The Influence of Temperature on Meloidogyne incognita on Soybean


  • John F. Nardacci
  • K. R. Barker


The effects of temperature and initial inoculum density of Meloidogyne incognita on soybean growth and nematode reproduction were investigated in greenhouse temperature tanks and in controlled-growth chambers. The interactions of initial inoculum density (P[subi]) and soil temperature in effects on shoot growth were adequately described by multiple-regression models. At the highest temperatures (30 or 32/28 C), moderate to high inoculum killed many plants. A PI of 27,000 eggs/15-cm-diam pot retarded shoot growth at 26 C. Only the greatest P[subi] (81,000 eggs/15-cm pot) suppressed shoot growth at 18, 22, or 20/16 C. Inoculation with 3,000 or 9,000 eggs/plant resulted in heavier root systems at all temperatures except 30 C. At that temperature, 9,000 eggs suppressed root growth. At 18 and 26 C, a P[subi] of 81,000 eggs was required to retard root growth. Nematode reproduction was related directly to temperature and P[subi] except at a density of 81,000 eggs/15-cm pot. Key Words: Glycine max, root-knot, population dynamics.