| This research is to find out the mechanism of bamboo's aging and flowering for providing a theoretical and production base of bamboo's rejuvenation. By investigating the past recordings, consulting local experienced bamboo farmers, and field visiting, the plot sites in Diqin Modern Technology Demonstration Zone for High-yield Phyllostachys praecox Cultivation are identified to study bamboo aging and flowering: 4 types with natural,2-3years mulching, 4-5 years mulching and 6-7 years mulching bamboo stand for bamboo's aging; 5 types with normally-grown, badly-grown(leave is getting smaller) and flowering bamboo stands for bamboo 's flowering. Bamboo aging time is identified by investigation of underground bamboo rhizome and buds . Bamboo plants with different flower differentiation are marked to observe if they will flower. C/N, value elements, including trace elements and endogenous ABA, GA3, IAA, Zr, IPA are analyzed for bamboo aging and flower. The results are as follows:1. Bamboo is getting aging with increase of mulching time, and has a marked turning point at 6-7 year mulching, i.e. bamboo aging is getting worse over 6-7 years, which is well coincided with change pattern of C/N value and hormonal ratio, esp. for GA3ABA,IAA+GA3/ABA.2. Different mulching year has different impacts on hormonal change of bamboo leave and rhizome. For bamboo leave, it has slight impacts on the content of GA3X ,IAA Zr, IPA and ABA, but no more impacts on the ratio of GA3, IAA, Zr and IPA to ABA, which indicates different mulching year has no effect on leave, i.e. no effect on leave aging. For bamboo rhizome, it has some bigger effects of both the content of GA3, IAA,Zr, IPA and ABA and the ratio of GA3, IAA, Zr and IPA to ABA, particularly a marked decline between 4-5 year mulching and 6-7 year mulching, which indicates different mulching year has a bigger effect on rhizome, or rhizome aging. In a word, bamboo aging caused by mulching is started from rhizome, not from leave..3. Hormonal regulation mechanism of bamboo aging is put forward, bamboo aging is regulated and controlled by ratio of GA3/ABA, IAA/ABA, GA3+IAA/ABA, i.e. bamboo aging is inhibited by that higher ratio, and promoted by the lower one, GA3/ABA plays a much more important role than IAA/ABA. Bamboo aging is not caused by less production of CTK in rhizome /roots and less supply to the aboveground part of bamboo, in fact CTK does not play role in bamboo aging.4. Bamboo aging mechanism trigged by mulching is put forwarded, which is a combination function of ABA and GA3, IAA dynamic regulation and element interaction of P ,Ca ,Al, Se, K, Ni, Mg, Mn;C/N ratio increase is a result of hormonal regulation, and not a primary cause to bamboo aging. Effects of elements on bamboo aging can be classified into 3 categories: no effect: N, Cu, Zn, Co. 2 Bamboo aging promoted by higher content: P,... |
