[Rice breeding by space technology].

In order to inquire into the influences of space conditions on rice breeding,the dry seeds of 12 rice varieties were carried by recoverable satellite. After recovery,these seeds were showed in the yield, the inheritance and variation of the characters of their progenies were observed and analysed. The results showed that the characters of the progenies mutated under space conditions segregated and varied in many aspects and directions,and the segregated and varied characters were heritable. These progenies posoessed significant transgressive inheritance, a plenty of variation types and variation was characterized by short breeding period. The results in this study indicated that space technology breeding could be developed and used as a new method of mutation breeding.

[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.

[A study of genetic stability of male sterile mutant of maize obtained from space flighted seeds].

OBJECTIVE: To select a male sterile mutant of maize through space flight for production application. METHOD: Air dried seeds of maize (Chuan Dan No. 9) were carried to space for 15 d. After returned to the earth, a male sterile mutant was selected and a sterile line was obtained through direction breeding. RESULT: It was found that the sterile material was thoroughly abortive. The sterile was trail stable and expressed a genetic feature of single recessive gene controlled nucleus sterility. CONCLUSION: The appearance of male sterile mutant was due to gene mutation caused by space conditions.

[Studies on character variation of parent of "Ganzaoxian 47" by space mutation].

OBJECTIVE: To breed a new variety from "86-70 selective line"--a late-maturing early indica rice variety with small spike, light grain and weak disease resistance by space mutation. METHOD: Dry seeds of "86-70 selective line" were carried by recoverable satellite, to a near earth orbit and sowed and planted on the earth after recovery, heritance and variation of the characters of SP1- SP9 generation were observed. RESULT: Because of comprehensive space mutation, the characters of their progenies were segregated and varied in many aspects and directions, and the segregated and varied characters were found to be heritable; by selecting early-maturing mutants from these progenies and cultivating them directionally, a new rice variety "Ganzaoxian 47 " was bred. In comparison with its parent, "Ganzaoxian 47" had superior agronomic and economic characters, significantly strong resistance to rice blast and so on, its filled grains per spike [correction of spile], kilo-grain weight and yield were increased by 37.9%, 5.3% and 22.5% respectively, but its growth and developmental duration were shortened by 14 d. CONCLUSION: This study provided a new demonstration for space mutation breeding by recoverable satellite, and indicated that space mutation was an effective and new approach to agricultural crops breeding.