Influence of Light Quality on Growth of Oil Rape Seedlings

Rape seeds were sown in the mixture of vermiculite，perlite and peat（3∶1∶1）in petri dish and grown under nine different light qualities（fluorescent（FL），plant growth light（PGL），red LEDs（R），blue LEDs（B），green LEDs（G），white LEDs（W）and different ratio of red and blue LEDs（RB 2∶1，RB 3∶1 and RB 4∶1））respectively.The sixth and fourteenth days after sowing，the height of rape seedlings from soil surface was highest under G followed by R and the lowest was under FL.All results showed that plants under monochromatic lights（G，R and B）had a higher up-ground growth and average growth rate than those under multi-spectrum lights.While the inversed results were obtained in root induction，area of leaves，chlorophyll content and stem diameter between monochromatic lights and multi-spectrum lights in this study.The average growth rate was different among the light qualities，but light qualities could not change the growth regular of early growth stage of oil rape seedlings.The results of fresh and dry weight also indicated that monochromatic lights were not suit for the growth of rape seedling，while the mixed-spectrum light qualities of LED red and blue were preferred in rape seedlings growth.The histological examination results also indicated that the mixed light qualities of red and blue had better effective in inducing formulation of vascular cylinder than FL did.All results from this study showed that red and blue LEDs（RB3∶1）was the best light qualities for the early growth of rape seedling.