Trade-off between dispersal and reproduction of a seed-borne nematode, Aphelenchoides besseyi, parasitic on rice plants

Abstract

AbstractThe effect of nematode infestation on dispersal and survival of both host plant and parasitic nematode was investigated experimentally using rice plants, Oryza sativa L. and Aphelenchoides besseyi Christie, a seed-borne ectoparasite. Nematode-inoculated plants produced a greater proportion of light seeds floating on water than non-inoculated plants. Nematode mortality was greater in light seeds than in heavy seeds. In the case of light seeds, the mean degree of seed swelling increased as the number of nematodes harboured increased, whereas it was constant with increasing numbers of nematodes for the intermediate and heavy seed groups. A smaller proportion of light seeds germinated and these took longer for seminal roots to protrude than from heavy seeds, irrespective of whether they derived from nematode-inoculated or non-inoculated plants. These results indicate a trade-off for rice seed specific gravity between dispersal and competition of rice seeds and another trade-off between dispersal and reproduction of nematodes harboured in the seed.