Ammonium, nitrate, and proton flux in fern gametophytes
Date
2024
Authors
Creasy, Em
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Abstract
Total net NH4+, NO3-, and H+ fluxes were investigated in three species of fern gametophytes: Polystichum munitum, Christella dentata, and Cyrtonium falcatum. Flux measurements were performed with a microelectrode ion flux measurement (MIFE) system. Overall, net NH4+ influx was seen in all gametophytes. Net NO3- efflux and net H+ influx was seen in most gametophytes. The gametophyte generation of C. dentata and C. falcatum displayed greater NO3- efflux than the sporophyte generation. On average, male P. munitum gametophytes displayed greater per-unit-area NH4+ uptake than female/hermaphrodite gametophytes, though the latter showed greater NH4+ uptake at the whole-organism level. This finding suggests that fern gametophytes may conform to the expectations of nutrient-based sex determination. This study was the first to perform precise ion flux measurements at discrete positions on fern gametophytes and sporophytes. This research provides greater insight into the nutrient ecology of fern gametophytes, an under-studied field.