Effects of Different Light Quality Ratios on the Growth of Hydroponic Forage Barley

【Objective】 To study the effects of different red and blue light ratios on the growth of hydroponic barley and determine the appropriate photoplasm. 【Methods】 Hydroponic forage barley was taken as the research object, the plant height, root length, fresh grass yield and dry grass yield of barley in one growth cycle were measured by LED white light, LED blue light and LED red blue light. 【Result】 The results showed that there were significant differences in the growth of barley under different light conditions. Under the condition of white light, the plant height of barley was 8.92 cm, which was significantly higher than those of the other two treatments. The plant height of blue light treatment was the lowest, 6.62 cm, which was significantly lower than those of the other two treatments; the root length of blue light treatment was the longest, 10.42cm, which was significantly higher than those of the other two treatments. There was no significant difference in the biomass of fresh grass and hay between blue light and red blue light, which was significantly higher than that of white light. 【Conclusion】 Under the condition of artificial light hydroponics, LED white light promotes the stem elongation and plant height of the upper part of barley plant, while the fresh weight, dry weight and root growth of the lower part are inhibited. Led blue light can promote the growth and biomass accumulation of barley roots, but plant height elongation is limited. The combination of red and blue LED can promote the increase of barley biomass, which is the recommended light quality for hydroponic cultivation of barley forage.