| Hazelnut is one of the world's six major nuts. It is valued to extension for its high economic value. Layering is the currently practiced propagation method which has a low propagation coefficient. Cuttings and grafting have low rate of seedling production. The excellent seedlings are in serious shortage in the face of the rapid development of hazelnut industrialization. In this paper, we have taken C. heterophylla×C. avellana 84-254,84-349, 82-11 and C. avellana L. Barcelona, Ehnes for materials to research hazelnut tissue culture technology and the air sub-layering systematically. We explored each aspect of the key measures with a view to setting up a high-performance hazelnut breeding system which can help to implement rapid propagation of hazelnut. The results are shown as follows:(1) The best way of sterilization was washed in tap water, then soaked in 75% alcohol for 15 s, followed by washing in sterilizing water, and in 0.1% mercuric chloride for 5 min before taking back the hazelnut stem. The pollution rate could be controlled at less than 10.00%.(2) Explant collection time had significant impact on pollution rate, browning rate and germination rate. April, May and June were the best time of collecting stems. The young shoots with buds of greenhouse seedlings and the upper part of young shoots of greenhouse layering were taken as hazelnut tissue culture material.(3) The tissue culture seedlings grew slowly. Leaflets were yellow in MS medium; produced too much callus in WPM medium; high germination rate and stem elongation in DKW. The DKW was the most suitable basic medium for hazelnut.(4) The proliferation and stem growth were best when adding 6-BA3 mg/L, IBA0.05 mg/L in proliferation medium of hazelnut through the comparative analysis of orthogonal test.(5) FeEDTA and organic chelate iron substantially reduced the yellow rate, and promoted the proliferation and growth of shoots. The organic chelate iron was better than FeEDTA in proliferation and stem elongation. The result was best when using organic iron chelate with a concentration of 150-200 mg/L in proliferation culture of hazelnut.(6) The glucose, sucrose, lactose, fructose greatly promoted hazelnut proliferation and growth of new leaves. The proliferation effect of glucose and fructose was markedly better than the other two types of sugar. Using glucose 30 g/L instead of fructose as the carbon source of hazelnut tissue culture reduced the experiment cost. The addition of coconut milk promoted differentiation of multiple shoot clumps, and the concentration of 3 ml/L was the best for the proliferation of hazelnut.(7) IBA was better than NAA in rooting effect. The rooting rate, average root number and average maximum root length were the best when adding IBA 2.0 mg/L in the medium, so the satisfactory rooting medium was 1/2DKW+IBA 2.0 mg/L. When sand matrix was chosen as the transplanting medium, the survival rate of hazelnut was 95.00%.(8) In the air-sub-layering of C. heterophylla×C.avellana test, the results indicated that, the concentrations of IBA had a significant impact on root index,2500 mg/L produced the optimal rooting effect. The rooting rate varied with the hazelnut cultivars, and 84-254 was significantly better than 82-11. The result of rooting differed significantly in June, July, and August in the rate of rooting, the root length, and the number of roots taken. June was the best time. The three matrix presented significant difference in rooting indices. When peat soil and perlite were mixed by a certain percentage (1:1), the root layering effect was increased significantly. The upper, middle and lower segments had differences in rooting effect. It is upper segment> middle segment> lower segment in rooting rate, root length, root number, and root indices. Sub-air-layering significantly improved the breeding coefficient of hazelnut, and thus raised the efficiency of hazelnut breeding greatly. |
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