The Mechanisms Of Light Quality Mediated Development And Nutrition Quality In Cherry Radish Plants

The area of vegetable cultivation has increasing in China generally,radish is one of the main vegetables.As the agriculture industrialize,greenhouse cultivation and plant factory have gotten steady developed.Although artificial light is the main supplied light source of greenhouses,not all light qualities can be used by plants,even against the growth of plants.The light quality used by plant photosynthesis are blue light that main absorption peaks at 450 nm and red light that peaks at 660 nm,but the other wavelengths of light in environment also have impacts on growth and development of plant.At sunrise and sunset or shade,the rate of far-red light rises,that leads to longer stem.Therefore,choosing appropriate light quality as artificial light source is the key to yield and economic effect of modern agricultural production.Hypocotyl of radish is the main edible part,its expand mechanism and the factors influencing the expand are still unclear.This article chose cherry radish(Raphanus sativus L.var.Radiculus Pers)as experiment materials,we first explored the impact of red light(R),blue light(B),and their mixture with far-red light(RFR and BFR)on cherry radish growth and photosynthetic characteristics.Then we explored the influence of light quality on expand of cherry radish hypocotyl and its relationship with hormones.Finally we researched the impact of light quality on nutrition qualities of cherry radish.The main results were as follows:1.Firstly,R and B promoted the growth of cherry radish underground part,but FR promoted the growth of cherry radish overground part,R and B promoted the synthesis of photosynthetic pigment,FR had inhibitory effect.The study found that under the R and B treatment,fresh weight and dry weight of cherry radish underground part were significantly higher than that under RFR and BFR,and the overground part of the fresh weight and dry weight and length were less than RFR and BFR treatment,suggested that R and B promoted the growth of cherry radish underground part,and FR accelerated the growth of underground part.Chlorophyll a and chlorophyll b,Chl a+b and carotenoid content in leaves under R and B treatment were significantly higher than that under RFR and BFR,suggested that R and B promoted the synthesis of photosynthetic pigment in cherry radish leaves,and FR could partly reverse the effect of R and B,thus phytochrome and cryptochrome were involved in cherry radish growth and photosynthetic pigment synthesis process.FR did not significantly influence photosynthesis,which suggested that R,B and FR influenced the growth and development of different parts of the cherry radish through allocating photosynthate to the overground and underground of plant.2.R and B promoted cherry radish hypocotyl enlargement,FR had inhibitory effcet of hypocotyl enlargement,and influenced expand of hypocotyl through the regulation of endogenous hormones content in the hypocotyl.We found under the mirror of 10 multiple,the hypocotyl cells under R and B were significantly greater than those under RFR and BFR,but cells number under R,B,RFR and BFR had no significant difference,the hypocotyl diameter under R and B were significantly greater than those under RFR and BFR.This suggested that FR does not affect the cell division of hypocotyl,but inhibited extension of hypocotyl cells,thus cherry radish hypocotyl swelled because of cell expansion.The content of IAA and JA under B treatment and W control were significantly higher than that under RFR and BFR.This showed that B and W promoted IAA and JA synthesizing and accumulating in the hypocotyl.IAA and JA promoted cell extension,so B and W promoted the hypocotyl expanding by increasing the content of IAA and JA in hypocotyl.FR inhibited hypocotyl expanding by decreasing the content of IAA and JA in hypocotyl.3.The study found that anthocyanins content under R and B treatment were significantly higher than that under RFR and BFR,this suggested R and B promoted the synthesis of anthocyanins in cherry radish leaves,FR inhibited it.Soluble protein content in the hypocotyl under B was significantly higher than other treatments,that suggested B promoted the synthesis of soluble proteins.Soluble sugar content of cherry radish plant was significantly higher under R than B,suggesting R was more advantageous to the synthesis of soluble sugar.The content of soluble sugar under RFR and BFR treatments were lower than those under R and W control,which suggested FR inhibited the synthesis of soluble sugar.B also promoted the accumulation of ROS in the leaves,but reduced the CAT activity in the leaves.