Effect Of Different LED Light Intensity And UV-B On Cucumber Growth And Nutritional Quality

The conditions of light,temperature,humidity,and nutrients required for plant production under artificial conditions can be precisely controlled.Therefore,the artificial environment for plant production is also called a plant factory which has become a research hotspot for high-efficiency agricultural systems in recent years.However,due to factors such as light environment limitations,it is currently applied only to a few leafy vegetable poduction.Cucumber is an important fruit-type vegetable that is widely grown all over the world.It is of great significance to develop a cucumber production technology in an artificial environment.LED（Light Emitting Diode）light sources have become the main source of light for plant growth or production due to low energy consumption,long service life,wavelength controllability,and characteristics of cold light sources.UV-B plays an important role in plant morphogenesis,growth and development regulation and pest control.However,the effects of suitable LED light intensity and UV-B addition at different growth stages of cucumber under artificial conditions are rarely reported.In this study,cucumber（Cucumis sativus）cv.Zhongnong 29 was used as the test material to observe the effect of different intensity of LED light on cucumber growth,photosynthesis,fruit quality and yield in its whole growth period under LED light environment.To explore the effect of adding UV-B radiation to the growth and yield of cucumber under LED light,the following main results were obtained:1.Under the LED light source of 200-700μmol m^-2s^-1with red-blue 9:1,the light intensity affected the growth,nutrition distribution,fruit quality and yield of cucumber plants.The photosynthetic efficiency of cucumber seedlings was significantly promoted under the LED light intensity of 300μmol m^-2s^-1.In the fruitingstage,the plant growth and development,photosynthesis,and fruit quality and yield had significant advantages under 700μmol m^-2s^-1light intensity.The seedling growth,fruit formation and yield were poor under light intensity of 200μmol m^-2s^-1.Therefore,it is considered that 300μmol m^-2s^-1 is a suitable light intensity at the seedling stage of cucumber,while cucumber requires 700μmol m^-2s^-1 or stronger light during the fruiting period.2.Under the LED light intensity of 700μmol m^-2s^-1with red/blue ratio 9:1,the UVB radiation time and dose parameters were tested and selected.We set 700-CK,700-10D,700-10N,700-15D,and 700-15N 5 treatments.The results showed that UV-B irradiation for10 min at night had obvious effect on inhibiting plant leggy and significantly increased fruit yield.UV-B treatment at night for 15 min significantly increased the nutritional quality of cucumber fruits and reduced the nitrate content.Therefore,it is believed that adding moderate UV-B radiation at night in LED light environment has a positive effect on improving cucumber fruit quality and yield.