Abstrato
Influence of abiotic and biotic factors on developmental biology of four ferns of Western 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- Phlebodium aureum; March-Pronephrium triphyllum and January for Sphaerostephanos unitus. Germination of spores occurred in a wide range of pH from 4 to 8. For Cheilanthes viridis, highest percentage of spore germination (88.81.61) occurred on Knudson C Solidmediumat 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 medium at pH 5.8. There were nomorphological 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 mediumat pH5.8. In Phlebodium aureumL. highest growth area aswell as highest sporeling emergence were recorded (33.41.21) inMi medium at pH 5.5. In Pronephriumtriphyllum (Sw.) Holttum, highest growth area and highest percentage (52.31.21) of sporeling emergence were observed in KNmediumat pH 5.8. In Sphaerostephanos unitus (L.) Holttum, KNmedium at pH 5.8 induced a maximum growth 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.
