Temporal changes in carbon dioxide exchange rates, acetylene reduction and distribution of nitrogen in barrel medic (Medicago trunculata [truncatula] Gaertn.) grown in the field
1986
Alston, A.M. | Puckridge, D.W. (Adelaide Univ., Glen Osmond (Australia). Waite Agricultural Research Inst.)
Estimates of dry weight production derived from daily values for net CO2 uptake gave a similar curve to measured dry weight but overestimated maximum dry weight by almost 20 percent. The difference is presumed to be due to materials lost from the roots. At maturity, dry weight and plant N content had declined by 10 and 14 percent respectively from their maxima of 1.02 kg per sq m and 26.1 g per sq m in October. All plant fractions except the litter and seed lost N. Acetylene reduction peaked at 39 mmol per sq m per day at onset of flowering 104 days after sowing, and declined to almost zero by 145 days; during this period, CO2 exchange rates were high and the plants were still accumulating N, from c. 14 g N per sq m at day 104 to 24 g at day 145. These changes are discussed in relation to environmental conditions and soil N content.
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