Abstrakt
Influence of abiotic and biotic factors on developmental biology as possible reason for endangered status of four ferns ofwestern ghats, India
M.Johnson, V.S.Manickam
The present study examined the influence of age, season and pH on spore germination, early gametophyte development and sporophyte formation of four rare and endangered ferns, viz. Cheilanthes viridis(Forssk.) Swartz, Phlebodium aureum L., Pronephrium triphyllum(Sw.) Holttum and Sphaerostephanos unitus(L.)(Holttum) ofWestern Ghats of South India. Highest percentage of spore germination was achieved only in the matured spore inoculated media, whereas the young spores failed to germinate. Highest percentage of spore germination was achieved in the spores collected in the month of February for Cheilanthes viridis; July-Phlebo dium aureum; March-Pronephrium triphyllum and January for Sphaeros tephanos unitus. Germination of spores occurred in a wide range of pH from4 to 8. For Cheilanthes viridis, highest percentage of spore germination( 88.8±1.61) occurred on Knudson C Solid medium at pH 5.8. Mitra liquid medium at pH 5.5 showed highest percentage(81.3±0.84) of spore germination for Phlebodium aureum. Pronephrium triphyllum(38.3±1.21) and Sphaerostephanos unitus(36.8±1.31) showed highest percentage of spore germination on Knops solid mediumat pH 5.8. There were no morphological differences among gametophytes grown under different pH optima. Gametophytes gave rise to new gametophytes and developed antheridia and archegonia after they were transferred to culture flasks. In Cheilanthes viridis(Forssk.) Swartz, high growth rate as well as high percentage( 85.8±1.15) of sporeling formation were observed in KC medium at pH 5.8. In Phlebodium aureum L. highest growth area as well as highest sporeling emergencewere recorded(33.4±1.21) in Mi medium at pH 5.5. In Pronephrium triphyllum(Sw.) Holttum, highest growth area and highest percentage(52.3±1.21) of sporeling emergence were observed in KN medium at pH 5.8. In Sphaerostephanos unitus(L.) Holttum, KN medium at pH 5.8 induced amaximumgrowth rate and high percentage(76.8±1.21) of sporeling emergence. The Isozyme profiles revealed the biochemical changes between the different developmental stages of selected ferns.
