The Strain Selection And Genetic Effect Of Excellect Maize Hybrid' Inbreds.

The degeneration of crop varieties is a universal phenomenon. It has an practice significance to delay variety degeneration. Using the inbred lines of zhengdan958,which is the largest area maize variety in China now, agronomic and ear characters, combining ability of them with different sources and generations was studied, through continuous individual selection by agronomic and ear characters and them's hybrid combination judgement in field. The result is following:1.There are difference in it's agronomic and ear characters of inbred lines from different sources. The plant and ear' height of chang7-2 from He'nan is positively higher than that from Gan'su. what the zheng58 lines shows is justly opposite to chang7-2 lines. And the lines from Gan'su is positively higher than from He'nan . There are commonly 15cm difference of the height of plant.The difference of plant'height can reach 25.53cm while planting in Hai'nan. The difference existed in different generation. The ear thickness and kernel rows number of chang7-2 lines from Gan'su is super to that from He'nan. The length of it from He'nan is super to that from Gan'su in summer of 2005. Besides kernel rows number, the ear characters of zheng58 lines from Gan'au are super to that from He'nan.2.The appearence of agronomic characters of related lines with different generations is correlated with basic material. The more higher of basic material, the more higher of it'generation. The sensetivenes of a line'agronomic characters vary with environmental condition. The length of ear and kernel rows number in second are larger than other generations. The thickness of ear and axle , kernel rows number is smaller in second generation.3.The combining ability of a same inbred'prosprity is different. The combining ability is conduced by the yield of hybrid combination in 2005 and 2006. Cluster analysis shows that:the combining ability difference among most chang7-2 lines is small. The difference of combining ability among zheng58 lines is larger than that among chang7-2 lines. There are small difference of combining ability of the same inbred lines from different source.4.The yield of hybrid combinations varies with the combination by the lines. The concludion of hybrid combinations'yield show that there are positively difference. The ratio of hybrid combination whose yield is higher than the control in 2006 is lower than that in 2005. During the hybrid combination judgement, the areola average yield of combination(2.81kg) is higher than that of the control(2.64kg). There isn't positively differenc between them. The height of plant and ear of combinations is positively higher than that of the control. The highest and lowest of combination yield are equally higher than that of the control and the variation coefficient of combination is also higher than that of the control.5.The appearance of hybrid combinations' yield and agronomic characters. The concludion of randomized blocked experiment with 9 combinations in 3 sites shows that there isnot positively difference between the combinations and the controls. The yield of 6 combinations is higher than that of controls and 3 combinations is lower than the controls, while the yield varies from -1.95% to 8.28%. As to the height of plant and ear, stem diameter,chlorophyll content, 9 combinations are higher or lower than that of the controls separately. Most combinations is more strong and healthy than the controls. The control is super than the combinations on leaf area.6.The combination attending henan province maize area experiment increase production 4.3% than the control(zhengdan958), and is the third highest in the experiment with impostively difference with other combinations. Electrophoretic analysis conducted by henan province seed management station shows that four bands are different between the combination and the control(zhengdan958). It also shows that essence difference exist among generations of an inbred line.