Infectivity variation of Discaria trinervis-nodulating Frankia in Patagonian soil according to season and storage conditions

CHAIA E; SOLANS M; VOBIS G; WALL LG

PHYSIOLOGIA PLANTARUM

WILEY-BLACKWELL PUBLISHING, INC

Año: 2007 vol. 130 p. 357 - 363

0031-9317

Changes in the infectious capacity of soil-borne Frankia from the same site may depend on environmental conditions. To test this, we examined the effect of season of sampling, sample storage protocol, and storage time. The nodulation capacity of Frankia from rhizospheric soils of Discaria trinervis (Hook et Arn.) Reiche (Rhamnaceae) growing in northwest Patagonia (Argentina) was measured using the most probable number method. Soil samples were collected seasonally and either stored moist at 4 ºC or air-dried at room temperature for few days. Old (air-dried) soil samples were also assayed. All soils nodulated D. trinervis seedlings. Nodulation units (NU) ranged from 44 (spring, moist-storage) to about 1 per millilitre of soil (summer moist, and summer and autumn, air-dried storage), with intermediate values in other samples. Soils stored for 12 years, 6 months or one week had similar NU. Frankia NU were positively correlated with soils water content (r = 0.6, P < 0.05), therefore it is likely that soil moisture is a relevant factor regulating soilborne Frankia nodulation ability in Patagonian soils. We suggest that Frankia can remain as spores or grow saprophytically in Patagonian soils.