Physiological And Ecological Responses To Enhanced UV-B Radiation In Rice And Barnyardgrass

The destruction of the ozone layer makes the UV-B radiation reaching the earth's surface stronger and stronger.The enhancement of UV-B has become one of the major environmental problems facing the world.Barnyardgrass is the main weed in rice field.It has the same life type as rice and affects rice yield.A comparative study of the physiological and ecological effects of enhanced UV-B radiation on rice and barnyardgrass can be used to investigate the differences in the response of rice and barnyardgrass to UV-B radiation.It not only provides a reference for exploring the effects of UV-B radiation on the interaction of plant species,but also provides a theoretical basis for the high yield of rice in the future and the control of weeds in rice fields.This study uses Shendao 6 and barnyardgrass as the research object,adopting potted artificially simulated UV-B radiation increase 5%and 10%,Comparing the photosynthetic characteristics,secondary metabolism,morphology,and biomass of rice and barnyard grass to the differences in the response to enhanced UV-B radiation,the main conclusions are as follows:?1?The enhancement of UV-B radiation reduced net photosynthetic rate,stomatal conductance,intercellular CO₂ concentration,transpiration rate,and SPAD of Shendao 6 and barnyardgrass,and reduced the utilization of light of Shendao 6 and barnyardgrass.Enhancement of UV-B radiation results in a decrease in the initial light energy capture efficiency and initial light energy conversion efficiency of Shendao 6 and barnyardgrass,and a decrease in the amount of electrons generated,resulting in a decrease in the total electron transfer efficiency and a decrease in the intrinsic quantum yield,thereby reducing the net photosynthesis rate of Shendao 6 and barnyardgrass.From the perspective of the whole growth period,the gas exchange parameters and fluorescence parameters of barnyardgrass were inhibited by UV-B radiation to a greater extent than Shendao 6.Therefore,in the enhanced UV-B radiation environment,the inhibition of photosynthesis of barnyardgrass was greater than that of Shendao 6.?2?The species of secondary metabolites produced by the enhanced UV-B radiation of barnyardgrass was more than that of Shendao 6.Shendao 6 increased the content of total flavonoids and anthocyanins in leaves.Barnyardgrass increased the content of total flavonoids,flavonoids,anthocyanins and carotenoids in leaves.UV-B radiation had less effect on the secondary metabolites content in the roots and soils of Shendao 6 and barnyardgrass.It can be seen that the response of the protective material of barnyardgrass to UV-B radiation is stronger than that of Shendao 6.?3?Under the enhanced UV-B radiation stress,photosynthetic capacity of Shendao 6 and barnyardgrass decreased,and the amount of organic matter was reduced.At the same time,the morphology and the biomass of various organs were inhibited,affecting the ratio of material partitioning,resulting in Shen rice.The overall biomass of Shendao 6 and barnyardgrass decreased,but the biomass of Shendao 6 decreased more than that of barnyardgrass.?4?Under the enhanced UV-B radiation conditions,the number of grains per panicle,number of panicles,and seed setting rate of Shendao 6 decreased,and the actual yield decreased.