METHANE CONSUMPTION DRIVEN NITROGEN FIXATION IN A TROPICAL SOIL ECOSYSTEM
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Date
2020
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Indira Gandhi Krishi Vishwavidyalaya, Raipur
Abstract
Methane consumption driven nitrogen fixation in a tropical soil ecosystem
The experimental soil under the present investigation falls under tropical zone of Central India having heavy clayey vertisol (TypicHaplustert).The experiment was conducted under lab condition IISS, Bhopal. The Methane (CH4) is a potent greenhouse gas and its concentration is rising alarmingly. However, it is not clearly understood how CH4influences plant growth and nutrient cycling in soil ecosystem. Toevaluate the effect of CH4 in the rhizosphere on pigeon pea, CH4 was injected into the rhizosphereat 1 ml d-1 and 4 ml d-1.
Plant growth was stimulated by lowering CH4 through nodulation, root and shoot biomass. Higher CH4 concentration (4 ml d-1) inhibited plant growth. Available NO3 was higher in low CH4 than higher CH4. Abundance of N2 fixers (nif gene) and methanotrophs (pmoA gene)increased with lowerCH4.To unravel the mechanistic process of CH4 driven plant growth promotion, CH4 consumption was evaluated under the influence of different nitrogen sources. CH4 concentrations tested were 1000 ppm and 10000 ppm. Nitrogen sources were N2(5%, 10%),NO3-N and NH4-N each at 10 mM and 20 mM. Three repeated CH4 feedings were carried out to determine nitrogenacquisition per unit of CH4 consumption. N2 stimulated CH4 consumption by about 21-22% over no nitrogen control, while both NO3 and NH4-N inhibited CH4 consumption by 12 to 37%. CH4 consumption was inhibited more by NO3-N than NH4-N irrespective of CH4 concentration. N2 stimulated abundance of both nif and pmoAgenes, NO3-N inhibited microbial genes, and NH4-N stimulated pmoA and amoA genes in soil irrespective of CH4 concentration. Nitrogen acquisition was expressed as µg N acquired g-1 soil ml-1CH4 consumed, ranged from12.56 to 34.97 with 1000 ppm CH4 and 1.58 to 4.35 with 10000 ppm CH4. Study concludes that CH4 stimulated pigeon pea through enhancing nodulation, N fixation and plant growth promoting microbial groups in the rhizosphere of pigeon pea.
Description
METHANE CONSUMPTION DRIVEN NITROGEN FIXATION IN A TROPICAL SOIL ECOSYSTEM
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