VIEW ARTICLE

Ecology and Epidemiology

Effect of Bacillus spp. on Increased Growth of Seedlings in Steamed and in Nontreated Soil. Patricia Broadbent, Senior Research Scientist, Biological and Chemical Research Institute, New South Wales Department of Agriculture, Rydalmere 2116, Australia; Kenneth F. Baker(2), Noelene Franks(3), and J. Holland(4). (2)Professor, Department of Plant Pathology, University of California, Berkeley, CA 94720; (3)Technical Officer (Scientific), Biological and Chemical Research Institute, New South Wales Department of Agriculture, Rydalmere 2116, Australia; (4)Research Agronomist, N. S. W. Department of Agriculture, Tamworth 2340. Phytopathology 67:1027-1034. Accepted for publication 8 October 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1027.

A steamed soil mix in a commercial nursery was infested with Bacillus spp. and sown with seeds of 10 plant genera representing eight families. The plant response varied from increased germination and top weight, or both, to no effect, to reduction of either or both of these characters. There was marked plant specificity in response to the bacteria introduced into the soil mixture. In all cases, inoculating with mixed bacterial cultures produced less response than inoculating with a single bacterial isolate. The increase in seedling growth usually was greater under low than under high nutrient levels. Tomato and celosia seedlings, which showed growth response to bacterial inoculation, did not differ from the controls in nutrient analyses of the foliage. Little phosphate was solubilized in vitro by the Bacillus spp. isolates studied, and they did not fix nitrogen under aerobic conditions. Seedlings of most genera grew better in a peat-sand mix steamed at 60 C for 30 min than in one steamed at 100 C for 30 min. The phytotoxic effect of the latter treatment was overcome in some cases by subsequent infestation of the mix with bacteria. Field responses to pelleting of cabbage and grain sorghum seed with various bacterial isolates also were obtained.