Effect of Light Quality on Pigment Formation in Brown Cotton Fiber

The aim of this study was to determine the effects of light quality on pigment formation and enzyme activity in cotton fibers.The different light qualities were achieved by covering cotton bolls with different colored film filters(red,yellow,blue-violet,and white).The contents of flavonoids,total phenols,and condensed tannins,and phenylalanine ammonia lyase activity were affected by different light qualities.The different light qualities could be ranked,in terms of their effects on the content of soluble condensed tannins in fiber,as follows: red lightcontrolyellow lightblue-violet light.The highest content of insoluble condensed tannin in cotton bolls was those treated with red light.A correlation analysis showed that both phenols and condensed tannin contents were positively correlated with fiber pigmentation.The flavonoid content was negatively correlated with fiber pigmentation.Condensed tannins are the direct precursors of the brown pigment in cotton bolls.