Maintenance respiration of Oryza sativa leaves at different growth stages as influenced by nitrogen supply

Maintenance respiration rate, R-M, irrespective of growth stages, increased with increase in nitrogen supply. The R-M increased almost in proportion with net photosynthetic rate, P-N, and biomass production during early growth stages, while it declined after anthesis. Significant positive correlation was observed between biomass production and P-N at all growth stages except tillering. Though R-M was positively correlated with biomass production during early growth stages, it was negatively correlated with the rate of increase in shoot biomass after flowering, which could indicate a possibility to identify certain cultivars endowed with low maintenance expenses despite building up biomass.