Abstract
We examined inter-patch variation in the degree of seed-set and seed size of white clover (Trifolium repens) in a T. repens-Zoysia japonica coexisting sward. Following questions were addressed : How efficiently does T. repens set seeds in this sward? Are there any differences in the degree of seed-set and seed size among T. repens patches and at different flowering times? If so, what features of patch will account for the differences ? Three classes of flower-heads distinguished according to their flowering time were collected at random from ten patches in the sward. They were measured for their number of florets, the number of seeds produced, the number of seeds per each pod, seed weight and peduncle length. Average number of seeds per pod was 1.31±0.31 (mean±SD) pooled over all patches, ranging from 0.92 to 1.83. The percentage of florets containing one or more seeds (fruit set) and florets containing three or more seeds were 68.8±10.2% and 16.3±8.3%, respectively. Significant differences in seed-set and seed size were found among the patches and among the flowering classes. Inter-patch differences in seed-set had no significant relationship with features such as patch size and average size of flower-head. However, it had a significant relationship with the average peduncle length of patch, suggesting the possibility of patch selection by pollinators. Patterns of the differences among the flowering classes were so complex. These findings showed that the patches differed considerably in the extent to which they contributed to seed number and quality of the entire sward. They also suggested that spatiotemporal patterns of T. repens seed-set in this sward may be partly related to the nature of polination behavior of honeybees and bumble bees.
