Effect of planting density and prunings on yam bean tuber yields and quality

In an effort to elevate yam bean (Pachyrhizus erosus (L.) Urban) from a garden crop to a commercial crop the optimal planting density and pruning management were studied in relation to yield and tuber quality under field conditions at CATIE, Turrialba, Costa Rica for varying accessions. For each accession the number of tubers decreased with decreasing plant density, the average weight of the tubers increased and the total fresh weight yields were maintained. This confirms that by manipulating the plant density the tuber quality can be targeted to a specific consumer demand. Reproductive pruning did in contrast not affect the total number of tubers ha ¹ but accessions differed (p<0.05) in their total yield responses although in all cases did the tubers increase in weight on average. This positive yield effect of reproductive pruning may potentially be used to increase yield and in areas where smaller sized tubers are preferred, to obtain the desirable tuber size at high plant densities at an earlier date thereby advancing the onset of the marketing season.