【摘要】 作者研究了秈粳杂种的生育特性及结实性等经济性状的遗传变异,认为以出穗期为主要指标进行选择,结合其他性状的变异动态,逐步确立优良系统,有助于提高选择的效率,和建立较为合理的杂交育种程序与方法。更多还原

【Abstract】 Since 1957 crosses between O.Sativa L.Subsp.Hsien and O.Sativa L.Subsp.Keng havebeen made with the object of breeding rice varieties possessing useful characteristics of thetwo subspecies.In the course of breeding studies,special attention was paid to the inheri-tance of the following characters,viz,heading date,fertility,number of florets per panicleand weight of grains.Hybrid vigor expressed in germination potentiality,tillering capacity and quantity ofvegetable growth of the F₁ hybrids was observed in comparison with their immediateparents.Cases of the so called transgressive inheritance in the hybrid generations,especiallyin F₂ and F₃ were registered,which involved both morphological and physiological characteris-tics.Many new characters and traits had never been seen in parents appeared in thesegenerations.Variations of heading date in the hybrid generations showed that（1）the F₁generations almost entirely turned out to be significantly late;（2）the range of variation ofheading date was smaller in F₁ and larger in F₂ and F₃,and tending to be smaller again in thesuccessive generations,while from F₄ on,lines with stable heading date may be established;and （3） in F₅ lines with stable heading date increased,but a differentiation into early and im-mediate ripening forms in the intermediate ripening lines was observed in this generation,which had not been found in the selected early lines.The mean fertility of F₁ based on 6 combinations of crosses,ranged from 18.7 to 67.0%.It could be promoted naturally as generations continued,although faster in the early genera-tions than in the later ones.Due to the result of directed selection in some F₄ lines the per-centage of individuals with fertility of over 70% already rose to 63.5%,and lines with fertilityand its range of variation similar to parents began to appear in F₅.However,the fertility re-mained rather unstable even in this generation.The number of florets per panicle in the hybrid generations showed a tendency of trans-gressive variation with the continuing appearance of large-panicled material which had beenselected as new stable lines in F₅.The range of variation is much larger in F₂ and F₃ thanin other generations,while the mean florets per panicle decreased with the succeeding genera-tions.Directed selection seemed to show positive influence on the enhance of the number offlorets per panicle. Inheritance of weight of grains was found to be rather stable in comparison withother characters except the heading date.Differences in range of variation and in meanweight of grains between generations were not significant,whereas significance differ-ences were observed between different selected lines,and the seed weight between parent andoffspring was positively correlated from F₃ to F₅.Preliminary analyses of the inheritance of those characteristics described above took usto assume that time sequence of tending to genetic stability would exist with the heading dateat first and then with the height of plant,seed weight and awnness followed.The variationof floret number per panicle and fertility seemed to be uneasy to fix.Further studies areneeded, not only for the sake of deepening our knowledge but for enhancing the efficiencyof selection in rice breeding studies.更多还原