Arbuscular mycorrhizal fungi (AMF) play a significant role for mine tailing rehabilitation due to their sensitivity towards a range of soil pollutants. This beneficial biological agent can enhance plant tolerance to heavy metal contamination. This study screened indigenous AMF associated with growing indigenous ferns and grasses in the mine tailings for potential use in rehabilitating a 3-decade abandoned mined out area in Mogpog, Marinduque. Pterocarpus indicus Willd. (narra) was used as the host plant to establish mycorrhizal fungi association. Among the treatments, indigenous AMF associated with Ferns 1, 2 and 5 generally improved the height and shoot diameter of the narra seedlings and the effect was comparable with commercially available AMF inoculants, MYKOVAM ® and MYKORICH ® . The dry weight of the roots and nodules was consistently improved by indigenous AMF from Fern2 and Grass1, which had comparable effect with MYKOVAM ® and MYKORICH ® . Overall, the total seedling dry matter of narra seedlings was significantly stimulated by AMF, irrespective of isolates' origin. The mycorrhizal root infection by AMF and number of spores in the soil were all high as compared with the uninoculated control counterpart. Lastly, AMF inoculation induced Cu retention in the roots of the seedlings. Thus the results imply that, the mined out indigenous AMF are potential agents to rehabilitate the abandoned mine tailings in the Philippines.
Diazotrophic bacteria (syn. nitrogen-fixing bacteria, NFB) are plant growth-promoting rhizobacteria known to facilitate nitrogen availability for plant nutrition. Biochar may serve as a refuge for colonizing microbes influencing the mycorrhizal richness and activities in the rhizosphere, thereby affecting the mycorrhization helping bacteria. This study isolated, characterized, and identified diazotrophic bacteria from the cacao (Theobroma cacao L.) rhizosphere treated with arbuscular mycorrhizal fungi (AMF) and bamboo biochar (BB). Initial screening of the cacao rhizosphere yielded 1.28x106 CFU of diazotrophic bacteria g–1 soilgrown in nitrogen-free malate medium. A total of 12 isolates were further assayed for acetylene reduction and phosphate solubilization activities. All putative diazotrophic bacterial isolates successfully reduced acetylene to ethylene gas, ranging from 16.35 ± 1.68 to 60.71 ± 2.57 ppm. Of the 12 putative diazotrophic bacterial isolates, 11 have shown phosphate solubilization activity on Pikovskaya’s medium with the solubilization index (SI) ranging from 1.12 ± 0.08 to 3.74 ± 0.16 mm. Analysis of the 16S rRNA gene sequences revealed that these diazotrophic bacterial isolates belonged to the genera Bacillus, Burkholderia, Rhizobium, and Ralstonia. These results provide evidence of candidate plant growth-promoting rhizobacteria from cacao that are potential source of biofertilizers to improve the growth and yield of cacao crops, especially in the Philippines. As agricultural options, biochar and AMF pose beneficial influence on plant growth-promoting bacteria, which primarily provide nutrients for several crops.
This study was conducted to test whether the ethanolic extract of the plant Cyperus kyllingia can exert antimitotic effects in actively dividing onion root tip cells, and toxic effects on alive brine shrimp. Onion bulbs and brine shrimps were exposed to solutions of C. kyllingia ethanolic extract at various concentrations for 24 h. Results showed that the extract can block mitosis in onion cells by causing spindle and chromosome damage, which results to mitotic anomalies. In effect, it induces pyknosis and cell death. Moreover, the effects on mitotic index, percentage of C-mitosis, and percentage of other mitotic anomalies are dose-dependent. The test extract can cause dose-dependent lethality in brine shrimp with an estimated LC 50 value of 13.47 ppm. The findings indicate that the test plant contains antimitotic and cytotoxic components that may be studied further in animal test systems as possible models of anticancer drugs.
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