Sorghum-Phosphate Solubilizers Interactions: Crop Nutrition, Biotic Stress Alleviation, and Yield Optimization

Sweet sorghum [Sorghum bicolor (L.) Moench] is a highly productive, gluten-free cereal crop plant that can be used as an alternative energy resource, human food, and livestock feed or for biofuel-ethanol production. Phosphate fertilization is a common practice to optimize sorghum yield but because of high cost, environmental hazards, and soil fertility reduction, the use of chemical P fertilizer is discouraged. Due to this, the impetus to search for an inexpensive and eco-friendly microbiome as an alternative to chemical P biofertilizer has been increased. Microbial formulations, especially phosphate solubilizing microbiome (PSM) either alone or in synergism with other rhizobacteria, modify the soil nutrient pool and augment the growth, P nutrition, and yield of sorghum. The use of PSM in sorghum disease management reduces the dependence on pesticides employed to control the phytopathogens damage. The role of PSM in the sorghum cultivation system is, however, relatively unresearched. In this manuscript, the diversity and the strategies adopted by PSM to expedite sorghum yield are reviewed, including the nutritional importance of sorghum in human health and the mechanism of P solubilization by PSM. Also, the impact of solo or composite inoculations of biological enhancers (PSM) with nitrogen fixers or arbuscular mycorrhizal fungi is explained. The approaches employed by PSM to control sorghum phytopathogens are highlighted. The simultaneous bio-enhancing and biocontrol activity of the PS microbiome provides better options for the replacement of chemical P fertilizers and pesticide application in sustainable sorghum production practices.

Phosphate Availability Modulates Root Exudate Composition and Rhizosphere Microbial Community in a Teosinte and a Modern Maize Cultivar

Domestication and breeding have impacted interactions between plants and their microbiomes in ways that are only beginning to be understood but may have important implications for recruitment of rhizosphere microorganisms, particularly under stress conditions. We investigated the responses of a modern maize (Zea mays ssp. mays) cultivar and its wild relative, teosinte (Zea mays ssp. parviglumis), to different phosphate availabilities. We appraised responses of the plant-microbial holobiont to phosphate stresses by profiling root exudate metabolomes, and microbial communities in the root endosphere and rhizosphere. We also performed plate assays to quantify phosphate solubilizing microorganisms from the rhizosphere. While root exudate metabolite profiles were distinct between the teosinte and modern maize under high phosphate, both plants shifted exudate compositions in response to phosphate stress toward a common metabolite profile. Root and rhizosphere microbial communities also responded significantly to both plant type and the phosphate availability. A subset of bacterial and fungal taxa were differentially abundant under the different phosphate conditions, with each of the three conditions favoring different taxa. Both teosinte and maize rhizospheres harbored phosphate solubilizing microorganisms under all growth conditions. These results suggest that the root exudation response to phosphate stress was conserved through the domestication of maize from teosinte, shifting exudation levels of specific metabolites. Although microbial communities also shifted, plate-based assays did not detect selective recruitment of phosphate solubilizers in response to phosphate availability.

Anaerobic Digestion of Pineapple Waste for Biogas Production and Application of Slurry as Liquid Fertilizer Carrier for Phosphate Solubilizers

Background: Pineapple peel wastes was seasonal which comprised of peels and rags. Their disposal posed a serious environmental pollution. Since pineapple peel was rich in cellulose, hemicellulose and other carbohydrates it was found to be a potential substrate for methane generation by anaerobic digestion.Methods: Here pineapple peel and pulp wastes were collected. The Hydraulic Retention Time of biogas (HRT) was monitored regularly for nine days and at three days intervals in gas collection bladders (Hans Seamless latex valve bladders). The slurry collected was periodically treated with phosphate solubilizers- Providencia rettgeri, a bacterial solubilizer and Meyerozyma gullerimondi, an yeast solubilizer. The biometric parameters of Ananas comosus was tested after slurry application. The germination percent of Passiflora edulis were also calculated.Result: The best combination of biogas slurry with maximum manorial content for phosphate solubilizers were treatment with cow dung and fruit waste in the ratio 1:2 with high amount of magnesium: 0.0037%, followed by 0.075 N and 0.00054% P which was selected for biometric observations for plants. Pineapple waste were good source for making biogas and slurry obtained could be utilized as carriers for phosphate solubilising liquid fertilizers.

