Apogamous sporophyte formation has been induced in 14 strains of seven species of normal fern gametophytes using a technique similar to the one reported earlier (Whittier and Steeves, Can. J. Bot. 38, 925ndash;930 (1960)). These gametophytes were supplied with suitable concentrations of sugar in the sterile culture medium for certain lengths of time which resulted in the formation of apogamous sporophytes. This investigation demonstrated that sucrose is more effective in inducing apogamy probably because it produces about half the osmotic potential as an equivalent percentage of glucose. Therefore more sugar can be made available to gametophytes before the osmotic potential deleteriously affects the prothallial growth and apogamy. This confirms the work carried out previously using sugar in the medium and it demonstrates that this method has general applicability for inducing apogamy in ferns. The sugar in the medium is felt to modify the carbohydrate metabolism enabling the prothalli to undergo a thickened growth and develop apogamous sporophytes.
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