Institut National de la Recherche Agronomique (INRA), Station de Génétique et d'Amélioration des Plantes, Domaine de Melgueil, 34130, Mauguio, France.
Theor Appl Genet. 1996 Mar;92(3-4):368-74. doi: 10.1007/BF00223681.
The utilization of exotic germ plasm is difficult due to its non-adaptability. This study investigates the possibility of exotic germ plasm loss during adaptation, and the effect of an additional cross with elite material on the breeding value of exotic x adapted material. The study was conducted on a temperate x highland tropical composite (or pool) developed in order to broaden the genetic variability of maize in north western Europe. The frequency of unique exotic alleles and the isoenzymatic polymorphism at four loci were analysed in the pool itself, in the pool after mild selection, and in the selected pool crossed with elite material. Based on these data, no significant deviation seemed to occur during the mild selection and the cross. The pool and the pool x elite germ plasm cross were evaluated in testcrosses with two complementary testers for both grain and forage production. The pool was later in maturity, more susceptible to lodging, and yielded less than the pool x elite germ plasm crosses for all evaluations. The highest estimates of genetic variance were obtained in the pool for earliness and height traits, and for yield. However, based on the predicted genotypic mean of the selected population, the pool had a lower breeding value than the pool x elite germ plasm cross. The pool x elite germ plasm cross is thus preferred to initiate selection.
由于外来种质的不适应性，其利用较为困难。本研究旨在探讨外来种质在适应过程中丢失的可能性，以及与优良材料进行额外杂交对适应后外来材料的育种值的影响。本研究以培育北欧玉米遗传多样性为目的，对温带 x 高原热带复合群体（或混合群体）进行了研究。分析了混合群体本身、轻度选择后的混合群体以及与优良材料杂交后的选择群体中外来等位基因的独特频率和四个基因座的同工酶多态性。基于这些数据，在轻度选择和杂交过程中似乎没有发生明显的偏差。利用两个互补的测验种对混合群体及其与优良材料杂交的群体进行了穗粒和饲草产量的测验杂交评估。与杂交后的选择群体相比，混合群体成熟较晚，倒伏敏感性较高，产量也较低。然而，基于选择群体的预测基因型均值，混合群体的育种值低于杂交后的选择群体。因此，杂交后的选择群体更适合作为起始选择。
