Study In Lateral Branch Cutting Technique And Rooting Mechanism Of Two Sympodial Bamboo

There are great amount of bamboo recourses in our nation, and among them sympodial bamboos were widely used. Bamboos can not only provide raw materials for timber processing and pulp-making, but also can be used as landscaping plants in order to improve the environment. Due to the special life history of bamboo, seedling becomes a restricting factor in the development of bamboo industry. In order to improve the efficiency of sympodial bamboo breeding, this study has used lateral branch of Dendrocalamopsis oldhami and Dendrocalamopsis beecheyana var. pubescens as cutting materials, analyzed the effects of cutting survival caused by different rooting media, branch ages, cutting periods and the kinds or concentrations of auxin. While in the meantime, analyzed the contents of nutrients and the changes of oxidase class activity in the process of cutting to reveal the cuttings rooting mechanism of Dendrocalamopsis oldhami and Dendrocalamopsis beecheyana var. pubescens. The results are as follows:1. According to the research for the forms of Dendrocalamopsis oldhami and Dendrocalamopsis beecheyana var. pubescens in the course of cuttings rooting, I found them both are the type of latent adventitious root primordial. The adventitious roots developed in three phases:the first 14 days as the stage of adventitious root primordial germination,14-21 days as the stage of adventitious roots occurrence, and the stage of adventitious roots development after day 21.2. To study the survival rates of Dendrocalamopsis oldhami and Dendrocalamopsis beecheyana var. pubescens, I used three different kinds of auxin,which were ABT#1,IBA and NAA with five concentration gradients as 200 mg/L,400 mg/L,600 mg/L,800 mg/L,1000 mg/L, and water as the control group. The results showed that the growth effect of ABT# 1 treatment was the best while IBA and NAA were not ideal. Inside the ABT treatment group, the highest survival rates were 52.22% and 80.00%.3. There were significant differences in rooting survival rates between different rooting media. When combined yellow soil and peat soil by 1:1, showed the best results, of which the survival rates were 46.67%and 72.22%, and peat soil only came the second, while the yellow soil only was the worst.4. There were great differences in rooting survival rates between different branch ages. The biennial branch showed the best results, of which the survival rates were 51.11% and 72.22%. Annual branch came as the second, of which the results were 32.22% and 44.44%.The perennial branch was the worst, of which the survival rates were 15.56% and 31.11%.5. There are no significant effects in Dendrocalamopsis oldhami cuttings’survival rates based on different cutting periods while the Dendrocalamopsis beecheyana var. pubescens cuttings showed otherwise. The collaterals of Dendrocalamopsis oldhami cutting in November showed poorest survival rate which was 50%. Both Dendrocalamopsis oldhami and Dendrocalamopsis beecheyana var. pubescens cutting in July showed the best survival rates which were 35.56% and 71.11%.6. During the rooting process, the variation in the soluble sugar content decreased at first then rose; and the variation of soluble protein content rose at first then decreased. Soluble sugar is the direct source of energy for cuttings, and it can be transformed from starch. Soluble protein not only can be the energy source of cuttings, but also can provide raw materials for enzyme synthesis during rooting. Both the contents of soluble sugar and soluble protein were higher in the Dendrocalamopsis oldhami cuttings than the Dendrocalamopsis beecheyana var. pubescens cuttings.7. The activity of POD,IAAO,PPO and SOD tied closely to the rooting process. In the stage of the adventitious roots’germination, the activity of POD, IAAO, PPO and SOD appeared a rising trend; when it came to the developing stage of the adventitious roots, the activity of POD, IAAO and PPO declined, while the activity of SOD remained stable. In the earlier stage of cutting, the activity of POD, IAAO, PPO increased, which could degrade auxin or induce the IAA- phenolic compounds, and encourage the adventitious roots to occur. In the lateral stage of cutting, activity of POD, IAAO, PPO decreased, which could increase the contents of auxin and encourage the adventitious roots to grow. PPO is a kind of protective enzyme, which can protect the cuttings in the troubled situations.