Cold Tolerance Identification And Genetic Analysis Of Agronomic Trait In Maize Germplasm

The early spring maize area is an important maize production basement in china, which has distinct ecoclimate condition. The low temperature in earlier spring is one of the most important factors to limit yield of corn in this area. The low temperature identification method was adopted to select maize germplasm with cool-tolerence, and genetic regularity in emergence period, seedling period ,plant and yield trait are also analyzed,it can provided information in increasing the efficiency of corn breeding.The constant temperature incubaton was used by setting three temprature gradients of 20℃, 11℃, 7℃. 60 stable inbreds were identified and selected in different levels, seedling rate and seedling index were used as selection criterions. 28 combinations between 3 inbreds that can tolerate low temperature in 7℃and 5 inbreds that can't tolerate low temperature were crossed with GriffingⅡdiallel mating design. These crosses were used to estimate cool-tolerence in emergence and seedling period under low temperature stress and to analyze genetic regularity in plant and yield traits. The main results are as follow:1. The inbred lines 2001-F32, FR1454, HR295, Line kin060, KN3 are selected and identified as cool-tolerence germplasm under 7℃.2. Correlation analysis indicats that correlations exist between relative germination index, relative seedling ratio, relative plant dry weight, relative root dry weight each other. Relative seedling ratio has correlation with relative root total length. These traits can be used as seedling indexes for cool-tolerence indentification.3. There are significante differences in the traits among GCA variance in different parents, SCA variance in relative seedling rate, relative seedling index, relative height of seedling, relative dry weight of seedling, relative dry weight of root, relative number of side root and relative length of all of the root. Additive gene effect is important in relative emergence ratio ,relative germination index, relative plant dry weight, relative root dry weight, relative total root length ,and narrow-sence heritability are generally lower than 50% ,the sequence from high to low are relative germination index, relative seedling ratio, relative root dry weight ,relative plant dry weight, relative root total length. These traits should be selected in higher generations.4. GCA and SCA variance of plant height, ear height, leaf number, ear length, kernels per row, yield per plant,2 kernels width , volume weight are high significant. The combinations of HR6×2001-F32, FR1454×2001-F32, MO17×FR1454, HR6×HR295 might be better combinations with cool-tolerence.5. The combining effect between GCA and SCA should be focused in selecting corn hybrids with cool temperature resistance by the seedling traits and the SCA effect is more important in selecting by yield traits. 6. The germplasm tested can be divided into three types by yield SCA cluster. The type①included HR6, FR1454, HL3 and 2001-F11; 3004 belonge to the type②; and 2001-F32, MO17, HR295 are in the type③.