INDUCED RESISTANCE MECHANISM OF SOME CHEMICALS AGAINST DOWNY MILDEW CAUSED BY Peronospora belbahrii IN BASIL

Abstract

Induced resistance methods in crop protection against pests and diseases are effective and environmentally friendly plant protection strategies. This study investigated the ability of Benzothiadiazole (BTH), Salicylic acid (SA) and Calcium silicate (CaSiO₃) to induce resistance in basil (Ocimum basilicum) against downy mildew caused by Peronospora belbahrii, through disease assessment and analysis of related  induced resistance mechanisms.The results show that foliar spraying BTH 50 mg/L and SA 1 mM at two days before infection, or soil drenching with CaSiO₃ 1 g/kg soil at seven days before infection, effectively reduces disease incidence and the percentage of infected leaf area.The increase Phenylalanine ammonia-lyase (PAL) enzyme activity in the early stage at 12 hours after infection (hai) and 24 hai in basil plants treated with BTH 50 mg/L, SA 1 mM, and CaSiO₃ 1 g/kg, as well as the increase in β - 1,3 - glucanase enzyme activity at 72 hai  in basil plants treated with SA 1 mM, BTH 50 mg/L, and CaSiO₃ 1 g/kg, are associated with the induced resistance mechanism in basil plants against downy mildew caused by Peronospora belbahrii.