Effect of Supplemental Irrigation on Reducing Cyanide Content of Cassava Variety Kasetsart 50

Abstract

Cassava’s cyanogenic potential, exacerbated during drought, remains a challenge to optimizing its production and consumption. This research investigated how supplemental irrigation during the dry season could reduce the cyanide content in the highly-cyanogenic cassava variety Kasetsart 50 (KU50). KU50 stakes were planted in May 2009 at Khao Hin Son Research Station, Inseechandrastitya Institute for Crop Research and Development, Kasetsart University, Chachoengsao province. A split-plot in a randomized complete block design was used, with three harvest periods (6, 9, 12 mth after planting; MAP) as main plots, three irrigation treatments (T0, rain-fed only; T1, 30mm.mth^-1, split into three applications; and T2, 60mm.mth^-1, split into three applications) as subplots, and four fi eld replications. Root samples harvested at 6, 9 and 12 MAP were analyzed for total cyanide, non-glucosidic cyanide (NGC), and bound cyanide contents in the whole root, peel and parenchyma. Roots harvested at 9 MAP had the lowest bound and total cyanide, and the highest starch content. T2 yielded the lowest NGC, bound and total cyanide, and the highest starch content. Thus, irrigating with 60mm and harvesting at 9 MAP produced the lowest cyanogenic content and highest starch percentage in cassava roots. No signifi cant effect was observed on the number of bulking roots, the plant height and plant top weight. However, supplemental irrigation signifi cantly (P < 0.05) increased the starch content and root yield, but reduced the protein content.