ÃÞ »¨ ѧ ±¨ Cotton Science 2009£¬21(2)£º121-126
Comparison of Photosynthesis in Brown, Green, and White Fiber Cotton Lines Abstract£ºColored fiber cotton usually yields less, though this phenomenon had been observed for long time. There were a few investigations about the reasons causing it. In order to give more information on the lower yield of colored fiber cotton, we measured several photosynthetic indexes such as leaf chlorophyll a and b content, Hill reaction activity, Ca2+- APTase and Mg2+- ATPase activity, and net photosynthesis rate as well as lint yield and yield components using three lines, which was white (XZ-003), brown (X008), and green fiber cotton (S029) as plant materials, at seedling, squaring, early flowering, middle flowering, late flowering, and boll opening stage. Result showed that the brown and green fiber cotton had lower lint yield, which was 33.7% and 41.9% lower than the white fiber cotton. The main differences among three materials existed in the middle flowering stage indicating its importance during photosynthesis. Compared to the white and green fiber cotton, brown fiber cotton had the lowest leaf chloroplast Hill reaction activity, Ca2+-ATPase, and Mg2+-ATPase activity particular in middle flowering stage. It also had the lowest net photosynthesis rate, which would result in the insufficient metabolism substrate supply. These results indicated a possibly physiological reason for low yield in brown fiber cotton. As for green fiber cotton, it had much higher chlorophyll content than white fiber cotton. Furthermore, it had similar activity of ATPase and higher net photosynthesis rate at middle flowering stage than white fiber cotton. However, despite of these advantages in photosynthesis, it still gained the lowest yield suggesting there were other reasons accounted for its reason.
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