Slag-based silicon fertilizer improves the resistance to bacterial fruit blotch and fruit quality of melon grown under field conditions

Abstract

Bacterial fruit blotch (BFB) caused by Acidovorax citrulli (Ac) is the most destructive bacterial disease affecting melon production in northeastern Brazil. Silicon (Si), which is widely recognized for suppressing plant diseases, has been proposed as a possible alternative for the control of BFB. Field experiments were conducted to evaluate the effects of slag fertilization on bacterial blotch development, soil chemical properties, plant growth and nutrition, and fruit quality. Melon hybrids AF 4945 and Medellín were grown in slag-fertilized (5.00 t ha−1) and non-fertilized plots, being inoculated with Ac 25 days after emergence. The slag fertilization significantly reduced the area under the disease progress curve (10%), disease index (14%) and disease incidence in fruit (12%) at harvest, regardless of hybrid. Slag fertilization improved the soil fertility, plant growth and nutrition after 55 days of cultivation. Tissue analyses showed no differences in Si accumulation between the melon hybrids. However, AF 4945 accumulated more Ca and Zn than Medellín, which was associated with higher reduction in disease intensity. Also, slag treatment increased fruit flesh thickness (8%) and soluble solids (7%). Our study confirms that the supply of slag to the soil previously assessed under greenhouse studies can reduce the severity and incidence of melon BFB while improving fruit quality under field conditions.