Response of matter production of two winter wheat genotypes with differing nitrogen efficiency to di-atmospheric CO2 concentration and nitrogen supply
不同氮效率基因型冬小麦物质生产对CO2浓度升高的响应研究

Atmospheric carbon dioxide(CO2) level continues to rise at an unprecedented rate and is expected to exceed 750 μmol·mol-1 by the end of the 21st century.Increasing atmospheric CO2 concentration has been associated to changes in global envi-ronment.The effect of elevated atmospheric CO2,as driven by global environmental change,on agricultural production remains un-clear.To further clarify this effect,leaf area,plant height,biomass and yield of two winter wheat varieties(the high N efficiency "Xiaoyan22" and the low N efficiency "Xiaoyan6") under different atmospheric CO2(375 μmol·mol 1 and 750 μmol·mol 1) and ni-trogen amendments 0,0.15 g(N)·kg 1(soil) and 0.30 g(N)·kg 1(soil)] conditions were measured in open-top chamber(OTC) pot soil experiments.Results showed that while ear length and plant height of "Xiaoyan22" were significantly higher,leaf area and stem height were lower than those of "Xiaoyan6" for the di-atmospheric CO2(750 μmol·mol 1) with nitrogen amended treatments.Com-pared with ambient atmospheric CO2 level(375 μmol·mol 1),di-CO2 concentration(750 μmol·mol 1) significantly improved yields of the two winter wheat varieties under N treatments.Yields of "Xiaoyan6" and "Xiaoyan22" were 90.5% and 52.9% greater under di-CO2 concentration with 0.15 g(N)·kg 1(soil) treatment and also 73.9% and 93.6% greater under di-CO2 concentration with 0.30 g(N)·kg 1(soil) treatment than those under the ambient CO2 condition.Di-CO2 concentration increased above-ground biomass,root biomass,total biomass,spikes per pot,grains per spike and yield of the two winter wheat varieties under the same nitrogen conditions.Although elevated N application exhibited no consistent effects on agricultural production,increasing N supply enhanced above-ground biomass,total biomass,grains per spike and yield.Above-ground biomass,total biomass,grains per spike and yield with di-CO2 condition were higher under 0.30 g(N)·kg 1(soil) treatment than under 0.15 g(N)·kg 1(soil) treatment.The results from this study indicated that increasing N supply benefited the positive effects of elevated CO2 on crop production.