Optimizing Sweetpotato Seed Root Density and Size for Slip Production

摘要

There is a research gap with respect to documenting the effects of sweetpotato (Ipomoea batatas) seed root density and size on transplant yield and quality. Field studies were conducted in 2012 and 2014 to determine the effect of sweetpotato seed root (canner size) density 12, 24, 37, 49, 61, 73, and 85 bushels bu (50 lb) per 1000 ft(2) on 'Covington' and 'Evangeline' slip production in propagation beds. Another field study was conducted in 2012 and 2013; treatments included canner, no. 1, and jumbo-size 'Covington' roots at 49 bu/1000 ft(2), to determine the effect of seed root size on slip production. As seed root density increased in the propagation bed, transplant production increased with no change in slip quality as measured by node counts and slip length except for stem diameter. In 2012, the best marketable slip yield was obtained at root densities of 73 and 85 bu/1000 ft(2). In 2014, marketable slip production of 'Evangeline' increased as seed root density increased at a greater rate than 'Covington'. In 2014, the best seed root density for marketable slip production was 49 to 85 bu/1000 ft(2) for 'Covington' and 85 bu/1000 ft(2) for 'Evangeline'. In 2012, potential slip revenues increased with an increase in seed root density up to 73 bu/1000 ft(2). In 2014, revenue trend was similar for 'Covington' as 2012; however, for 'Evangeline', revenue was greatest at 85 bu/1000 ft(2). Seed root size had no effect on marketable slip production when using a once-over harvest system. Results suggest growers would use a seed root density from 49 to 85 bu/1000 ft(2) depending on variety, and any size roots for production of optimum marketable slips. Selection of optimum seed root density also depends on grower needs; e.g., high seed root density strategy will have a higher risk due to the upfront, higher seed costs, but potentially have higher profits at harvest time. Lower seed root density strategy would be a lower initial risk with a lower seed cost, but also potentially have lower net revenues.