Shideh Mojerlou, Naser Safaie, Azizollah Alizadeh, Fatemeh Khelghatibana
Abstract
To evaluate appropriate models for prediction of temporal progress of wheat Septoriosis caused by Septoria tritici, epidemiological studies were conducted in greenhouse and
field for two consecutive growing seasons in 2006-2007 and 2007-2008. Disease progress was determined on five wheat cvs. Tajan, Zagros, Koohdasht, Shanghai, Shirrodi and two lines (N-80-60 and N-80-19) using a complete randomized block design with four replicates. Field experiments were carried out at Araghi-mahale research station in Gorgan province. Inoculation was repeated three times, in 15 days intervals. After symptom appearance, disease index was recorded and continued until flag leaf infection, every other day. Disease progress was recorded by Saari- Prescott (Double digit) method. Various epidemiological models including Monomolecular, logistic, log- logistic, Gompertz and Weibull were used to evaluate disease progress. Fitness of different models was examined by Coefficient of Correlation, Maximum Error, Root Mean Square Error, Coefficient of Determination, Modeling Efficiency, Coefficient of Residual Mass Parameters. The results of field experiments showed that monomolecular model was not a suitable model for any cultivar or line due to high RMSE and CRM, low CD and EF. The greenhouse experiments confirmed these results as well. Logistic model had high efficiency in all cultivars and lines with the exception of N-80-19 in 2006-2007. In this line, log- logistic model was evaluated as the most suitable model. Based on field experiments in 2007-2008 logistic model in cvs. Shirrodi, Shanghai, and N-80-6 line and log- logistic model in cvs. Tajan, Zagros, Koohdasht, N-80-6 and N-80-19 lines were the most appropriate models. The results of greenhouse experiments revealed that logistic model was evaluated as the most suitable model excepting Shanghai and N-80-19. Log- logistic and Weibull (c=2) models were considered as preferred models in Shanghai and N-80-19, respectively. Greenhouse experiments were repeated twice and both of them confirmed these results. Generally, based on the results of field and greenhouse studies, logistic and log- logistic were the most appropriate models. This study examined temporal progress of wheat Septoriosis on common cultivars in the north of Iran for the first time.
Key words:
Epidemiological models, temporal progress, wheat, Septoria tritici