以玉米自交系698-3及其改良系为试验材料,比较研究改良系与原自交系性状差异；利用4×10不完全双列杂交模式,分析不同改良系产量配合力及组合杂种优势表现,明确其遗传改良效果和育种利用潜力。结果为：各改良系在吐丝期、株高、主要经济性状及产量等方面均产生了不同程度的变异,改良系K336有13个性状与自交系698-3达到显著或极显著差异,是表型差异最大的改良系,而改良系SP698-3-17和SP698-3-11的表型差异最小,仅5个性状与自交系698-3差异达显著或极显著水平；单株产量GCA正效应较大的改良系依次为K336、K389和698-3GT42,多数改良系组合单株产量SCA效应差异不显著,仅205-11×698-3GT1109、205-11×K336和205-11×698-3R 3个组合表现出显著或极显著正向改良；多数组合统一对照优势为显著负优势,只有组合205-11×K336达显著正优势,其优势值达12.27%,36个改良系组合的分类对照优势多数为正优势,其中7个组合的正优势达显著或极显著水平。综上,改良系K336和K389的产量及主要经济性状和产量配合力均得到显著改良,其组合特殊配合力以及杂种优势总体表现较高,可作为高产育种用亲本；育种实践也证明,改良效果最好的系为K389和K336,分别为适宜丘陵区旱地两熟全程机械化种植品种正红505和高淀粉玉米品种正红532的父本。
英文摘要:
Maize inbred line 698-3 and its improved lines were selected as research materials, the character differences between inbred 698-3 and its improved lines were comparatively studied through morphological data; in order to understand genetic improvement effect and breeding potential, heterosis and combining ability of yield were analyzed by 4×10 incomplete diallel cross. The main achievements were as follows: 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 line 698-3. The improved line K336 have the most difference of phenotypic characters, and its 13 characters reach significant difference in comparison with the 698-3. In contrast, improved lines SP698-3-17, SP698-3-11 are all the least difference of phenotypic characters, they only have 5 characters reach at the 1% or 5% significant level. Positive GCA effect value of yield were in sequence of K336, K389 and 698-3GT42, most of improved line combinations in SCA of yield had not significant difference in comparison with the CK, and only combinations 205-11×698-3GT1109, 205-11×K336 and 205-11×698-3R reach at 1% or 5% positive significant level. Most of combinations’ unification heterosis reach at 5% negative significant level in comparison with Chuandan418, and only the 205-11×K336 reach at 5% positive significant level, with the value of 12.27%,the corresponding heterosis of most of 36 improved line’s combinations are positive value in comparison with corresponding 698-3 combination, among them, 7 combinations reach at 1% or 5% positive significant level. In summary, the main economic characters and yield and their yield GCA of improved lines K336 and K389 have a better improvement, some of their combinations’ yield SCA, and yield heterosis all have a better performance, they could be used as ideal parents in high yield breeding. Maize-breeding practice has also proved that, the improved lines K389 is male parent of the hybrid zhenghong505 which is more appropriate full mechanized planting variety in the two cropping system in hilly rainfed
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