ISSN:
1573-5036
Keywords:
Bradyrhizobium japonicum
;
effectiveness
;
infectiveness
;
intrinsic antibiotic resistance
;
rhizobium
;
serology
;
soybean
;
Thailand
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Over 1500 root-nodule bacteria were isolated from a range of uninoculated soybeans, and one cowpea, ‘trap-hosts’, sown in 1985 into traditional soybean-growing areas of soybean-growing areas of northern Thailand. Most isolates were slow-growing Bradyrhizobium japonicum. Using a modified ‘bottle-jar’ technique, 586 of the isolates were tested with a range of soybean hosts and one cowpea host. The results indicated: (a) a very high level of infectiveness, with only one isolate failing to nodulate one host, and 95% forming \s〉20 nodules per plant; (b) a high level of effectiveness of fixation of nitrogen by the local rhizobium populations with soybeans; (c) evidence of selection of effective strains by both soybean and cowpea hosts in the field; These results strongly suggest that there is no need for selection of soybean germplasm for compatibility with the local rhizobium populations. 1500 isolates were examined serologically using antisera to both US and Thai strains. While there was greater compatibility between the local isolates and Thai antisera, there was no obvious geographic relationship within or between isolates at the local or regional level. Inter-site differences were as great as inter-regional differences. Antibiotic resistance patterns, examined on 116 isolates, were useful for separating isolates for effectiveness testing, but the degree of variability was great, and the patterns differed greatly from published data on US collections. The considerable superiority in effectiveness of fixation of this collection, over that of a collection made from comparable trap hosts in Nigeria, and the lack of common serological and antibiotic resistance patterns with strains of US origin, illustrate the uniqueness of this collection, and emphasise the value of intensive study of natural populations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00014778
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