Responses of Marchantia polymorpha to Nutrient Supply and Photoperiod

Marchantia grows readily on glass cloth in an open moist chamber when supplied with an appropriate nutrient solution. A method for growing it under controlled conditions of nutrient supply and photoperiod is described. A male and a female strain of Marchantia polymorpha were employed, each strain propagated vegetatively from a stock grown from a single plant. 2. A range of fifty-six nutrient solutions, each having an osmotic concentration of approximately 0.285 atmospheres, was used. The cations involved were K, Ca, and Mg, and the anions NO3, PO4, and SO4. 3. Cultures containing the cations K and Mg but without Ca all regenerate new thalli, formed in the main from adventitious buds arising from cells on the ventral side of the thallus at the midrib region. In cultures lacking NO3 and PO4 the ventral layers of cells develop a red-violet color in the walls. The absence of Mg and SO4 does not result in so striking a response as lack of the other ions. Phosphate is required in very small quantities. Up to the limits of the quantities supplied, plants make greater growth with increasing amounts of NO3, provided all other ions are present. 4. Some of the plants were grown on long photoperiod, 18 hours of light out of each 24-hour cycle, and on short photoperiod, 9 hours of light out of each 24. The differences between the lots of plants grown on the two photoperiods were both quantitative and qualitative. Irrespective of the range of nutrient supply, plants on long photoperiod were larger and had greater dry weight than similar plants on comparable solutions on short photoperiod. Irrespective of the range of nutrient supply, plants on short photoperiod produced a greater total number of gemmae cups but on long photoperiod a greater number of gametangiophores than comparable plants on short photoperiod.