摘要:为研究干旱条件下小麦水旱地品种回交后代群体农艺性状改良效应，本研究以旱地品种‘长6878’为供体亲本、水地品种‘济麦22’为轮回亲本获得的回交二代（BC2）后代材料，对其株高、穗长、穗下节间长、分蘖数、小穗数、穗粒数、单株生物学产量、单株粒重、千粒重、经济系数等10个农艺性状进行相关、聚类和主成分分析。结果显示，回交后代材料在株高、穗长、穗下节间长、分蘖数等性状偏向于轮回亲本‘济麦22’，同时在小穗数、穗粒数、单株生物学产量、单株粒重、千粒重、经济系数等性状中存在超亲效应。相关分析表明，经济系数与单株粒重显著正相关，而单株粒重又与株高、穗长、分蘖数、小穗数、穗粒数、单株生物学产量、千粒重等7个性状达极显著正相关水平。在欧式距离40处，BC2群体分为4类，以轮回亲本‘济麦22’为核心的第Ⅱ类占BC2代总数的30.5%，供体亲本‘长6878’单独划为第Ⅳ类；在欧式距离45处将第Ⅰ类（占BC2代总数的58%）和第Ⅱ类合并成一个新的类群，即群体中88.5%的BC2单株和轮回亲本划分为一类。主成分分析得到5个主成分因子对BC2代农艺性状变异累计贡献率为85.51%，并筛选出综合得分高的10个株系，可作为后代重点选育。综合以上结果，在BC2代已经取得了良好的农艺性状定向遗传改良效应，为回交定向改良小麦抗旱水分高效利用和选育新品种提供理论依据和技术支撑。
关键词:小麦/
回交二代/
抗旱/
农艺性状/
改良效应
Abstract:The winter wheat growing season in the Huang-Huai-Hai area of China is often exposed to drought stress posing a serious threat to the safety of food production. The molecular design breeding by using backcross selection and molecular marker-assisted selection to improve breeding of drought resistant and high water use efficiency varieties become a new direction of future wheat breeding. A total of 200 BC2 (the second backcrossing generation) plants were obtained from the hybridization between dryland variety 'Chang 6878' as donor parent and irrigated variety 'Jimai 22' as recurrent parent. Ten agronomic traits, including plant height, spike length, internode length under spike, tiller number, spikelet number, grains per spike, biomass per plant, grain weight per plant, 1000-grain weight, economic index, were investigated to analyze the hybridization and backcross effect by the analysis of correlation, cluster and principal component. The results showed that the plant height, spike length, internode length under spike and tiller number of BC2 plants were biased in favor of the recurrent parent 'Jimai22', while the spike number, grain number per spike, biomass per plant, grain weight per plant, 1000-grain weight, economic index showed super-parents effect. The correlation analysis showed that grain weight per plant was extremely significantly correlated with plant height, spike length, tiller number, spikelet number, grains per spike, biomass per plant, 1000-grain weight. And grain weight per plant was significantly and positively correlated with economic index. The cluster analysis showed that BC2 population was divided into 4 groups at the Euclidean distance 40. The Class Ⅱ including 'Jimai 22' accounted for 30.5% of the total BC2 generations, while 'Chang 6878' was divided into Class Ⅳ separately. Class Ⅰ (58% of the total number of BC2) and Class Ⅱ were merged into a new group at the Euclidean distance 45, therefore 88.5% of BC2 individuals and 'Jimai 22' were classified into the same cluster. The principal component analysis obtained five principal components, which contributed over 85.51% of variance, and ten BC2 strains with high comprehensive score were screened as the key choice in the future. These results implied positively direction of genetic improvement in the BC2 generation, which provided theoretical basis and technical support for the water use efficiency and drought-resistance breeding by wheat backcross.
Key words:Wheat/
Second backcrossing generation/
Drought resistance/
Agronomic traits/
Improving effects
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