In vitro spore germination and gametophytic growth development of a critically endangered fern Pteris tripartita Sw.

The effects of sucrose, pH and plant growth hormones on spore germination percentage and gametophyte growths of Pteris tripartita were studied. Various morphological structures of gametophytes were observed namely, filamentous, spatulate and heart stages in the MS culture medium with hormones. After 15 days, the spores of P. tripartita were sprouted in MS basal medium fortified with pH, sucrose and hormones. Maximum spore germination rates (84%) were observed in 70 g/L of sucrose and 79.33% in pH 5.7. On the other hand, the maximum gametophyte sizes were observed both in 40 and 50 g/l of sucrose on half strength MS medium. The maximum growth of gametophyte lengths (484.39 and 507.72 µm) and widths (846.58 and 1270.98 µm) were observed in both pH 5.7 and 6.7. Among three different hormones, the utmost number or percentage of spores were sprouted in GA3. However, the in vitro cultures of spore having the capability to increase the spore germinated due to addition of adequate nutrition in the culture medium and also reduce the contamination as well as environmental factors. Key words: Pteris tripartita, spore germination, sucrose, hormone, MS medium.