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ZAMBENEDETTI, Elisandra Batista et al. Evaluation of monocyclic parameters and intensity of the Asian soybean rust (Phakopsora pachyrhizi) in both several soybean genotypes and canopy position. Summa phytopathol. [online]. 2007, vol.33, n.2, pp.178-181. ISSN 0100-5405. http://dx.doi.org/10.1590/S0100-54052007000200012.
Soybean rust caused by the fungus Phakopsora pachyrhizi, has been known to drastically reduce yields. Diverse studies are now in progress, to search information on the genetic resistance of cultivar currently planted. The objective of this study was to evaluate the both incubation and latent period and the progress of soybean rust on several genotypes and three canopy position in greenhouse. The cultivars used were Uirapuru, BRS 134 Pintado, BRS 154, BRS 215, BRS 231, FT 2 and PI 459025 with a Ppp4 gene of resistance for soybean rust. Inoculations were performed by spraying inoculum suspension on the leaves. Disease incidence and severity were assessed every five days after the first disease symptoms were observed until plants were dead. The incubation period was six days for all genotypes evaluated. However, the latent period varied from six to twelve days. The incidence and severity values were transformed in proportion as the area under the disease incidence curve (AUDIC) and area under the disease severity curve (AUDSC). The cultivars BRS 134 Pintado, FT 2 and BRS 231 showed high values for AUDIC and were significant different from the others. PI 459025 showed the lowest value for AUDIC. AUDSC for PI 459025 cultivar was the lowest and FT 2 showed the highest value. Difference from disease intensity on eight genotypes, in function of the canopy position, only was observe to plant medium part.
Keywords : Glycines max (L.) Merrill; disease progress.