Silicon in the management of bacterial wilt in three tomato varieties

Resumo

The effect of silicon (Si) supplementation on tomato seedling production of ‘Santa Clara’, ‘TY 2006’ and ‘Yoshimatsu 4-11’ cultivars (cvs.) was evaluated, aiming at the management of bacterial wilt caused by Ralstonia solanacearum (Rs). Seedlings of the three cvs. were produced in substrate without silicon (-Si) or with 3 g of calcium silicate/kg of substrate (+Si) and transplanted to soil with Rs (+Rs). The resistance components evaluated for 15 days were: incidence (INC) and severity (SEV), with calculation of the bacterial wilt index (BWI) and area under the disease progress curve (AUDPC). Additional variables analyzed included: plant growth, fresh and dry mass, reactive chlorophyll index, Si content in leaf tissues and Rs population in the stem. The enzymatic activities of phenylalanine ammonia-lyases (PAL), β-1,3 glucanases (GLU) and peroxidases (POX) were measured in the three cultivars produced in substrates (+Si) and (-Si) at the times: 0 to 96 h after transplanting. Si supplementation in the ‘Santa Clara’ and ‘TY 2006’ cultivars led to a reduction in the disease evaluated by SEV (33.2 and 42%) and BWI (21.7 and 10%), respectively. Si supplementation in the substrate did not affect growth, chlorophyll index, Si accumulation in the leaf or the Rs population in the stem tissues. Higher PAL and GLU enzymatic activity was observed at some moments in the three cultivars. Thus, tomato seedling production in substrate with Si can be a component in bacterial wilt management.