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Increase in soil pH due to Ca-rich organic matter application causes suppression of the clubroot disease of crucifers
| Title: | Increase in soil pH due to Ca-rich organic matter application causes suppression of the clubroot disease of crucifers |
| Authors: | Niwa, Rieko Browse this author | | Kumei, Toshiaki Browse this author | | Nomura, Yoshinobu Browse this author | | Yoshida, Shigekata Browse this author | | Osaki, Mitsuru Browse this author | | Ezawa, Tatsuhiro Browse this author →KAKEN DB |
| Keywords: | Calcium | | Clubroot disease | | Organic matter | | Plasmodiophora brassicae | | Soil-borne pathogen | | Soil pH | | Suppressive soil |
| Issue Date: | Mar-2007 |
| Publisher: | Elsevier Ltd |
| Journal Title: | Soil Biology and Biochemistry |
| Volume: | 39 |
| Issue: | 3 |
| Start Page: | 778 |
| End Page: | 785 |
| Publisher DOI: | 10.1016/j.soilbio.2006.09.027 |
| Abstract: | Clubroot disease of cruciferous plants caused by the soil-borne pathogen Plasmodiophora brassicae is difficult to control because the pathogen survives for a long time in soil as resting spores. Disease-suppressive and conducive soils were found during the long-term experiment on the impact of organic matter application to arable fields and have been studied to clarify the biotic and abiotic factors involved in the disease suppression. The fact that a large amount of organic matter, 400 t ha−1 yr−1 farmyard manure (FYM) or 100 t ha−1 yr−1 food factory sludge compost (FSC), had been incorporated for more than 15 yr in the suppressive soils and these soils showed higher pH and Ca concentration than the disease conducive soil led us to hypothesize that an increase in soil pH due to the long-term incorporation of Ca-rich organic matter might be the primary cause of the disease suppression. We have designed a highly reproducible bioassay system to examine this hypothesis. The suppressive and conducive soils were mixed with the resting spores of P. brassicae at a rate of 106 spore g−1 soil, and Brassica campestris was grown in a growth chamber for 8 d. The number of root hair infections was assessed on a microscope. It was found that the incorporation of FYM and FSC at 2.5% (w/w) to the conducive soil suppressed the infection and that the finer particles (5 mm) of FSC inhibited the infection and increased soil pH more effectively. Neutralization of the conducive soil by Ca(OH)2, CaCO3 and KOH suppressed the infection, but the effectiveness of KOH was less than those of Ca(OH)2 and CaCO3. Acidification of the suppressive soils by H2SO4, promoted the infection. The involvement of soil biota in the disease suppression was investigated using the sterilized (γ-ray irradiation) suppressive soils with respect to soil pH. The γ-ray irradiation promoted the infection at pH 5.5, but no infection was observed at pH 7.4 irrespective of the sterilization status. All these observations suggest that soil pH is a major factor in disease suppression by organic matter application and that Ca and soil biota play certain roles in the suppression under the influence of soil pH. |
| Relation: | http://www.sciencedirect.com/science/journal/00380717 |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/18647 |
| Appears in Collections: | 農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 丹羽 理恵子
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