JpnJPhycol_36_37.pdf 290 KB
Effects of temperature on the uptake kinetics of ammonia-N and nitrate-N by Porphyra yezoensis thalli.
The uptake kinetics for ammonia-N and nitrate-N by Porphyra yezoensis thalli were examined under various temperatures (4-18°C). The carbon and nitrogen contents of the frond were 341.9±24.8 and 52.5±10.4 mg•g dry wt-1, respectively, and the C/N ratio was 6.80±1.58. The uptake parameter, Ks, for ammonia-N varied from 48.3 to 182.7 µgN•l-1, and Vm was from 0.0033 to 0.0082 h-1. The Ks for nitrate-N varied from 10.1 to 53.9 µgN•l-1, and the Vm was from 0.0005 to 0.0013 h-1. These parameters both for ammonia-N and nitrate-N showed the maxima at 14°C. Comparing the Vm of ammonia-N with that of nitrate-N under the same temperature, ammonia-N was taken 6.3-9.4 times faster than nitrate-N by the frond. These parameters expressed in common logarithms were converted by the quadratic equations to absolute temperatures; for ammonia-N, VA=S × 10-29.642(103/T)2+206.93(103/T)-363.23/(S+10-39.556(103/T)2+ 276.17(103/ T)-479.77) and for nitrate-N, VN = S × 10-32.464(103/T)2+227.45(103/T)-401.36/(S+10-37.051(103/T)2+257.50(103/T)-445.69). These equations consisting of the major factors such as ammonia-N and nitrate-N concentrations and temperature which are controlling the growth of Nori frond are considered to be useful in estimating the production capacity of Nori cultural ground.