Screening and characterization of nutrient solubilizing phytobeneficial rhizobacteria from healthy coconut palms in root (wilt) diseased tract of Kerala, India

Aim: Isolation, screening and characterization of beneficial rhizosphere bacteria associated with healthy (field-resistant) coconut palms in root (wilt) disease endemic hotspot areas of Kerala. Methodology: One hundred and ten rhizobacterial isolates associated with healthy coconut palms of root (wilt) diseased tract of Kerala were isolated and screened in-vitro for IAA production and solubilization of fixed forms of mineral nutrients. Seven isolates showing multiple phytobeneficial properties were characterized and the selected isolate was tested for its biopriming effect on maize. Results: Of the total isolates screened, 54 isolates produced IAA. Among the nutrient solubilizers, silicate solubilizers (57%) and phosphate solubilizers (48%) dominated. Of the seven isolates with multiple phytobeneficial properties, five rhizobacterial isolates belonged to Enterobacteriaceae family including three Enterobacter spp. The isolate T4HFB9 belonged to Acinetobacter sp. The green fluorescent Pseudomonas isolate K3HPSB2, showed 99% sequence similarity with Pseudomonas migulae. Seed biopriming of maize with Pseudomonas sp. strain K3HPSB2 recorded significant increase in germination percentage and seedling vigour index over untreated control. Interpretation: Disease-resistant coconut palms in RWD endemic tracts host a good proportion of phytobeneficial rhizosphere bacteria,with demonstrable multiple plant growth promoting traits. Multi-nutrient solubilizing Pseudomonas sp. with bioinoculant prospects has been selected for further studies on bio-priming for palm health management in RWD endemic tracts.

Isolation, identification and characterization of phosphate solubilizing bacteria in soils of coal mines landfills of Chhattisgarh

Phosphate solubilizing bacteria have the ability to solubilize the insoluble phosphates and to improve the quality of soil health and fertility. Efficacy of phosphate solubilizing microorganisms has been identified on the basis of kinetics and phosphorus accumulation. In this study, twenty eight soil samples were collected from different coal mines landfills of Chhattisgarh and occurrence of phosphate solubilizing bacteria (PSB) was isolated, purified and identified. In addition, the phosphate solubilizing capacity of bacteria based on the formation of visible or halo zone on Pikovskaya agar plates (PVK) and broth having tricalcium phosphate (TCP) and rock phosphate (RP) as a phosphate source was estimated at Dr. C.V. Raman University, Kota, Bilaspur (Chhattisgarh). The result revealed dominance of Pseudomonas syringae as major phosphate solubilizers, along with Bacillus subtillis followed by Pantoea dispersa, Bacillus circulans. Use of these PSB as bioinoculants increased the available P in soil to the extent of 194 and 246 µg/ml of P. the soluble P in case of rock phosphate was less than tricalcium phosphate. The maximum solubilization was observed after 15 days follow by a decrease in amount of soluble P.

Digestate as Biofertilizer for the Growth of Selected Vegetables and Illumina analysis of Associated Bacterial Community

ABSTRACTChemical content of crops above desirable level, high cost, in addition to land and water pollution is a major drawback of applying chemical fertilizers. In this study, Digestate was used as a biofertilizer for the growth of selected vegetables. Furthermore, Illumina platform was employed to unravel the bacteria community of the digestate. Corchorus olitorius, Amaranthus hybridus, Bot-celosia argentia and Talinum triangulare were grown in 16 experimental pots for 35days using cured digestate. Soil treated with chemical fertilizer was used as a positive control while the soil without any fertilizer was used as a negative control. The plant height of Talinum triangulare for soil treated with digestate was 23.5cm and 34cm by days 7 and 35 respectively after plant emergence. Corchorus olitorius had stunted growth under same treatment. Whereas, Bot-celosia argentia and Amaranthus hybridus grew poorly on all treatments. The statistical analysis showed a significant difference (p≤0.05) between Talinum triangulare grown in soil treated with digestate (plant height = 23.50, plant number =10 at day 7) compared with those treated with NPK (plant height = 18.50, plant number = 6.50 at day 7). The plant height and number for untreated soil at day 7 were 10.90 and 5.0 respectively). The Illumina sequencing of the digestate revealed the presence of some beneficial soil bacteria including Clostridium, Bacillus, Pseudomonas, Actinobacteria, and Micrococcus. The presence of these bacteria known to be Nitrogen fixers and Phosphate solubilizers confer biofertilizer potential to the digestate.

