Effects Of Elevated CO₂ Concentration And Water Shortage On Photosynthetic Physiological Characteristics Of Wheat

On the basis of OTC test platform,a wheat variety was selected for long drought 58.A pot experiment was carried out in the Shanxi Agricultural University State Building test base from 2015 to 2016.The effects of CO₂ concentration and water stress on the characteristics of gas exchange and the performance of PSII reaction center were studied,and the response laws of stomatal specificity of leaves were clearly defined,and the accumulation of biomass was analyzed.The response trend of Wheat Photosynthetic Physiology,growth characteristics and yield under the CO₂ concentration and water stress in the future is to provide reference for wheat production under the condition of increasing CO₂ concentration and reducing the complex climate change under the condition of precipitation.The results of the test are as follows:?1?.Under normal water,elevated CO₂ concentration can make wheat stomatal conductance?G_s?and transpiration rate?T_r?significantly reduced 43.11%and 23.56%,respectively,and the intercellular CO₂ concentration?C_i?and water use efficiency?WUE?increased significantly by 43.28%and 37.31%respectively.Under water stress,the increase of CO₂ concentration can significantly reduce the net photosynthetic rate?P_n?and stomatal conductance?G_s?by 21,15%,67.38%and stomatal threshold?L_s?by 41.64%,respectively.?2?.Under normal water,elevated CO₂ concentration can make wheat effective photochemical efficiency?Fv'/Fm'?significantly reduced by 24.34%.Under water stress,the increase of CO₂ concentration can significantly reduce photosynthetic electron transfer rate?ETR?by 27.38%.?3?.Under normal water,elevated CO₂ concentration can make wheat leaf epidermis and lower epidermis stomatal density and stomatal limitation,the stomatal apparatus circumference were significantly reduced 18.51%and 31.41%,18.51%and 32.67%,4.78%and 1.89%,make the epidermis stomatal apparatus area is significantly reduced by 7.05%.Under water stress,CO₂ concentration increases the circumference and area of the stomatal apparatus,and stomatal density and index remain unchanged.?4?.Under normal water,elevated CO₂ concentration can make wheat leaf area(L_area),specific leaf area?SLA?,photosynthetic nitrogen use efficiency?PNUE?significantly increased 125.05%,170.39%and 125.05%respectively,the flag leaf unit leaf area(N_area)significantly reduced 63.74%nitrogen content.Under water stress,the increase of CO₂ concentration significantly reduced PNUE by 26.05%.?5?under normal water,the increase of CO₂ concentration can significantly reduce the dry weight of wheat leaves by 33.26%,and the dry weight of stem and ground parts in the jointing and heading stages by 36.61%,28.86%,34.98%and 17.59%,respectively.Under water stress,the increase of CO₂ concentration can significantly reduce the dry weight of wheat leaves by 34.31%in heading stage and 55.34%in the ground during grouting stage.?6?under normal water,the increase of CO₂ concentration can significantly increase the stalk thickness of wheat by 13.33%,spike weight,grain number,grain weight of ear and the number of pregnant spikelets by 22.72%,19.8%,25.39%and 10.76%.Under water stress,the increase of CO₂ concentration significantly increased the stem diameter of wheat by 21.6%,spike weight,grain number and number of fertile spikelets by 32.5%,34.71%and 27.14%,and non-pregnant spikelets by 20.9%.Under high CO₂ concentration,water stress significantly reduced the stem diameter of wheat by 25.49%,and the ear weight,grain number,grain weight of ear and the number of fertile spikelets by 50.92%,46.28%,49.36%and 38.19%.