[Studies of inheritance and application in rice breeding of the large grain mutant induced in space environment]

The inheritance and utilization of a stable large-grain mutant,selected from the induced generation derived from japonica Nongkeng 58 after space treatment carried by recoverable satellite, were analyzed. The results indicated that the grain volume of the large-grain mutant was quantitative trait controlled by multiple genes. The large-grain mutant had characteristics of slender grain,favorable scent, high apparent grain quality and good compatibility with japonica,and can be used as a valuable resource for improving grain quality. When high yield japonica variety with bad looking quality was used as a recurrent parent to cross with the mutant and a procedure of a limited backcross combined with identification of brown rice quality in segregation generations was applied,some japonica lines with good looking quality were developed. The utility of the limited backcross method for improvement of quantitative traits was discussed.