Comparative Penetration and Development of Meloidogyne Naasi in Wheat and Oat Roots

Abstract

Direct observations of root penetration by Meloidogyne naasi larvae into 'Pawnee' wheat and 'Wintok' oats were made using micro-observation chambers. Effects of inoculum density, exposure time, and temperature on larval penetration and nematode development were investigated in wheat and oats. The maximum number of larvae penetrated the wheat and oat roots at the 2000 level of inoculum density, but the maximum percent penetration was at the 500 level for wheat and at the 200 level for oats. In both wheat and oats an ascending trend in larval penetration was more discernible during the first 96 hours than during 96 to 192 hours. Maximum penetration occurred at 25°C in both wheat and oat roots. Cell necrosis in association with larvae was common in oats. Three times as many larvae matured and laid eggs in wheat as in oat roots. Analysis of hostparasite relationships suggests that 'Pawnee' wheat is highly susceptible, and 'Wintok' oats tolerant or moderately resistant to M. naasi.