Browse by author
Lookup NU author(s): Dr Christoph Schmidt, Professor Carlo Leifert
Full text for this publication is not currently held within this repository. Alternative links are provided below where available.
Pseudomonas fluorescens B5 and Bacillus subtilis MBI 600 colonized sugar beet seedlings at matric potentials of -7 × 103, -140 × 103, and -330 x 103 Pa and under five temperature regimes ranging from 7 to 35°C, with diurnal fluctuations of 5 to 22°C. No interaction between matric potential and temperature was observed. In situ bioluminescence indicated physiological activity of Pseudomonas fluorescens B5. Colonization of the root at ≥4 cm below the seed decreased at very low matric potential (-330 × 103 Pa). Total population size of Pseudomonas fluorescens B5 per seedling was significantly increased at -140 × 103 Pa. However, matric potential had no significant effect on the population density of Pseudomonas fluorescens per gram of root fresh weight and did not affect the distribution of the population down the root. Total population size per seedling and downward colonization by Pseudomonas fluorescens B5 were significantly reduced at high temperatures (25 to 35°C). Maximum colonization down the root occurred at intermediate temperature (15°C) at both matric potentials (-7 × 103 and -140 × 103 Pa). Addition of B. subtilis MBI 600 to the seed had no effect on rhizosphere populations of Pseudomonas fluorescens B5. Populations of B. subtilis MBI 600, which consisted largely of spores, were slightly reduced at lower matric potentials and were not affected by temperature. Survival and dry weight of plants in soils infested with Pythium spp. decreased with increasing soil temperature and matric potential, indicating an increase in disease pressure. However, there was no significant interaction between the two factors. At -330 × 103 Pa, soil dryness but not Pythium infection was the limiting factor for plant emergence. At temperatures of 7 to 25°C and matric potentials of-7 × 103 to -120 × 103 Pa, treatment with Pseudomonas fluorescens B5 increased plant survival and dry weight. At 7°C and -120 × 103 Pa, there was almost complete emergence of seeds treated with Pseudomonas fluorescens B5. Antagonistic activity of Pseudomonas fluorescens B5 decreased with increasing soil temperature and decreasing matric potential. At 25 to 35°C and -7 × 103 Pa, no effect was observed. In regimes with different day and night temperatures, the maximum (day) temperature was decisive for disease development and antagonistic activity. B. subtilis MBI 600 displayed no significant antagonistic effect against Pythium ultimum and did not influence the performance of Pseudomonas fluorescens B5 in combined inocula.
Author(s): Schmidt CS, Agostini F, Leifert C, Killham K, Mullins CE
Publication type: Article
Publication status: Published
Journal: Phytopathology
Year: 2004
Volume: 94
Issue: 4
Pages: 351-363
ISSN (print): 0031-949X
ISSN (electronic): 1943-7684
Publisher: American Phytopathological Society
URL: http://dx.doi.org/10.1094/PHYTO.2004.94.4.351
DOI: 10.1094/PHYTO.2004.94.4.351
Altmetrics provided by Altmetric
