| In order to study the effects of enhanced UV-B radiation on the morphological damage mechanism of photosynthesis in mango leaves,this paper uses the robust"Tainong No.1" mango tree as the test material,using 24kJ/m2 d(low dosage)and 96kJ/m2 d(high dosage)UV-B UV lamp was simulated in the field to enhance UV-B radiation treatment,and the tree yield and main fruit quality,leaf photosynthetic physiological index,leaf pigment protein composition,leaf optical microstructure and ultra-line lechanism were observed.The change.Results are as follows:(1)The high-dosage treatment caused a significant decrease in tree yield,and the fruit quality decreased significantly,which seriously affected the economic benefits of mango.Low-dosage treatment had no significant effect on tree yield and fruit quality,showing the dose and accumulation effects of treatment.(2)The high-dosage treatment reduced the net photosynthetic rate and transpiration rale of the leaves,and the stomatal conductance showed a trend of increasing first and then inhibiting,and the effect of the late stage was not significant.The low-dosage treatment showed the promotion of partial time periods on the above observation indicators,while the rest Time difference is not significant.(3)High-dosage treatment reduced the content of chloroplast pigment protein,induced the production of new protein molecules,causing chloroplast damage;low-dosage treatlent also induced the production of new proteins,but the pigment protein as a whole did not change significantly.(4)Low-dosage treatment resulted in shortening and thickening of the leaf tissue of the leaf palisade,no significant change in the sponge tissue,the leaf remained intact,and the boundary between the sponge tissue and the palisade tissue was clear;the high-dosage treatment resulted in the fragmentation of the long-strip cells of the leaf palisade into small cells.However,it is mixed with the sponge tissue cells,and there is no obvious boundary between them.The sponge tissue cells become larger,the cell gap becomes larger,and the cells are loose.(5)The high-dosage treatment resulted in a very thickening of the stratum corneul on the surface of the leaf,and the stomatal opening was reduced and the number increased,showing a morphological change against UV-B radiation.Low-dosage treatment of stratum corneum thickening was not significant,but the number of stomata also increased significantly.It can be seen that high-dosage enhanced UV-B radiation treatment inhibits leaf photosynthesis mainly by destroying palisade tissue and damaged chloroplast in leaf photosynthetic structure;UV-B radiation enhancement induces significant thickening of the stratum corneum surface and reduces stonatal opening.It weakens the damage of UV-B radiation,but it also hinders the absorption of carbon dioxide by leaves,affects leaf transpiration and stomatal conductance,inhibits leaf photosynthesis through stolatal limitation,and then causes tree yield reduction and fruit quality deterioration.Low-dosage treatment has a certain effect on the micro-structure of the leaf,which makes it beneficial to resist the adverse morphological changes,but does not destroy its basic structure and does not cause obvious damage to the chloroplast,and has no significant effect on photosynthesis,so the tree yield and Fruit quality has no significant effect. |