INTERVENSI MANUSIA TERHADAP KOMUNITAS RHIZOSFIR: REVIEW (Human Disturbance on Rhizosphere Communities: Review)

AbstrakWalaupun tersembunyi di dalam tanah komunitas rhizosfir merupakan penentu kehidupan di muka bumi dan berperan penting pada pelestarian alam. Rhizosfir merupakan daerah di sekitar perakaran tanaman yang dihuni oleh berbagai mikrobia tanah yang berperan dalam menentukan pertumbuhan dan kesehatan tanaman. Struktur dan komposisi komunitas mikrobia sangat dipengaruhi oleh macam, konsentrasi dan komposisi eksudat akar. Perubahan yang terjadi pada tanaman (umumnya sangat dipengaruhi oleh aktivitas manusia) mempengaruhi komunitas rhizosfir, sebaliknya komunitas rhizosfir akan menentukan struktur tumbuhan dan fungsi ekosistem. Review ini membahas pengaruh aktivitas manusia yang mempengaruhi kualitas lingkungan terhadap komunitas mikrobia di rhizosfir, yang merupakan hasil kajian dari berbagai sumber terbaru yang dianalisis secara induktif. Aktivitas manusia yang dikaji meliputi praktek pertanian intensif, deforestasi hutan menjadi perkebunan serta perubahan iklim. Hasil kajian menunjukkan bahwa praktek monokulturisasi telah menurunkan biodiversitas mikrobia rhizosfir, menurunkan kinerja enzim tanah dan menurunkan keragaman dan konsentrasi senyawa glukosinolat untuk melawan patogen. Pengolahan tanah, pemupukan anorganik dan penggunaan pestisida telah menurunkan biodiversitas mikrobia rhizosfir. Sebaliknya pemupukan organik tidak berpengaruh terhadap biodiversitas mikrobia tanah. Perubahan fungsi hutan menjadi kebun intensif telah merubah dominansi kelompok mikrobia serta kemampuan mikrobia sesuai fungsinya di ekosistem. Perubahan iklim berdampak pada peningkatan suhu tanah, hal ini telah mengubah komposisi mikrobia rhizosfir. Perubahan komposisi, dominansi dan kemampuan mikrobia di rhizosfir tersebut dapat merubah komposisi populasi tumbuhan di atasnya. Hal ini dapat mengubah keseimbangan dan fungsi ekosistem yang berakibat pada berubahnya kesejahteraan manusia.AbstractEven though it is hidden underground, rhizosphere communities define the life in this earth planet and has an important role on nature preservation. Rhizosphere is the zone of soil adjacent immediately to plant roots which inhabited by varies species of beneficial soil microbes for facilitating plants growth and health. Human activities are strongly influence on plant performance. Alteration on plant growth and health statues determine rhizosphere communities that will define the vegetation structures and ultimately ecosystem functions. This paper discuss the negative influences of human activities (anthropogenic factors) on the environment to the rhizosphere communities. Especially the impacts of intensive farming, deforestation and climate changes. It is sourced from current referrences in inductive analysis. One of intensive farming management is monoculture that is not only drastically depleted microbes diversity in the rhizosphere hence decresed soil enzimes activities, but also reduced glucocynolates production, a crucial compound against pathogen. Whereas, tillage, fertilizers and pesticide application significantly diminished microbe biodiversity. Organic fertilizers, on the other hand, did not give crucial impacts this biodiversity. Modify forest into estate have changed domination of groups and lessened capability of phosphate solubilizers. While climate changes, that enhance soil temperature escalation, have altered rhizosphere microbes composition and structure. Replacement of composition, domination, abundance and capability of rhizosphere communities will modify composition and structure of vegetation aboveground. Eventually, will alter the ballance and functions of the ecosystem, which determine the wealth of human population in the earth.

Evaluation of impacts of potato crops and livestock farming in Neotropical high Andean Páramo soils, Colombia

Páramos are Neotropical ecosystems that result from insular formations dominated by tufted hair grasses and shrubs, and are located above the continuous forest track and below the perpetual snowline of the highest peaks in the Northern Andes. The aim of this research was to check the reliability of the hypothesis that the potato cultivation and livestock farming activities modify the quality of Páramo soils. For this, soil samples were taken from soil used with three different purposes at two different heights: Páramo with the least possible intervention, and Páramo where the activities of potato cropping and livestock farming were carried out; from these, and that have been determined to have physicochemical properties, abundance of functional groups of microorganisms (nitrogen-fixing, phosphate solubilizers, cellulolytic microorganisms), and enzymatic activities (urease, protease, β-glucosidase, acid, and alkaline phosphatase). The gravimetric humidity, apparent density, organic carbon, cation exchange capacity, urease, acid phosphatase, and β-glucosidase showed statistically significant differences (P < 0.05), indicating that there is a change in the quality of the soil that is exposed to agricultural activities. As for microorganisms the hypothesis was not confirmed; there are warning signs for the future in the case of continuing with these practices, but there are no significant differences.