Ceras foliares epicuticulares de espécies congêneres da mata e do cerrado

Abstract

Recebido em 06.09.95. Aceito em 29.0l.96.RESUMO-(Ceras foliares epicuticulares de espécies congêneres da mata e do cerrado). Espécies de ceo'ado e mata foram analisadas quanto à sua composição em ceras foliares epicuticulares e de seus componentes hidrocarbonetos. Observou-se nas espécies de cerrado uma tendência a teores de ceras pouco maiores que os de espécies de mata estacionai semidecídua. A porcentagem de hidrocarbonetos nas ceras foi maior na maiOlia das espécies de mata que nas espécies congêneres de cerrado. Pela análise em CG, os hidrocarbonetos mostraram predominância de C 29 e C 31 apresentando um comprimento médio da cadeia de carbono dos homólogos menos variável em espécies de mata, em torno de 30,S, que de cerrado nas quais este valor variou de 28,S a 31 ,3. Os resultados são discutidos em relação ao provável papel ecológico das ceras e sua aplicação como marcadores taxônomicos.Palavras chave: ceras epicuticulares; cerrado, floresta semidecídua; ai canos, ecologia. ABSTRACT-(Foliar epicuticular waxes of congeneric species from forest and cerrado vegetation).Four woody species of cerrado and five woody species of seasonal semideciduous forest were analysed concerning the contents of epicuticular waxes and their parafinic profiles. The cerrado species showed a tendency to higher contents of epicuticular waxes and lower proportion of hydrocarbons than the forest species. The C 29 and C 31 alkanes were dominant in ali species and the average lenght ofthe hydrocarbon chains were around 30,S in the forest species and from 28,S to 31 ,3 in the cerrado species. The ecological and taxonomic aspects of this characteristics are discussed.

PHYSICAL AND CHEMICAL DEFENSES OF Cenostigma pyramidale (FABACEAE): A PIONEER SPECIES IN SUCCESSIONAL CAATINGA AREAS

“…Analysis of the n-alkane profile revealed that the leaf epicuticular wax of Cenostigma pyramidale has chains ranging from 25 to 33 carbon atoms. These results agree with those found in plants studied in dry tropical forests (VARANDA;SANTOS, 1996;OLIVEIRA;MEIRELLES;SALATINO, 2003). Oliveira, Meirelles and Salatino (2003) observed that the n-alkane fractions formed mainly by homologs with 27-33 carbon atoms, which were the most effective wax components to reduce water loss.…”

Major Constituents of the Foliar Epicuticular Waxes of Species from the Caatinga and Cerrado

“…The taxonomic sig nificance of alkane patterns of Velloziaceae, a typ ical group from the Campos Rupestres, was evaluated by Salatino et al (1989;1991), while Mimura et al (1998) did the same in connection with plants of the genus Huberia (M elastomataceae) from the Campos Rupestres. Varanda and Santos (1996) have compared the alkane patterns of plants from the Cerrado and mesophytic forests. Among these studies, only that of Salatino et al (1985) provided a comprehensive analysis of the foliar epicuticular waxes; the other studies focused only on the composition of the alkane fraction.…”