Induced Mutations for Plant Breeding·Agricultural Biotechnology
To investigate the effects of space mutation on the growth and physiological characteristics of four woody flowers， a new generation of manned experimental spacecraft was used to carry the seeds of Delonix regia， Jacaranda mimosifolia， Callistemon speciosus， and Cassia fistula. After returning to the ground， the growth characteristics， leaf morphology， pigment content， and physiological activities of the container seedlings were determined. The results showed that after space mutation the survival rate of D. regia increased by 6.92 percentage points， whereas that of J. mimosifolia and C. speciosus decreased by 8.12 and 10.66 percentage points， respectively， and the survival rate of C. fistula had no significant change. The growth characteristics of D. regia and C. fistula seedlings， such as plant height， ground diameter， leaf number， and leaf （axis） area were decreased by 25.74% and 45.15%， 11.14% and 19.51%， 9.13% and 31.60%， 33.62% and 32.26%， respectively. The plant height， ground diameter， leaf number， and leaf length of C. speciosus seedlings andtheaxis length and axis area of J. mimosifolia seedlings were increased by 64.93%， 37.09%， 118.25%， 18.78%， 26.49%， and 37.29%， respectively. The soluble sugar content of D. regia， J. mimosifolia， and C. speciosus seedlings leaves increased by 36.46%， 16.77%， and 7.23%， respectively. The soluble sugar content and PDHA activity of C. fistula seedling leaves were decreased by 8.59% and 39.83%， respectively. Combined the results of correlation analysis， it was deduced that space mutation inhibited the growth and leaf morphological characteristics of D. regia and C. fistula seedlings， causing negative variation. While space mutation caused positive variations in the growth and leaf shape characteristics of C. speciosus seedlings and the leaf shape characteristics of J. mimosifolia seedlings. It had no significant effect on the pigment content of the four woody flower seedlings. The impacts of space mutation on the physiologically active substances in the leaves of D. regia，J. mimosifolia， and C. speciosus seedlings were more significant than that on C. fistula. These results indicate that space mutation had an vital effect on the growth and development of four woody flower seedlings. The impacts of space mutation varied with the different characteristics of the tree species. It is an effective way to improve the germplasm of woody flowers.