Spatial-temporal analysis of wheat leaf rust disease )Puccinia triticina Eriks( in Southwestern Iran

Leaf rust is one of the most important diseases and influences the sustainable cultivation of wheat. Therefore, for the first time in Iran, the spatial pattern and temporal progress of this disease were assessed in five wheat cultivars, including Chamran 2, Star, Ofogh, Kavir, and Boolani, with different resistance levels in 2015-16 and 2016-17 cropping years. In both years, disease progress curves (DPCS) showed a sigmoid-like shape, and the rate curves had an obvious inflection point, both the features of Gompertz and logistic models. Plots of transformed, predicted disease intensity values and residual patterns indicated that disease intensity data fit closely with Gompertz and logistic models. Gompertz and logistic models with a bit of variation gained R2 above 90 % in all cultivars. Based on the results, there is no direct relationship between cultivar resistance and best-fitted models, as in both years, logistic and Gompertz models fitted properly with disease intensity data for all cultivars. In the Gompertz model, the mean rate of increase (rG) per unit of disease in the resistance (Chamran 2) and susceptible (Boolani) cultivars were 0.052 and 0.09, respectively, and in the logistic model (rL) were 0.12 and 0.144, respectively. Results indicated that in the first weeks after the appearance of the disease symptoms, the spatial pattern of diseased plants was aggregated, and the amount of the dispersion index and lloyd’s Index of Patchiness in the first and second years were 8.9, 9, and 1.3, 1.2, respectively. Three weeks after data collection, the spatial pattern became random.

Spatial-temporal analysis of wheat leaf rust disease )Puccinia triticina Eriks( in Southwestern Iran Keywords:

wheat , leaf rust , spatial pattern , temporal progress , dispersion index