| Dwarf culture is the development direction of the world apple industry. One of the main way to realize the dwarf culture is using dwarf rootstocks. Compared with the dwarfed interstock, the self-rooted stock had high uniformity, early fruited, high yield, good quality, and many other advantages. Propagation ways of self-rooted dwarf mainly were using the layering, cuttage and tissue culture. Compared with grafting and layering, tissue culture had many advantages, such as less material, high propagation coefficient and so on. Taking the new dwarf rootstocks strains chosed by the Apple research team of the AUH and the cold-resistant apple dwarf rootstock 71-3-150 and 60-160 bred by Russia as experimental materials, the growth state and the physiological or biochemical indicators of tissue culture treated with different ratio of plant growth regulators were explored. The rapid propagation system by tip culture was etablished. It can guarantee that self-rooted stock seedlings applied to production rapidly and provide reference for rapid micro-propagation of apple dwarf rootstock.The main results were as follows:1. March 20 is the suitable period to get materials among March 20, June 10 and August 2. Annual branches were taken on March 20, water cultured indoor. The new shoot length was longer than 1.5 cm, inoculated it on the medium. Then the lowest pollution rate(10%) and the highest survival rate(76.7%) were obtained.2. Explants were disinfected with 70% ethanol for 30 s and 0.1% Hg Cl2 solution for 8 min, the pollution rate was low(7.5%) and the survival rate was high(77.5%). After sterilizing with Hg Cl2, we can take the explants of browning stock ST soaked in 25 mg·L-1 VC solution for 20 min instead of the last time distilled water rinse. Then it can effectively reduce the browning rate of the explants.3. For the apple stock 71-3-150、No. 6、No.111 and so on, the optimal ratio of PGR for induction culture was 6-BA 1.0 mg·L-1 + NAA 0.05mg·L-1. For each stock, the optimal PGR ratios for subculture and rooting culture were as follows: subculture medium for 71-3-150 was 6-BA 1.0 mg·L-1 + NAA 0.05 mg·L-1, rooting medium was IAA 1.0mg·L-1 + IBA 0.6 mg·L-1. For No.111 subculture medium were 6-BA 0.5 mg·L-1 + NAA 0.1mg·L-1 + 1.5 g·L-1PVA, 1.0 mg·L-1IBA for rooting medium respectively, No. 6 strain subculture medium was 6-BA 1.0 mg·L-1 + NAA 0.05 ~ 0.1mg·L-1, Rooting medium was IAA 1.0 mg·L-1 + IBA 0.4mg·L-1. The subculture medium for 60-160 strain was 6-BA1.0 mg·L-1 + NAA 0.05mg·L-1, rooting culture medium was IAA 1.0 mg·L-1 + IBA 0.6 mg·L-1. Subculture medium for No. 28 and 9-3 was 6-BA 1.0 mg·L-1 + NAA 0.1mg·L-1, rooting medium was IAA 1.0 mg·L-1 + IBA 0.4mg·L-1. No. 1, No.36 and 3-45 subculture medium were 6-BA 0.5 mg·L-1 + NAA 0.1 mg·L-1, the concentration of IBA for rooting was 1.0mg·L-1. For the rootstock No. 111, No. 1, No. 36 and 3-45, they need 7 days culture under darkness, then cultured under the light/dark cycle of 12h/12 h when they are rooting culture.4. The cuttings surviving rate was 33.3 % using subcultured plantlets of No.6, which was treated 15 min in 500 mg·L-1IBA. The subculture plantlets were cultured on the rooting medium for 2~4 days then trained in greenhouse for 9 days, which had yet to grow roots, the cuttings surviving rate was 98 % higher.5. There were no significant differences in protein for plantlets of different treatments, but there was consistent between the chlorophyll content and leaf color. PPO, POD and CAT activity of the tissue culture plantlets had certain correlation with the growth state. When the growth state of the tissue culture plantlets was better, chlorophyll content is higher, POD, SOD and PPO activity is lower and the CAT activity is higher. There was no obvious regularity of PAL activity for the tissue culture plantlets of different treatments.6. The content of endogenous hormone ZR of No. 111 tissue culture plantlets increased at first and then decreased in the range of 0.05~0.15 mg·L-1 of exogenous hormone NAA in the same concentration of exogenous hormone 6-BA(0.5~1.5 mg·L-1). ZR had the same trend within 0.5~1.5mg·L-1 of 6-BA in the same concentration of NAA. The content of endogenous hormone GA of tissue culture plantlets 71-3-150 increased at first and decreased subsequently in the range of 0.5~1.5 mg·L-1 of 6-BA, but the other endogenous hormones had no obvious regulation by the application of PGRs.7. The growth coefficient of 71-3-150 was very significant negatively correlated with the content of endogenous GA(r = 0.91), significant negatively correlated with GA/ZR ratio, and significant positively correlated with the ratio of IAA/GA. The plantlet height of 71-3-150 were significant negatively correlated with the content of endogenous GA and the ratio of GA/ZR, and was significant positively correlated with IAA/GA ratio. The growth coefficient of No.111 had very significantly negatively correlation with the content of endogenous ZR and positive correlation with GA/ZR ratio. The correlations between plantlet height of No.111 and the content of measured endogenous hormones or their ratio were not significant. |
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