Contribution of fern gametophytes to the growth of produced sporophytes on the basis of carbon gain

Abstract

Sporophytes appeared on most gametophytes of Thelypteris palustris (Salisb.) Schott that reached a certain size, which is interpreted to be a critical size of gametophytes for the production of sporophytes. After sporophytes were produced, attached gametophytes ceased dry weight growth, but the gametophytes which did not produce sporophytes grew successively. It was hypothesized that matter produced by gametophytes was being supplied to young sporophytes. Photosynthesis and respiration of gametophytes with attached sporophytes were not significantly different from that of gametophytes without sporophytes. Photosynthetic activity of gametophytes dropped from 0.18 to 0.03 μmol CO2 g−1 s−1 during the growth period. The higher photosynthetic rates of gametophytes in the early growth stage were important for reaching the critical size for sporophyte production in a short time. Sporophytes in the ‘one leaf stage’ averaged 0.14 μmol CO2 g−1 s−1 of photosynthetic activity. The results show that sporophytes that had expanded the first leaf grow by their own photosynthetic production. Gametophytes allocated the photosynthate for sporophytes and it was an important aid before the one‐leaf stage. The supportive role of gametophytes ended at that stage.

Gametophyte contribution to sporophyte growth on the basis of carbon gain in the fern Thelypteris palustris: effect of gametophyte organic-matter production on sporophytes

“…The growth patterns of cut and intact gametophytes were similar. The growth of SGs decreased during the ten days after sporophyte emergence; thereafter, growth ceased, as observed in a related study by Sakamaki and Ino (1999). Figures 2b-2d show the growth of sporophytes produced on CGs and IGs.…”

“…They noted that sporophyte development would affect the formation of successive sporophytes and affect decay of the gametophytes by the inhibitor. In our previous study (Sakamaki and Ino 1999) we demonstrated that in the first 10 days after emergence of a sporophyte, gametophyte organic matter production was sufficient to produce two or more sporophytes. In addition, two or three sporophytes of similar size can, rarely, grow on a single gametophyte.…”

“…Gametophyte resource cost of production of sporophytes Gametophyte growth was calculated by use of the equation (Sakamaki and Ino 1999):…”

“…Schott, sporophytes are supported by gametophytes until the first leaves develop; the sporophytes then grow on the organic matter they produce themselves. Archegonia form on gametophytes that grow larger than a given size (critical size; Sakamaki and Ino 1999). One fern gametophyte usually forms several archegonia simultaneously; typically, however, only a single sporophyte will grow on a gametophyte.…”

Germination of spores and growth of gametophytes and sporophytes of Rumohra adiantiformis (Forst.) Ching (Dryopteridaceae) after spore cryogenic storage

“…According to Sakamaki & Ino (1999), gametophytes allocated photosynthate for sporophyte growth and it was an important aid before the one-leaf stage. They concluded that the higher photosynthetic rates of gametophytes in the early stage were important for reaching the critical size for sporophyte production in a short time.…”