Effects Of Elevated Surface O₃Concentration And Reduced Solar Radiation On Physiological Indicators, Fluorescence Characteristics And Yield Of Soybean

In recent years, the obviously global dimming of solar light resulted by increasing of aerosol loading and the increasingly elevated surface O3concentration resulted by increasing of air pollution has received extensive attention around the world. Reduced solar radiation and elevated surface O3concentration can adversely impact the growth and yield of crops. Therefore, a throughout understanding of the stress effects of reduced solar irradiance and elevated O3concentration would be useful to assess physiological indicators, fluorescence characteristics and yield of agricultural crops.In this paper, we conducted a field experiment in Nanjing area by using the soybean as the experimental plants. Starting from jointing to maturity, the plants were subjected to4treatments in field (CK, OTC; T1,80%natural light; T2,100nL·L-1O3;T3,100nL·L-1O3and80%natural light). On the basis of shading and O3experiment, we researched the influencing mechanism of reduced solar irradiance and elevated O3concentration on physiological indicators, fluorescence characteristics and yield of soybean. The results will provide some basis reference for assessment the effects of climate change on soybean. The main conclusions of this paper were as follows:(1) Combination of reduced radiation and O3stress can significantly increased the contents of pigment (Chlorophyll a, Chlorophyll b), membrane lipid peroxidation, soluble sugar, soluble protein, total free amino acid of soybean and increased the acivities of superoxide dismutase (SOD), catalase (CAT).(2) Pm, Ik, Yield and qP of reduced radiation and O3stress combination treatment decreased significantly; L(PFD), NPQ, Y(NPQ),(1-qP)/NPQ of reduced radiation and O3stress combination treatment increased significantly. Fv/Fm of combination treatment decreased significantly; Combination treatment has no significant influence on a and Y(NO). Combination treatment showed that solar irradiance and O3in combination enhanced the negative effects on chlorophyll fluorescence Characteristics of soybean.(3) Combination of reduced radiation and O3stress can significantly increased the plant height, leaf area of per plant of soybean and significantly decreased the total dry weight of per plant and nodule dry weight of soybean. Solar irradiance and O3in combination enhanced the negative effects on dry matter accumulation and nitrogen fixing capacity of soybean.(4) Combination of reduced radiation and O3stress can significantly decreased the per plant pod number, per plant seeds, per plant seed weight,100-grain weight and yield of soybean. Solar irradiance and O3in combination enhanced the negative effects on the growth and yield of soybean.