Effect of culture media on growth and pigmentation of Fusarium oxysporum f. sp. lentis isolates

Abstract

The present study was undertaken to find out the suitability of culture media for the study of cultural variability among 40 Fusarium oxysporum f.sp. lentis isolates using Potato dextrose agar (PDA) and Czapek's Dox agar (CDA) medium. Of them 35 isolates showed growth of <7 mm/day (slow growth rate), while 5 isolates showed >7-10 mm/day (medium growth rate) on CDA. On PDA, all three types of growth rates were observed. On CDA medium, appressed and fluffy growth pattern was observed in 30 and 10 isolates, respectively while on PDA, 6 isolates were appressed and 34 fluffy type. Similarly, all isolates expressed white to dull white mycelia colour on CDA but on PDA, 20 isolates showed white to dull white, 13 isolates showed light orange to dark orange and 7 isolates as light purple to dark purple colour mycelia. Similar variations were also observed with respect to substrate colour produced by the isolates. Light buff to buff colour substrate was produced by 32 isolates, light brown to dark brown by 5 isolates and light purple to dark purple by 2 isolates on CDA. IIowever, on PDA medium, light buff to buff colour substrate was produced by 13 isolates, light brown to dark brown by 18 isolates and light purple to dark purple colour substrate by 9 isolates. Thus, potato dextrose agar medium showed higher differential cultural behaviour of F. oxysporum f. sp. lentis isolates than Czapek's Dox agar medium, hence, the former was better suited for studying the cultural variability in F. oxysporum f. sp. lentis.