Análise fisiológica e anatômica de folíolos em diferentes estádios de desenvolvimento de plantas jovens de andiroba (Carapa guianensis Aubl.).

Abstract

This research aimed to evaluate leaflet concentration of ehloroplastic pigments and changes in gas exchange, carbohydrates accumulation and anatomical characteristics as a function of leaflet development in young andiroba plants (Carapa guianensis Aubl.). Andiroba seedlings were cultivated under greenhouse conditions, under continuous irrigation, in 20 L pots filled with flat loam latosol. The experiment evaluation has started by the identification of leaflet developmental stages (LDS), visually performed according leaflet coloring. Six different LDS (El, E2, E3, E4, E5 and E6) were identified. Net CO, assimilation rate (4) was negative in El, reaching positive values from E2 to E6. At least in parts, negative 4 in El may be explained by the lower chlorophyll a concentration. Nevertheless, 4 significantly increased from E2 to E6, concomitantly to increases in both Chl a+b and Chl a. Stomatal conductance (gs), transpiration (E), and 4/E reached higher averages from E4 to E6. Leaflet sucrose and starch increased according LDS at least in parts in response to increased 4. Anatomical assessments suggest no significant differences in leaflet tissues and structures according LDS. Both epidermal waxes, parenchyma cells, extrafloral nectaries, and stomata structure did not vary with LDS. Higher accumulation of starch and higher frequency of stomata in abaxial epidermis was registered in mature leaflets. Nevertheless, higher frequency of trichomes was observed in youngest leaflets.

This research aimed to evaluate leaflet concentration of chloroplastice pigments and changes in gas exchange, and carbohydrates accumulation as a function of leaflet development in young andiroba plants (Carapa guianensis Aubl.). Andiroba seedlings were cultivated under greenhouse conditions, under continuous irrigation, in 20 L pots filled with flat loam latosol. The experiment evaluation has started by the identification of leaflet developmental stages (LDS), visually performed according leaflet coloring. Six different LDS (El, E2, E3, E4, E5 and E6) were identified. Net CO; assimilation rate (4) was negative in El, reaching positive values from E2 to E6. At least in parts, negative A in El may be explained by the lower chlorophyll a concentration. Nevertheless, 4 significantly increased from E2 to E6, concomitantly to increases in both Chl a+b and Chl a. Stomatal conductance (gs), transpiration (E), and 4/E reached higher averages from E4 to E6. Leaflet sucrose and starch increased according LDS at least in parts in response to increased A.

Qualitative differences in anatomical structures were evaluated according leaflet developmental stage (LDS) of Carapa guianensis (Aubl.) by determining its structural organization using microscopic and micro-chemical techniques. Quantitative assessments were performed just for leaflet frequencies of stomata and trichomes. There were no marked differences in anatomical structures disregarding LDS. Therefore, leaflets from all developmental stages presented similar deposition of epicuticular wax layer, similar cell arrangement in both adaxial and abaxial epidermises, and mesophyll tissue characterized by palisade and sponge parenchyma forming a dorsiventral symmetry. Leaflets were hipostomatic from El to E3 and amphystomatic from E4 to E6, however, stomata were anomocytic regardless LDS. Extrafloral nectaries, glandular and tector trichomes, crystals and starch were common to all LDS. The midrib was composed by sclerenchyma cells with xylem facing the adaxial epidermis and phloem faced to abaxial epiderm. Slightly spherical crystals (drusen) were commonty found in pairs, with greater frequency in abaxial epidermis and in secondary veins. À starch sheath was found regardless LDS, however, higher starch accumulation was clearly evident in mature LDS (such as E5 and E6) rather than in juvenile (El to E4).