| Carya illinoensis is the tree specie which has ecological and economic values. It can produce high-grade nuts, be used as landscaping tree and high-grade timber.C. illinoensis originats in the United States and Northern Mexico. It has been introduced to China for 110 years, but industrial development has not formed until now. Propagation technique is one of the core techniques which restrict its industrial development. Nursery link of C. illlinoensis include cultivation of stock, grafting techniques. As C. illlinoensis has strong deep root characteristic, the development of lateral roots is not easy.When using traditional field nursery method, seedlings were called bare root seedings which have few lateral roots, and the survival rate of transplanting is low. At the same time, because of high levels of tannin substances in C. illlinoensis plant, the graft survival rate is low. In order to shorten the period of nursery, cultivate high quality stock seedlings, and increase the survival rate of grafting, the following were studied:The container nursery technique was used, and appropriate substrate formula and container size were selected. To overcome the roots wrapped in the bottom of the container, the chemical root controlling technique were tested. In order to promote thickening of stock seedling and reach the graft diameter as soon as possible, effects of chemical growth regular and topping times on thickening of rhizome were inspected. As to improve grafting survival rate, different grafting methods, grafting periods, grafting environment, bud section, and grafting times were investigated.Research was carried out at Lu He test base of Nanjing Lv Zhou Technologies during 2008-2010. The main results were as follows:1. Selection of container size and substance formula:Compare to the quality of seedlings cultured in the same height different diameter container, results indicated that with larger of the diameter, the development status was better. The maximum specifications(16cm×20cm)of container foster root in many seedlings growth indices were significant. But considering the economic cost, large vessel had high price and low space utilization, was not the most applicable. With comprehensive analysis of seedling development conditions, and economic benefit,12cm x 20cm specifications container was the best for C. illlinoensis. Number and dry weight of lateral root of seedlings cultivated in six matrix formulas were significantly higher than control. Plant height increment and ground diameter incremental were the biggest when planted in Formula No.4, was 30.8 cm and 4.08 cm respectively. The second better were formula No.1, No.7, and No.5. The number of seedling lateral roots was the biggest (15623) when planted in Formula No.7, followed by formula No.1,2,5. Considering seedlings'quality and cost, Formula No.5: peatmoss soil:loess:plant ash=5:3:2 was the optimal formula.2. Chemical root controlling technique:The results showed that Cu(OH)2 had significant inhibition on seedlings'growth, on the contrary, ZnCCO3 had no inhibition on seedlings'growth, but certain stimulation.20,180 mg·L-1 ZnCO3 and 60 mg·L-1 Cu(OH)2 had significant root controlling effect. But considering the best validity and cost,120 mg·L-1 ZnCO3 was the best chemical root controlling regeant.3. Effect of chemical growth regulator and topping times on thickening growth of seedings:Different concentrations GA3 and pp333 solution respectively were sprayed to container seedlings, and different concentrations GA3 solution were daubed on container seedlings'stem base; and were topped 3 times during the initial of growth peak period. Results showed that spraying GA3 significantly improved C. illinoensis seedlings'height growth, but had no influence on thickening growth. Daubing the stem base with GA3, spraying with pp333, and topping all could significantly improve C. illinoensis seedlings' thickening growth. Compared with controls, treatement daubed stem base with GA3 increased rhizome diameter 26.90%～76.55%, pp333 treatment increase 21.70%～66.04%, but the topping treatment only increased 3.79%～23.48%.600 mg·L-1 GA3 solution daubing on stem base had best effect of improving thickening of rhizome, and the second was 300 mg-L'1 pp333 spaying, increased 71.12% and 66.04% of rhizome diameter respectively when cmpared with control.4. Graft technology:(1) Different method, period, buds section, environmental conditions of grafting were studied during the growing season. The results showed that, square budding with phloem could get 63% higher survival rate than with xylem, and the effect of grafting was high from early July to mid-september, the survival rate was 77.5%～90.0%, and the best grafting period was early August to early September, survival rate reached 85.9%～90.0%.When used square budding with phloem method, if used the middle bud, survival rate of grafting was 85.2%, increased 22.0% and 25.0% compared with the top bud and lower bud separately. Under openenvironmental condition(field), survival rate reached 81.3%, was 50.1% higher than in greenhouse (High temperature and high humidity)condition.(2) The effect of square budding in different periods of the growing season and the cut branches connect pick method in different periods of the spring were compared.The results showed that the survival rate of square budding during growing season (June to October) changed as a parabol, among it, survival rate was the highest from beginning of August to beginning of September, was 84.2%～90.0%.Survival rate of the branches connect in spring was relatively lower. Among them, the survival rate on April 18th was the highest, 60.7%. When grafted in the growing season, if later than August 22th, the grafted bud could not sprout out during this year, and kept it through the winter.The growth of grafting plants after budding duing growth season were measured in the end of next June. Results indicated that grafting time was earlier, the seedling height, roughness, leaf number were higher. When budding grafting during growing season, if the buds of scion plants became mature, daily average temperature was about 27℃, highest survival rate of grafting could be got. The survival rate of branches connect in Spring was generally low, and before late April, the the temperature was higher, the survival rate was higher. Spring branches connect was earlier, the seedling growth was bigger. |
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