Resumen

CARDONA, R. Vertical distribution of sclerotia of Macrophomina phaseolina in a natural infested soil in Portuguesa state. Rev. Fac. Agron. [online]. 2006, vol.23, n.3, pp.285-293. ISSN 0378-7818.

The vertical distribution of M. phaseolina sclerotia among the influence of the temperature and humidity were evaluated on a soil infested naturally. The essay was carried out at the experimental field Turén, which is part of INIA-Portuguesa, in a plot of 285 m² with a totally randomized blocks design, where treatments were depths (0-5 cm, 5-10 cm, 10-20 cm) and the blocks were the collection dates of the samples. The plot was sowed in succession with the corn-sesame crops, doing the evaluations in the seasons of scarce precipitations, 30 days after had emerged the sesame seedlings and ended on the terminal phase of flowering; for this, soil samples were taken with a borehole of 20 cm of height and 10 cm of diameter. On each depth, 5 sub-samples were taken to create one of 250 g, these were air-dried for 24 h in a lab and sclerotia were extracted using the flotation method. The lineal regression analysis for the three depths showed a highly significant negative association (P<0.01) among variables humidity and quantity of sclerotia, and a highly positive association (P<0.01) among temperature and sclerotia content variables. The lineal regression analysis showed a highly significant association (P<0.01) among variables temperature, humidity and sclerotia content. It was determine that at a higher depth, the quantity of sclerotia reduces the humidity content increases and the differences between the maximum and minimum temperatures reduce.

Palabras clave : Charcoal root; temperature; humidity; distribution.