Behavior of rubber tree clones to the South American Leaf Blight (SALB) and potential impact of global climatic changes on the disease occurrence / Comportamento de clones de seringueira ao mal das folhas e potencial impacto das mudanças climáticas globais na ocorrência da doença

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

26/02/2010

RESUMO

The unsuccessfulness of the natural rubber cultivation (Hevea spp.) on the cultivation areas in Brazil is due, mostly, to the occurrence of the rubber tree South American Leaf Blight (SALB), caused by the fungus Microcyclus ulei (P.Henn. v. Arx.). The strategies of the disease management are based on the genetic resistance of plants to the SALB, on the phenological characteristics of the used clones and on the climatic conditions which determine the epidemics. This work had as objectives to evaluate the behavior of eighteen rubber tree clones to the SALB in the region of Cachoeiro do Itapemirim-ES, study the disease progress and evaluate the possible impacts of the global climatic changes upon the spatial distribution of SALB in Brazil. The experiment was carried out in the Experimental Farm Bananal of North of the Capixaba Research Institute, Technical Assistance and Rural Extension (INCAPER) on Pacotuba district, in Cachoeiro do Itapemirim-ES, where 18 clones were evaluated as it follows: 1- RRIM 600; 2- RRIM 802; 3- RRIM 725; 4- RRIM 711; 5- RRIM 926; 6- IAC 300; 7- IAC 301; 8- IAC 302; 9- PB 324; 10- PB 355; 11- PB 326; 12- PB 260; 13- PB 306; 14- PR 255; 15- PR 261; 16- IAN 873; 17- FX 3864 and 18- GT 1. The evaluations were carried out on each 15 days, being withdrawn, about 30 leaflets per tree. The disease was quantified from the number of collected leaflets, showing or not characteristic symptoms of the SALB and classified accordingly with the disease development stages and the lesion kind, determining the percentage of foliar area by diagrammatic scale. The SALB occurred on the rubber trees leaflets during the whole experimental period, which the higher or smaller intensity of the disease varied accordingly to the resistance level of the clones and the year station. The clones FX 3864, RRIM 725, RRIM 711, IAC 300 and IAN 873, present on group 3, were the clones which presented higher resistance to the SALB, the clones PB 260, GT 1, PR 255, PB 324, IAC 302, PR 261 and IAC 301, present on group 2, were classified as moderately resistant, the clones RRIM 926, PB 355, RRIM 802, RRIM 600, PB 326 and PB 306, present on group 1 were considered as susceptible to the disease. For the study of the potential impacts of the global climatic changes about the SALB, maps were elaborated about the risk areas to the occurrence of the disease, monthly, considering the actual climatic conditions and the future sceneries A2 and B2, for the decades of 2020, 2050 and 2080 put available by Intergovernmental Panel on Climate Change (IPCC). The climatic conditions were classified in four categories, accordingly with the potential risk of occurrence of the disease, considering the temperature (T) and the air Relative Humidity (RH): i) highly favorable; ii) favorable; iii) relatively favorable and iv) unfavorable. The data about the future climatic sceneries were xvi provided by GCM Change Fields. In this work it was utilized the simulation model Hadley Centre for Climate Prediction and Research (HadCm3), using the software Idrisi 32. Based o the obtained results it was observed that it must happen a reduction on the highly favorable area and favorable to the rubber tree SALB, in a way that this reduction will be gradual for the decades of 2020, 2050 and 2080, being higher on the scenery A2 than on scenery B2. Some areas of the country will become more able to the cultivation, what may propitiate the appearance and/or higher development of some new planting areas

ASSUNTO(S)

microcyclus ulei mudanças climáticas globais resistência microcyclus ulei recursos florestais e engenharia florestal gnotypes global climatic changes genótipos resistance

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