Resumo

RODRIGUEZ CONTRERAS, María Elsa et al. Relation of plant height and competence with incidence and dispersion of Septoria tritici on rainfed wheat. Rev. Mex. Cienc. Agríc [online]. 2010, vol.1, n.3, pp.351-361. ISSN 2007-0934.

Septoriosis is a wheat disease that exist in high areas with rainy seasons in the Mexican Highlands. With the aim of analyzing the relation of plant height and density on the incidence and severity of this disease, six lines of seasonal tall wheat and short wheat with competition (furrows 30 cm apart) and without competition (furrows 70 cm apart), were evaluated in the spring-summer cycles of 2005 and 2006, in Juchitepec, State of Mexico and Nanacamilpa, Tlaxcala. The tall lines were of a late cycle, with plants almost double in height (124 cm vs 65 cm), with greater yield and grain weight, and greater resistance to leaf rust. This proves that the effect of Septoria tritici was different in both lines. The tall lines in the treatment with competition matured in 136 days and the treatment without competition, in 138 days. In both treatments, plant height, yields of grains from 25 stems and the weight of 1 000 grains were statistically equal. The variables of maximum infection and the area under the progress curve of Septoria tritici, were greater in the treatments with competition. In the short lines, the treatment with competition matured in 132 days, and without competition at 135 days. The analysis showed that the plant height and weight of 1 000 grains variable were statistically equal; on the other hand, the yield of grains from 25 stems was lower in the treatment with competition (16.9 g) than without competition (20.6 g). Maximum infection was lower in the treatment without competition (59%) than with competition (85%). The aerial variable under the progress curve for Septoria tritici was greater when there was competition (1 748).

Palavras-chave : Septoria tritici; leaf rust; seasonal wheat; short lines; tall lines.

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