Effects Of Light Environment On Growth,Yield And Quality Of Water Spinach

Plant factory is an efficient agricultural system that artificially controls the growth environment of crops to realize the continuous production of crops.One of its main characteristics is the utilized of artificial light sources to achieve intelligent control of light environment.As one of the important artificial light sources in plant factory,light emitting diodes?LEDs?mainly control the light environment of plant factory by light quality,light intensity and photoperiod,enhance the efficiency of crops to use light energy,and then improve their yield and quality.The previous study have been reported on the effect of a single factor of light on the yield and quality of leafy vegetables,and mainly foused on lettuce,but there are few studies on the comprehensive regulation of plant light environment on the photosynthetic characteristics,yield and quality of water spinach.Therefore,in order to provide some reference for the cultivation and light environment utilization of water spinach in plant factory,the experiments used LED as light source to study the effects of light quality,light intensity and photoperiod on the photosynthetic characteristics,growth and development,nutrient uptake,yield and quality of hydroponic spinach under plant factory conditions.The main results were as follows:1.Compared with white light,the combination of red?R?and blue?B?light was more conducive to the growth and nutrient substance accumulation of water spinach,and along with the increasing of the proportion of R light,dyield per plant and Pn of water spinach were increased significantly,while the root activity and the content of K were decreased.When the ratio of light quality was R:B=2:1,the content of Vc,soluble protein,total phenol and flavonoids of water spinach was significantly higher than other treatments,and the content of nitrate was the lowest,the yield was higher and the quality was better.2.With the increment of light intensity within a certain range,the biomass and nutrient content of water spinach significantly increased.When the light intensity was 400?mol·m^-2·s^-1,the content of yield per plant,Pn,Rubisco activity and PSII of water spinach were the highes,however under the 450?mol·m^-2·s^-11 treatment,the Pn was decreased,and qP was increased.This showed that excessively high light intensity lead to the increasement in the heat dissipation of the optical system and thus reduced the photochemical efficiency.In addition,the light intensity of 400?mol·m^-2·s^-11 could significantly improve the content of Vc,total phenol,flavonoids and anthocyanin of water spinach,and had a high nutritional value.3.Compared with other treatments of photoperiod,the control photoperiod of 12 h/12htreatment significantly improved the photosynthetic characteristics and PSII performance,and the content of soluble protein,Vc,total phenol was increased significantly.However,when the period of daytime was more than 12 h,the yield per plant,Pn and?PSII increase rate were decreased,and several indices of the quality were slightly reduced.Furthermore,the increment of cultivation cost was not conducive to the efficiency and high-quality cultivation in plant factories.