Abstract

A study was conducted to determine the effect of sweet potato growing methods on the yield of three sweet potato varieties. The field experiment took place at Africa University farm in Mutare, Zimbabwe. The trial employed a 5 x 3 factorial design arranged in a Completely Randomized Block Design (CRBD) with three replicates, blocked against irrigation lines. The five different sweet potato growing methods used were: Treatment 1 (use of mounds), Treatment 2 (use of ridges), Treatment 3 (flat method/minimum tillage), Treatment 4 (use of sacks), and Treatment 5 (use of plastic buckets). The three sweet potato varieties grown were: Beauregard (orange-fleshed), Okinawa purple (purple-fleshed), and German II (white-fleshed). Data were collected on both growth and yield parameters. The growth parameters measured included sweet potato vine length, number of leaves, and number of branches. The yield parameters measured included sweet potato tuber length, diameter, yield in tons per hectare, and harvesting index. From the yield parameters, the study showed that sweet potato varieties performed differently under the various growing methods. The Beauregard variety produced the highest overall yield of 15.5 tons per hectare (p < 0.05) under Treatment 4 (use of sacks). The Okinawa purple variety achieved its highest yield of 9.83 tons per hectare (p < 0.05) under Treatment 4 (use of sacks), while German II recorded its highest yield of 13.7 tons per hectare (p < 0.05) under Treatment 1 (mounds). All varieties recorded their lowest yield in Treatment 5 (plastic buckets), which was significantly different from the highest yields observed with the other growing methods. The highest overall harvesting index of 44.6% was obtained by the Okinawa purple variety grown in Treatment 1 (mounds). The German II and Beauregard varieties recorded their highest harvesting indices of 40.5% and 38.7%, respectively, from plants grown in Treatment 4 (use of sacks). All varieties exhibited their lowest harvesting index from plants grown in Treatment 5 (plastic buckets). The study demonstrated how different growing methods impact the yield and growth of three sweet potato varieties. The research showed that Beauregard and Okinawa purple varieties yield best with the use of sacks, while the German II variety performs optimally with mounds. The findings provide valuable insights for optimizing sweet potato cultivation and offer practical guidance for farmers and researchers aiming to enhance sweet potato production.

Key words: Agronomy, harvesting index, sweet potato, variety, yield.