| As a modern agricultural high-efficiency production system,the artificial light plant factory can realize automatic high-precision control of environmental factors to achieve continuous production throughout the season.Exploring the importance of light quality and light intensity on the improvement of plant yield and nutritional quality in the plant factory environment.LED（Light Emitting Diode）is considered to be one of the most ideal light sources for green plants at this stage.In this study,lettuce was used as the test material,and the effects of different light quality ratios,different light intensities,and different UV-A intensities on the basis of white light were respectively studied on the growth and development of lettuce under LED light sources.The main results are as follows:1.In the study of the effects of different red-blue ratio on lettuce,the light intensity was set as 200μmol·m-2·s-1,and the red-blue ratio（R:B）was T1（R:B=1:1）,T2（R:B=3:1）,T3,T4（R:B=5:1）（R:B=7:1）,T5（R:B=9:1）and CK（white light）,a total of six processing.The results showed that compared with CK,red and blue combined light T3（R:B=5:1）,T4（R:B=7:1）,T5（R:B=9:1）could increase the yield per plant,and it increased with the increase of red light proportion.Under the combined irradiation of red and blue light,the nutritional quality of lettuce was better than that of white light,Especially when the ratio of red to blue light was 5:1,it had the best improvement effect on the nutritional quality of lettuce,and the nitrate content was significantly reduced by6.33%to 30.17%compared with other treatments.The results showed that under R:B=5:1 light source,the photosynthetic pigment content of leaves increased by4.70%～38.05%compared with other treatments,and the net photosynthetic rate was significantly higher than other treatments.Fv/Fm,ΦPSⅡ,q P,Fv/Fo reached the maximum value under T5（R:B=5:1）.Through principal component analysis of several indicators of lettuce,it is concluded that the comprehensive score is the highest when R:B=5:1.Therefore,it is determined that the hydroponic lettuce has the best effect when the red-blue ratio is 5:1.2.In the study of the effects of different light intensiities on lettuce,five light intensiities of 70,120,170,220 and 270μmol·m-2·s-1 were set,and the ratio of red and blue light was 5:1.The results showed that biomass accumulation was positively correlated with light intensity,and the content of water-soluble protein and VC also increased with the increase in light intensity.and root activity was in the same direction.When the light intensity was 220μmol·m-2·s-1,the photosynthetic pigment content,Fv/Fm,φPSⅱ,q P,Fv/Fo,Rfd,total phenol content and flavonoids content reached the maximum,and nitrate content was the lowest,which was 2925.25mg·kg-1.Compared with other treatments,it was significantly reduced by 10.30%～17.84%.Through principal component analysis of several indicators of lettuce,the highest comprehensive score was obtained when the light intensity was 220μmol·m-2·s-1.Therefore,when the ratio of red to blue was 5:1,the light intensity suitable for lettuce growth was 22μmol·m-2·s-1.3.In the study of the effect of adding different intensities of UV-A on lettuce under the same light intensity,the white light intensity was set to 220μmol·m-2·s-1,and the UV-A intensity was set to T1（350u W·cm-2）,T2（450u W·cm-2）,T3（550u W·cm-2）and CK in total four treatments.The results showed that compared with CK,the addition of UV-A radiation decreased the yield per plant,and the yield per plant decreased with the increase of UV-A intensity.Nitrate content was significantly increased at T2 and T3 compared with CK,and there was no significant difference between T1 and CK.When adding350u W·cm-2UV-A intensity,the photosynthetic pigment content,Pn,Gs,Tr,soluble sugar content and VC content were significantly improved compared with CK.Through the principal component analysis of multiple indicators of lettuce,it was also concluded that the lettuce had the highest comprehensive score when 350u W·cm-2UV-A radiation was added. |
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