Physiological Studies of Two Fungi Isolated from Nymphaea Odorata

ABSTRACT

Physiological studies of Dichotomophthoropsis nymphaearum and Sclerotium hydrophilum were undertaken to determine the growth parameters for these two fungi. Optimum or near-optimum growth of D. nymphaearum occurred at temperatures of 25 and 30 C. Optimum temperature for growth of S. hydrophilum was 30 C, although maximum sclerotial production occurred at 25 C. Both fungi were able to utilize all of the carbon sources tested. Dichotomophthoropsis nymphaearum gave lower mycelial yields on xylose, while S. hydrophilum grew poorly on maltose. Both fungi utilized inorganic and organic nitrogen sources, but mycelial yields were lower when ammonium sulphate served as the nitrogen source. Glycine was also a poor nitrogen source for S. hydrophilum. Thiamine was required by both isolates of D. nymphaearum studied and by one of the isolates of S. hydrophilum. Light was not found to be essential for conidium production by D. nymphaearum or for the initiation of sclerotia by S. hydrophilum, although it did affect maturation of these structures. Pairing of six isolates of each fungus in all possible combinations and on several media failed to give evidence of a sexual response or production of a sexual state.

Key Words:

• Dichotomophthoropsis nymphaearum
• Sclerotium hydrophilum
• physiology
• water lily