Studies On Compositive Factors And Genetic Characters Of Fiber Quality Of Transgenic Insect-Resistant Hybrid Cotton

Cotton varieties containing the Bt gene have been widely accepted and planted on a significant number of cotton area all around the world and in our country since 1996 in order to control the insects and weeds. The hybrids varieties containing a transgenic parent have been widely planted in cotton production zone of China . The application of the hybrid insect-resistant cotton can, on one hand, keep its resistance to insect while greatly increasing its yielding, on the other hand, the problems of fiber quality is also gradually being stressed and considered. Now the researchs are described as follows:The research started by drawing out project in 2000 and conducted in Ningxiang County of Hunan Province in 2001. According to analysis of incomplete diallel cross, 36 hybrid combinations were made with the insect-resistant cotton varieties A1^A6 of the DPL as male parents, and domestic conventional cotton varieties B7^B12 as female parents, the hybrids. were denominated obverse cross from H37 to H72; 36 inverse cross combinations were made from H1 to H36 with the domestic conventional cotton varieties B7^B12 as male parents and the insect-resistant cotton varieties A1-A6 of the DPL as female parents. The combination comparing experiment and fiber quality testing were conducted in 2002²003 in the seven ecological spots such as Changsha County, Ningxiang County, Nan Xian County, Lixian County of Hunan Province, Tongling City of Annuli Province, Yang Zhou City of Jiangsu Province and Linqing City of Shandong Province. In 2003, the comparison experiment of the F₁ and F₂ generations of eight combinations was conducted in the same seven regions. In 2004, an experiment for influence of cultivation factors on fiber quality was conducted in Lixian County of Hunan Province.The study include: (1) analysis of compositive factors of the fiber quality traits and investigation of relativities between fiber traits; (2) geneticcharacteristics of fiber quality traits; (3) ecological adaptability of fiber quality characters; (4) comparing fiber characters of obverse cross and inverse cross Fj generation; (5) comparing fiber quality characters of Fi and F2 generations; (6) influence of cultivation factors on fiber quality.The following thirteen indexes of the fiber quality are measured by using a HVI900 system, including Upper Half Mean Length (Len ), Uniformity Index (UI), Strength (Stir), Elongation Rate (El), Micronaire Value (Mic), Spinning Consistency Index (SCI ) and Count Strength Product (CSP). We have systematically done research on related characteristics of the fiber quality characters of the transgenic insect-resistant hybrid cotton.The main research results are as follows:1. The generalized fiber quality includes the breeding quality (genetic quality), productive quality, commercial quality and spinning quality of the cotton fiber. The result shows that the generalized fiber quality can be expressed in four principal components. The f]rst principal component is called as fiber length factor and Spinning Performance factor, which have a contribution rate of 36.17%. The second principal component is Impurity factor which is an outside factor and has a quality influencing rate of 18.34%. The third principal component is Strength factor and External Color factor which have a contribution rate of 15.65%. The fourth principal component is Short Fiber factor which has an influencing rate of 10%. These four principal components have an accumulated contribution rate of 80.2% in the generalized quality.2. The fiber quality in a narrow sense with 8 quality traits contains spinning performance and quality characters of breeding, which can be described by three principal components. The first principal component is the spinning and fiber length factor, with a high contribution rate of 53.83%; the second principal component is the short-thick-strong fiber factor, that is, Short Fiber Index, Micronaire value factor, and Strength factor, with an influence rate on the quality in a narrow sense of 19.21%; and, the third principal component is the Elongation Rate factor, with a contribution rate of 13.14%. The accumulated variance contribution rate of the three principal components is 86%.3.The breeding fiber quality only contains the 6 quality indexes that canbe directly measured by the breeder, the result of the principal component analysis showed the following: the first principal component is the fiber length factor, with a contribution rate of 43.1%, which is positively correlates with the Uniformity Index and Strength and negatively correlates with the Micronaire value and Elongation Rate; the second principal component is the short-thick-strong fiber factor, including the three characters of Short Fiber Index, Micronaire value factor, and Strength factor, with an influence rate on the quality of 25.34%; and, the third principal component is the Elongation Rate and Uniformity Index factor, with a contribution rate of 15.04%. The accumulated variance contribution rate of the three principal components is 83.5%.4. The average value of the variation coefficients of the all the fiber quality characters shows that the Micronaire Value has the largest variation coefficient, namely 16.12%. The Uniformity Index has the smallest variation coefficient, namely 1.54%. The average value of the variation coefficients can. be arranged in size: Micronaire Value > Spinning Consistency Index > Elongation Rate > Strength > Count Strength Product > Upper Half Mean Length > Short Fiber Index > Uniformity Index. The variations coefficients of the Micronaire Value, Spinning Consistency Index and Elongation Rate of the fiber quality are large, which shows that they are greatly influenced by environmental factors while the Uniformity Index, Upper Half Mean Length and Short Fiber Index, lightly influenced by environmental factors, have a good genetic stability.5. By analyzing combination ability for the fiber quality in this research, the general combination effect of all the characters of the fiber quality accounts for above 74% of the total combination ability, which is obviously larger than the effect of the special combination ability. This indicates the function of the genetic genes is mainly the additive effect. The general combination ability of the Strength is the highest and the Spinning Consistency Index lowest. They can be arranged in size: Strength (100%) > Elongation Rate (96.26%) > Micronaire Value (93.47%) > Upper Half Mean Length (92.7%) > Uniformity Index (84.04%) > Short Fiber Index (83.68%) > Count Strength Product (83.18%) > Spinning Consistency Index (74.77%).6. From the results of the heritability of all the characters of the fiberquality, the Upper Half Mean Length has the highest generalized heritability and the Uniformity Index has the lowest generalized heritability. They can be arranged in size: Upper Half Mean Length (59.5%)> Count Strength Product (55.32%)> Elongation Rate (48.19%)> Spinning