ABSTRACT
The study was conducted to determine fungal communities associated to strawberry plant roots, densities of nematodes in fumigated soil and physico-chemical properties of soil in three commercial strawberry plots (Dlalha, Ouled Aguile and Gnafda) located in Gharb region and visited three times during 2013-2014 season. Under a slight variation of soil temperature and humidity with specific physico-chemical characteristics, a high infestation level of soil by nematodes was marked in the studied farms over the periods of sampling. The lowest number was observed in the first visit attaining 1000 units/g of soil, increased to 5000 units/g of soil in the second sampling period at one site and in the last visit, a significant decrease trend occurs for the big plot which the number of nematodes was reduced to 1500 units/g of soil. The analysis of fungal communities colonizing roots of strawberry plants showed the presence of 13 fungal species. Rhizoctonia solani presented a higher frequencies of isolation from roots of Festival variety reaching respectively 36% and 26.72% in the first and the second visits of Dlalha farms compared to those recorded in the second visit of Ouled Aguile (18%) and Gnafda (13.6%) farms. The Fusarium genus was represented by F. solani, Fusarium sp.1 and Fusarium sp.2 detected at frequencies not exceeding 7.08%. Those of C. gloeosporioides reached 12%, Phytophthora sp. (15.8%). In addition, the appearance of A. alternata, C. herbarum, Aspergillus sp., Circinella sp., Ulocladium sp. and Trichoderma asperellum was more frequent during the three sampling periods.
ABSTRACT
The objective of this paper was (a) to estimate the CO2 soil efflux in a Mature Transitional Tropical Forest Amazonia and a area of Pasture in the north of the Mato Grosso; (b) to analyzer the influence of the soil humidity and temperature, and accumulated litter. The measurements had been carried through with device of CO2 absorption for infra-red ray (EGM/WMA-2 PP System, Hitchin Hertz, UK) in may/2005 to april/2006. The average values of the CO2 efflux of the ground in the Forest and the area of 5,45 and 4,94 µmolm-2s-1 Pasture µmolm-2s-1, respectively. In the dry season the behavior of the CO2 efflux of the ground was similar in the Mature Transitional Tropical Forest Amazonian and in the area of Pasture, and in the wet season the ecosystems had presented distinct behaviors, and the CO2 efflux of the ground in the area of Pasture was superior to the one in the Transitional Forest. It is essential that if it evaluates the influence of other factors in the CO2 efflux in ecosystems located in one same ecótono for the attainment of new answers that contribution to clarify doubt atmospheric CO2 emission to them the worldwide level.
O objetivo deste trabalho foi (a) estimar o efluxo de CO2 do solo em uma Floresta de Transição Amazônica Cerrado e em uma área de Pastagem localizadas no norte do Mato Grosso, e (b) verificar a influência da umidade e temperatura do solo, e serrapilheira acumulada no efluxo de CO2. As medições foram realizadas com aparelho de absorção de CO2 por infravermelho (EGM/WMA-2 PP System, Hitchin Hertz, UK) de maio/2005 a abril/2006. Os valores médios do efluxo de CO2 do solo na Floresta e na área de Pastagem foram de 5,45 e 4,95 µmolm-2s-1, respectivamente. Uma resposta satisfatória do efluxo de CO2 do solo e a serrapilheira acumulada, ocorreu somente na estação seca. Na estação seca o comportamento do efluxo de CO2 do solo foi semelhante na Floresta de Transição Amazônica Cerrado e na área de Pastagem, e na estação úmida os ecossistemas apresentaram comportamentos distintos, e o efluxo de CO2 do solo na área de Pastagem foi superior ao na Floresta de Transição. É essencial que se avalie a influência de outros fatores no efluxo de CO2 em ecossistemas localizados em um mesmo ecótono para a obtenção de novas respostas que contribuíam para esclarecer as dúvidas da emissão de CO2 em nível mundial.