The Influence of Temperature on Meloidogyne incognita on Soybean.

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(i)) 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 P(i) of 27,000 eggs/15-cm-diam pot retarded shoot growth at 26 C. Only the greatest P(i) (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 Pi of 81,000 eggs was required to retard root growth. Nematode reproduction was related directly to temperature and P(i) except at a density of 81,000 eggs/15-cm pot.