Abstract
In Costa Rica yields of eddoe (Colocasia esculenta var. antiquorum) cormels are generally low (7 t ha-1). To determine the physiological reasons, the accumulation and partitioning of dry matter (DM) was monitored from 0 to 243 days after planting in an experiment comparing five management regimes. The rate of total DM accumulation was low; the maximum observed was 107 kg ha-1 day-1. Furthermore, the partitioning was unfavourable; only 9 t ha-1 of the highest tuber yield of 37 t ha-1 (fresh) consisted of marketable cormels. Yields were strongly correlated to the leaf area, which reached a low peak late in the crop cycle, and declined soon after. The low leaf area index constrains DM production by the crop and allows weeds to grow strongly. The DM has to be partitioned over several organs, but only the cormels are marketable. These problems might be solved by selecting or breeding for a more efficient plant type, and by ensuring rapid and even sprouting of seed cormels so that the canopy closes quickly.
