| Walnut (Juglans regia L.) is both an elite economic species and one of the important nut. It has long cultivated history and widely distributed in our country. But the conventional breeding limits the rapid expansion and extension for elite walnut variety for long breeding cycle ,low propagation coefficient and low survival rate.Stock cultivating, nurse seed grafting, methods to improve the micro-grafting's survival rate and scion cultivating methods was researched in this article.The major improvement and innovation was that great breakthrough has been achieved in major technology.The main results were as follow:1. Comparative tests of shoots stock cultivation methodsCurrently, Cultivating a walnut grafted seedlings costs at least 2 years, and even 3 or 4 years. As rootstock, the One-year-old seedling is not able to meet the grafting demands.while our experiments showed that the walnut grafted seedlings to be seedling-selling only in 1 year.The results were as follow: Peat and perlite (1:1) with sand and mushroom residue (1:1) was the appropriate matrix which cultivated walnut rootstock shoots. The walnut germinated quickly, grew fast and was conducive to grafting; grafting rate was above 70% in late May.Arch Shed enhanced the sprouting of walnut seeds which seedlings were the largest and most conducive to grafting, grafting rate was 71.33%. The growth of seeds sowing in autumn was significantly improved. The earlier the seeds sowed in autumn the better the growth of seedlings, which would favor the grafting next summer.2. Study on nurse seed grafting methods of Juglans regiaThe paper used the tender scion cleft-grafting,the modified square budding grafting and bud grafting with xylem. The grafting survival rates were respectively 95.00%, 86.67% and 63.33% and the scion's yearly increments were respectively 48.78cm, 38.59cm and 35.93cm. The walnut tender scion cleft-grafting was superior to others. Because three grafting methods used the buds had different location on the scion. So the three methods can be used in practice at the same time to make a full use of the scion. The study made it feasible to be seedlings after grafting one year.3. Study on improving the micro-grafting survival rateThe tests of different growth regulators showed that the graft survival rate was 56.69% the highest which soaked scion in the solution with 6-BA 1.0mg·L-1and IBA0.1mg L-1. The test of conserving the scion at different temperatures and moisture showed that the Survival Rate was 50.00 % the highest when the scion fully embedded and only keep top of the scion out at the temperature of 26-28℃. The tests of the infection of different culture environment on the graft survival rate showed that suitable training environment of grafted seedlings was that on the incubator, relative humidity was above 95% , the temperature was 28±2℃, light was 16h·d-1, light intensity was 18001x, then moved the grafted seedlings in the incubator with relative moisture 60-70% after 5 days. The other conditions kept the same. The survival rate was up to 46.65 %; the test with Different training time of seedlings showed that graft survival rate was highest 53.35% when training the plantlet 6 days.4. Study on cultivation of improved variety scionThe test of one-year-old grafted seedlings showed that the method of pruning 1/4 of the seedlings was the best; The test of Tissue culture cultivation breeding varieties scion showed that the bud reproduction capabilities in tissue culture were in great differences, with the coefficient of 3.11 in three months while training breeding improved scion's propagation coefficient was 4.17 in three months. |
