Calcium Nutrition Affects Resistance of Tomato Seedlings to Bacterial Wilt

Abstract

The relationship between Ca nutrition and bacterial wilt development was studied on three tomato (Lycopersicon esculentum Mill.) cultivar seedlings with various degrees of resistance to the disease. Seedlings were transplanted into nutrient solutions with Ca at 0.4, 4.4, or 20.4 mm. One week after initiating the Ca treatment, tomato seedlings were inoculated by wounding the stem with scissors dipped in a suspension of the pathogen (Pseudomonas solanacearum E.F. Smith). Disease development was rapid in `Ponderosa' (a susceptible cultivar) at all Ca concentrations. Increased Ca concentration in the nutrient solution reduced disease severity in `Zuiei' (a moderately resistant cultivar). Resistance was negated at the low Ca concentration in `Hawaii 7998' (a highly resistant cultivar). Pathogen populations in stems decreased with increased Ca concentrations and degrees of resistance.