Entomopathogenic Fungi on Hemiberlesia pitysophila

Hemiberlesia pitysophila Takagi is an extremely harmful exotic insect in forest to Pinus species, including Pinus massoniana. Using both morphological taxonomy and molecular phylogenetics, we identified 15 strains of entomogenous fungi, which belong to 9 genera with high diversities. Surprisingly, we found that five strains that were classified as species of Pestalotiopsis, which has been considered plant pathogens and endophytes, were the dominant entomopathogenic fungus of H. pitysophila. Molecular phylogenetic tree established by analyzing sequences of ribosomal DNA internal transcribed spacer showed that entomopathogenic Pestalotiopsis spp. were similar to plant Pestalotiopsis, but not to other pathogens and endophytes of its host plant P. massoniana. We were the first to isolate entomopathogenic Pestalotiopsis spp. from H. pitysophila. Our findings suggest a potential and promising method of H. pitysophila bio-control

A novel strain D5 isolated from Acacia confusa.

We isolated a novel strain D5 from nodules of Acacia confusa. Under strict sterile conditions the strain could successfully nodulate Acacia confusa, A. crassicarpa and A. mangium, with nitrogenase activity ranging from 18.90 to 19.86 nmol·g(-1)·min(-1). In the phylogenetic tree based on a complete 16S rRNA gene sequence, the sequence of strain D5 shared 99% homology with that of four species of genus Pseudomonas. The 685 bp nodA fragment amplified from strain D5 shared 95% homology with the nodA sequence of 9 species of genus Bradyrhizobium, with a genetic distance of 0.01682. The 740 bp nifH gene fragment was amplified from strain D5. This strain D5 nifH gene and Bradyrhizobium spp. formed a branch, showing 98% homology and a genetic distance of 0. The homology between this branch and the Bradyrhizobium spp. DG in another branch was 99%, with a genetic distance of 0.007906. These results indicate that this strain D5 is a new type of nitrogen-fixing bacterium

Effects of Biochar and Plant Growth-Promoting Rhizobacteria on Plant Performance and Soil Environmental Stability

(1) Background: Biochar and plant growth-promoting rhizobacteria (PGPR) are widely used as amendments to increase the availability of nutrients and the diversity of the bacterial community within soil. (2) Methods: In this study, we investigated the effects of biochar and PGPR amendments on plant performance, soil physicochemical property, and soil microbial diversity, as well as their relationship in a Eucalyptus (clone DH32−29) plantation in Guangxi, China. We determined the microbial AWCD, Simpson, Shannon, and McIntosh indices, and soil inorganic nitrogen (NH4+, NO3−), total phosphorus (TP), total potassium (TK), total nitrogen (TN), and plant growth and nutrient concentrations; (3) Results: Biochar-only had a significant impact on soil microbial community function, although the effects on plant performance were limited. PGPR plus biochar was found to significantly increase the diversity indices of soil microbes, as well as soil TK and TP. Besides, soil microbes displayed a preference for carbohydrates rather than other carbon sources. (4) Conclusion: Soil microbial functional diversity responded to changes in plant performance and, therefore, it could indicate soil ecological stability and ecosystem productivity. These findings may suggest that biochar and PGPR could potentially maintain ecological sustainability in the soil and improve plant performance through altering soil physicochemical properties in a eucalyptus plantation

Effects of Biochar and Plant Growth-Promoting Rhizobacteria on Plant Performance and Soil Environmental Stability

(1) Background: Biochar and plant growth-promoting rhizobacteria (PGPR) are widely used as amendments to increase the availability of nutrients and the diversity of the bacterial community within soil. (2) Methods: In this study, we investigated the effects of biochar and PGPR amendments on plant performance, soil physicochemical property, and soil microbial diversity, as well as their relationship in a Eucalyptus (clone DH32−29) plantation in Guangxi, China. We determined the microbial AWCD, Simpson, Shannon, and McIntosh indices, and soil inorganic nitrogen (NH4+, NO3−), total phosphorus (TP), total potassium (TK), total nitrogen (TN), and plant growth and nutrient concentrations; (3) Results: Biochar-only had a significant impact on soil microbial community function, although the effects on plant performance were limited. PGPR plus biochar was found to significantly increase the diversity indices of soil microbes, as well as soil TK and TP. Besides, soil microbes displayed a preference for carbohydrates rather than other carbon sources. (4) Conclusion: Soil microbial functional diversity responded to changes in plant performance and, therefore, it could indicate soil ecological stability and ecosystem productivity. These findings may suggest that biochar and PGPR could potentially maintain ecological sustainability in the soil and improve plant performance through altering soil physicochemical properties in a eucalyptus plantation

