Comparison of the flowering behavior of the long-day plant Lemna gibba G3 from different laboratories

Abstract

In an effort to determine the cause for the wide discrepancies in the level of flowering response reported for the long-day plant Lemna gibba L., strain G3, cultures of L. gibba G3 were obtained from the laboratories of W. S. Hillman (G3-H), R. Kandeler (G3-K), Y. Oota (G3-O) and and A. Pieterse (G3-P) and compared to the L. gibba G3 (G3-C) from this laboratory. Under continuous light all cultures gave FL% values of 77 or above, and on a 9L:15D short-day treatment, all cultures were completely vegetative. However, on daylengths of 10 to 12 hr, small but statistically significant differences were obtained for the different cultures. The critical daylength curves for G3-G, which showed the shortest critical daylength, and G3-K, which showed the longest critical daylength, differed by approximately one hour. Salicylic acid treatment caused flower promotion in each culture, but statistically significant differences were obtained between some of the cultures in their response to salicylic acid. It is concluded that the large discrepancies in the flowering responses of L. gibba G3 that have been reported are due primarily to differences in culturing methods and counting procedures in the different laboratories. However, the results also indicate that there may be distinct cultures of L. gibba G3 that exhibit small physiological and/or genetic differences that would make precise quantitative comparison between different laboratories very difficult.