Abstract
The role of cinnamic acid in resistance of black pepper to black stem rot were studied by using Lampung Daun Lebar (LDL), Jambi and Bangka variety. Intact and detached leaves were inoculated with two Phytophthora isolates namely Belitung and Bogor isolate. The development of symptom and cinnamic acid content were measured on infected leaves using Spectrophotometer uv vis on ware length of 200 - 400 run. The result indicated that cinnamic acid rapidly decreased during the first2 days after inoculation. Based on the symptom and cinnamic acid content, Bangka variety was proved to be more resistant than the other two black pepper varieties
