摘要 : In early 1970, a breeding program was initiated at Agriculture and Agri-Food Canada, Quebec to develop winter hardy rootstocks for cold climates. Seeds harvested in 1975 from controlled crosses between '<i>Malus robusta</i> R-5' a... 展开 In early 1970, a breeding program was initiated at Agriculture and Agri-Food Canada, Quebec to develop winter hardy rootstocks for cold climates. Seeds harvested in 1975 from controlled crosses between '<i>Malus robusta</i> R-5' and 'M.26' or with 'Budagovsky 579490' (B.490) were germinated under greenhouse conditions, and about 1000 seedlings were subsequently planted in 1980 in a nursery and evaluated. Subsequent orchard evaluation of these rootstocks in several locations within Quebec begun in 1984 resulted in the selection of nine of rootstocks named the St. Jean (SJ84) series: SJP84-5218, SJP84-5217, SJP84-5230, SJP84-5198, SJP84-5162, SJP84-5231, SJP84-5174, SJP84-5189 and SJP84-5180 which were released for commercial evaluation. All of the SJP84 rootstocks are winter hardy, easier to propagate in stool bed compared to 'O.3' and produce a thick and vertical growing sucker in stool bed. No sign of mildew, scab, woolly aphids or incompatibility was observed on these clones. 收起