Effects Of Different Ratios Of Red And Blue Light On Tomato Seedlings Growth And Stomatal Movement

Tomato?Solanum lycopersicum L.?is one of the most widely cultivated vegetables in the world with special flavor and rich nutrition,and its cultivation area is one of the largest vegetables in the world.Tomato seedlings are affected frequently by weak light and uneven illumination as a kind of economic crop in facilities,meanwhile,but also the unsuitable proportion of light quality in plant factories.All of them could have serious effects on the normal growth and development of tomato,which results in the decrease of yield and quality of tomato.However,the light utilization of plant is mainly concentrated in the red and blue light regions of the light spectrum.Therefore,it is a critical subject to research how to promote growth and development,increase yield and improve quality of tomato using different proportions red and blue light.The tomato?Solanum lycopersicum L.?cultivar‘Jinpeng chaoguan'was used as experimental material.White light was regarded as control and different proportions red and blue light as treatments group[?Red;R?,?Red/Blue=2;2R1B?,?Red/Blue=1;1R1B?,?Red/Blue=1/2;1R2B?and?Blue;B?].The effects of different proportions red and blue light on photosynthetic characteristics of tomato seedlings,anatomical structure of leaf and ultrastructure of chloroplast through different treatments on tomato seedlings under different light quality was researched.Also,the change trends of stomatal conductance?Gs?and stomatal aperture of leaves under different treatments with time extend were tested.The article analysed the protein structure of H⁺-ATPase,and relative expression of some relevant genes?SLHA1,SLHA2 and SLHA4?.The results as followed:1)The photosynthetic pigments,photosynthetic morphological index,fresh and dry mass,plant height,stem diameter and root are all have changed dramatically under different proportions red and blue light treatments.Red and blue light combination can increase drastically the ratio of the chlorophyll a and chlorophyll b,2R1B and W treatments can enhance significantly the photosynthetic rate?Pn?of tomato seedlings.R,1R1B and 2R1B treatments increase markedly the total fresh and dry mass of tomato seedlings and healthy seedling index reached the 1.82 and 1.90 under 1R1B and 2R1B treatments,significantly higher than those under other treatments.The value of plant height and stem diameter were increased under R and 2R1B,and roots of them are more healthy under 2R1B and 1R1B.2)The anatomical structure of leaves and the ultrastructure of chloroplast were affected significantly by different proportions red and blue light.Palisade tissue of leaf was found in a tighter arrangement under 1R1B,1R2B and W,and they are thicker under red and blue light combination treatments,under the treatment of 2R1B and 1R1B,the size of starch granules was smaller than that of R,the chloroplast stroma and the grana lamellae were clear,and the thylakoid was stacked and arranged neatly and denser,which makes leaves to capture and utilise much more light energy.3)The stomatal conductance?Gs?and stomatal stomatal aperture are affected dramatically by different proportions red and blue light.Stomata opened quickly under1R1Band 1R2B with 200?mol·m^-2·s^-11 light intensity,stomatal conductance and stomatal aperture reached a plateau after 30min light treatment.H⁺-ATPase is a critical gene to regulate stomatal movement,SLHA1,SLHA2 and SLHA4 can express specifically in leaves if tomato,which plays a key role to open stomata under different light quality.The relative expression of SLHA1,SLHA2 and SLHA4 have changed significantly under different light quality with different time.After time treatment,the relative expression of SLHA1 and SLHA4 were upregulated,while the relative expression of SLHA2 remained unchanged and the relative expression of SLHA1,SLHA2 and SLHA4 were downregulated under some treatments,all of them indicate that SLHA1 and SLHA4 are key genes to regulate stomatal open.The relative expression of SLHA1 and SLHA2 were upregulated under suitable red and blue light treatment,then induce the stomata open and the stomata aperture have the relationship with photosynthsis of tomato seedlings,and the healthy index of seed lings were increased eventually.