Research On Seedling Fast Propagation And Multi-traits Comprehensive Selection In Alnus Formosana Clones

Taiwan alder (Alnus formosana) originated in China Taiwan was up to more than30m in height and to more than30cm in DBH in the origin. It has been widely cultivated due to good characteristics of fast growth, straight trunk form, softy timber, straight texture, easy processing. It has been used as high-quality materials for making wood floor and furniture, also for making particleboard and paper making. With the industrial development, Taiwan alder seedlings has been in short supply, the market demand of Taiwan alder seedlings is growing. In order to meet the needs of production on clones seedlings of Taiwan Alder, rapid propagation techniques of clones and comprehensive breeding of multiple characters of excellent clones in Taiwan Alders have been necessarily studied.Based on clones varieties of Taiwan Alder selected by Hunan Academy of Forestry, rapid propagation and selection, photosynthesis, vegetative growth, reproductive growth and wood properties of clones seedlings of Taiwan alder had been studied by the experiment method of completely randomized block design. The main conclusions were showed as follows:1. Bud numbers of Taiwan alder clone of cutting orchard depended mainly on the genetic characteristics and planting density, but also closely related with the stem height, pruning, fertilization.2kinds of high-yielding clones cuttings, Xiang Qi F03and Xiang Qi F04, were selected from Taiwan alder clones.1m×2m of planting density and90cm of plant stem height were appropriate for the establishment of the Taiwan alder clones.2. Cuttings rooting rate of Taiwan alder showed significantly difference among clones of different ages. A significant reduction in cuttings rooting rate were showed in more than4years old.15kinds of clone varieties which rooting rate reached more than80%were selected, they were Xiangqi F01, Xiangqi F02, Xiangqi F03, Xiangqi F04, Xiangqi F05, Xiangqi F06, Xiangqi F07, Xiangqi F08, Xiangqi F09,Xiangqi F10, Xiangqi F11, Xiangqi F12, Xiangqi F13, Xiangqi F14and Xiangqi F15. In simple conditions, early September was the best as cutting time because of the highest rooting rate, pure sand was the best as cutting medium because of the highest survival rate. Cutting with terminal bud or1to2leaves significantly increased the rooting rate. There were significant difference of rooting rate among cutting treated by different concentrations GGR, the effect of300mg/L concentration GGR was the best.3. Adventitious root of Taiwan alder cuttings formed two types of thedermal rooting and callus rooting, the most of cutting roots belonged to thedermal rooting, but few of cutting roots contained these two types. The rooting ability of Taiwan alder clones were positive related with the rooting rates.4. The mathematical models were established between the seedling numbers per unit area and the height growth or diameter growth of Taiwan alder, respectively. The relationship model of the numbers per unit area and the average height of seedlings were y=2.0147x-30.9568(50≤x≤70). The relationship model of the numbers per unit area and the average diameter of seedlings were y=156.3578—169.1596x (0.4<x≤0.6)5. The researches of photosynthetic physiology were showed that light saturation point, the compensation point and apparent quantum efficiency of Taiwan alder were1177.8μmol·m-2·s-1,20.0μmol·m-2·s-1,0.0345, respectively. It illustrated Taiwan alder could enough used low light.6. The impact of Nitrogen, phosphorus, potash fertilizer on photosynthetic characteristics of Taiwan alder was observed. Photosynthesis of Taiwan alder treated with N12P12K9fertilizer was strongest in25kinds of fertilizer treatment. The Photosynthetic rate was positively related with transpiration rate, photosynthetic active radiation, air temperature and leaf temperature, respectively. Intercellular CO2concentration was negatively with photosynthetic rate and transpiration rate, respectively. Leaf water pressure deficit was influenced by air relative humidity. Air relative humidity obviously affected by temperature, light intensity, and was significantly negatively correlated with transpiration rate.7. Bred four excellent growth traits alder clones:4clones varieties of Taiwan alder were selected as excellent growth traits. They were F02, F07, F12and F21.8. The range of basic wood density from the clones tested were0.4747g.cm-30.3032g.cm-3. the3clones varieties of the larger basic wood density were selected, they were F02、F12and F15.9. The range of wood cellulose content from the clones tested were45%to55%, the3clones varieties of the larger cellulose content were selected, they were F02, F11, F12and F15.10. The wood fiber length of Taiwan alder belonged to intermediate length. Fiber length-width ratio were greater than35, and the range of fiber length-width ratio were mainly between37～50. The difference of the fiber length, width and length-width ratio were small in arithmetic groups. The difference of them was not significant between the clones.11. Density variation of9years old Taiwan alder belonged to the model which was slowly increased from the pith outward curve, and no significant difference of density was observed between annual ring segments. Cellulose contents of5clones of Taiwan alder tested were different at annual ring segments. Radial variation of fiber length was still an upward trend, fiber width were different largely between annual ring segments. The ratio of fiber length to width increased with increasing in the growth rings, the ratio in4-6years of growth rings increased by5.49%over1-3years of growth rings, the ratio in7-9years of growth rings increased by3.21%over4-6years of growth rings.12. Using breeding model in which the growth was made as the main program of clones selection and the improvement of wood properties were made as the sub program of clones selection, multiple traits of Taiwan alder clones were selected.3clones of Taiwan alder which the best in the growth and wood property were firstly selected, they were F02, F07, F12.13. Seed grain weights of10clones were largely different. The seed grain weight of clones F05which were up to1.09g was maximum, the seed grain weight of clones F05which were up to0.42g was minimum. The coefficient of variation (CV) of single fruit seed rate ranged from25%to37.42%. There were significant difference of the cone length, width and fresh weight between the clones tested. A comprehensive analysis were done that the clones F05was the best in the seed traits among all of the clones tested in our study.