To assay the chitinase activity, one gram of crown tissue was ground using a pre-chilled pestle and mortar with 0.1 M sodium citrate buffer (pH 5.0) at 4 C. The homogenate was centrifuged at 10,000 rpm for 20 min. The supernatant was used as a crude enzyme extract for assaying chitinase activity. Similarly, for the extracts of b-1, 3-glucanase and phenylalanine ammonia-lyase (PAL) enzymes, 0. 05 M sodium acetate buffer (pH 5.0) and 0.1 M sodium borate buffer (pH 7.0) at 4 C respectively were used. The changes in the chitinase activity were determined by colorimetric assay described by Boller and Mauch (1988). The PAL activity was determined as the rate of conversion of L-phenylalanine to transcinnamic acid at 290 nm as described by Dickerson et al. (1984) and b-1, 3-glucanase activity was assayed by the laminarindinitrosalicylic acid method (Pan et al., 1991). The results from these assays were graphed using Microsoft Excel.