Revista de tecnología microbiana y bioquímica

Abstracto

Comparative Efficacy of Potassium Salts Against Soil-borne and Air-borne Fungi and Their Ability to Suppress Tomato Wilt and Fruit Rots

Jabnoun-Khiareddine H, Abdallah R, El-Mohamedy R, Abdel-Kareem F, Gueddes-Chahed M, Hajlaoui A and Daami-Remadi M

Potassium sorbate (PS), potassium bicarbonate (PB) and dipotassium hydrogen phosphate (DPHP) were assessed for their antifungal activity against Fusarium oxysporum f. sp. lycopersici (FOL), F. oxysporum f. sp. radicis-lycopersici (FORL), F. solani, Verticillium dahliae (VD), Rhizoctonia solani, Colletotrichum coccodes, Pythium aphanidermatum, Sclerotinia sclerotiorum, Botrytis cinerea and Alternaria solani. They were screened for their ability to suppress Verticillium and Fusarium wilts, and Fusarium Crown and Root Rot (FCRR), for their effects on tomato growth, and for their potential control of Botrytis, Alternaria, Rhizoctonia and Anthracnose fruit rots. PS (0.25-1.5%), DPHP (0.1-0.6 M) and PB (0.1-0.6 M) inhibited fungal growth in a concentration-dependent manner, with the greatest inhibition achieved using the highest concentrations. Inter specific variations in sensitivity were detected with P. aphanidermatum, S. Sclerotiorum and B. cinerea being the most sensitive to all salts. Single treatments using PS (0.25%), PB (50 mM) and DPHP (50 mM) resulted in varied degree of protection against wilts. PS led to 50, 78.26 and 65% lower wilt severity as respectively compared to VD-, FOL- and FORL-inoculated controls. PS had significantly increased plant height, root and aerial part fresh weights by 20.61, 30.76 and 33.02%, respectively, compared to FORL-inoculated plants and had improved root fresh weight by 42.18 and 32.87% compared to FOL-and VDinoculated plants, respectively. PB-based treatment led to 60.86 and 30% lower Fusarium wilt and FCRR severity but did not suppress Verticillium wilt. DPHP suppressed only Fusarium wilt by 65.21%. Used as fruit treatment, DPHP and PS significantly decreased Botrytis, Rhizoctonia, Alternaria and Anthracnose fruit rots by 46.68 and 30.81%, 14.04 and 15.74%, 20 and 31.67%, and 19.17 and 25.24%, respectively, compared to inoculated and untreated controls. PB-based treatment resulted in 12.83% significantly lower Rhizoctonia fruit rot. These results showed that PS may be used as potential abiotic agent for successfully controlling fungal tomato diseases.