The Role of Calcium Nutrition on Fusarium-Wilt Syndrome in Muskmelon

The influence of various calcium salts was evaluated on non‐inoculated muskmelon plants and on plants inoculated with the Fusarium ‐wilt pathogen, and maintained in silica sand or vermiculite. Disease severity of inoculated seedlings maintained in vermiculite was markedly higher than that of seedlings grown in silica sand, and onset of wilt was recorded earlier in the former. These trends were more conspicuous in seedlings treated with Ca 2+ , especially when this cation was accompanied, by nitrate. In vermiculite–compared with silica sand, Mg and K contents in the shoot were higher while Ca values were lower. Irrespective of the form of calcium salt or the plant's growth medium, the Ca concentration was higher in Fusarium ‐inoculated shoots while K content was depleted, compared with non‐inoculated plants.