Studies In The Characteristics Of Fiber And Heterosis In Colored Cotton

This study was mainly conducted for 8 colored cotton lines in two aspects: The first was investigation in ultrastructure and development of fiber cells, biochemical characteristics of pigment in fiber cells. The second was cytological observation of microsporogcncsis for cytoplasmic male-sterile (CMS) lines with colored fiber phenotypes and application of CMS in cotton heterosis. The aims were to understand some characteristics of pigment formation and fiber development, and then looked for some methods to resolve problems of low yield, bad quality and other defects in the colored cotton by heterosis. The main conclusions are as follows: Pigment in colored fiber cells could be extracted by HNO3/ethanol, but not successful by organic solvent (ethanol, aether and dimethylbenzene), acid and base solution. There were three types of fibers according to cellulose content of fiber and optical density (OD) value of fiber pigment extracted solution. The first was white fiber which content of cellulose was over 90% and OD value was less than 0.01. The second was green and light brown fibers whose cellulose contents were between 80% and 90% and OD values from 0.01 to 0.35. The third was brown and deep-brown fibers whose cellulose contents were below 80% and OD values more than 0.60. According to the change of QD value and cellulose content during fiber development, two stages, the 20 DPA (days post anthesis) and 3ODPA, were important for formation and accumulation of fiber pigment. The color of brown fiber became deeper and deeper during the 30-35DPA, which might be related to rapid increase of pH and dehydration for fibers. Formation and accumulation of pigment in green fibers could be observed in the 15-2ODPA. It was suggested that pH drop was favor to fiber cell elongation and secondary wall thickening during the fiber cell development. Electron microscopic examination of white, brown and green fiber revealed that each cell wall of these three types of fibers was composed of primary wall, secondary wall and lumen from outside to inside. However, the green fiber had numerous concentric osmiophilic rings around the lumen, whereas white and brown fibers showed no these rings. It was supposed that these rings be formed by green pigment deposition every day during fiber development. Brown fiber cell had not only a large lumen where a lot of deep dyed substance was deposited, but also fork structure which grown up to be a branch from the wall of main fiber cell. This dyed substance might contain brown pigment, but the mechanism for the formation of fork structure was not clear. Content and role of mineral elements in different colored fibers and their development were different, since there were some facts as follows. 1) N element iii content in non梒ellulose substance in green fiber was more than in the white and brown fiber. 2) P element content was associated with pigment accumulation in brown and green fiber. 3) the change of K and Ca content was related to development of fiber quality. 4) Mg element was related to pigment formation and accumulation in green fiber. 5) Zn was related to pigment formation and accumulation of brown fiber. Cytological observation of microsporogenesi s for a cytoplasmic male-sterile (CM S) cotton lines with brown fiber phenotype was performed in comparison with its maintainer line. The results of study showed that the abortion of auxocyte cells in the CMS anther...