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The effect of moisture potential on growth and survival of root nodule bacteria in peat culture and on seed
Author(s) -
Griffith G.W.,
Roughley R.J.
Publication year - 1992
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1992.tb04962.x
Subject(s) - rhizobia , moisture , horticulture , peat , inoculation , trifolium subterraneum , biology , water content , strain (injury) , zoology , botany , bacteria , agronomy , chemistry , nitrogen fixation , ecology , geotechnical engineering , organic chemistry , anatomy , pasture , genetics , engineering
Peat from three sources was dried, milled and packed separately in polyethylene bags and sterilized by irradiation. The carrier was impregnated with broth cultures of either Rhizobium leguminosarum bv. trifolii strain WU95, Bradyrhizobium japonicum strain CB1809 or B. lupini strain WU425 and sterile water to provide five moisture potentials in the range > ‐ 1 × 10 4 ‐ 1 × 10 6 Pa. The packets were stored at 26°C under conditions which restricted moisture loss. Numbers of root nodule bacteria were counted at intervals up to 12 weeks. No single moisture potential was optimum for all strains in all carriers because of a significant ( P < 0.05) interaction between moisture potential × strain × carrier × time. Where direct comparisons could be made, all strains survived best at ‐ 1 × 10 4 and/or −3.2 × 10 4 Pa. Seeds of Trifolium subterraneum and polypropylene beads (used to avoid seed coat toxicity), were inoculated with WU95 prepared in two sources of peat and at each of the above moisture potentials and stored at 15°C. Seed coat toxicity significantly effected the log death rate ( k ) of WU95 on subterraneum clover seed for the period 0–0.25 d ( k 1.796) compared with k ‐ 0.399 for polypropylene beads. In the first 24 h moisture did not affect survival but by 28 d rhizobia grown in Badenoch peat survived best at −3.2 × 10 4 Pa. In Millicent peat, survival was equally as good at −3.2 × 10 4 and −1 × 10 4 Pa.