Abstract
Two pot experiments were conducted using elite lines and near isogenic lines (NILs) of winter wheat in a controlled environment to evaluate the effect of time of inoculation and subsequent increase in temperature during grain-filling on Fusarium head blight (FHB) and deoxynivalenol (DON) on the infected wheat grains. The experiments were a complete factorial combination with randomised replicates. Fusarium graminearum was used to spray inoculate wheat spikes at glume loose (GL). GL was established when the lower glume could be opened with a thumbnail. Fusarium inoculation was done at glume loose (GL+0), 4 and 8 days after (GL+4 and GL+8), respectively. Pots transferred to controlled environment cabinets set at 23/15oC or 28/20oC. Results reveal that FHB severity showed a significant (P<0.05) cultivar and temperature interaction in both elite and near isogenic lines. High temperature increased FHB severity by 35% in the NILs. DON concentration showed cultivar sensitive in both sets of cultivars. Inoculation at GL+4 which corresponded with the mid-anthesis gave the highest FHB severity and DON concentration in NILs, while the elite cultivars showed cultivar sensitive to DON accumulation regardless of the time of Fusarium inoculation.
Highlights
Fusarium head blight (FHB), which is caused by some species of Fusarium of which F. graminearum and F. culmorum are of interest in the UK is regarded as one of the most serious fungal disease in wheat worldwide (Xu and Nicholson, 2009)
In near isogenic lines (NILs) of Mercia, the temperature x cultivar effect was significant (P
Our results showed that in the Mercia background, Rht-D1b on average had higher FHB severity
Summary
Fusarium head blight (FHB), which is caused by some species of Fusarium of which F. graminearum and F. culmorum are of interest in the UK is regarded as one of the most serious fungal disease in wheat worldwide (Xu and Nicholson, 2009). Disease transmission through the release of spores from infected debris under field conditions could occur any time before and after flowering, extending the receptive period of plants to Fusarium infection (Siou et al, 2013) This explains the higher DON content often found in wheat spikes with relatively few visible symptoms (Hallen-Adam, 2011). Cowger and Arrellano (2013) explored the impact of late infection on disease development and toxin production when inoculation was done from 0 to 20 days after mid-anthesis with four F. graminearum isolates Their result showed that the period of maximum reception was 10-14 days after anthesis, while the occurrence of rain after anthesis extended the level of Fusarium susceptibility and increased the proportion of low symptoms and grains containing high DON. These have resulted to lack of agreement about the precise length of the phenological window of vulnerability to infection and DON accumulation in wheat grains (Del Ponte et al, 2007)
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