Effects of Enhanced UV-B Radiation and O_3Stress on Physiological Characteristic of Winter Wheat Separately and in Combination

【摘要】：Open-top chamber experiment with field-grown winter wheat (Triticum aestevum L) was conducted from6th March to20th May2010, at the Agro-meteorology Experiment Station of Nanjing University of Information Science and Technology. This was to access the single and the integrated effect of enhance UV-B radiation and ozone stress on the physiological characteristics of winter wheat. Darkening treatments and removing leaves methods were used to analyze contribution rate of different green organs to yield after flowering. Winter wheat was treated with enhanced UV-B radiation and ozone,8hours per day (9:00-17:00), for a total of50d. Before fumigation, O3concentration around OTC (field) was detected by EC-9810(B) Ozone Monitoring Instrument for about11days (from9:00to17:00, the instrument automatically read a data every5min). The result show that03concentrations was8.19-63.8n1·L-1, and8h average concentration was35.27nl· L-1. Enhanced UV-B and O3reduced chlorophyll of the flag leaf and the green organs, carotenoid and the gas exchange whereas the intercellular CO2concentration (Ci) changed slightly. The contents of Malondialdehyde, flavonoid, relative conductance increased due to UV-B and ozone treatment. The interactive effects were however, less than additive. The darkening treatment generally increased the chlorophyll contents but not much significant. Assessment of the yield characteristics at the final harvest showed that ozone and UV-d induced decreased the number of grain per ear, the weight of the ear stem and root and1000-grain weight. Generally the1000-grain weight and the grain weight per ear almost declined as a result of the removal of the flag leaf and the darkening of the green organs in the various chambers. The distribution of the dry matter of the ear under the flag leaf removal and the darkened treatments on the other hand decreased with an exception of the darkened sheath where increase occurred in most chambers whiles the proportion of the dry matter distribution of the stem and the root almost increased in the chambers for the various treatments.