Genotypic Variation in Ammonia Volatilization Rate of Rice Shoots and Its Relationship with Nitrogen Use Efficiency

Abstract

Gaseous nitrogen losses from rice plant tissues may be closely related to nitrogen use efficiency (NUE),the research on which may provide a theoretical supplement in nitrogen nutrition and a technical parameter for higher NUE genotype screening.Pot experiments under solution culture with four nitrogen concentrations of 0,20,40,and 80 mg N L-1 respectively,were carried out to assess the correlation between ammonia volatilization rate (AVR) from booting stage to milking stage and NUE of different rice varieties including higher NUE type of Yangdao 6 and BG34-8,lower NUE type of Wuyujing 3 and Zhenshan 97B.The results showed that the peak AVR of Yangdao 6 and Wuyujing 3 was 11.0 and 10.4 mg N h-1 pot-1 respectively at panicle initiation stage,the peak AVR of BG34-8 and Zhenshan 97B was 22.5 and 23.4 mg N h-1 pot-1 respectively at booting stage.The AVR increased with the nitrogen concentration increasing in the culture solutions for a given genotype,the range of increase was larger in lower-NUE varieties Zhenshan 97B and Wuyujing 3 than in higher-NUE varieties Yangdao 6 and BG34-8.There were significantly negative correlations between AVR and aboveground nitrogen accumulation (r = -0.6768**),NUE in grain production (r = -0.6158*),fertilizer-N agronomic efficiency (r = -0.6667**),and fertilizer-N physiological efficiency (r = -0.8353**),when all the tested genotypes were cultured in higher nitrogen concentration of solution (80 mg N L-1).The general conclusion of the research is that there are significant genotypic differences in AVR,and the higher-NUE genotypes have lower AVR than the lower-NUE genotypes.Hence,lower AVR under higher nitrogen concentration of culture could be an effective parameter for higher-NUE genotype screening.