Influence of Potassium and Nitrogen Fertilization on Parasitism by the Root-knot Nematode Meloidogyne javanica

Y. Spiegel, E. Cohn, U. Kafkafi, Meira Sulami


The influence of various c oncentrations of K[sup+], nitrogen sources, and inoculation with root-knot nematode Meloidogyne javanica were evaluated in tomato plants. Increased potassium concentration increased top and root fresh weights of intact plants and fresh weights of excised roots. Nitrate-fertilized plants weighed more than plants receiving ammonium independent of the K level in the medium. Nematode counts on roots were not affected by nutritional differences in intact or excised roots. In intact roots a high percentage of males was recorded at low K[sup+] levels, whereas in excised roots the proportion of males in the population rose as the K[sup+] levels increased. Inoculated intact roots accumulated K[sup+] when the level of potassium supply was low; infected excised roots contained less K[sup+] than did nematode-free roots. Key words: ammonium, nitrate, nutrition, physiology, potassium.

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