GROWTH AND YIELD RESPONSE OF SWEET POTATO [Ipomoea batatas (L.) Lam.] VARIETIES TO PLANTING METHODS AND ROW SPACING AT WOLAITA SODO, SOUTHERN ETHIOPIA

Sweet potato is one of the important root crops in Wolaita, however, the productivity of the crop is low partly due to the use of inappropriate planting methods and plant densities for varieties grown. Therefore, this study was conducted to determining the effect of planting methods and planting population on growth and yield of two improved sweet potato varieties (Awassa-83 and Kulfo). The three planting methods (top of the ridge, one side of the ridge, and flat bed) and three row spacings (50 cm, 60 cm and 70 cm) along with varieties were arranged in 2x3x3 factorial combinations and laid out in randomized complete block design (RCBD) with three replications. The results showed the significant effect of at least one of the three main factors (variety, planting method and plant spacing) and the possible two factors interactions on all the measured parameters. Moreover, the three factors were interacted significantly influenced most of the yield components. Variety Awassa 83 planted on top of the ridge at row spacing of 70 cm produced significantly highest marketable storage root yield of 24.12 t ha-1where as, variety Kulfo planted on top of the ridge at spacing of 70 cm had significantly highest total storage root yield (37.9 t ha- 1), number of primary branch (9.3), above ground fresh biomass (381.1g/p), shoot dry root weight (146 g/p) root fresh weight(1396 g/p), root dry weight (491.5 g/p),storage root length(27.12cm),storage root diameter(13.27cm)and unmarketable storage root yield(20.8t ha-1). Generally, both varieties planted on top of ridge in combination of each row spacing recorded significantly highest mean values for most of growth and yield components, while the lowest mean values were registered from flat bed planting method. The significant influence of one or more of the three main factors, possible two and three factors interactions on plant growth, yield components and storage root yield suggested the importance of using high yielding variety with appropriate planting method and plant spacing to improve the productivity of the crop. Thus, variety Awassa 83 and kulfo at 70 cm spacing planted on top of the ridge recommended to improve the productivity of marketable root yield and foliage yield respectively in the study area