LIGHT- AND DARK-GROWTH IN LONG-DAY DUCKWEED,LEMNA GIBBAG3, AS AFFECTED BY KINETIN

摘要

Under short-day conditions the growth or the production ofΣfronds inLemna gibbaG3 was stimulated by KIN (10−5M); the longer the nyctoperiod, the greater the stimulation was. Under long-day conditions KIN was slightly inhibitory for the first 2 days, but promotive thereafter. IAA (10−5M) reversed the growth inhibition by KIN in long-days, and DCA (10−4to 10−6M) and also CA (10−4to 10−6M), although less effectively, cancelled the growth promotion by KIN in short-days. DCA (10−5M) little altered the KIN inhibition in the first 2 days of light culture, nevertheless it alleviated strikingly the KIN promotion in the subsequent illuminated days.These and relevant findings explained the above-described promotion and inhibition by KIN of the duckweed growth in terms of in vivo level of a cofactor (probably auxin) which may be under the regulative influence of photoperiodic conditions given. Moreover, some bearing of the above conclusion on flowering mechanism in this long-day duck-weed