Fungi Caused By Paulownia Wood Discoloration Mechanism And Control Techniques

ln order to prevent paulownia wood stain, the study in this paper ascertainedthat paulownia stain has something to do with fungi, separated and purified 2kinds of stain fungi, and identified them; Probed paulownia disco1orationmechanism, including the color change pattern of paulownia wood and itsmain chemical composition variation; Discussed the possibility and feasibilityof preveilting paulownia stain, provides some measures to control it;According to the mechanism that paulownia stain is mainly caused by fungi,carried out the research to prevent stain, and gained ideal resuIts. Theresearch results show that:l. Paulownia wood stain belongs to microbiology discoloration, and ncitherchemical nor light discoloration.2. Two fungi that caused stain are Alternaria alternata(Fr.) Keissl) andRhizopus sp. That can make paulownia wood change its color from white todark brown, which is similar to what the paulownia stain. is like inproduction.3. The color changing pattern of paulownia affected by fungi is as follows:Color difference △E~* increase obviously with the time going, the whitedegree of wood is decreasing in a way that changing from milk white to red,and finally to dark black; Lightness L~* is decling from 70 to 50 or so, withthe time going, and would continue to descend. Redness or greennesscharomaticity a~*, bluness or yellowness chromaticity b~* changing wavily,but the general trend is toward dark brown.4. In this papcf, tbe chemical components of paulownia (Paulownia elongata)are analyzed before and aftcr fungi rotting the wood, the results show thatthe substances extracted from invaded paulownia wood after fungi erosionare increased with different level, ligin amount is relatively heightened,semi-ce1lulose is obviously declined, celluse changed litt1e. The study onchemical components from paulownia invaded by fungi with FTIR andESCA instruments indicates that the structure of semi-cellulose is changedin some degree.5. The stain of paulownia wood caused by fungi is obviously affected by PHvalue, the wood color is seriously stained by fungi when the PH is within4~6..6. The control study show that the technology using enzyme retard agent,fungicide, adjustment of PH value can prevent paulownia stain effectively.The color value of paulownia wood such as color difference bE', rednessor greenness charomaticity a', bluness or yellowness chromaticity b', whitedegree TW can reach all the standard of A grade for export.