Growth of sweet potato (Ipomoea batatas L.) as affected by pH in solution culture

Abstract

Sweet potato (Ipomoea batatas L.) is the most important food crop in many Pacific nations. The crop is propagated from stem cuttings in soils varying widely in pH and other chemical properties. However, little is known about the effects of pH on the growth of sweet potato. This paper reports the effects of a range of pH treatments (3.0 to 8.0) in solution culture on root and top development from cuttings of four sweet potato cultivars (Wanmun, Lole, Hawaii and Beerwah Gold) over 14 d. At pH 3.0 and 3.5, no root growth occurred. Increasing the pH to 4.0 significantly increased root and top development. Further slight increases in growth were evident at higher pH, the optimum pH for root and top growth varying from 4.5 to 7.0 for the four cultivars. Generally, as pH increased there was a decrease in the concentration of nutrients remaining in solution at the end of the experimental period. This was especially so with K which remained high at pH 3.0 and 3.5; little residual K was present at pH 4.0 to 8.0.