Study on comparison of rootstocks for Gonggan (Citrus reticulata Blanco cv. gonggan)

Graft affinity,growth of tree,quality of early fruit setting as well as high yielding,yield and fruit quality of different graft unions were studied systematically using Guangdong Lemon(Citrus limonia Osbeck),Suanju(Citrus reticulata Blanco),Jiangxihongju(Citrus reticulata Blanco),and Large leaf and flower Trifoliate Orange 〔Poncirus Trifoliata(L.) Raf.〕as rootstocks for Gonggan.The results indicated that four rootstocks for Gonggan appeared excellent graft affinity with no significant differences.All rootstocks seemed to form tree-crown early,and Gonggan with Trifoliate Orange rootstock had moderated vigor as well as dwarf tree-crown.Gonggan with Trifoliate Orange and Guangdong Lemon rootstocks had great quality of early fruit setting as well as high yielding,and yields of the stage of beginning to bear fruit appeared significant difference compared with that of Gonggan with Suanju and Jiangxihongju rootstocks.However,there were no significant differences among yields of all Gonggan during the harvest stage.The fruits with Trifoliate Orange,Suanju and Jiangxihongju rootstock possessed great quality,containing a high level of dissoluble condensate,total sugar and acid.On the contrary,Gonggan with Guangdong Lemon rootstocks had undesirable quality with vesicle collapsed fruits,containing relatively low level of dissoluble condensate,total sugar and acid.It was recommended that Trifoliate Orange,Suanju and Jiangxihongju as the appropriate rootstock for Gonggan in Guangdong province,while Guangdong Lemon was unsuitable when used as rootstock for Gonggan.