Problems associated with breeding winter wheat for head scab resistance
1997
Ablova, I.B. | Slusarenko, A.N. (Krasnodar Lukyanenko Research Institute of Agriculture (KNIISH), Krasnodar (Rusia))
Epiphytotics of head scab caused by Fusarium spp. have been severe in the southern regions of Russia since 1986, most likely due to higher relative humidity levels and changes in wheat cultivation practices. Rotations with maize have increased the incidence of scab because maize debris is a source of initial inoculum. Besides management practices, breeding for resistance is used to control head scab. The plant uses many mechanisms to minimize pathogen damage, and they function at different stages of ear and kernel development. Resistance depends on pathogen characteristics and weather conditions. These factors help to explain the variability of disease reactions both within and among varieties, as well as among years. Some varieties, such as Partizanka, sustain more damage when inoculated late, whereas others, such as Massive, suffer less. Differences in the degree of damage to head, glumes, and kernels were observed in most varieties. The influence of pollen on F. graminearum spore germination has been investigated. Initially, specific pollen secretions were found to promote or depress conidial germination. With the aim of finding resistance to scab, 1500 winter wheat selection samples and 200 samples of local and foreign wheats are annually screened using artificial inoculation. Data to date show variation for resistance, but no immunity. Glume damage and kernel damage were found to be poorly correlated. Furthermore, there appears to be poor correlation between glume damage and accumulation of the toxin deoxynivalenol (DON) in the kernel. Some varieties show low glume damage but high DON accumulation; therefore, toxin content and glume damage should be evaluated separately.
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