<正>Rubisco is a key enzyme which controls theprocess of photosynthesis and phototespi-ration.It is very abundant in the leaf and isvery sensitive to many environmental factors.we studide the changes,caused by cold-hard-ening and chilling stress,in activity,Proteincontent,and the characters of Rubisco in riceseedlings(Tesanal 2).The treatment of cold-hardening at 14℃and under a PFD(photo flux density)of 75