Publications by authors named "Roland V Rallos"

3 Publications

  • Page 1 of 1

Influence of potassium-solubilizing bacteria on the growth and radiocesium phyto-transfer of Brassica rapa L. var. perviridis grown in contaminated Fukushima soils.

J Environ Radioact 2021 Jun 17;237:106682. Epub 2021 Jun 17.

Institute of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo, 183-12 8509, Japan; The Faculty of Food and Agricultural Science, Fukushima University, Kanayagawa, Fukushima City, Fukushima, 960-1296, Japan.

The supply of K, being the chemical analog of Cs, affects the phytotransfer of radiocesium such as Cs from contaminated soils and its accumulation in plant tissues. Since K and Cs have high affinity to the same clay particle surfaces, the presence of potassium-solubilizing bacteria (KSB) could increase the availability of not only K in the rhizosphere but also of radiocesium. In this study, we obtained five KSB isolates with the highest solubilization capacities from soybean rhizosphere on modified Aleksandrov medium containing sericite as K source. Based on biochemical and 16S rRNA gene sequence analysis, we identified the bacteria as Bacillus aryabhattai MG774424, Pseudomonas umsongensis MG774425, P. frederiksbergensis MG774426, Burkholderia sabiae MG774427, and P. mandelii MG774428. We evaluated the KSB isolates based on plant growth promotion and Cs accumulation in komatsuna (Brassica rapa L. var. Perviridis) grown in three soils collected from Miyanoiri, Takanishi, and Ota contaminated by Cs from the Fukushima accident. Inoculation with KSB showed beneficial effects on plant growth and increased the overall plant biomass production (~40%). On the average, KSB inoculation resulted in the removal of 0.07 ± 0.04% of Cs from the soil, more than twice the control. But similar to the effect of KSB inoculation on komatsuna biomass production, different KSBs performed variably and exhibited site-specific responses independent of their K-solubilizing capacities, with higher Cs phyto-transfer in roots than in shoots. In terms of root transfer factor (TF), values were highest in komatsuna plants grown in Miyanoiri and Ota soils inoculated with P. frederiksbergensis and Burkholderia sabiae, while they were highest in Takanishi soils inoculated with Bacillus aryabhattai and P. umsongensis. These TF values were also much higher than previously reported values for komatsuna grown in Cs-contaminated Fukushima soils inoculated with other rhizobacteria. Thus, KSB inoculation significantly enhance not only the growth of komatsuna but Cs uptake.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jenvrad.2021.106682DOI Listing
June 2021

Isolation and Screening of Indigenous Plant Growth-promoting Rhizobacteria from Different Rice Cultivars in Afghanistan Soils.

Microbes Environ 2019 Dec 14;34(4):347-355. Epub 2019 Sep 14.

Institute of Agriculture, Tokyo University of Agriculture and Technology.

To develop biofertilizers for rice in Afghanistan, 98 plant growth-promoting rhizobacteria were isolated from rice plants and their morphological and physiological characteristics, such as indole-3-acetic acid production, acetylene reduction, phosphate and potassium solubilization, and siderophore production, were evaluated. The genetic diversity of these bacteria was also analyzed based on 16S rRNA gene sequences. Of 98 bacteria, 89.7% produced IAA, 54.0% exhibited nitrogenase activity, and 40% showed phosphate solubilization and siderophore production. Some isolates assigned to Pseudomonas (brassicacearum, chengduensis, plecoglossicida, resinovorans, and straminea) formed a relationship with rice, and P. resinovorans and P. straminea showed nitrogen fixation. Rhizobium borbori and R. rosettiformans showed a relationship with rice plants and nitrogen fixation. Among the isolates examined, AF134 and AF137 belonging to Enterobacter ludwigii and P. putida produced large amounts of IAA (92.3 μg mL) and exhibited high nitrogenase activity (647.4 nmol CH h), respectively. In the plant growth test, more than 70% of the inoculated isolates showed significantly increased root and shoot dry weights. Highly diverse bacterial isolates showing promising rice growth-promoting traits were obtained from Afghanistan alkaline soils.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1264/jsme2.ME18168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934389PMC
December 2019

Towards integrated management of a shallow tropical lake: assessment of water quality, sediment geochemistry, and phytoplankton diversity in Lake Palakpakin, Philippines.

Environ Monit Assess 2019 Jul 6;191(8):485. Epub 2019 Jul 6.

Department of Environmental Science, School of Science and Engineering, Ateneo de Manila University, Loyola Heights, 1108, Quezon City, Philippines.

The limited carrying capacities of shallow tropical lakes render them more vulnerable to ecological problems like eutrophication. Unregulated human activities such as unsustainable aquaculture and urbanization can alter ecosystem dynamics rapidly, and this warrants more comprehensive researches than what has been previously conducted. Here, we presented an integrated assessment of the nutrient dynamics, phytoplankton diversity, and sediment geochemistry in Lake Palakpakin, a shallow tropical lake of volcanic origin, to understand its deteriorating ecological state. Water, phytoplankton, and sediment samples were collected, and in situ water quality measurements were done during wet and dry seasons in four critical areas in the lake, namely, the inlet, center, sanctuary, and outlet. Results revealed that high light extinction coefficient (1.13 m), high turbidity (28 NTU), high phosphate concentration (> 2.0.5 mg/L), and the abundance of Microcystis aeruginosa, Anabaena helicoidea, and Lyngbya sp. indicate that from a relatively healthy lake in 2008, Lake Palakpakin has become a eutrophic to hypereutrophic freshwater body. High concentrations of available nutrients such as N and P were detected in the center and sanctuary sediments, which drive the internal nutrient loading in the lake. We recommend that management efforts be directed towards a whole-ecosystem approach in addressing the problem of eutrophication, especially in shallow tropical lakes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10661-019-7617-7DOI Listing
July 2019
-->