J. C. Bouwkamp and L. E. Scott
Total yield and yields of sweet potatoes measuring 5-9 cm diameter (No. I size) and 2.5-5 cm diameter (No. 2 size) were found to be highest at the closest spacing studied (30 cm between plants, 90 cm between rows) after a full season’s growth (120 days). This effect occurred because as spacing between plants decreased, the number of roots per plant increased but not at an equivalent rate. Thus, when possible, sweet potato growers should practice close spacing and plan to control root size distribution by delaying the harvest date. If this is not feasible (due to various time constraints), root size distribution can be affected by wider spacings. In general, wider spacings (up to 60 cm) will result in any given root size distribution earlier, but with less yield.
Annals of Tropical Research 2 (1):(1980)