秋播小麥의 出穗期關聠形質의 遺傳과 早熟多收性 育種

Inheritance of Earliness, and Improvement of Early Maturing and High Yielding Winter Wheat Varieties in Korea

Korea has long been practised double cropping system and needed to improve early maturing and high yielding varieties. Consequently, extensive researches on the genetics of maturity and associated physiological factors such as photo-insensitivity, vernalization requirement, earliness in narrow sense and winter hardiness were made and. the results were discussed. Genetic studies for vernalization requirement using Vrn isolines revealed that Olmil may carry unknown Vrn factors different from the tested 4 Vrn genes. Most of early maturing varieties seemed to carry two Vrn genes. Photo-insensitivity was determinded to be controlled by a dominant majon gene is some crosses while more than one gene was recognized in the other crosses. Earliness in narrow sense was also indentified as a highly heritable character, but its effect on the heading is rather small than that of photo-insensitivity. Selection scheme facilitated with different winter temperatures due to location differences has resulted desirable breeding lines of early maturity with good level of winter hardiness. Early maturing and high grain yield which is con-tradicatory phenomenon in the biological system has been sucessfully assembled in the currently released varieties. This achievement was possible by increasing number of tillers per unit area while maintaining 1000 grain weight at the unchanged level and slight decrease in number of kernels per spike.