Growth responses of Matteuccia struthiopteris plants from northern and southern Norway exposed to different temperature and photoperiod treatments

Plants of the fern Matteuccia struthiopteris from northern and southern populations in Norway were studied in a phytotron. Relative growth rate (RGR), growth period, and sporophyll production were measured under different photoperiod (12-24 h) day-length and temperature (9 - 21 degreesC) treatments. For the southern plants, there were no significant differences between the different light treatments, but for the northern plants there was a significant (p < 0.01) linear increase in the mean maximum RGR with increasing day-length. Small, but statistically significant (p < 0.01) differences were found between northern and southern plants when the mean maximum RGR-values were compared. When plants from different origin were exposed to different treatment, there were major differences between the populations in the production of sporophylls (p < 0.0001). Southern plants produced in average three times more sporophylls than the northern plants, and they had also higher proportions of fertile plants. Diurnal alternating temperature treatments gave no significant (p > 0.05) effect on the mean maximum RGR compared with constant temperatures, but they gave significantly higher production of sporophylls. In general, the northern plants had a higher temperature threshold (approximately 12 degreesC) for sporophyll production than the southern plants (approximately 9 degreesC). Plants exposed to 24 h with natural light were generally more often fertile than plants exposed to a shorter photoperiod. The mean maximum RGR-values and time needed to develop the fronds at the 9 degreesC treatment were fairly equal to those found under natural conditions close to the altitudinal distribution limit of M. struthiopteris in W Norway. In general, the investigation showed that the applied temperature and light treatments affected sporophyll production more than vegetative growth.