Open AccessAnisotropy, in Density and in Distance, of the Dispersal of Yellow Rust of Wheat: Experiments in Large Field Plots and Estimation
Author(s) -
Samuel Soubeyrand,
Jérôme Enjalbert,
Álex Sánchez,
Ivan Sache
Publication year - 2007
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto-97-10-1315
Subject(s) - anisotropy , biological dispersal , spore , parametric statistics , probability density function , statistics , stripe rust , biology , field (mathematics) , physics , mathematics , optics , botany , population , plant disease resistance , demography , biochemistry , sociology , gene , pure mathematics
Long-distance dispersal of spores generally presents anisotropy. This anisotropy can appear in the mean number of spores deposited along a given direction (anisotropy in density) and in the mean distance that a spore travels in a given direction (anisotropy in distance). Specific experiments together with a statistical methodology are proposed to study this effect. The experiments are based on the use of a point source of a traceable inoculum and susceptible trap plots in large resistant field plots. The anisotropy is characterized by two functions: a directional density function and a mean distance function which are related with the anisotropies in density and distance, respectively. A nonparametric approach is developed to estimate these functions and to help in choosing a parametric model. Then, the parametric model is estimated. In two field experiments, migrations up to 175 and 225 m from the source were detected, with ≈25% of the trap plots infected. Whatever the experiment, the two estimated anisotropies presented different shapes (i.e., the number of spores dispersed in a given direction was not proportional to the mean distance travelled by these spores).