Effect of Physical Factors on Gametangial Induction, Fertilization and Sporophyte Development in the Moss Bryum Argenteum Grown in Vitro

Summary Cultures of Bryutn argenteum, a dioecious moss, were raised aseptically from single spores. Normal gametophytes were formed at 25 ± 2 °C in 3500 to 4000 lx of continuous illumination. Gametangial formation in both male and female clones is affected by temperature, light intensity and photoperiod. Both sexes exhibit maximum gametangial formation at 25 ± 2 °C. Lowering of temperature to 10 ± 2 °C lowers the response. Light intensity within the range 1800 to 2000 lx is optimum for gametangial induction. Higher light intensities favour vegetative growth. Bryum behaves as a quantitative day‐neutral plant, since it becomes fertile even in an 8 h photoperiod. Gametangial induction increases with increasing day‐length, and the best response is observed with continuous illumination. Flooding of mixed cultures is necessary for fertilization. Although sporophytes appear in cultures maintained both at 18 ± 2 °C and at 25 ± 2 °C, the higher temperature is more favourable for the proper development of capsules.