Effects Of Light Quality And Photoperiod Environment On Spinach Growth And Development

In this dissertation,the spinach variety 'Fishhongwang spinach F1'was used as the experimental material.The new LED solid state lighting was used to precisely control the light quality.The light quality and photoperiod of different LEDs were used to study spinach seed germination,Leaf photosynthetic physiology,growth morphology and nutritional quality of the spinach.Under the influence of red and blue light,the effects of different photoperiods on spinach twitching and related physiological bases were discussed.In order to promote the germination of spinach seeds,improve the growth and quality of spinach to provide a suitable light environment;It revealed the changes in physiological and biochemical substances that affected the process of spinach twitching.It provided a theoretical basis for the regulation of light environment.The main conclusions are as follows:1.Effect of different light quality and photoperiod on spinach seed germination.The results showed that the white light(W)treatment of spinach seed germination was better than the dark(CK)treatment,which showed that spinach is more conducive to seed germination in the presence of light.Under different treatments of light quality,red light promoted the germination of seeds.Red-blue mixed light could increase the seed germination rate,but the germination rate was slower and the vigor index was lower than dark treatment.While Blue light suppressed the germination of seeds.With the extension of daylength during the photoperiod,the interaction of light quality and photoperiod on seed germination was more complicated,and the promotion effect was gradually more obvious.The treatment of red light at the photoperiod of 16h/d the photoperiod of 16h/d was most beneficial to the gerrmination of seeds,the followed was at the photoperiod of 14h/d by red and white light treatment.2.Effects of different LED light qualities on the biomass production photosynthetic pigment content and chlorophyll fluorescence parameters on spinach were studied.The results showed that red-blue mixed light(1R1B)could increase the chlorophyll content of spinach compared to the white light(W)treatment,but the red and blue single light was the opposite.Blue light(B)had the greatest synergistic effect on spinach carotenoids and followed by red-blue light(1R1B),while red light(R)had the least effect on the synthesis of carotenoid the synthesis of carotenoid.The red and blue mixed light(1R1B)had the highest Y(?),qP,Y(NO),and qN.The red and blue mixed light(1R1B)was more conducive to the growth and development of the leaves than the red and blue light and the white light,and could effectively increase the biomass accumulation of the spinach and maintained the growth balance in the underground and overground.It can be seen that the absorption and utilization of red and blue mixed light(1R1B)by spinach is high,which is conducive to the growth of spinach.3.Effects of different ratios of red and blue light on the growth and quality of spinach.The results showed that the spinach with different red and blue ratios was superior to the control white light treatment.In the light environment with red/blue light=3:1,the spinach had the best growth pattern and highest yield on its overground.In terms of nutritional quality,sAt the same time,spinach has the highest soluble sugar content,the lowest nitrate content,protein and vitamin C content are higher than the control white light treatment.From the comprehensive analysis of the upper form of spinach,biomass production and nutritional quality,the light quality environment with red/blue light ratio of 3:1 was most suitable for spinach growth and cultivation.4.At 12h/d photoperiod,compared with white light,there was no significant difference in spinach twitching between white light and red-blue mixed light,but the fresh weight of spinach leaves in the red and blue mixed light(3R1B)environment was significantly higher than that in white light treatment.This shows that red-blue mixed light(3R1B)has little effect on spinach reproductive growth(flower bud differentiation,bolting),but it can affect the vegetative growth of spinach.Spinach showed pre-existing convulsions at light temperatures of 18-20? and photoperiod>12h/d.Spinach convulsions were most obvious at photoperiod of 14h/d.It was confirmed that spinach is a typical long-day plant,and flower buds differentiated.Not strictly required for low temperature conditions.5.Under red-blue mixed light(3R1B),different light cycles have different effects on spinach twitches.photoperiod longer 12h/d could cause the spinach produce bolting in advance,which reduced the production of vegetative organs on the above-ground spinach and reduced the yield.The treatment time of 16h/d,18h/d and 14h/d photoperiod spinach was on the 25d,23d and 22d after bolting.the spinach contains higher soluble sugar and soluble protein in the early stage of bolting in the condition of longer than 12h/d photoperiod treatment.In summary,spinach grow under the red-blue mixed light,after two leaves and one choy sum planting,the length of the growth cycle should not exceed 22d,25d and 23d when grown in the photoperiod environment of 14h/d,16h/d,and 18h/d.23d.In the actual production of spinach,the control of the harvest period effectively prevents the occurrence of pre-bolting.6.Effects of different photoperiods on the physiological and biochemical substances involved in the seizure process of spinach.The results showed that soluble sugar content and GA content increased gradually before bolting,reached the highest when bolting,and decreased significantly after bolting,while soluble protein was found the least in the early bolting,a significant drop in the time of bolting,and increased later period of bolting.POD activity and SOD activity increased gradually in the early stage of spinach bolting and reached the maximum at the time of bolting.The activity of CAT decreased in the early stage of spinach bolting and increased during bolting.After bolting,the activity of CAT decreased significantly.It is thus clear evident that the accumulation of soluble sugar and GA content,the decrease of protein content,the increase of POD activity,the increase of SOD activity and the decrease of CAT activity may all be the important factors inducing bolting of spinach.