Effect of weak light stress on features and physiological characteristics of Scaevola aemula cutting seedlings.

The cutting seedlings of Sunfan were put under controlled lighting environments,with the full lighting percentage of 100%,45% and 15%,respectively.The result showed that illumination intensity obviously impacted the growth of cutting seedlings.With the enhancement of weak light stress and the extension of time,leaves became less with smaller area and thinner pants,resulting in higher victimization index.In a short time(15days)in the 45%light transmittance of the light stress,the plants grew normally,Chl a,Chl b,Chl(Total)value increased obviously,but Car,Car/Chl(Total),Chl a/b value visibly decreased.No obvious differences were found in soluble protein and POD activity.In a short time(15days)in the 45% or 15% light transmittance,soluble sugar,MDA and SOD activity obviously decreased.In a short time(15 days)in the 15% light transmittance of the light stress,chlorophyll in leaves had no obvious difference.In a long time(30-60days)in the 15%light transmittance,compared with the control,the plants grew difficultly and showed extremely significant difference;Soluble protein,MDA content,POD and SOD activity were obviously increased.Weak light stress can inhibit the production of MDA and soluble sugar and induce chlorophyll,soluble protein,osmotic adjustment substances,SOD and POD,forming synergistic physiological response system to response to week light stress.