Abstract

SAMANIEGO GAXIOLA, José Alfredo. Germination and survival of (Phymatotrichopsis omnivora) sclerotia in response to NaOCl and dextrose in soil. Agric. Téc. Méx [online]. 2008, vol.34, n.4, pp.375-385. ISSN 0568-2517.

Sclerotia of Phymatotrichopsis omnivora can survive for 20 years in the soil; however, if sclerotia are exposed to chemical agents or microbial competition in soil, survival is reduced to few weeks. The objective of this research was to study the germination and survival of P. omnivore sclerotia, treated first with a solution of NaOCl and then exposed to microbiota competition in soil supplemented with dextrose. The experiments were carried out at 'La Laguna' Research Station of the National Research Institute for Forestry, Agriculture and Livestock under a completely random factorial design. Sclerotia were immersed in 200, 500 and 3 000 ppm NaOCl solutions during 0.3, 1, 8, and 72 h. at two temperatures, 15-20 and 28 °C, afterwards were placed in soil added with 0.0, 0.125, 0.25 and 0.5 mg g^-1 of dextrose during 14 days under saturated conditions at 28 °C. Sclerotia immersed into a 3 000 ppm solution of NaOCl during 20 min showed 90% germination in sterile sand and PDA and only 15% in non-sterile sand and PDA. When sclerotia were germinated before being immersed in NaOCl, viability was 100% in all substrates utilized. Survival of sclerotia decreased with the increase in the time of immersion, concentration of NaOCl, and concentration of dextrose added to the soil. Sclerotia immersed during one hour or more in 1 000 ppm or higher of NaOCl solution and placed in soil with 0.25 or 0.5 mg g^-1 of added dextrose showed a maximum survival of 20%. Sclerotia survival was high in some treatments at 15-20 °C than in similar treatments at 28 °C, possible due to a protective effect of NaOCl on sclerotia exposed to soil microbiota enhanced by added dextrose.

Keywords : fungistasis; saturated soil; soilborne fungi.

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