analyzed after 0, 1, 2, 4 and 6 months. The analyzes mainly focused on the physicochemical parameters (Grain size analysis, pH, Cation exchange capacity (CEC), the sum of exchangeable bases (SBE) and the saturation rate (V). Obtained results indicated that the application of basalt greatly improved the chemical properties of oxisoils from Ngaoundéré: the pH changes from acidic (5.5) to weakly acidic (6.5); the saturation rate, as well as the sum of exchangeable bases and the cation exchange capacity increased. Physicochemical properties of the soil are closely accompanied by an increase in fertility. It appears that 10 and 20% treatments are the most efficient treatments. Thus, the basalts from Manwi can be recommended as petrofertilizer to improve the chemical properties of impoverished soils and especially for plants requiring alkalis and alkaline earth.

Fungal Population and Physicochemical Characteristics of Abattoir-Impacted Soil in Iwofe, Rivers State

Aim: To determine the fungal population and physicochemistry of abattoir impacted soil in Iwofe, Rivers State. Study Design: This study focused on Abattoir impacted soil. Statistical analysis of data and interpretation was carried out. Place and Duration of Study: Abattoir impacted soil was collected from three points in an abattoir located in Iwofe, Rivers State while the unpolluted soil which served as control was collected from the Rivers State University, Port Harcourt in January, 2021. Methodology: Standard microbiological techniques were used: the fungal population was determined by inoculating aliquots of an appropriate dilution resulting from a ten-fold serial dilution on prepared Sabouraud dextrose agar plates in duplicates. Plates were later incubated for 3-5 days after which colonies were enumerated and used in obtaining the fungal population in the soil samples while distinct colonies were subcultured for macroscopic and microscopic identification of fungi. The physicochemical parameters and heavy metals were analyzed using standard methods. Results: Fungal load in the control and abattoir impacted soil were 1.09×105 and 3.9×104 CFU/g, respectively. The fungal load of the control soil was significantly higher (P˂0.05) than the abattoir impacted soil. The fungal isolates identified in the abattoir impacted soil were Microsporium sp, Aspergillus niger and Candida sp while Aspergillus niger, Aspergillus flavus, Fusarium sp, Penicillium sp, Mucor sp and Rhizopus sp were identified from the control soil. The pH, temperature, nitrate and phosphate of the abattoir soil were 6.7, 28.33℃, 27.83(mgKg-1) and 1055(mgKg-1), respectively. The concentrations of Cadmium, Iron and Lead in the abattoir Impacted soil and control soil were 0.81, 563.35 and 7.12 mgKg-1, 0.51, 582.0 and 3.18 mgKg-1, respectively. The physico chemistry and heavy metals in the abattoir soil were within acceptable limits. Discussion and Conclusion: The findings from this study showed that heavy metals in abattoir impacted soil had an impact in the fungal population which led to the isolation of only three fungal isolates belonging to Microsporium sp, Candida sp and Aspergillus niger. More so, despite the presence of heavy metals in the abattoir impacted soil, the metals were all within permissible limits. Thus, the abattoir impacted soil was not heavily polluted.

TAXONOMIC COMPOSITION OF FUNGI COMMUNITIES IN THE RHIZOSPHERE OF FABA BEANS

The taxonomic composition of rhizosphere complexes of microscopic fungi was determined under nine varieties of faba beans grown in small-plot experiments on black soil with a pH of 7.6, ob-serving zonal agricultural techniques (Belgorod, Russia). It was revealed that under different vari-eties of faba beans the list of micromycete species is not the same, but their number is lower than in control soil. The number of micromycete propagules in the rhizosphere of beans (34 ± 1.7 thou-sand CFU / g soil) is on average 2 times higher than in the control soil (17 ± 1.2 thousand CFU / g soil). The greatest species diversity was found in the varieties Velena and Akvadul (18 and 16 species, respectively). The mycocomplexes of the Tsarskiy Yield and Leader varieties were dis-tinguished by the greatest similarity with the control. Phytopathogenic fungi Fusarium oxysporum dominated in the rhizosphere complexes of all studied varieties of vegetable beans, and the spe-cies A. fabaе, C. herbarum, and U. botrytis were present only in the rank of random species in my-cocomplexes under some varieties.

EFFECTS OF SOIL SOLARIZATION ON FUNGAL AND BACTERIAL POPULATIONS ASSOCIATED WITH AMARANTHIS VIRIDIS L. (AFRICAN SPINACH) IN LAGOS, NIGERIA

Soil solarization is increasingly used to control soil-borne pathogens because it is environment-friendly. However, performance varied geographically, necessitating experimental trials before its introduction. This study assessed the effects of solarization on soil-borne bacteria and fungi, growth, and proximate composition of Amaranthus viridis (African spinach) in Lagos, Nigeria. Two raised beds were solarized for six weeks with a transparent and black polyethylene sheet, and a non-solarized (control) bed was equally made. The vegetable seeds were planted and their growths were recorded for four weeks. Soil samples at 15-20cm deep and leaves were obtained for microbiological and proximate analysis, respectively. The mean temperature of transparent xxpolyethylene’s soil was 45.33 oC, black polyethylene (35 oC), and non-solarized (33.50 oC). The mean height and width of transparent polyethylene’s A. viridis were 24 and 3cm, black polyethylene (19 and 2.2 cm), and non-solarized (17 and 1.6cm). The transparent polyethylene’s soil had 3100 and 250 cfu/g bacterial and fungal colonies, black polyethylene (3200 and 1900 cfu/g), and non-solarized (37000 and 1900 cfu/g), respectively. The proximate contents of the transparent polyethylene’s A. viridis were (70 moisture, 10 ash, 4.24 protein, 1.45 fat and 9.94 % fibre), black polyethylene (73.35 moisture, 8.36 ash, 3.1% protein, 1.23 fat, and 6.77 % fibre), and non-solarized (76.09 moisture, 5.91 protein, 3.15 ash, 1.31 fat and 6.75 % fibre). Overall, statistical differences (p ≤ 0.05) existed between the solarized and non-solarized and between transparent and black polyethylene (transparent>black>non-solarized). Thus, solarization could be an effective strategy for controlling soil-borne bacteria and fungi of A. viridis in the area studied.

The use of Pseudomonas spp. as bacterial biocontrol agents to control plant disease

Most Pseudomonas biocontrol strains are associated with the rhizosphere of plants, where they control soil pathogens by antibiosis or competition, and leaf pathogens via induced systemic resistance. Genome mining and the division of the vastly heterogeneous genus Pseudomonas in phylogenomic (sub)groups has clarified the relation between biocontrol characteristics and phylogeny. Based on their activity, Pseudomonas biocontrol strains come in three types. A first type, represented by P. chlororaphis, P. protegens, P. corrugata and P. aeruginosa (sub)group strains, produces an arsenal of secondary metabolites with broad antimicrobial activity. The second type is found in the P. putida, P. fluorescens, P. koreensis, P. mandelii, and P. gessardii (sub)group. The spectrum of biocontrol properties of these strains is less diverse and involves siderophores and cyclic lipopeptides. The third type colonizes above-ground plant parts. Strains from this type mainly belong to the P. syringae group and are used to control postharvest pathogens. This chapter starts with recent advances in Pseudomonas taxonomy and a summary of its most important biocontrol traits. It then provides an overview of the most important Pseudomonas groups and subgroups harboring biocontrol strains. Examples of well-characterized and representative biocontrol strains show the links between phylogeny, ecology and biocontrol traits. The chapter concludes by reviewing commercially-available biocontrol strains.