Crescimento inicial de Piptadenia stipulacea (Benth.) Ducke (Mimosaceae) e Anadenanthera colubrina (Vell.) Brenan var. cebil (Griseb.) Altshul (Mimosaceae) sob diferentes níveis de sombreamento

Abstract

Crescimento inicial de Piptadenia stipulacea (Benth.) Ducke (Mimosaceae) e Anadenanthera colubrina (Vell.) Brenan var. cebil (Griseb.) Altshul (Mimosaceae) sob diferentes níveis de sombreamento RESUMO (Crescimento inicial de Piptadenia stipulacea (Benth.) Ducke e Anadenanthera colubrina (Vell.) Brenan var. cebil (Griseb.) Altshul (Fabaceae) sob diferentes níveis de sombreamento). Este trabalho teve como objetivo verifi car como as características morfofi siológicas diferem entre duas espécies da Caatinga com diferentes necessidades de luz para o crescimento inicial, apresentando a hipótese de que P. stipulacea caracteriza-se como espécie heliófi la e A. colubrina como umbrófi la, nas primeiras fases de vida. Conduziu-se um experimento em blocos ao acaso, no qual plântulas de ambas as espécies foram submetidas aos tratamentos de pleno sol, 50%, 70% e 90% de sombra durante seis meses. Foram avaliados aspectos morfológicos (altura, diâmetro, número de folhas e alocação de biomassa) e fi siológicos (teores de clorofi la a, b e total, e razão clorofi la a/b). Os resultados mostraram que as espécies apresentam diferentes exigências de luz durante o crescimento inicial. Plântulas de P. stipulacea apresentaram maior taxa de crescimento relativo e maior diâmetro a pleno sol, menor razão raiz/parte aérea e menor conteúdo de clorofi la total quando comparadas às plântulas de A. colubrina. Os melhores resultados de P. stipulacea a pleno sol e A. colubrina em níveis intermediários de sombra corroboraram com a hipótese deste trabalho e são consistentes com a área de ocorrência de cada espécie. Palavras ABSTRACT(Early growth of Piptadenia stipulacea (Benth.) Ducke and Anadenanthera colubrina (Vell.) Brenan var. cebil (Griseb.) Altshul (Fabaceae) exposed to diff erent levels of shade). Th is study aimed to verify how morpho-physiological characteristics diff er between species of the Caatinga with diff erent light requirements for initial growth, and had the hypothesis that P. stipulacea is light-demanding and A. colubrina is shade-tolerant in the early stages of life. We conducted a randomized block experiment in which seedlings of both species were subjected to treatments of full sun, 50%, 70% and 90% shade for six months. We evaluated morphological (height, diameter, number of leaves and biomass allocation) and physiological (a, b and total chlorophyll content, and ratio of chlorophyll a/b) features. Th e results showed that these species have diff erent light requirements during early growth. Seedlings of P. stipulacea showed a higher relative growth rate and larger diameter when growing in full sun, and a lower root/shoot ratio and lower total chlorophyll content when compared to seedlings of A. colubrina. Th e best results were for P. stipulacea in full sun and A. colubrina at intermediate levels of shade, which corroborate the hypothesis of this work and are consistent with where each species grows.

Influence of luminosity on the initial growth of Carapa guianensis, Clitoria fairchildiana and Inga edulis tree seedlings

“…Rego & Possamai (2006) stated that, for some species, the reduction of height growth under natural light is associated with an increased light availability, increases in leaf temperature, intensification of respiratory rate and induction of stomata closure, leading to a reduction of carbon sequestration. This behavior, a lower growth in height when exposed to sunlight, was also reported for several tree species during the juvenile phase (Scalon et al, 2006;Silva et al, 2007;Dutra et al, 2012;Ferreira et al, 2012). In contrast, Portela et al (2001), in a study on responses of tree of two tree species under different shading conditions, verified that C. fairchildiana was higher in the sunlight treatment after 150 days of experiment.…”

Morpho-anatomy of leaves and yield of pineapple plant in intercropping with cassava

“…According to Almeida et al (2005), the lower accumulation of chlorophyll in such leaves compensates for the higher levels of light intensity. Under conditions of appropriate radiation, chlorophyll molecules are synthesized and degraded at the same rate, but in the presence of excess sunlight, the rate of degradation is intensified (FERREIRA et al, 2012). No differences between treatments were observed with respect to the concentrations of Chlb or Chla/Chlb ratios ( Table 2).…”

GERMINAÇÃO E CRESCIMENTO INICIAL DE Machaerium brasiliense VOGEL (FABACEAE) EM CASA DE VEGETAÇÃO

“…Vários estudos têm sido realizados sobre a germinação e o crescimento de espécies de Fabaceae nativas (SCHUMACHER et al, 2004;FERREIRA et al, 2012;M ONDO et al, 2008;RODRIGUES et al, 2007), no entanto foram encontrados poucos registros considerando a germinação e o crescimento de M. brasiliense. Estudos sobre a época adequada para colheita das sementes e desempenho germinativo em câmara de germinação de M. brasiliense foram realizados por Guimarães e Barbosa (2007).…”