EFFECT OF ABIOTIC AND BIOTIC STRESS AND CROP MANAGEMENT ON HEALTH CONDITION AND YIELD OF CEREALS
Wheat production has become a global problem due to the climate change impact on wheat farming systems, pest management and control. Yield loss predictions are usually made using regression models with either biotic or abiotic factors as predictor variables, but only a few of them have considered the combined effects of multiple diseases and climatic conditions. Moreover, efficacy of fungicides in pest control and their effect on yield increase is usually analyzed in respect to the level of disease index and yield achieved in untreated plots, without taking into consideration the influence of other environmental elements. This study was conducted in order to determine the combined effects of biotic factors (disease indices) and abiotic factors (climatic elements and efficacy of fungicides) on yield achievements of winter wheat varieties. Field trials were set up under naturally occurring inoculum of the prevalent economic pathogens of wheat in the period 2006-2017. Model varieties Barbee and Durumko, known to have various degrees of susceptibility to wheat pathogens, were used in the study. General linear model function of Minitab 17 (trial version) was used for all the analyses. It was determined that yield loss in untreated plots was significantly influenced by the combined effects of multiple diseases and climatic elements. Moreover, it was determined that the relationship between fungicide efficacy and yield achievements was not straightforward and that it should be analyzed in respect to the combined effects of biotic and abiotic factors.