Evaluation of nano iron and zinc chelated fertilizers on okra Abelmoschus esculentus infected with Meloidogyne javanica

Root-knot nematodes, Meloidogyne species are among the most critical plant-parasitic nematodes attacking okra Abelmoschus esculentus (L.) Moench in tropical and subtropical regions. In the present study, the effects of various levels of zinc and iron on okra infected with M. javanica were investigated under greenhouse conditions in a completely randomized factorial design with five replications. Four-leaf stage seedlings of the susceptible okra, cv. Clemson Spineless were inoculated with 8000 eggs of M. javanica per pot. Five days later, the soil of each pot was treated with a combination of iron or zinc (0, 1, 3, and 6 mg∙kg-1 soil) from nano chelated iron and zinc fertilizer sources. Sixty days after inoculation, plants were harvested, and okra growth indices and nematode population indices were determined. Results showed that vegetative indices increased in most cases compared to non-treated plants. Fruit fresh weight of inoculated plants treated with iron at the rate of 1 mg∙kg-1 soil + zinc at the rate of 3 mg∙kg-1 soil from nano chelated iron and zinc fertilizer sources increased by 205%, compared to inoculated control plants. Combined application of iron at the rate of 6 mg∙kg-1 soil + zinc at the rate of 6 mg∙kg-1 soil from nano chelated iron and zinc fertilizer sources reduced the number of eggs, galls, and egg masses per root system and the reproductive factor (224, 415, 455 and 231%, respectively) compared to non-treated plants.