Studies On Regeneration And Hardening-off Of Chinese Dwarf Cherry

The Chinese dwarf cherry (Cerasus humilis Bag.), a small fruit tree, belongs to the cerasus genus of Rosaceae family. The cultivars were bred by Shanxi Agriculture University in recent years. Among these newly bred cultivars, three cultivars were used in this experiment to study the callus inducing of leaf, the differentiation, regeneration, hardening-off and transplanting of plantlet. The main results are as follows:(1) Different hormone, different concentration could have different percentage of callus induction. The medium MS+6-BA0.12-0.16+NAA 0.8~ 1.2 was the best. The medium MS+6-BA0.20+NAA0.8-1.2 seconded to it.(2) The percentage of callus induction was affected by some factors, such as origin of leaf, position of leaf, part of leaf and laying model. Tube seedling leaf was better than greenhouse seedling leaf. Field leaf was the worst. In the same shoot, upper leaf was better than middle leaf. Lower leaf was the worst. In the same leaf, middle part was better than back part. Front part was the worst. Face of leaves upward was better than back of leaves upward.(3) It would take two weeks in darkness that the callus of the explants was switched on, then the callus amplification and its further differentiation must be in light.(4) Significant differences of callus inductive rate and index of induction were found among the various genotypes of explants ,"Nongda No.3"was the easiest one .(5) Medium MS+2, 4-D1.4mg/L was the optimum medium for callus proliferation. The optimum medium of inducing callus to form buds was l/4MS+ZT2.0mg/L, l/4MS+BA2.0mg/L seconded to it.(6)The optimum medium of shoot induction was MS+6-BA0.2mg/L+NA A0.1 mg/L, MS+6-BA0.2mg/L+IAA0.05mg/L seconded to it.(7)The medium of inducing roots was l/2MS+lAA1.2mg/L for No.4. The medium of inducing roots wasl/2MS+IAA2.4mg/L for No.3 and No.5(8)During hardening-off in natural light, the survival rate of transplant was the highest when the tissueculture bottle was covered with a lid for 10d and opened for Id. When plantlets were transplanted intomixture ground-substance under a small plastic shed and temperature was kept between 18℃ to 30℃,humidity between 80% to 100% during early stage, 50% to 60% during late stage, were survival rate oftransplant reaches 90%. After 45d to 50d, when the plantlets were transplanted into a plastic culture plate,the survival rate of transplant exceeded 95%.The experiment has studied the technique about callus induction of leaf, plant regeneration and hardening-off of Chinese dwarf cherry. This technique is relatively complete and provides some basis of studies for clonal variation and gene transformation.