Preliminary findings on active root distribution of pepper on different supports using 32P tracer

P. Y. Yau, K. C. Tham and B. Kadmin

Abstract

The root activities of pepper and its support plant within 150 cm radial distance from the trunk and 100 cm depth were measured using the radioactive ³²P tracer soil injection technique. Root activity of pepper trailed on timber post (kulim) was compared with those trailed on live Erythrina indica and Gliricidia maculata. The experiments were conducted on deep sandy clay loam (Rengam series) derived from granite at Kluang. Generally, the type of support influenced active root distribution. On timber post, about 50% of the active roots were confined close (50 cm radial distance) to the trunk and 80% of which were within the surface 30 cm of soil. However, for pepper on Erythrina, there was a wider spread of the active roots beyond the 50 cm radius and over greater depths. In contrast, about 59% of the active roots of the associated Erythrina tree were found close (50 cm) to the trunk and distributed throughout the 100 cm depth. For pepper on Gliricidia, the active roots were fairly uniformly distributed both laterally and vertically within the soil profile while most (67%) of the active Gliricidia roots were found close (5 cm depth) to the surface distributed throughout the 150 cm radius.

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