Effect of seed moisture content on satellite carrying mutation

There is a new way to get space induced mutant by changing the moisture content of forage seed. The moisture content of alfalfa seed located five levels: 9% (natural water content), 11%, 13%, 15%, 17%. One part of tested seeds were carried by the China's seed-breeding satellite, Shijian-8, from Sep. 9 to 24 in 2006, another part was stored on ground. After the retrieval, performance of key agronomic traits and leaf ultrastructure of plant derived from spaceflight were tested and evaluated. The number of branches, leaf area and height of the nature moisture content were the highest among ground control. The treatment of 9% and 11% was inhibited, the number of branches and leaf area and height of carrying group are lower than the control group(P < 0.05); while the 13%, 15% and 17% group were higher than control significantly (P < 0.05). And the effect of the 13% and 15% group are significant (P < 0.05). Great changes had occurred on ultrastructure on mutations induced by spaceflight factors: bigger chloroplasts of irregular shapes, bigger and more numerous starch grains contained in chloroplasts, less grana and granum-thylakoid stakes of chloroplast. And it aggravated with the moisture content increasing. So we conclude that different moisture content had effect on alfalfa plant growth and development, the 13% to 17% group were lower than the 9% group in the height, number of branches and leaf area; Satellite carrying had different impacts on plant growth and development, especially for seeds of high moisture content. The 13% to 17% carrying groups were higher than corresponding control group in the height, number of branches and leaf area; As the moisture content of carrying seeds increasing, changes of plant ultrastructure aggravated; The moisture content of 13% to 17% of alfalfa seeds was appropriate to satellite carrying. (author)