Abstract: In this greenhouse study eight (8) isolates of Macrophomina phaseolina, MP120, MP30, MP218, MP210, MP29, MP32, MP24, and MP23 isolated from soybeans grown in Mississippi were compared based on their pathogenicity potential. Soybeans (Viking 2265(OG)) were planted in pots infested with one of the eight isolates of M. phaseolina and uninfested control pots in six replicates randomized black design at Mississippi State University North Farm. One important parameter that was monitored in this study is temperature. Temperatures measured in pots across all replicates were not significantly different (P≥0.05) according to analysis of variance (ANOVA). The pathogenicity was determined using seedling survival and growth at 9, 14, 22, and 28 days after planting, plant height, and root-hypocotyls discoloration at 28 days. The results showed that there were no significant difference (P≥0.05) in stand densities between the thick (white feathery) and the thin (black dense) isolates but showed significant difference in plant height compared to the control. Hypocotyls discoloration ratings were severe for thin isolates compared to the thick isolates and control. Hypocotyls discoloration ratings were significantly higher for MP23, MP29, and MP218 covering both isolate types. Plant height was significantly reduced in pots infested with MP23, and MP210 compared to all other isolates and control. All isolates were reisolated from diseased tissues of soybean plants and confirmed using Koch’s postulate. The results from this study showed that the isolate cultural types of M. phaseolina did not vary in pathogenicity overall but some differences in individual isolates were evident.
Keywords: Macrophomina phaseolina, pathogenicity, isolates, stand densities, hypocotyls, discoloration, Koch’s postulate.
Title: Pathogenic Variability among Macrophomina Phaseolina Isolates Associated With Soybeans
Author: Lord Famiyeh, Todd Mlsna
International Journal of Life Sciences Research
ISSN 2348-313X (Print), ISSN 2348-3148 (online)
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