Research On The Role Of Nonlinear Parameters Of Traits Variations In Spring Wheat Breeding

The fractal dimensions of segregating population for traits were calculated with Cantor set fracta] estimating approach according to B.B.Mandelbrot( 1977) on 6 sets of genetic analytic materials crossed by 10 Spring Wheat cultivars(or lines), which each set included parents, Fl, F2, B1, B2,and their selling descendantsæ¡­2, F3, BIF2, B2F2. and 13 traits in 1998 and 11 traits in 1999 were observed respectively. The overvalue ratios and the function between the overvalue ratios and corresponding trait values was estimated on the basis of accumulative ratios of each trait distribution. The harmonizing index of traits structure in a plant of wheat was evaluated according to the assessment meaning of fractal dimensions. And the correlations between the target trait and harmonizing index of plants in a segregating population were studied. The role of the nonlinear parameters in the spring wheat breeding was the emphasis of the analyses. All data treatments were conducted with the statistic softwares of SAS~ DPS and Excell 97 on the relevant statistic models. The results showed as follows: I .The relations between diverse types and corresponding scales conformed to the fractal law in all traits of wheat. The fractal dimension of each trait, or D, was a decimal between 0 and 1. It indicated that the distribution of a trait in a separating population was displayed in in- continuity as the observing scale decreasing. The little D showed an obvious in-continuity. The meaning of the parameter in wheat breeding is the most deep potential in trait improvement with a big LX a wide range of scales~ a big C.V.% in a population, as plant weight. tillers~ kernels/plant and grain weight/plant, and a deeper potential with a little LX a moderate range of scales~ a big C.V. % in a population, as grain weight/ear~ weight/stem and ear kernels/ear, and a limited potential with medium levels in the same 3 aspects as weightll000 grains~ harvest index, and a shallow potential with low levels in the same 3 aspects as plant height~ ear length~ spikelets and fertile spikelets. 2. The different function type of overvalue ratios in various range in data of a trait in a segregating population was observed. The function type of overvalue ratios in a population was in close association with the genetic structure of a trait The results showed that a deep potential in a trait improvement with power function~ little parameter~ wide target range and large percentage of over-parents in the target range as tillers~ grain weight/plant. kernels/plant and plant weight, a deep improving potential in a little difficulty of traits with exponent function~ big parameter~ wide target range as weight/stem and ear~ grain weight/ears Dr. Research on the Role of Nonlinear Parameters of Trait Variations an Spring Wheat Breeding Li Z.F. iii kernels/car, a medium improving potential of traits with exponent fimction. big parameter. medium width of target range as weight/bOO grains, harvest index, a little improving potential of traits with exponent function, narrow target range as plant height. ear length. spikelets. fertile spikelets. The traits with deep improving potential should be key objectives in breeding. 3. The harmonizing index was estimated as a numerical indicator to identif~?the degree in unanimity in the performances of traits in a plant. The results showed that the performances were coordinated each other among traits in a plant if the harmonizing index was less than 1. The correlative analyses on the relation among the index. goal trait and improving potential in the seg...