Abstract
Effects of shading (relative light intensity: RLI 100%, 80%, 70%, 50% and 30% of natural sunlight) on growth and seed production of Paspalum urvillei Steud., a perennial weed, were investigated and the following results were obtained.
1. Plant height increased with decreasing relative light intensity. Tiller number decreased at higher RLIs.
2. Total dry matter weight (top dry matter weight plus root dry matter weight) and top dry matter weight attained high values at 70% and 80% RLIs. These results may be attributed to the increases in leaf area and tiller number.
3. In the characters associated with seed production all but 1, 000 seed weight increased at 80% RLI, resulting in maximum seed production at this RLI.
4. In this weed, both growth and seed production were enhanced under lower shading conditions, indicating that control programs should be crried out in advance of the time when the crop provides sufficient shade cover for the weed.
