Genetic Study On Waxy Corn Dwarf Mutant Material DN13261

In 2018,We found that several plants in the male parent DN132610 lines were significantly lower than the others at Liangping Experimental Base of Chongqing Three Gorges Academy of Agricultural Sciences,followed by bagging and self-pollination.up to2020,there were three consecutive self-pollinations,the progenies showed dwarf stem and did not showed noticeable segregation in the progenies and the dwarfing character was genetically stable.Therefore,it was preliminarily determined as a dwarf mutant material（DN132610-1）.In the current study,phenotypic identification,stress resistance research,genetic model analysis,breeding potential analysis,and other studies were carried out,andthis work provide a theoretical basis for further use of this material in production.The main results are as follows:1.The results showed that the plant height of wild type（cultivated species）and mutants was 164.07±7.09 cm and 145.71±9.59 cm in 2021,157.63±8.13 cm and 140.41±11.22cm in 2022,respectively,and the reduction rate plant height of mutants in 2021 and 2022 was11.0%and 10.9%respectively;The ear height was 51.49±9.02 cm and 39.59±6.78 cm in2021,44.40±4.11 cm and 36.80±3.32 cm in 2022,respectively.The reduction of ear height of the mutant in 2021 and 2022 was 23.11%and 17.1%respectively;The stem height above the ear node was 112.57±6.10 cm and 106.12±7.33 cm in 2021,113.23±6.24 cm and103.61±7.21 cm in 2022,respectively.The reduction of the mutant in 2021 and 2022 was5.7%and 8.4%respectively.The reduction of ear height was greater than that of stem height above the ear in two years.Hence,the reduction of plant height of the mutant was mainly caused by the reduction of ear height.As the plant height of the mutant decreased,the leaf length at the ear node and the number of tassel branches decreased,which significantly reduced the number of rows per ear and the number of kernels per row2.With the increase in planting density,the lodging rate of wild type and mutant plants,the length of the third internode,and the disease index of sheath blight all increased,while the strength of breaking resistance gradually decreased.There was no obvious change in the cultivation of the third stem thick,on the contrary,the mutant showed a trend of decreasing gradually with the increase of planting density.Under different densities,the stem diameter and bending strength of the mutant were greater than those of the wild type.The length of the third internode was shorter than that of the wild type.The lodging rate was significantly lower than that of the wild type.At each planting density,the disease index of the mutant sheath blight was higher than that of the cultivated species,but the difference was not significant（F=0.895）,and at high density（120000 plants/hm²）,the disease index of the mutant sheath blight of the cultivated species and the mutant were 51.85 and 57.78,respectively,showing moderate resistance.3.In order to cultivate dwarf maize varieties,six generations of the population were obtained by crossing the wild type DN132610 and the mutant material DN132610-1 to explore the genetic characteristics of the plant height.The study showed that the most suitable genetic model of dwarf maize mutant was E-1,that is,two pairs of additive-dominance-epistatic major genes+additive-dominant polygene mixed genetic model.The heritability of B₁,B_2,and F₂in the segrgared generation population was 57.26%,58.12%,and 76.85%,respectively,and the genetic contribution of major genes accounted for the main part.The variation caused by environmental factors accounted for 42.74%,41.88%,and23.15%respectively.The heredity of plant height was greatly affected by the environment,and there was an interaction effect between heredity and the environment.In the breeding process of dwarf maize,we should pay attention to the influence of environmental effects on the plant height of maize,and increase the biological adaptability and wide adaptability of new dwarf maize varieties.4.The study showed that there were significant differences in plant and ear height in hybrid combination between female parent N151,N13259 and cultivated species and mutant,while there were no significant differences in hybrid combination between ZN06-1,N17012 and wild type and mutant..except for number of rows per ear show a significant difference in hybrid progenies between wild type and mutant,,and the hybrid progenies of the mutant were superior to the hybrid progenies of the cultivated species,there was no significant difference in the third node length,stem diameter,ear length,ear diameter,bald tip,kernel number per row,fresh 100-grain weight,and cooking quality.The general combining ability of the ear length of DN132610 and DN132610-1 were 0.18 and 0.03,the bald tip was0.27 and 0.33,the ear diameter was 0.04 and 0.17,the plant height was-0.05 and-1.33,the ear height was-0.35 and-5.20,the grain depth was 0.03 and-0.06,the ear row number was0.56 and 1.54,the grain number per row was-0.07 and 0.09,the 100-grain weight was-1.15and-1.86,the stem diameter of the third node was 0.01 and-0.07,and the length of the third node was-0.50 and-0.26,the cooking quality was 1.09 and 1.23 respectively.Except for the relatively large difference in the general combining ability of plant height,ear height,and row number per ear,the difference in other characters is small.The lower general combining ability of plant height and spike height is the better,while the higher of the number of rows per spike is the better.The dwarfing mutation will reduce plant and ear height,and increase the number of rows per ear,and have no significant effect on other traits.The general combining ability is better than that of wild type and has the potential for utilization.During maize breeding,GCA and SCA play an important role in the high yield of hybrid combinations.To combine excellent hybrid combinations,at least one material with high GCA should be selected as the parent.