Effects of severity of apical shoot harvest on growth and tuber yield of two sweet potatoes varieties

Abstract

Leaf harvesting of sweet potato during vegetative stage is common in most parts of Liberia. There is little information on the effects of severity of apical shoot harvesting on tuber yield of sweet potato. Experiments were conducted in 2017 at the Federal University of Agriculture, Abeokuta to determine the effects of severity of apical shoots harvest on growth and tuber yields. Experiment consisted of two varieties (SHABA and SPK-004) and three levels of cutting severity; no cutting, cutting of 15 and 30 cm long apical shoots at 4-weeks. Treatments were arranged in split plot with variety as the main plot and cutting severity as sub-plot arranged in (RCBD) with three replications. Data were collected on vine length, number of leaves per plant, number of branches per plant, leaf area, and leaf area index, fresh and dry apical shoots weight, tuber, unmarketable yield, marketable yield and total number of tuber. Data collected on growth, yield parameters were subjected to  analysis of variance and mean values separated using standard error at (p<0.05). In cutting severity, vegetative growth and tuber yield of SHABA were significantly higher than those of SPK-004. Cutting at 15 cm long apical shoots gave higher total tuber yields in SHABA than SPK-004. Cutting at 30 cm long apical shoots increased fresh apical shoot weigh in SPK-004 than in SHABA. For SHABA and SPK-004 had more tuber weight than 30 cm long apical shoots. Therefore, sweet potatoes whose apical shoot was cut at 15cm long for 4 weeks are recommended.      Key words:  Bacterial blight, disease development, grain yield, planting densities, percentage severity index.