RESEARCH REPORTS FROM INSTITUTE FOR AGRO-MICROBIOLOGY, Vol. 5, 2001 p.33-54
Copyright © Institute for Agro-Microbiology. All Rights Reserved.
ARTICLE
3.Characteristics of Microflora in the Root Zone of Potato and Carrot Plants as Affected by Field Management
Hiroyasu Tabuchi, Tomoko Naitoh, Akiko Kosugi, Shoji Nakagawa, Ichio Nioh(Institute for Agro-Microbiology)
About the root zone of potato and carrot plants from which a farming systems and soil management are different, comparison of the microflora was performed. The potato plants were got from the farmer’s fields, and the carrot plants were from the experiment fields. We discussed about the difference between the rhizosphere microflora of the crops under the environment with which various factors combined, and the rhizosphere microflora of the crops under the environment where only the kind of fertilizers differ.
1. We compared the bacterial and fungal flora in the root zone of potato plants cultivated under Nature-Farming systems (NF) that are similar to organic farming systems, with those under conventional farming systems (CF). The fields under NF and CF were adjacent to each other in Mishima city, Shizuoka, Japan, and managed by different farmers. There was no appreciable difference between both systems in the number of aerobic bacteria and actinomyces in the potato roots and soils. The number of fluorescent Pseudomonas in the samples from NF was higher than that of CF. MIS (Microbial Identification System, MIDI Inc.) was used to identify the aerobic bacteria isolated from the roots. MIS indicated that the same bacterial species were isolated from both samples as the most abundant species. Based upon MIS analysis, the diversity of the root-colonizing bacteria of potato under NF was higher than that under CF. Comparison of the root fungal flora by the root-washing technique showed that Fusarium sp. and Trichoderma sp. were isolated from NF roots and CF roots, respectively, as the main fungi. The diversity of the root fungi under NF was higher than that under CF. The bacteria showing an antifungal activity against a phytopathogen, Rhizoctonia solani, were isolated from the NF potato roots rather than from the CF roots. In the inoculation experiment to Komatsuna (Brassica campestris L. repifera group) seeds, the bacteria showing a root and hypocotyl promoting activities and an activities promoting a number of root hair were isolated from the NF potato roots rather than from the CF roots.
2. It compared about bacterial flora of the root zone of carrot plants which grown with chemical fertilizers and organic ones. There was no appreciable difference among each treatments in the number of aerobic bacteria and fluorescent Pseudomonas in the carrots roots.
As for the result which is different by two experiments having been obtained, the point that the chemical properties of the soil between the two experiments differs, the point that object crops differ, or the point that factors other than the kind of manure had influenced was considered to be the cause.
Keywords: root-inhabiting microflora, Nature-Farming, MIS (Microbial Identification System), microbial diversity, antifungal activity, potato, carrot, fluorescent Pseudomonas