The pattern of growth increment zones, the cambial growth dynamics and the structural variation in wood formation of Swietenia macrophylla King, Carapa guianensis Aubl., and Cedrela odorata L. (Meliaceae) were investigated in order to understand the relationship of site conditions and sustainable growth in Central Amazonian plantations. Trees were available from 8-, 17-, 23-, and 57-year-old plantations, and from primary forests in Manaus (Amazônia), Santarem (Pará), and Aripuanã (Mato Grosso). The wood anatomical structure and the annual increments of 61 Swietenia, 94 Carapa, and 89 Cedrela trees were studied for different tree heights. The curves of annual increments were cross-dated and tested for synchronisation. The cambial growth dynamics of up to 52 trees per species were dated by means of dendrometer measurements, monthly labelling by pinmarkers, and extracted cambium samples investigated using a microscope. The intraannual course of the growth and structural variation was compared with the water supply of the soil and insect attacks (Hypsipyla grandella (Zeller) Lep.).In Swietenia and Carapa parenchyma and vessel bands as well as bands of resin canals were observed. Within the xylem of Cedrela, alternating bands of fibres and vessels surrounded by paratracheal parenchyma were found; bands of resin canals were only occasional. In the juvenile wood of Swietenia and Carapa no synchronization of the increment curves was possible, whereas the increment curves obtained in the juvenile wood of Cedrela showed parallel run in growth. The increment curves obtained in adult wood of Swietenia and Cedrela indicate an annual formation of increment zones, whereas the number of increment zones in the xylem of Carapa was approximately 50% higher than the tree age (years) indicating that the growth increments of Carapa also were not annual during the adult phase of growth.The study of the intraannual growth dynamics of the trees showed that the formation of parenchyma bands in Swietenia is induced by dry periods before a cambial dormancy. The formation of parenchyma bands of Carapa was induced by extremely dry and extremely wet periods before a cambial dormancy, whereas fibre bands in Cedrela were induced by dry periods before a cambial dormancy and the formation of vessel bands embedded in paratracheal parenchyma was induced by wet periods after a cambial dormancy. In addition, insect attack (Hypsipyla grandella) induced locally restricted formation of parenchyma bands and bands of resin canals in Swietenia, Carapa and Cedrela.
O conhecimento dos prováveis impactos das mudanças climáticas globais sobre a ocorrência de doenças de plantas é de grande importância para o setor agrícola, pois permite a elaboração de estratégias de controle. O presente trabalho teve por finalidade estudar os possíveis impactos das mudanças climáticas sobre a sigatoka-negra da bananeira, por meio da elaboração de mapas de distribuição da doença confeccionados a partir dos cenários disponibilizados pelo IPCC. Os mapas mostraram que haverá redução da área favorável à doença no país. Tal redução será gradativa para as décadas de 2020, 2050 e 2080 e de forma mais acentuada no cenário A2 que no B2. Apesar disso, extensas áreas ainda continuarão favoráveis à ocorrência da doença, especialmente no período de novembro a abril.
Em setembro de 2003, em Manaus, Amazonas, foram observadas manchas foliares, muito semelhantes àquelas de sigatoka-negra causada por Mycosphaerella fijiensis em folhas de Heliconia psittacorum. Efetuou-se o isolamento do patógeno e, para o teste de patogenicidade, foi utilizada a técnica de inoculação cruzada com os isolados de H. psittacorum e de bananeira (Musa spp.) da cv. Prata Anã. Em ambas as espécies o teste foi positivo. Com o auxílio do microscópio óptico, da literatura disponível e dos testes de patogenicidade, confirmou-se que H. psittacorum é hospedeira de M. fijiensis, sendo este o primeiro relato da ocorrência de M. fijiensis em helicônias.
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