Can the Inherent Antioxidant in Yellow-Fleshed Cassava Varieties (Manihot esculenta Crantz) and Fertilizer Application Suppress Root Rot?

Abstract

Cassava root rot disease has been reported to cause huge losses of fresh root yield particularly when harvesting is delayed. The improved yellow-fleshed cassava varieties naturally contain antioxidant whereas antioxidant has been widely used to control plant root rot diseases in the tropics. The experiment was carried out at Federal University of Agriculture, Abeokuta, Nigeria in 2013/2014 and 2014/2015 cropping seasons to investigate: 1) the possibility of inherent antioxidant in yellow fleshed cassava root tuber to control root rot disease, 2) role of fertilizer application on tuber rot incidence and 3) delay harvesting of tubers on root rot incidence and, yield. The experiment was laid out in randomly completed block design arranged in a split-split plot and replicated three times. The main plot, subplot and sub-subplot treatments were four cassava varieties, 5 nitrogen levels, 4 potassium levels. Cassava harvested at 14th month produced the lowest root rot, longest tuber root and highest root yield in 2013/2014 and 2014/2015. TMS 98/505 (white-fleshed cassava) variety had the highest root rot. Cassava root yield had a positive correlation with tuber girth, number of tubers, tuber length and negative correlation with root rot at 14 and 16th months in 2013/2014 and 2014/2015, respectively. It was concluded that the white-flesh cassava varieties could not be delayed beyond 14 MAP, but the yellow varieties can further be delayed to 16 MAP. Besides, the study affirmed that white-fleshed cassava variety had the highest rot incidence suggesting that inherent antioxidant in yellow-fleshed cassava varieties can minimized rot incidence. However, fertilizer do not seem to influence tuber root.

Keywords

• antioxidant
• fertilizer
• cassava varieties
• delay harvesting
• tuber rot