Effects Of Potassium Supply On Growth,Yield And Quality In Peanut And Simulation Under Enhanced UV-B Radiation

A large number of chlorofluorocarbon,nitrogen oxides and other substances come into the atmosphere due to human activities,causing the depletion of stratospheric ozone.If the atmosphere stratospheric ozone reduce by 1%,the ultraviolet radiation which reaches the ground will increase by 2%.The decrease of stratospheric ozone results in a significant increase in UV-B radiation that reaches the ground and has an important impact on the ground plants.However,plants do not grow under the influence of a single factor,and it is difficult to correctly assess the biological and ecological effects of global changes by considering the effects of a single factor on plants.Therefore,the current research on the combined effect of UV-B radiation and other factors has been paid more and more attention by researchers both at home and abroad.Potassium is a necessary nutrient for crops,participating in photosynthesis,sugar metabolism,synthesis and transport process of protein and fat.It also can adjust the opening and closing of the pores and the osmotic pressure of the cells,thereby enhancing the drought,cold,disease,salt,lodging resistance of plant.In addition,the growth and development of plants can be promoted by increasing the application of potash fertilizer and the main economic traits can be changed significantly.Whether it can alleviate plant growth retardation or photosynthetic efficiency decline caused by the enhancement of UV-B radiation via regulating the amount of potassium,there is still a lack of reports.Peanuts are one of the four most important oil crops in the world.At the same time,peanuts need more potassium and the potassium status of soil also affects the effect of UV-B radiation on plants.Therefore,the study of the effects of UV-B radiation interacting with potassium on plants is necessary.In this study,peanuts are used as materials to study the effects of potassium application on growth and development,yield(100-pod weight,fruit weight per plant,number of pods per plant,yield per unit area,etc.)and quality(content of protein,fat,oleic acid,linoleic acid,etc.)of peanut,respectively under natural light and UV-B radiation enhanced conditions through field trials.Furthermore,it discusses the mechanism of UV Radiation which damages peanut and the protective measures,and provides a new way to reduce the damage of UV-B radiation on crop which is of great theoretical and practical significance to improve the yield and quality of peanut.The main findings are as follows:(1)Physiological characteristics of peanutCompared with the control,in the lower needle period,podding period and full fruit period of peanut,the enhancement of UV-B inhibits the chlorophyll content,net photosynthetic rate,stomatal conductance,transpiration rate and water use efficiency of peanut leaves.And with the increase of UV-B radiation intensity,the decrease of chlorophyll content,net photosynthetic rate,stomatal conductance,transpiration rate and water use efficiency of peanut also increase.Under the natural light condition,the chlorophyll mean value of high potassium treatment was 6.38%higher than that of low potassium treatment.The enhancement of UV-B radiation reduces the daily averagenet of photosynthetic rate,transpiration rate,stomatal conductance and water use efficiency of peanut leaves,but increases the daily mean of intercellular CO2 concentration.And the diurnal variation of net photosynthetic rate of peanut leaves were "double peaks".Increasing the application of potassium fertilizer can promote peanut growth and enhance chlorophyll content,net photosynthetic rate,transpiration rate,stomatal conductance and water use efficiency.To a certain extent,it can alleviate the inhibition of enhancement of UV-B radiation on the net photosynthetic rate and transpiration rate of peanut.(2)The growth and development and yield of peanutsThe enhancement of UV-B radiation can inhibit the plant height of peanut.The plant height of different growth period is shorter than the plant height in control group.And the dwarfing degree increases with the increase of UV-B radiation.UV-B radiation increased 20%,peanut plant height decreased 3.11%UV-B radiation increased 40%,plant height decreased 8.70%.The enhancement of UV-B radiation results in a decrease in peanut yield and this tendency of decrease become more obvious with the increase of UV-B intensity.The results show that the enhancement of UV-B radiation increases the number of peanuts per plant pod,empty blight rate,kilograms of fruit,but reduces the yield of pods,pod theoretical yield,100-grain weight,kernel rate,and thereby reduces the yield of peanuts.Under natural light,the pod yield of peanut treated with high potassium was 7.99%higher than that of peanut treated with low potassiumHowever,increasing the application of potassium fertilizer can significantly increase the number of pods in peanut plants,the yield of pods,the theoretical yield of pods,the kernel rate,the 100-grain weight and reduce the empty blight rate to promote the increase in peanut yield and its constituent factors.Furthermore,appropriately raising the application of potassium fertilizer can make the peanut production to further improve.(3)The quality of peanutsThe enhancement of UV-B radiation can increase the fat content of peanut.Linoleic acid shows a downward trend,while protein,oleic acid and O/L(oleic acid/linoleic acid)show an upward trend.So that it can improve the stability of peanut oil and storage resistance,reducing the nutritional quality of peanuts.Increasing the application of potassium fertilizer can improve peanut protein,oleic acid,linoleic acid and ratio(O/L)to varying degrees,while the peanut fat content decreases.Under the natural light condition,the fat content of peanut treated with high potassium and low potassium decreased 2.18%.It makes the peanut oil more stable and more resistant to storage.But the oil rate decreases and nutritional quality improves.(4)In this study,DNDC model was used to simulate the effects of UV-B enhancement and potassium application on peanut yield.The sensitivity of the model was analyzed.The influencing factors of peanut yield simulated by this model were potash fertilizer application rate>UV-B>annual mean temperature>annual precipitation.It was found that the N-RMSE was less than 6%and R2 was greater than 0.5 under different experimental treatments.It was proved that the simulated value obtained by DNDC model was in good agreement with the measured value,and the change of peanut yield could be basically simulated...