The Effects Of Exogenous Gibberellin On Growth Of Moso Bamboo Seedling

To study the growth mechanism of bamboo stem, and explore the effects of exogenous hormones on bamboo plant physiological and biochemical aspects, different levels(0, 20, 40, 60 mg·L-1) of gibberellin(GA3) were spraying on Moso Bamboo seedlings, 4 times in total, each spaced about 20 days apart. After tiller stopped sprouting, phenotypic characteristics of neonatal tiller(new germinal bamboo seedling) such as plant height, node number, internode length, blade quantity, the ground diameter, the neonatal tiller number and the size of blade are investigated; neonatal tiller stem is longitudinally divided into basal, middle and tip, making paraffin section and taking bamboo pulp part for the analysis of neonatal tiller stem microstructures, such as stem wall thickness, vascular bundle density, vascular bundle size, catheter diameter, long cell size and short cell size; fiber properties of neonatal tiller such as fiber cell length, fiber cell width, fiber cell aspect ratio, fiber cell wall thickness, lumen diameter and wall-cavity ratio are explored in parts by fiber dissociation; endogenous hormone levels of neonatal tiller such as GA3, IAA, ZR, ABA are detected in parts by Enzyme-linked Immunosorbent Assays; the relationship between internode length and fiber cell longth is discussed, get the following results.1. The plant height, internode length and blade quantity of neonatal tillers show clear rising trend with the increase of GA3 spraying level. Compared to control(0 mg·L-1), the plant height of neonatal tiller under 20, 40 and 60 mg·L-1 GA3 treatment respectively 0.56, 1.19 and 1.21 times larger than control(0 mg·L-1), the average internode length respectively increased 0.49, 1.05 and 1.10 times, and the quantity of blade respectively increased 35.61%, 48.35% and 38.68%; but there is no significant difference between each treatment and control on the neonatal tiller number, node number and the ground diameter.2. The long cell length of neonatal tillers stem show clear rising trend with the increase of GA3 spraying level. Compared to control(0 mg·L-1), the basal long cell length under 20, 40 and 60 mg·L-1 GA3 treatment respectively increased 12.05%, 18.92% and 19.38%; the middle long cell length respectively increased 17.40%, 25.96% and 25.73%, the tip long cell length respectively increased 7.80%, 9.55% and 12.39%, while there is no significant difference between each treatment and control in the stem wall thickness, vascular bundle density, vascular bundle size, catheter diameter, long cell width and short cell size.3. The fiber cell length and the fiber cell aspect ratio of neonatal tillers stem show clear rising trend with the increase of GA3 spraying level. Results showed that 20,40,60 mg·L-1 GA3 treatments have all increased the length of fiber cell significantly(P<0.01), respectively 13.17%,20.68% and 31.46% longer than control on the whole; however, the effect of each treatment on fiber cell width is not obvious, so that the fiber aspect ratio increases, which is conducive to the fiber quality improvement. Besides, the effects of GA3 treatment on fiber cell wall thickness, lumen diameter and fiber tissue proportion are not obvious.4. The levels of endogenous hormones GA3 and IAA in neonatal tillers stem increase, while levels of ZR and ABA decrease after GA3 spraying. The level of GA3 in neonatal tillers stem under 20, 40 and 60 mg·L-1 GA3 treatment respectively increased 23.96%, 39.44% and 46.05% on the whole; the level of IAA respectively increased 5.14%, 8.64% and 12.67%; the level of ZR respectively decreased 6.88%, 18.86% and 22.93%; the level of ZR respectively decreased 10.84%, 17.25% and 45.17%.5. Internode elongation have a significant relation with fiber elongation in neonatal tiller.Research shows that the use of GA3 can significantly improve the fiber quality of Moso Bamboo seedlings neonatal tiller, but no significant effect on improving fiber production. Besides, correlation analysis indicates that gibberellin promotes the elongation of stem fiber cell on microstructure, resulting in the elongation of internode and stem in apparent.