| The narrower genetic background has become the first constraint factor for the sustainable development of China’s maize breeding and production, Enhancing genetic improvement was one effective way to broaden the genetic basis of maize germplasm for the shortcomings of the existing germplasm resources. Maize Inbred line444belonged to the Tangsipingtou consanguinity, was an important germplasm resource of maize breeding in northern China in the1990s, however, it existed the shortcomings of non-resistance of head smut, pre-leaf yellow-white bars, shorter ear and few Row grains. In order to improve the shortcomings, in2004, Northeast Agricultural University took444as the recurrent parent, targeted selection of54domestic excellent inbred lines as donor parent, by3generations of backcrosses and4generations of selfing constructed161the high generation backcrossing introgression lines (BILs, BC3F4). In this experiment, excellent58backcross introgression lines randomly selected had been appraised on agronomic traits and resistance evaluation to head smut and the leaf blight. According to the NC II genetic mating design to compound hybridized combination, we took44backcrossing introgression lines from different donors and4testers represented different groups as material to analysis the combining ability and heterosis of tested backcrossing introgression lines and evaluate the utilization value in breeding. It provided a theoretical basis for the effective utilization in Maize Breeding in China. The main results were as followed:(1) The evaluation results of agronomic and yield traits showed that J45,J141,J33,J70, J78,J79,J97and J147performed well and better than444in yield and its components, these could be prior used in breeding. The growth period range of58backcrossing introgression lines of444was117-129d, the growth period of5BILs (J45, J46, J133et.al) was significantly shorter than444; the flowering interval of26BILs (J70, J2, J6et.al) was shorter than444; the plant height and ear height of6BILs (J125, J84, J52et.al) were lower than444; the yield per plant of14BILs (J3, J33, J52et.al) was higher than444; the100-seed weight of8BILs (J30, J45, J73et.al) was higher than444; the seed-producing percentage of20BILs (J136, J27, J14et.al) was higher than444; the ear length of11BILs (J33, J41, J79et.al) was longer than444; the ear diameter of12BILs (J98, J141, J70et.al) was thicker than444; the aixs diameter of43BILs (J2, J32, J84et.al) was less than444; the ear row of17BILs (J41, J45, J28et.al) was more than444; the row grains of34BILs (J127, J151, J121et.al) was more than444.(2) Artificial inoculation results of head smut showed that the rate of disease of the52backcrossing introgression lines were lower than444, accounted for89.66%, it indicated backcrossing introgression lines had a larger increase than recurrent parent444for resistance level of head smut. high resistance line is J15with donor parent chuan273, accounting for1.73%of the tested materials;5selected lines performance disease-resistance, include J2, J28, J31etc. with donor parent ji446,90141-2, mo17, accounting for8.62%of the tested materials;10selected lines performance medium resistance, include J3, J6, J27etc. accounting for17.24%of the tested materials;36selected lines performance suscept, include J9, J12, J14etc. accounting for62.07%of the tested materials;6selected lines performance high-suscept, include J40, J70, J105etc. accounting for10.33%of the tested materials.(3) Artificial inoculation results of leaf blight showed that although there were not high resistant and high susceptible materials, the disease index of45BILs were lower than444, accounted for77.59%, the resistance of444’s BILs was overall improvement. The disease-resistance line is J25with donor parent U8112, accounting for1.73%;46selected lines performance medium resistance, include J2, J3, J6etc. accounting for79.30%of the tested materials;11selected lines performance suscept, include J9, J52, J65etc. accounting for18.97%of the tested materials.(4) Combining ability analysis showed that the general combining ability of yield traits of6backcrossing introgression lines(J45, J25, J97, J60, J63, J30)of444were better than444; the top10combinations of specific combining ability effects of yield per plant were J58×Qi319, J25×Qi319, J84×Qingxi9808, J30×Qingxi9808, J68×Qi319, J78×Qingxi9808, J97×Zheng58, J15×PH4CV, J154×Qi319and J133×PH4CV.(5) Heterosis analysis show that by the yield per plant control test, it existed16combinations in yield were more than jidan27, accounting for26.23%, include Qingxi9808xJ147, Zheng58xJ12, Zheng58xJ9etc, increase range of yield was0.9～23.4g;49combinations in yield were more than xingken3, accounting for79.03%, include PH4CV×J105, PH4CV×J15, Zheng58xJ60etc, increase range of yield was0.8-30.5g;3combinations in yield were more than xianyu335, accounting for5.66%, include Qi319×J105, Qi319×J68and Qi319×J58, increase range of yield was6.8～17.3g.(6) The yield per plant of27.27%hybrid combinations as Qingxi9808was more than Qingxi9808×444; the yield per plant of59.09%hybrid combinations as PH4CV was more than PH4CV×444; the yield per plant of40.91%hybrid combinations as Qi319was more than Qi319×444; the yield per plant of36.36%hybrid combinations as Zheng58was more than Zheng58×444, the rate of transgressive heterosis was higher, It illustrated that there had significant effect in the improvement of yield trait. |
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