Optimizing shoot proliferation and rooting of micropropagated Japanese quince (Chaenomeles japonica (Thunb.) Lindl. ex. Spach)

Japanese quince (Chaenomeles japonica) does not proliferate or root easily. In vitro proliferation and rooting of three genotypes of Japanese quince were tested in seven modified Murashige & Skoog (1962) (MS) media and six rooting treatments to optimize the micropropagation method. The interaction of proliferation media and rooting treatments was also studied. The proliferation media were modified by varying the concentration of either N-6-benzyladenine (BA 0.5-2.0 mg/l), iron chelate (NaFeEDTA 36.7 or 73.4 mg/l, or FeEDDHA 41.62 mg/l) or the macro nutrients (3/4-1/1), or by adding indole-3-butyric acid (IBA 0.1 mg/1). Proliferated shoots were either transferred to greenhouse for immediate planting in soil free substrate or pretreated in vitro. The pretreatment methods involved a two week treatment either with IBA (1.0 mg/1) or a hormone free 3/4 MS-medium before the shoots were placed in peat/vermiculite with or without dipping in IBA (2h in 250 mg/l or 5 sec in 500 mg/1) solution. The response to the different proliferation media was very genotype-dependent. Immediate planting of shoots resulted in poorer rooting (10 %) compared to planting pretreated shoots (68 %) suggesting that the absence of BA during the pretreatment period improved rooting. The combination of hormone free pretreatment and 2 h bath in IBA resulted in highest rooting (77 %, sum of root length 11.8 cm) for all genotypes.