Maturity Effects on Colony-Forming Units of Macrophomina phaseolina Infection as Measured using Near-Isogenic Lines of Soybeans

摘要

Charcoal rot f Macrophomina phaseolina^) causes significant yield losses in soybean /Glycine max (L.) Men.]. The actual effect of maturity on disease severity can be confounded by geno-typic background. We evaluated disease severity using two sets ofnear-isogenic lines (NIL) differing in maturity genes. Field experiments were established on two soil types (sandy loam and clay) and evaluated over two years (2008 and 2009). Disease severity, expressed as colony-forming units (CFU), was evaluated for each line at physiological maturity. Within a year, similar levels of disease severity were observed on both soil types. Regression analysis indicated no significant (P < 0.05) relationship between maturity and CFU for either set of ML on either soil typein either year. Adding selected environmental variables (rainfall, temperature, etc.) to the equation allowed the detection of a significant relationship in only one environment (P = 0.0306, F — 6.00). Results demonstrated little evidence of a relationship between maturity and disease severity.