The effect of salinity on host resistance to the citrus nematode, Tylenchulus semipenetrans, was tested in a greenhouse experiment on six citrus rootstocks: the highly nematode-resistant Swingle citrumelo and trifoliate orange, the moderately nematode-resistant Carrizo citrange and Troyer citrange, and the highly nematode-susceptible Cleopatra mandarin and sour orange. Sodium chloride and CaCl were added to irrigation water every other day during a 3-week period 6 months after seedling emergence. A total of 167 moles NaCl and 29.4 moles CaCl was added per cubic meter soil. Soluble salts in soil were leached prior to inoculation with 73 000 nematodes per plant. Eight weeks after inoculation, resistance was evaluated in terms of female development and number of offspring produced. Salinity increased nematode egg production by two to 10-fold in all rootstocks but did not change the relative levels of nematode resistance among rootstocks.
