Calcium Nutrition and the Infection of Eucalypt Seedlings by Phytophthora cinnamomi

Abstract

In water culture with the pH maintained at 5.2. higher levels of calcium increased the dry weight of developing leaves, roots, and the total dry weight of eucalypt seedlings both susceptible ( E . Sieberi) and tolerant ( E . Maculata) to Phytophthora cinnamorni. Calcium levels of 64 ppm did not reduce seedling mortality nor relieve the growth reduction associated with P. cinnamomi infection in the susceptible seedlings. The calcium concentration and total calcium content of developing leaves of E. sieberi were significantly lower in inoculated than in uninoculated seedlings. In the tolerant E. maculata seedlings, there was no significant reduction in developing leaf or total dry weight with inoculation, but a reduction in root dry weight occurred. Calcium concentrations and total calcium content did not differ significantly in leaves of inoculated and uninoculated seedlings of E. maculata.