Studies On Rapid Propagation Of Walnut Through Tissue Culture

The seedlings and pieces from walnut of 20 years were selected as experiment matrials. The experiment systematically studied such stages during the tissue culture of walnut as getting explants, building aseptic propagation lines, multiplicative propagations, rooting and transplanting. And discussed some key methods such as sterilization and preventing browning. But the contamination and browning of the explants from walnut of 20 years were serious. So the No.of shoots and calli wasn't meet the needs for statistical analysis. So some conclusions could be drawn through tissue culture of seedlings stems and leaves of walnut. The basic medium was modified DKW. The optimum hormone treatment of inducing axillary buds germination through walnut stems was BA0.5mg/L+KT0.5mg/L+IBA0.02mg/L. The optimum hormone treatment of forming callus through walnut leaves was 6-BA0.01mg/L+2,4-D0.01mg/L. The optimum hormone treatment of the multiplicative propagation of aseptic shoots was BA0.005mg/L+IBA0.001mg/L. The optimum hormone treatment of callus propagation was BA0.01 mg/L+2,4-D0.8mg/L. The optimum hormone treatment of inducing callus to form buds was KT0.8mg/L+NAA0.4mg/L. The basic medium of inducing roots was 1/2DKW+sucrose15g/L+agar7g/L. When the concentration of NAA was 10.0mg/L, the rooting rate was the highest and the growth of root was very vigorous. The survival rate of transplanting was the highest in the peat substrate. This experiment studied the effect of different buds positions in walnut stems on germination ability and the effect of different explants type and culture condition on callus fomation. The results showed that the suitable inoculating materials were the buds of apical buds or the 4th and 5th buds beneath the apical buds and the better materials were young walnut leaves in the aspect of inducing callus. And the culture condition of inducing callus was illumination. The experiment studied the effect of Penicillin on controlling contamination of walnut explants. The results showed the method of Penicillin (80μg/ml) and Derosal (3g) to soak walnut explants was significant in preventing contamination. This experiment studied the effect of PVP (polyvinylpyrrolidone) on inhibiting browning of walnut explants. The results showed browning was effectively controlled with PVP (250mg/L) to soak walnut explants and using PVP (100mg/mL) as the additional ingredients of medium. With the method of triquadratic regression combianation design, the results showed that the ability of inhibiting PPO activity was PVP>Na2S2O3(sodium thiosulphate)>AgNO3(silver nitrate).