Effects of light qualities on accumulation of oxalate, tannin and nitrate in spinach

Red light(RL), blue light(BL) and yellow light(YL)were obtained from fluorescent lamp lights. With the same intensity of white light(WL) as control, the effects of light quality on biomass, oxalate, tannin and nitrate accumulation in spinach were studied. The results showed that changes of nitrate and oxalate contents were different in petiole and leaf blade among various treatments, while the trends of plant growth increment were the same. Leaf blade had more proportion than petiole in fresh weight. Under different qualities, the increase of leaf blade and petiole fresh weight in turn were WL(CK)>YL>RL>BL. RL was better to the formation and accumulation of dry matter and carbohydrate. Nitrate concentration in petiole was significantly higher than that in leaf blade. The petiole was the dominant place for nitrate accumulation, and the variation of nitrate concentrations in leaf blade was significantly higher than that in petiole. The oxalate content in leaf blade was higher than that in petiole under WL and YL treatments, but it was opposite under RL and BL treatments. And the total oxalate content of RL treatment was the lowest. Although spinach biomass was lower under RL treatment, the nitrate and total oxalate contents could be reduced obviously. The quality of spinach was improved by RL treatment.