THE DEVELOPMENT AND INFLUENCE OF MELOIDOGYNE-INCOGNITA AND MELOIDOGYNE-JAVANICA ON WHEAT

Abstract

The effects of soil temperature and initial inoculum density (Pi) of M. incognita and M. javanica on growth of wheat (T. aestivum cv. Anza) and nematode reproduction were studied in controlled temperature baths in the glasshouse. Nematode reproduction was directly proportional to temperature between 14-30.degree. C for M. incognita and between 18-26.degree. C for M. javanica. Reproduction rates (Pf/Pi, where Pf = final number of eggs) for Pi of 3000, 9000 or 30,000 eggs/plant were greatest at each temperature when Pi = 3000. Maximum M. incognita reproduction rate (Pf/Pi = 51.12) was at 30.degree. C. At 26.degree. C, M. javanica reproduction (Pf/Pi = 14.82, 9.02, and 4.23 for Pi = 3000, 9000, and 30,000, respectively) was about half that of M. incognita when Pi = 3000 or 9000, but similar when Pi = 30,000. Reproduction of both species was depressed at 14-18.degree. C. Shoot and root growth and head numbers were inversely related to soil temperature between 14-30.degree. C, but were not affected by the Pi of M. incognita when 7-day-old seedlings were inoculated. When newly germinated seedlings were inoculated with M. incognita or M. javanica, the Pi did not affect shoot and root fresh weights, shoot/root ratio and tillering, but it reduced root dry weight (M. javanica at 26.degree. C) and increased shoot dry weight (M. incognita at 18-22.degree. C). The optimum temperature range is lower for wheat growth than for nematode reproduction. ''Anza'' wheat is a good host for M. incognita and M. javanica, but it is tolerant to both species.