Effect Of Elevated CO₂ On Growth And Yield Of Broomcorn Millet Under Different Water Conditions

With the development of the economy,human activities lead to a large number of greenhouse gas emissions and make CO2 concentration continues to rise.At the same time,climate warming and water shortages have led to the occurrence of droughts in most parts of the world,especially in the already arid areas.The continuous increase of atmospheric CO2 concentration and the serious deficit of water directly or indirectly affect the growth and yield of crops.Millet in China’s grain production,a small crop,but is of great significance in the arid areas of agricultural production.Therefore,the study of the effects of CO2 enrichment and drought on the growth and yield of millet will provide a reference for the future production of grains in arid areas in the future climate change.In this study,the experiment was conducted to study the effects of different water conditions under the high CO2 concentration(OTC)on the photosynthetic characteristics,chlorophyll fluorescence kinetics parameters,photosynthetic pigments,stress resistance index,leaf sugar content,plant morphology,biomass,yield and spike weight and 1000-grain weight..The test results are as follows:(1)Under different water conditions,the increase of CO2 concentration could promote the photosynthetic capacity of the seeds,and the net photosynthetic rate,water use efficiency,while decrease transpiration rate and stomatal conductance and this effect was more significant under drought stress.Therefore,high CO2 concentration can improve the photosynthetic capacity of millet leaves,especially under drought stress.(2)Under different water conditions,the effect of high CO2 concentration on the chlorophyll fluorescence parameters and the change of photosynthetic pigment content were different due to the different growth period and interannual variation.The specific reasons need further study.(3)At the booting stage under different water conditions,the increase of CO2 concentration increased malondialdehyde,soluble sugar content and starch content,and the content of malondialdehyde.Soluble sugar and starch was increased under drought stress which indicated that high CO2 concentration can increase the drought resistance of millet leaves at booting stage.(4)Under different water conditions,with the CO2 concentration increased,the stem diameter,the number of knots and the ear weight of the millet were increased.Under different water conditions,the increase of CO2 concentration increased the biomass and yield of millet.