The effect of mineral fertilization on fungi colonizing potato (Solanum tuberosum L.) tubers after harvest and after storage

Abstract

The paper presents the results of a three-year exact experiment conducted in Bałcyny, in which a late potato cultivar, Jasia, was grown. The objective of the study was to determine the effect of different levels of mineral fertilization: A (N 80 kg × ha^-1 P 80 kg × ha^-1 K120 kg × ha^-1) and B (N 120 kg × ha^-1 P 144 kg × ha^-1 K156 kg × ha^-1), and foliar fertilization (Basfoliar 12-4-6, ADOB Mn and Solubor DF) on the quantitative and qualitative composition of fungal populations colonizing potato tubers. Fungi were isolated immediately after harvest and after a five-month storage period. After seven days of incubation, fungal colonies were transferred onto agar slants for microscopic identification. Over the entire experimental period, more pathogenic fungi were obtained from potato tubers analyzed after storage (62.9% of the total fungal population after storage) than from those analyzed immediately after harvest (39.1%), and the greatest number of fungi was reported in 2004. Rhizoctonia solani was isolated most frequently, followed by Colletotrichum coccodes and Alternaria alternata. Pathogens of the genus Fusarium and the species Helminthosporium solani were not numerous. In the treatment A with soil mineral fertilization with lower NPK rates, larger numbers of pathogenic fungi were noted in 2004 after harvest and after five-month storage, and in 2005 after harvest. At the remaining dates of analysis, pathogens were more frequently isolated from potato tubers in experimental variant B with higher NPK rates. Immediately after harvest, the highest number of pathogenic fungi was isolated in the treatment with foliar application of ADOB Mn and Basfoliar 12-4-6. After five-month storage, pathogens most often colonized potato tubers in experimental variant B with foliar application of Solubor DF, Solubor DF and ADOB Mn, and in experimental variant A with a combination of fertilizers. In the other fertilization variants, including in the control treatment, the population size of pathogenic agents remained at a similar level.