Effect of zinc fertilization on rice plants and on the population of the rice-root nematodeHirschmanniella oryzae

The effect of different levels of zinc fertilization applied by two methods on the growth and yield of rice infected with the rice-root nematode,Hirschmanniella oryzae was assayed under the field conditions. A positive correlation between zinc concentration and both rice grain yield andH. oryzae total population was found. Only the seed-soaking method of zinc application, significantly increased the rice growth and the nematode total population density. Increasing percentages of nematode total population and growth and grain rice yield caused by the soaking method were more than those of the second one. In case of the first method the nematode total population ofH. oryzae reached the peak 60 days after transplanting and then declined thereafter as the rice plants reached maturity. While, in case of the second method, the nematode total population reached the peak 90 days after transplanting as the rice plants reached maturity.