The influence of light quality on the growth and fecondity of Meloidogyne infesting tomato


  • A. F. Bird
  • M. R. Sauer
  • R. N. Chapman
  • B. R. Loveys


Loveys (pers. comm.) showed that xylem sap from tomato plants grown under fluorescent light contained more cytokinin than from plants illuminated by tungsten filament lamps. In his experiments there was no difference in either the temperature or the amount of photosynthetically active radiation (400-700 nm). At present there is some conflict expressed in the literature about the influence of cytokinins on nematode growth in susceptible plants. On the one hand Brueske and Bergeson (1972) have shown that root-knot nematodes can cause a decrease in the amount of cytokinin in the root tissues and xylem exudates of tomatoes, and on the other, van Staden and Dimalla (1977) have shown that root-knot nematodes increase the amounts of cytokinins in roots, but do not appear to alter the cytokinin complement of the xylem sap. They thought the change to cytokinin concentrations in infected roots was due to accumulation of cytokinins by the nematodes themselves (Dimalla and van Staden, 1977). There appears to be a relationship between the degree of resistance to nematodes in plants and the presence of cytokinins. Thus Dropkin et al. (1969) and Kochba and Samish (1971) have shown that exogenously supplied cytokinins make resistant tomato plants more susceptible, and Kochba and Samish (1972) have shown that cytokinin levels are lower in resistant peach rootstocks than in susceptible ones. However, Skene and Antcliff (1972) did not find any difference in the cytokinin content of the sap from the nematode-resistant rootstock Salt Creek compared with the susceptible Sultana rootstock. In the investigation described here we observed the growth of Meloidogyne javanica (Treub) Chitw. in plants grown under conditions known to lead to changes in the cytokinin levels of the sap.