Effects of Red and Blue Light Emitting Diodes(LEDs) on the Growth and Development of Lettuce(var. Youmaicai) / 航天医学与医学工程

ABSTRACT

Objective To investigate the characteristics of higher plant grown in red and/or blue light and test the capability of red and/or blue light emitting diodes(LEDs) used as the artificial lights for plant growth in controlled ecological life support system(CELSS).Methods Lettuce(Lactuca sativa var.Youmaicai) was cultivated in sole white LED,sole red LED and combined red and blue LEDs,respectively.Its growing status,physiological characteristics and the content of nutrients were evaluated,which were adopted to select the best combination of red and blue LED for plant growth.Results Red light promoted the radial growth of lettuce plants,and blue light was propitious to their transverse extension and synthesis of chlorophyll and carotenoid;lettuce plants couldn't grow normally in sole red light;with the gradual increase of blue light proportion(5%~20%),there were some active effects on the growth of lettuce plants,for instance,the improvement of photosynthesis,transpiration and fluorescence(Fo,Fv/Fm and qN),the increasing of contents of chlorophyll,carotenoid and nutrients and the enhancement of total biomass;the adverse effects of blue LED on the growing of lettuce plants appeared gradually with the addition of blue light(25%~50%).Its biomass of shoot decreased significantly,which induced the increase of the ratio of root/shoot.Conclusion The combined red and blue LEDs is propitious to lettuce(var.Youmaicai) growth and the best lighting condition is the combined 90% red and 10% blue light.