The effect of tissue N and P on growth of Porphyra yezoensis (strain U-51) blades in suspension cultures was investigated. Blades had the ability to store N in excess of requirements. The critical (0.40% fresh wt) and subsistence (0.153% fresh wt) levels of N were constant regardless of N source (NO3- or NH4+) or light level. Blades did not have the ability to store excess P over the range of P loads given. The subsistence quota for P was higher when NH4+ was given, suggesting a decreased ability to utilize tissue P for growth. NO3- was a better source of N than NH4+ in terms of growth. Blades became bright green in colour when N limited, suggesting a link between phycoerythrin and tissue N. The optimal molar N:P of 13-15 was constant regardless of N source (NO3- or NH4+) or light level. N:P < 13-15 indicated N limitation, while N:P >13-15 indicated P limitation. P limited and light limited blades could store more N when NH4+ was given, than when NO3- was the N source, suggesting physiological mechanisms for taking advantage of this usually ephemeral N source, even when growth was limited. N and P reserves were used up relatively quickly (5 days), a characteristic of opportunistic species. Tissue analysis for N and P was a useful technique for determining nutrient status of P. yezoensis blades in land based tanks. As long as tissue N >0.40% fresh wt. and an N:P supply ratio of 13-15 is maintained, blade growth is not limited by N or P.
CITATION STYLE
Hafting, J. T. (1999). Effect of tissue nitrogen and phosphorus quota on growth of Porphyra yezoensis blades in suspension cultures. In Hydrobiologia (Vol. 398–399, pp. 305–314). Springer Netherlands. https://doi.org/10.1007/978-94-011-4449-0_36
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