ABSTRACT
Plant parasitic nematodes are major threats to Brazilian and world agriculture. Among them, Pratylenchus brachyurus and Meloidogyne incognita stand out as major pests for several crops, including corn, cotton, soybean among others, which can be components of integrated crop-livestock-forestry systems (ICLFs). In this context, information about the host status of eucalypts (Corymbia spp. and Eucalyptus spp.) to plant parasitic nematodes becomes more relevant in Brazil, due to the use of eucalypts in ICLFs. If tree components used on this system increase the population density of P. brachyurus and M. incognita, it is possible that these pathogens could damage shorter-cycle crops. Since information about the host status of eucalypts to plant parasitic nematodes is scarce, this study evaluated the host status of some eucalypt species to P. brachyurus and M. incognita. Two greenhouse trials were done to evaluate the reproduction of P. brachyurus and one to M. incognita, using some of the most cultivated species and hybrids of eucalypts in Brazil. The population growth of P. brachyurus increased on Corymbia citriodora, Eucalyptus grandis, Eucalyptus dunnii × Eucalyptus urophylla, and E. grandis × E. urophylla after ~90 days of inoculation. Conversely, despite M. incognita reproducing well in the control plants, no individuals were recovered from C. citriodora, E. urophylla and E. grandis × E. urophylla, which were classified as resistant plants. Based on both obtained and available data, M. incognita poses no threat to eucalypt species today. However, P. brachyurus is suggested to be a threat to eucalypts.
Subject(s)
Tylenchoidea , Eucalyptus , Nematoda/pathogenicity , Soybeans , Forestry , Agricultural Pests , Zea mays , GossypiumABSTRACT
ABSTRACT: The objective was to estimate the wood yield and essential oil content in three clones of eucalyptus that were planted in four contrasting arrangements and intercropped with sorghum. Eucalyptus clones MA2001 (Eucalyptus camaldulensis x E. tereticornis), A144 (Eucalyptus urophylla x E. grandis), and GG100 (Eucalyptus urophylla x E. grandis), were planted in single rows (10x2m), double rows (2x3+15m and 2x3+20m); and, triple rows (2x3x2+10m) in a randomized, complete block design experiment with four replicates. Our results demonstrated that planting spacing did not influence the essential oil yield or diameter at breast height in the clones. However, higher density plantings were shown to result in higher fresh weight of branches and leaves per plant. MA2001 grew taller, produced higher quantity of fresh biomass of branches and leaves per plant and volume of wood per hectare, and yielded more essential oil yield than the other clones. We concluded that MA2001 is the most suitable of the clones tested here for cultivation in water deficit conditions.
RESUMO: O objetivo do trabalho foi estimar o rendimento de madeira e o teor de óleo essencial de clones de eucalipto em diferentes arranjos, consorciado com sorgo. Foram utilizados 3 clones de eucalipto: Clone 1 (MA2001-Eucalyptus camaldulensis x E. tereticornis); Clone 2 (A144-Eucalyptus urophylla x E. grandis); Clone 3 (GG100 - Eucalyptus urophylla x E. grandis). Os clones de eucalipto foram plantados nos diferentes arranjos: em linha dupla, sendo 2x3+15m e 2x3+20m; linhas simples 10x2m e em linha tripla, sendo 2x3x2+10m. O delineamento experimental adotado foi o de blocos casualizados, com quatro repetições, sendo os tratamentos referentes a 3 clones de eucalipto e 4 arranjos de plantas diferentes. Os resultados mostraram que menores ou maiores espaçamentos não influenciaram no rendimento de óleo essencial e no diâmetro da altura do peito. Porém, menores espaçamentos podem proporcionar maior matéria fresca de ramos e folhas por planta. O clone MA2001 (Camaldulensis x Tereticornis) por ter apresentado maior altura de plantas, maior matéria fresca de galho e folhas por planta, maior volume de madeira por hectare e maior produtividade de óleo essencial pode ser o mais indicado para cultivo em condições com maior déficit hídrico.