BIOMASSA, CRESCIMENTO E RESPOSTAS ECOFISIOLÓGICAS DE PLANTAS JOVENS DE <i>Bertholletia excelsa</i> BONPL. SUBMETIDAS A DIFERENTES NÍVEIS DE IRRADIÂNCIA

Abstract

RESUMOA castanheira-da-amazônia (Bertholletia excelsa Bonpl.) é uma espécie exigente de luz, pois em floresta nativa, a espécie depende da formação de clareiras para alcançar o tamanho reprodutivo e em plantios florestais demonstra rápido crescimento inicial quando exposta a altos níveis de irradiância. No entanto, os aspectos ecofisiológicos dessa espécie sob condições contrastantes de irradiância não foram investigados. Nesse estudo, além das características de crescimento, objetivou-se analisar pela primeira vez o grau de plasticidade das respostas ecofisiológicas de Bertholletia excelsa quando submetida a ambientes de irradiância contrastantes. Plantas jovens de Bertholletia excelsa foram cultivadas em três condições de irradiância: baixa (20-300 µmol m -2 s -1 ), moderada (800-1000 µmol m -2 s -1) e alta (1900-2100 µmol m -2 s -1 ). Foram analisadas características de crescimento, trocas gasosas, teores de pigmentos cloroplastídicos e, no fim do experimento, o acúmulo e partição de biomassa. Plantas jovens de Bertholletia excelsa demonstraram maior acúmulo de biomassa, crescimento e fotossíntese quando expostas aos ambientes de moderada e alta irradiância. A condição de baixa irradiância estimulou maior partição de biomassa para a parte aérea em contraposição ao sistema radicular e maior concentração foliar de pigmentos cloroplastídicos. Bertholletia excelsa possui plasticidade fisiológica sob condições contrastantes de irradiância, sendo o maior crescimento e acúmulo de biomassa, em ambientes de moderada e alta irradiância, promovidos pelo melhor desempenho fotossintético, ao passo que o balanço positivo de carbono sob baixa irradiância é assegurado pelo investimento em estruturas de interceptação e captação de energia. Palavras-chave: Castanheira-da-amazônia; trocas gasosas; crescimento inicial; espécie arbórea tropical. ABSTRACTBrazil nut (Bertholletia excelsa Bonpl.) is a light-demanding species, because in natural forest, the species depending of formation of clearings for reach reproduction size and in forest plantation, showing fast initial growth when exposed to high levels of irradiance. However, the ecophysiological traits of this species under contrasting conditions of irradiance were not investigated. In this study, in addition to growth traits, we investigated for first time the degree of plasticity of ecophysiological response of Bertholletia excelsa when subjected to contrasting irradiance environments. Young plants of Bertholletia excelsa were cultivated under three conditions of irradiance: low (20-300 µmol m -2 s -1

Growth and survival over ten years of Brazil-nut trees planted in three anthropogenic habitats in northern Amazonia

“…Average diameter growth in our study (AAI d = 2.1 cm year -1 ) was intermediate compared to other studies that reported rates of growth in diameter of less than 1.4 cm year -1 to over 3 cm year -1 (Scoles et al 2014). Our results from the current study are in agreement with those obtained in experimental plantations of B. excelsa (in monoculture or mixed-species culture) in open areas with no vegetation cover (Fernandes and Alencar 1993;Tonini et al 2005;Costa et al 2009;Souza et al 2008), and confirm B. excelsa as a promising species for reforestation of degraded areas, on account of its high rate of survival, excellent growth in intense light conditions, and resistance to prolonged drought (Fernandes and Alencar 1993;Salomão et al 2006;Costa et al 2009;Souza et al 2017, Schimpl et al 2019. Furthermore, B. excelsa produces a large amount of dead organic matter in the form of leaves, thus promoting the cycling of nutrients in soils through litter production (Schroth et al 2001;Silva et al 2008;Costa et al 2009).…”

CHICKEN MANURE AND LUMINOUS AVAILABILITY INFLUENCE GAS EXCHANGE AND PHOTOCHEMICAL PROCESSES IN Alibertia edulis (Rich.) A. Rich SEEDLINGS

“…Similarly, young plants of Bertholletia excelsa Bonpl. (Souza et al, 2017), Anadenanthera falcata (Benth.) Speg., and Stryphnodendron adstringens (Mart.)…”

“…The luminosity in the environment where a species is introduced, planted, and cultivated is a determining factor in the success of silvicultural practices and in the recovery of degraded areas as this depends on the resilience capacity of the species to ensure its survival and stability of growth. High or low light availability can trigger physiological changes such as the photosynthetic metabolism of plants through leaf changes (Bunce, 2016;Souza et al, 2017), involving differences in the magnitude of electron transport and the proton gradient that potentiates phosphorylation (Jim et al, 2016).…”

Recruitment Niches of Enterolobium contortisiliquum (Vell.) Morong: Functional Acclimations to Light

“…Similar results for Cars M in E. contortisiliquum were found by Lima et al [55], even though their values were larger than ours; Fagus sylvatica, a broad-leaved species that tolerates very deep shaded conditions, had values more similar to ours of 1.56 mg g −1 in sun leaves and 2.29 mg g −1 in the shade [47]; Bertholletia excelsa Humb. & Bonpl., Lecythidaceae also had larger quantities of Cars in shade seedlings [72]. Even though a high Chl (a + b M ) and high SLA are consistent with the primary demand of shade leaves for light-harvesting compounds, these results raise the question of whether investment in Cars is more important for shade than sun leaves.…”