Effects of different light quality ratio on growth and photosynthesis capacity in pakchoi under excess nitrate stress

Abstract

In this study, light-emitting diode (LED) was used as light source to cultivate pakchoi in hydroponics. The effects of red light and far red light ratio (R: FR) of 0.7, 1.0 and 4.2(CK) on the growth and photosynthetic characteristics of pakchoi under different nitrate stress concentrations were studied. The results showed that the growth indexes, gas exchange parameters (except intercellular CO2 concentration) of pakchoi decreased significantly under excess nitrate stress. And the growth of pakchoi was more inhibited under high nitrate stress concentration. Under low R: FR ratio, the growth indexes and net photosynthetic rate of pakchoi increased significantly, while the intercellular CO2 concentration decreased significantly, and the effect was achieved when R:FR=0.7. Therefore, reducing R: FR ratio can alleviate the inhibition of excess nitrate stress on the growth and improve the yield of pakchoi.