The interactive effects of elevated CO2, temperature and N supply on N concentration and allocation in rice (Oryza sativa L.)
The study was conducted to examine the effects of elevated CO2, temperature and nitrogen supply on the N concentration, content and allocation, biomass and root:shoot ratios in rice plants. Rice (Oryza sativa L. cv. IR 72) was grown in growth chambers under combinations of two CO2 (375 and 750 mL L-1), temperature (29/21 and 34/26C day/night) and N (40 and 80 mg L-1) regimes from sowing until grain maturity. The total nitrogen concentrations were significantly lower in CO2-enriched plants in both temperature regimes at all harvests except at flowering. The total plant N content was significantly higher under elevated CO2 in both temperature and N treatments during the vegetative stage with greater CO2 effect at high temperature treatment. Plants supplemented with high N had significantly higher total plant N concentrations and contents in all CO2 and temperature treatments. The allocation of N to the leaves was significantly lower at elevated CO2 and at ambient temperature at all harvests. CO2 effect was more pronounced at ambient temperature at grain maturity. Elevated CO2 significantly enhanced the allocation of N to the culms under a high N supply at flowering and grain maturity, and to the roots under a low N supply and ambient temperature treatments at all harvests except at 27 days after sowing. The allocation of N to the panicles was significantly reduced under high N supply. CO2-enriched plants grown at high temperature had significantly reduced N allocation to the grains. The enhancement of total biomass by elevated CO2 was greater at high temperature and N. Root:shoot ratios increased under CO2 enrichment with greater effects at ambient temperature and low N. IR 72 may exhibit an efficient uptake and utilization of N during early vegetative stage under global warming condition.
Baysa, MC; Tremmel, DC; Reynolds, JF; Rivero, GC; Tabbada, RA
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