Photoperiodic Response of Flowering in Monochoria korsakowii Regel et Maack and M. vaginalis (Burm. f.) Kunth

Abstract

Photoperiodic response of flowering in M. korsakowii and M. vaginalis was studied using a growth chamber under a strict photoperiod. Under an 8-hour photoperiod, M. korsakowii and M. vaginalis flowered 41 and 48 days after sowing, respectively. No flowering was observed under photoperiods longer than 15 hours. Therefore, both species were considered to be qualitatively short-day plants.
Flowering photoperiod response of M. korsakowii and M. vaginalis was also studied under field conditions by sowing seeds from March to October. In both species the number of days to flowering decreased when the plants were sowed from March to August. No flowering was observed when the plants were sowed in September and October. The time limit of sowing suitable for flowering corresponded to the middle of August in both species.
Intraspecific variation of M. korsakowii and M. vaginalis in the number of days required to flower after sowing was examined under field conditions in Kyoto Prefecture by using many accessions collected from Hokkaido to Kyushu. Both species apparently showed a geographical cline in this physiological character, and the higher the latitude of the collection site was, the earlier the accessions flowered. M. vaginalis flowered earlier than M. korsakowii when a comparison was made between their accessions from similar latitudes.