VARIATION IN THE CONCENTRATION OF SURFACE TERPENOIDS IN STORAGE ROOTSOF CENTENNIAL SWEET-POTATO

The effect of plant to plant variation and root size, weight, and loca tion on storage root surface terpene chemistry of Centennial sweetpota to was investigated under field conditions. In plants grown in pots, t he magnitude of the variation in concentration of boehmerol and boehme ryl acetate between plants in different pots, plants within pots, root s from a single plant, and location on individual roots was evaluated. Significant differences in boehmerol or boehmeryl acetate due to stor age root location order along the axis of the underground stem were fo und for some individual plants, but the trend was not consistent among plants. A similar response was found for the distance down the underg round stem at which the storage root was attached. Differences in surf ace chemistry between roots from a single plant appeared to be control led by factors other than location along the main axis. Storage root l ength to diameter ratio accounted for 42% of the variation in boehmero l. The inverse of root density and its squared value combined accounte d for 36% of the variation in boehmeryl acetate. These relationships w ere found among roots growing within a 5-m-diameter area of field, but were not present when the roots were from different sites. In pot exp eriments the greatest variance was due to pots; the within root variat ion was the smallest. Results of this study suggest that when selectin g against boehmerol or boehmeryl acetate, more than one root per plant should be used to compensate for within plant variation, while one me asurement per root was adequate.