Survival ofRhizobium trifolii in soil following inoculation of arrowleaf clover
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Arrowleaf clover (Trifolium vesiculosum Savi) is an annual forage legume that is sown in south-eastern USA when temperature and moisture conditions may not be suitable for survival of inoculant rhizobia. Survival of two antibiotic-resistant strains of rhizobia on seed or quartz particles was evaluated under controlled conditions in the laboratory. At 30C and 75% r.h., lime coating of inoculated seed, soil pH (4.2 and 6.7), and surface or subsurface sowing of inoculated seed did not significantly (P = 0.05) affect the survival of either rhizobial strain. The use of gum arabic as an inoculant adhesive resulted in better rhizobial survival than sucrose or water, but even with gum arabic treatment the population of strain 162Y10 declined from c. 10,000/seed to less than ten/seed in six days. Survival of strain 162Y15 appeared better and c. 200 rhizobia/seed survived for six days. When inoculated seed were incubated at 45C, soil pH, method of sowing, lime coating of the seed, and r.h. (75% and 100%) did not influence rhizobial survival. The gum arabic adhesive enhanced survival over the use of sucrose but survival was still poor. No viable rhizobia were detected after two days of incubation. High r.h. (100%) and 30C favoured survival and growth of both rhizobial strains when inoculated onto quartz particles placed on, or mixed into, soil at pH 4.2. Coating inoculated quartz particles with lime increased the growth of rhizobia under these conditions, but sucrose and gum arabic were equally effective as inoculant adhesives. 1985 Oxford University Press.