DROUGHT STRESS ALLEVIATION: THE CONTRIBUTION OF A SOIL BACTERIUM AND AN ARBUSCULAR MYCORRHIZAL FUNGUS IN SCALLION

Authors: Paris Chakravarty and Charles Zhang

Paris Chakravarty: Pasteur Laboratory, Department of Microbiology, 158 N. Glendora Avenue, Ste S, Glendora, California 91741, U.S.A.

Charles Zhang: Pasteur Laboratory, Department of Microbiology, 158 N. Glendora Avenue, Ste S, Glendora, California 91741, U.S.A.

ABSTRACT

Recent climate change and global warming have caused extreme heat and low rainfall which negatively affected soil nutrient, fertility status, decreased water content, and changed physio-chemical properties of agricultural soils in many parts of the globe. As a result of drought, crop production is seriously reduced. The beneficial effects of soil microorganisms including arbuscular mycorrhizal fungi and rhizospheric bacteria on crop production and soil health are vital for the sustainable management of stressed agricultural practices. The present study evaluated the effects of an arbuscular mycorrhizal fungus, Rhizophagus irregularis, and a rhizospheric bacterium, Pseudomonas flourescens, alone and in dual inoculation on the survival, growth, mycorrhizal colonization, nutrient uptake, glomalin production, and soil aggregation of Allium fistulosum plants. In water-stressed soil, seedling survival, growth, total biomass, nutrient uptake, glomalin production, and soil aggregation were significantly increased when inoculated with R. irregularis and P. flourescens. Dual inoculation with R. irregularis and P. flourescens produced vigorous seedlings which contained higher amount of nitrogen, phosphorus, potassium contents, glomalin production, and soil aggregation compared to single inoculation. The present results indicate that arbuscular mycorrhizal fungi and beneficial rhizospheric bacteria offer potential for biofertilizers and mitigating drought in A. fistulosum plants.

Keywords: Global warming, drought stress, arbuscular mycorrhizal fungi, rhizospheric bacteria, scallion.

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