Stool Layering Ability of Thirty-One Apple Rootstock Cultivars

Abstract

Twenty-seven apple clonal rootstocks were compared for stool layering ability in a randomized and replicated trial 3, 4 and 5 years after planting. Observations on the rooting of four other apple rootstocks in stool layer beds in adjacent non-replicated plots are also included. The mean number of rooted shoots produced per m of row increased from the third to the fourth year and then leveled off. The change in production of rooted shoots among rootstocks with year was small. Thirteen rootstocks, including V5-38, Malling-Merton (MM.)111, Malling (M.)26, Budagosky (B.)54-118, MM.106, Morden (MO.)56-4, M.4, B.490, B.491, M.27, B.54-233, Alnarp 2, M.7, Jork 9, Robusta 5, P-18, and P-16 were significant by higher than or indistinguishable from M.9 in production of rooted shoots. P-22, B.9, P-2, P-1, Ottawa 3, and MO.56-3 produced significantly fewer rooted shoots than M.9. Antonovka, I48-41, and M.25 produced very few rooted shoots. Production of rooted shoots was closely related to rooting ability but the most productive rootstocks tended also to produce the highest number of shoots per meter. Furthermore, the amount of root formation was greatest on shoots of the most productive rootstocks. In the observation block, MARK, B. 54-146, YP(Mb-4) propagated as well as M.9, whereas M.20 did not. B.54-146 was noteworthy because of the numerous, long roots that developed on its shoots.