ISSN:
1573-5036
Keywords:
indigenous soil rhizobia
;
Medicago sativa L.
;
nitrogen fixation
;
regrowth cycles
;
Rhizobium meliloti
;
symbiotic effectiveness
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Studies were conducted to evaluate whether field-grown cultivars of alfalfa (Medicago sativa L.) nodulate differentially with members of a soil population ofRhizobium meliloti, and to determine the influence of the dominant nodule occupants on N2-dependent growth of the same cultivars under greenhouse conditions. Nodules were sampled from four replicate plots of ‘Vernal’, ‘Anchor’, and ‘Saranac’ alfalfa, and the isolates analysed serologically. Results from agglutination tests identified serogroup 31 as a dominant nodule occupant. A significant cultivar effect was observed, with a greater and more consistent occupancy rate by serogroup 31 across the replicates on Vernal (60%) compared to Anchor (24%) or Saranac (36%). The symbiotic effectiveness of the parent isolate of serogroup 31 was evaluated on each cultivar over four successive harvests in a greenhouse study. Significant cultivar x N source interactions for herbage dry weight resulted following the second harvest. Of the three cultivars, only inoculated Vernal responded with an increase in shoot dry weight and N2 assimilated relative to N supplemented plants between harvests two and three. In separate greenhouse experiments, field isolates of serogroup 31 from nodules on Vernal produced homogeneous, effective responses both on Vernal and Anchor. In contrast, serogroup 31 field isolates from Anchor nodules were highly heterogeneous in effectiveness on the parent host, with poorly effective isolates being substantially more effective on Vernal. The data indicate that attention should be given to the potential impact of the indigenousR. meliloti population upon cultivar ranking at specific field locations, and also to strain-cultivar idiosyncracies when carrying out physiological sutidies of regrowth characteristics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02220719
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