High irradiance and temperature inhibit the germination of spores of the fern Rumohra adiantiformis (Forst.) Ching (Dryopteridaceae)

Abstract

ABSCTRACT -(High irradiance and temperature inhibit the germination of spores of the fern Rumohra adiantiformis (Forst.) Ching (Dryopteridaceae)). Rumohra adiantiformis (Forst.) Ching is a fern (Dryopteridaceae) which is used to compose floral arrangements. Fertile fronds were harvested in the "Permanently Protected Area" of Ilha Comprida, São Paulo, Brazil. Sterilized spores were germinated in Mohr liquid medium modified by Dyer. The effect of 72%, 54%, 17% and 9% of total irradiance on germination under field conditions, was analyzed. Experiments were carried out in March (I), April (II) and August of 2000 (III). Under 54% and 72% of total irradiance in Experiment I (March) the germination was completely inhibited and partially inhibited under 72% of total irradiance in Experiment II (April). The lowest mean germination time ( t -) was observed under 9% of total irradiance in Experiments II (11.62 days) and III (8.80 days) respectively, followed by 17% in Experiment III (10.12 days) and 9% of total irradiance in the Experiment I (11.62 days ). The effect of temperatures of 15 ± 1, 20 ± 1, 25 ± 1 and 30 ± 1 ºC on germination was also analyzed. The lowest mean germination time (7.93 days) was observed at 25 ± 1 °C followed by 20 ± 1 °C. The highest mean germination time was observed at 15 ± 1 °C (12.10 days) followed by 30 ± 1 °C (10.63 days), which inhibited germination. The germination of R. adiantiformis was photoinhibited by high irradiance and partially inhibited by the highest temperature tested.RESUMO -(Alta irradiância e temperatura inibem a germinação de esporos da samambaia Rumohra adiantiformis (Forst.) Ching (Dryopteridaceae)). Rumohra adiantiformis (Forst.) Ching é uma pteridófita (Dryopteridaceae) usada para compor arranjos florais. Frondes férteis foram coletadas na "Área de Preservação Permanente" Ilha Comprida, São Paulo, Brasil. Esporos esterilizados germinaram em meio de Mohr modificado por Dyer. O efeito de 72%, 54%, 17% e 9% de irradiância total sobre a germinação em condições ambientais, foi analisado. Experimentos foram conduzidos em março (I), abril (II) e agosto (III) de 2000. Sob 54% e 72% de irradiância total, em março a germinação foi completamente inibida e parcialmente inibida sob 72% de irradiância em abril. O menor tempo médio de germinação ( t -) foi observado sob 9% de irradiância total nos Experimentos II (7,93 dias ) e III (8,80 dias), respectivamente, seguidos de 17% no Experimento III (10,12dias ) e 9% de irradiância solar total no Experimento I (11,62 dias). O efeito de temperaturas de 15 ± 1, 20 ± 1, 25 ± 1 e 30 ± 1 ºC sobre a germinação também foi analisado. O menor tempo médio de germinação (7,93 dias) foi observado a 25 ± 1 °C seguido de 20 ± 1 °C. O maior tempo médio de germinação foi observado a 15 ± 1 °C (12,10 dias) seguido de 30 ± 1 °C (10,63 dias), que inibiu a germinação. A germinação de R. adiantiformis foi fotoinibida pela alta irradiância e parcialmente inibida pela temperatura mais alta testada.

Spore germination of Gleichenella pectinata (Willd.) Ching (Polypodiopsida-Gleicheniaceae) at different temperatures, levels of light and pH

“…In the present work, the germination of G. pectinata was partially inhibited at 30ºC. For R. adiantiformis and P. lepidopteris, the germination was also partially inhibited at 30 ºC (Brum andRandi 2002, Viviani andRandi 2008). Similar results were observed by PerezGarcía and Riba (1982) with some tree ferns: Lophosoria quadripinnata (Gmel.)…”

“…G. pectinata showed the highest germination percentage from 5 to 20% of sunlight. (Filippini et al 1999, Renner and Randi 2004, Brum and Randi 2002, Hiendlmayer and Randi 2007, Viviani and Randi 2008. According to Haupt (1990Haupt ( , 1991Haupt ( , 1992 and Raghavan (1989) high temperatures seem to inhibit the gene expression and protein synthesis mediated by phytochrome during fern spore germination.…”

Germination of spores and growth of gametophytes and sporophytes of Rumohra adiantiformis (Forst.) Ching (Dryopteridaceae) after spore cryogenic storage

“…Desiccation is one of the usual methods of cell dehydration before freezing in liquid nitrogen (Withers & Engelmann 1998). The best sterilization method to achieve total decontamination and high germination percentages for this species involves the use of a 15% (v/v) solution of commercial sodium hypochlorite (2% of active chlorine) for 10 min before the spores had been filtered through sterile filter paper by vacuum, washing several times with sterile distilled water and dried in a laminar flow hood for 30 min (De Brum & Randi 2002). This method does not affect spore germination of R. adiantiformis but under light microscopy, a disruption of the external spore coat was verified.…”

“…De Brum & Randi (2002) analyzed the effect of irradiation and temperature on the germination of sterilized spores of R. adiantiformis. The lowest mean germination time ( t -) was observed under 9% and 17% of irradiation.…”

<BR>Viabilidade de esporos de <I>Dicksonia sellowiana</I> Hook. (Cyatheales, Dicksoniaceae) e <I>Rumohra adiantiformis</I> (Forst.) Ching (Polypodiales, Dryopteridaceae) armazenados sob refrigeração<p>doi: 10.5007/2178-4574.2009v38p15

“…Segundo Filippini et al (1999), os esporos recém coletados de D. sellowiana são fotoblásticos positivos e atingem a máxima porcentagem de germinação a 23 ± 2°C em luz branca após sete dias de inoculação e permaneceram viáveis após dois anos de armazenamento sob refrigeração apresentando 82% de geminação após 10 dias de inoculação. Para R. adiantiformes, Brum & Randi (2002) observaram que a germinação de esporos recém-coletados atingiu a estabilização após 10 dias de cultivo.…”