Comparative Studies On Main Characters And Combining Ability Of Improved Lines Derived From Maize Inbred Line698-3

Germplasm resources are viewed as a material base for crop breeding. Evaluation research and expansion of maize germplasm has very important significance for crop breeding and agricultural development. In this paper, maize inbred line698-3, its improved lines and their test cross combinations were selected as research materials. The character differences between inbred698-3and its improved lines were comparatively studied through morphological data; in order to understand genetic improvement effect and breeding potential, heterosis and combining ability of main agronomic and economic characters were analyzed by4×10incomplete diallel cross. Hence, provide references for maize breeding. The main achievements were as follows:1. The analytical results of phenotypic characters showed that improved lines have various degrees of variation in silking stage, plant height, main economic traits and yield compared with the original maize inbred line698-3. Among all the14characters tested, the improved line K336have the most difference of phenotypic characters, and its13characters reach significant difference in comparison with the698-3(p<0.01or p<0.05); improved lines698-3GT42, K389, and K318have more difference of phenotypic characters than that of the698-3, and have11-12characters respectively reach at the1%or5%significant level; improved lines698-3GT1109, SP698-3-6and698-3R have6-9characters respectively reach at the1%or5%significant level. In contrast, improved lines SP698-3-17, SP698-3-11are all the least difference of phenotypic characters, they only have5characters reach at the1%or5%significant level.2. The results of combining ability analysis indicated that,2-7improved lines had significant difference in different characters compared with the698-3(p<0.01or p<0.05). Among them, plant height and barren ear tip length of7improved lines, kernel depth of2, the other characters of3-5had significant difference as compared with that of the698-3(p<0.01or p<0.05). Among them, improved lines in ear height and yield all showed a positive effect, and positive GCA effect value of yield were in sequence of K336, K389and698-3GT42; improved lines in silking stage and kernel depth all showed a negative effect; improved lines in the other characters varied toward two directions, among them, most of improved lines in plant height, ear length, ear diameter, kernel per row and100-kernel weight showed a positive effect; ones in barren ear tip length and kernel rate showed a negative effect; the same improved lines number in ear rows showed a negative and positive effect. As far as specific combining ability, most of improved line combinations in SCA of yield had not significant difference(P>0.05) in comparison with the CK, and only combinations205-11×698-3GT1109,205-11×K336and205-11×698-3R reach at1%or5%positive significant level. The combination with the largest TCA effect value of yield was205-11×K336, the second was Jh96C-2xK336, and the third was Jh96C-2x SP698-3-17.3. The analytical results of yield heterosis showed that most of combinations’ unification heterosis reach at5%negative significant level in comparison with Chuandan418, and only the205-11×K336reach at5%positive significant level, with the value of12.27%. The corresponding heterosis of most of36improved line’s combinations are positive value in comparison with corresponding698-3combination, among them,7combinations reach at1%or5%positive significant level. Corresponding heterosis’s value of combination205-11×K336is the highest, with the value of29.78%, the second is K169xK389with a value of19.05%, the other5combinations range from11.38%to18.58%.4. In summary, compared with the698-3, improved lines K336and K389showed that period of duration is shorten, plant height become tall, and the tassel branch numbers are increased, the main economic characters and yield have a better improvement; and their yield GCA have significant improvement (p<0.01), some of their combinations’ yield SCA, yield TCA and yield heterosis all have a better performance. Hence, the improved lines K336and K389could be used as ideal parents in high yield breeding. However, the adverse influence of their plant height and tassel branch number should be noticed in practical application.