Effects Of Red And Blue Light Quality On Growth,Development And Photosynthetic Characteristics Of M9 Apple Rootstock Seedlings

Light is one of the essential factors in the growth and development of plants.Visible light of different wavelengths will affect the growth and development of plants,and will also have good or bad effects on the quality and quality of fruits.The dominant apple producing areas continue to expand to the high-altitude areas in the northwest,and the differences in light quality and photoperiod between different producing areas will also cause differences in apple yield and quality.In fruit crops,there are still few studies on light quality on its photosynthesis,physiological characteristics and fruit quality.To explore the effects of red and blue light on the growth characteristics,photosynthesis and carbon and nitrogen metabolism of seedlings,provide a theoretical basis for the study of the physiological and biochemical reaction mechanism mediated by red and blue light,and also provide a suitable light environment for apple ecological division and high-quality and high-yield cultivation.Selection and technical regulation provide an important basis.In this experiment,three elemental light treatments of red,white and blue were set up to determine the growth characteristics,ultrastructure of leaf plastids,photosynthetic characteristics,carbon and nitrogen content of apple seedlings under different light quality treatments,as well as RNA-seq.The main analysis results show that:1.Compared with the white light treatment,the blue light treatment obviously hinders the elongation and growth of the plant and the elongation of the leaves,but can promote the thickening of the leaves;contrary to the blue light,the red light treatment accelerates the elevation of the plant,the enlargement of the leaves,and the red light and blue light treatment can promote the development of the root system of apple seedlings.2.Compared with white light treatment,blue light treatment promoted the development of leaf tissue structure and chloroplast,which was beneficial to light absorption,and significantly promoted the stomatal conductance,transpiration rate and photosynthetic efficiency of leaves.After light treatment,the leaf palisade tissue will be loosened and the chlorophyll content will be reduced,which is not conducive to the accumulation of plant chlorophyll and reduces the photosynthetic rate.3.Compared with white light treatment,blue light treatment can promote the accumulation of soluble sugars and starch in plant leaves,and red light treatment can promote the accumulation of soluble sugars,but is not conducive to the accumulation of starch;blue light treatment can promote the accumulation of ammonia nitrogen content and the accumulation of three enzyme activities（GDH,GOGAT,NR）related to nitrogen metabolism.4.RNA-seq analysis of apple seedling leaves showed that both blue and red light treatments significantly upregulated the expression of genes related to carbon and nitrogen metabolism.Blue light treatment can promote the synthesis of amino acids and flavonoid metabolism,and red light treatment can induce plant hormone signal transduction.