Effects of Different LED Light Qualities on Cucumber Seedling Growth and Chlorophyll Fluorescence Parameters

【Objective】 The differences of cucumber seedling growth,as well as variances of chlorophyll content and chlorophyll fluorescence parameters were studied.【Method】Red light,blue light,red+blue(R+B) light generated by light-emitting-diode,white light as control,were applied to study the influences of different LED light qualities such as W,R,B,7R/3B,8R/2B,9R/1B on cucumber seedling leaves with Yinpei 99 as materials.【Result】 The differences of cucumber seedling showed that although treatments by single red light,blue light or white light had no significant effect on plant height and leaf length or width,obvious increase was observed about stem diameter,contents of chlorophyll and carotenoid in the blue light treatment.Moreover,the highest biomass,and NPQ were observed in red light treatment,with typical character of sun plants due to higher ratio of chlorophyll a/b.Furthermore,it was showed that a several combination of red+blue(R+B) treatment was beneficial to the growth of cucumber seeding,and seedling index,dry plant weight,Fv/Fm、ФPSII and qP were significantly higher than those of single red or blue light treatment.【Conclusion】 It was concluded that 8R/2B treatment showed its superiority with significant increase of plant height,seedling index,dry plant weight as well as Fv/Fm,ФPSII and qP,so 8R/2B treatment enhanced the opening degree,the light energy conversion efficiency of photosystemⅡ,and protected the effect of photosystemⅡ.