Effets de concentrations élevées de sels sur la croissance, la sporulation et la pigmentation de Trichoderma spp.

Abstract

On agar media supplemented with NaCl (5% = 856 mM), 7 Trichoderma spp. [T. hamatum, T. harzianum, T. koningii, T. longibrachiatum, T. pseudokoningii, T. saturnisporum and T. viride] aggregates and an isolate intermediate between T. harzianum and T. viride (T. 410) grew more slowly, sporulated poorly and had no characteristic pigmentation of the colonies, NaCl or KCl concentrations inducing albinization differed with different isolates. CaCl2 (90-270 mM) reversed the anti-sporulating effect of NaCl (856 mM) on T. 410, and stimulated conidiation in media with no NaCl added. Gliocladium virens, but not G. roseum, reacted like Trichoderma to NaCl. Fourteen other fungal genera [Alternaria radicina, Ascochyta pinodella, Aspergillus flavus, Cephalotrichum sp., Drechslera spp., Fusarum oxysporum, Neurospora crassa, Penicillium spp., Phomopsis sclerotioides, Rhizoctonia solani, Gaeumannomyces graminis, Paecilomyces sp., Trichothecium roseum and Verticillium dahliae] offered various reactions. Since 856 mM NaCl decreases osmotic potential (.pi.) of the media used from -1.2 to -41 bars, the influence of .pi. on T. 410 was examined. After 3-4 days, maximal growth was observed between -1.2 and -10 bars. Growth was reduced to 50% at about -30 bars. No growth occurred at about -90 bars. No pigmentation was observed at -32 bars (NaCl) and -41 bars (KCl). Abundant sporulation and pigmentation occurred at -31 bars with CaCl2 as the sole electrolyte added. Na+ was toxic at high concentration. The possible use of Trichoderma in biological control was discussed.