Evaluation of Soil Total Nitrogen as an Indicator of Soil Bacterial Community Response to Biochar and Plant Growth-Promoting Rhizobacteria Applications

Biochar and plant growth-promoting rhizobacteria (PGPR) are widely used as an amendment for soil physicochemical properties and soil bacterial community diversity. In Guangxi, China, we carried out a study to determine how PGPR and biochar influence the soil’s environmental stability in an Eucalypt plantation. We applied biochar and PGPR in a contrasting application manner to an acidic red loam soil. Thus, three treatments were set up as 5 × 1010 CFU·mL−1 PGPR-only (MB0), 20 t·hm−2 biochar-only (B20), and co-application of 20 t·hm−2 biochar and 5 × 1010 CFU·mL−1 PGPR (MB20), as well as no biochar and no PGPR (M0B0). Our results indicated that MB20 significantly decreased the soil total nitrogen (TN) and increased the soil total phosphorus (Soil TP), soil ammonium nitrogen (NH4+), and soil water content (SWC) when compared with the control. The MB20 also significantly increased the Simpson, ACE, and Chao indices of the soil bacterial community’s diversity relative to the control. We also observed a significant effect of the Soil TN on both the bacterial community and the functional diversity in soil. These findings may indicate that assessing the soil N status is expected to be an essential indicator of the soil microenvironment’s response to biochar and PGPR applications

Biochar and Rhizobacteria Amendments Improve Several Soil Properties and Bacterial Diversity

In the current context, there is a growing interest in reducing the use of chemical fertilizers and pesticides to promote ecological agriculture. The use of biochar and plant growth-promoting rhizobacteria (PGPR) is an environmentally friendly alternative that can improve soil conditions and increase ecosystem productivity. However, the effects of biochar and PGPR amendments on forest plantations are not well known. The aim of this study is to investigate the effects of biochar and PGPR applications on soil nutrients and bacterial community. To achieve this goal, we applied amendments of (i) biochar at 20 t hm−2, (ii) PGPR at 5 × 1010 CFU mL−1, and (iii) biochar at 20 t hm−2 + PGPR at 5 × 1010 CFU mL−1 in a eucalyptus seedling plantation in Guangxi, China. Three months after applying the amendments, we collected six soil samples from each treatment and from control plots. From each soil sample, we analyzed several physicochemical properties (pH, electrical conductivity, total N, inorganic N, NO3−-N, NH4+-N, total P, total K, and soil water content), and we determined the bacterial community composition by sequencing the ribosomal 16S rRNA. Results indicated that co-application of biochar and PGPR amendments significantly decreased concentrations of soil total P and NH4+-N, whereas they increased NO3-N, total K, and soil water content. Biochar and PGPR treatments increased the richness and diversity of soil bacteria and the relative abundance of specific bacterial taxa such as Actinobacteria, Gemmatimonadetes, and Cyanobacteria. In general, the microbial composition was similar in the two treatments with PGPR. We also found that soil physicochemical properties had no significant influence on the soil composition of bacterial phyla, but soil NH4+-N was significantly related to the soil community composition of dominant bacterial genus. Thus, our findings suggest that biochar and PGPR amendments could be useful to maintain soil sustainability in eucalyptus plantations

Phylogenetic dendrogram of strain D5 <i>nifH</i> gene.

<p>Phylogenetic dendrogram of strain D5 <i>nifH</i> gene.</p

Nodulation of strain D5 inoculated plants.

<p>A. <i>Acacia confusa</i>, B. <i>Acacia crassicarpa</i>, C. <i>Acacia mangium</i>, D. <i>Glycine max,</i> and E. Control.</p

The nodulation rates of strain D5 inoculated <i>Acacia confusa</i>, <i>A. crassicarpa, A. mangium</i>, and <i>Glycine max</i>, and the corresponding nitrogenase activities of root nodules.

<p>The nodulation rates of strain D5 inoculated <i>Acacia confusa</i>, <i>A. crassicarpa, A. mangium</i>, and <i>Glycine max</i>, and the corresponding nitrogenase activities of root nodules.</p

PCR results of 16S rRNA of strain D5.

<p>PCR results of 16S rRNA of strain D5.</p