Analysis Of Growth,Xylem Structure And Heartwood Extraction Of Dalbergia Odorifera T.Chen Based On Artificial Regulation

Dalbergia odorifera T.Chen has a slow natural timber and a shortage of natural resources.Accelerating and expanding the planting of D.odorifera and obtaining high-quality D.odorifera wood have become the key problems to be solved in the artificial cultivation of D.odorifera.In this study,7-year-old D.odorifera was used as the research object.Two-year artificial interventions of gibberellin(GA_2%,GA_3%,GA_4%),indoleacetic acid(IAA_0.4%,IAA_0.6%,IAA_0.8%),calcium application(Ca₅₀,Ca₁₀₀,Ca₁₅₀),film mulching and calcium application(F+Ca₅₀,F+Ca₁₀₀,F+Ca₁₅₀)were conducted on D.odorifera to explore the effects of different artificial interventions on the growth,xylem structure,and heart extract composition of D.odorifera.In order to provide new methods,new ideas and theoretical basis for artificial regulation of D.odorifera growth and heartwood formation.The main conclusions are as follows:（1）With the increase of gibberellin concentration,the height increment of D.odorifera showed an upward trend,and the DBH increment first increased and then decreased.The catheter diameter and the ratio of catheter tissue increased first and then decreased.There was a significant positive correlation between the catheter diameter and the increment of DBH（r=0.998,P<0.05）.The vessel density decreased first and then increased,and the proportion of wood ray tissue decreased.The contents of polyphenols and total flavonoids in heartwood increased first and then decreased.Sapwood showed an upward trend,and the polyphenol content of sapwood was highly significantly negatively correlated with the ratio of wood ray tissue（r=-0.999,P<0.05）.Among all gibberellin treatments,GA_3%treated wood contained more heartwood characteristic products,which had a good effect on promoting the formation of heartwood of D.odorifera.（2）With the increase of indoleacetic acid concentration,the height increment of D.odorifera showed a downward trend,and the DBH increment first decreased and then increased.The diameter,density and tissue ratio of the catheter decreased first and then increased,while the tissue ratio of wood ray increased.The content of polyphenols and total flavonoids in heartwood and sapwood increased first and then decreased.In all indoleacetic acid treatments,IAA_0.6%treated wood contained more heartwood characteristic products,which had a good effect on promoting the formation of heartwood of D.odorifera.（3）With the increase of calcium application,the height increment of D.odorifera increased first and then decreased,and the DBH increment decreased first and then increased.The catheter diameter and the ratio of catheter tissue decreased first and then increased,the catheter density increased first and then decreased,and the ratio of wood ray tissue increased.The contents of polyphenols and total flavonoids in heartwood decreased first and then increased.Among all calcium application treatments,Ca₅₀ contained more characteristic products of heartwood,which had a good effect on promoting the formation of heartwood of D.odorifera.（4）In the film mulching treatment,with the increase of calcium application,the height increment of D.odorifera increased first and then decreased,and the DBH increment increased.The catheter diameter and the ratio of catheter tissue decreased first and then increased,the catheter density increased first and then decreased,and the ratio of wood ray tissue increased first and then decreased.The contents of polyphenols and total flavonoids in heartwood decreased first and then increased.The content of total flavonoids was significantly positively correlated with the diameter of xylem duct（r=0.999,P<0.05）.Among all calcium application and film covering treatments,F+Ca₁₅₀ contained more characteristic products of heartwood,which had a better effect on the growth and heartwood formation of D.odorifera.In conclusion,the treatments of gibberellin,indoleacetic acid,calcium application,calcium application and film mulching can promote the growth or heartwood formation of D.odorifera in varying degrees.Among them,F+Ca₁₅₀had the best comprehensive performance in promoting the growth of height and DBH of D.odorifera and the formation of characteristic components of heartwood,which provided a reference for the artificial cultivation of D.odorifera.