Consistency Index (42.41%)> Strength (29.76%)> Micronaire Value (19.8%)> Short Fiber Index (18.9%) > Uniformity Index( 17.5%) o The generalized heritability basically has the same regularities with the special heritability.7. The grey correlation analysis shows that correlative coefficient between the quality and yield of the hybrid cotton fiber is low and there is little correlation between the two. Therefore, in selecting and breeding the high yield hybrid combinations, debasing the quality is not a necessary cost, and meanwhile, selecting and breeding high quality hybrid combinations will not bring inevitable influence on enhancing the yield. In addition, the correlation between the quality characters, the related property and size of which cannot be determined like the multivariate analysis of correlation, can provide the primitive geometric similarity between the characters, which plays a practical role in determining and selecting the quality characters.8. The 12 hybrid parents in the experiment can be divided into three groups by the clustering analysis: the first group include five parents (Al, A6, A3, B7, and Bll); the second group five parents (A2, A5, B8, B9, and B12); and, the third group two parents (A4 and BIO). Calculated on the basis of the average genetic distance, the parent genetic difference within groups is little, and the hybrid combination produced by mutual combining and matching has little advantage; however, the parents genetic difference between groups is much distinguished , and the hybrid combining and matching can breed high quality combination. The obverse cross 36 hybrids are divided into 4 groups, and it is proves that the combinations with much parent difference have comparatively favorable hybrid advantage, in which for special strongly combined parents, the quality indexes all show that the parents have much genetic difference between each other and those parents belongs to different groups.9. The ecological adaptability research and analysis of different fiber quality traits of the 37 combinations at 7 ecological regions shows the following: (1) the same combination has different fiber qualities at differentecological regions, that is, for the fiber quality; various types (combinations) have their own optimum and most inadaptable ecological planting areas. (2) The adaptability of different fiber quality indexes of the same variety with different ecosites.10. The comparison research of the fiber quality indexes of the 16 materials, that is, Fi and F2 of the 8 combinations, at 7 experimental sites shows as follows: (1) although there is obvious difference on yield between the insect-resistant hybrid cotton Fj and F2, there is little difference between the two in fiber quality. Except that there is obvious difference in fiber length, there is no obvious difference between the other 7 indexes and the frequency distribution trends basically the same. However, seen from the difference between the individuals of various fiber indexes and their frequency distribution, it shows that the range of the fiber quality variation of F2 increases, the proportion of poor quality fiber increases, and the proportion of high quality fiber decreases; and therefore, the quality of fiber declines. (2) Combining with the actual situation of the cotton production, we conclude as follows: hybrid cotton Fi and F2 are both generations of fiber quality character separation. In the production, the cotton fiber produced from sowing F] seeds is in fact already the fiber on the seed of F2, and the fiber produced from the hybrid seeds of F2 is the fiber on the seed of F3, which is the generation that will continue to separate. Only for the seeds of Fj produced through hybridizing the two parents, the fibers produced on the seeds are uniform but not separated. Therefore, that the generations of Fi and F2 have the similar change in quality index actually results from the genetic variation of generations.11.The comparison research in fiber quality, yield, and insect resistance of generation Fi between obverse cross and inverse cross of the 36 combinations shows the following: (1) in the various indexes of the fiber quality of Fj generation between obverse cross and inverse cross combinations , except the Short Fiber Index and Count Strength Product, obverse cross combinations values of the other 6 indexes are all larger than the inverse cross values, however, the difference is not significant, which shows that there is no difference in fiber quality between two, and the quality character heredity of the cotton fiber is not cytoplasmic heredity. (2) Seenfrom the yield, there is significant difference between obverse cross and inverse cross combinations of Fi generations in either gross cotton yield or ginned cotton yield. (3) Seen from the infestation percentage of the boll by the third and fourth generation cotton bollworm, the inverse cross values are all less than the obverse cross values, which shows the insect resistance of the obverse cross combination is comparatively better than that of inverse cross, and proves that the insect resistance character originated from the Bt gene is completely dominant heredity. The yield of the hybrid combination with the local high quality type as its female parent is obviously higher than that of the hybrid combination with the insect-resistant cotton as its female parent.12. By studying on four factors' effects to fiber characters and comparison between Quadratic-Orthogonal-Rotating Regression analysis and projection pursuit regression analysis. The results show that projection pursuit regression is a better analysis ways to fiber quality. The effect value of the four cultivated factors can be arranged in size: DPO Planting Density> Kainite Fertilizer > Nitrogenous Fertilizer. There are different principal factor in different fiber quality index and conclude the best planting measure project in order to obtain the best fiber quality. The research still affirmed that obvious factors' effect difference exists between Fi and F2 so that the different planting measure must be adopted in Fj and F2 generation. The innovation of this thesis lies in the following:1. First put forward the dividing conception of generalized fiber quality character, fiber quality character in a narrow sense, and breeging fiber quality character; through the principal component analysis, this thesis puts forwards the important indexes to appraise the breeding fiber quality, and these indexes are successively as follows: Upper Half Mean Length, Short Fiber Index, Strength, and Micronaire Value. This is more complete than the three traditional indexes of Upper Half Mean Length, Strength, and Micronaire Value.2. First make the comparison research of the obverse cross and inverse cross combination in fiber quality, insect resistance, and yield, and put forward that the Fi seed production of obverse cross and inverse cross that are male and female parents of each other shall be prohibited in the actual production.3. The idea is first put forward that the hybrid F] and F2 belong to...