Specialeforsvar: Oliver Mørk
Different types of flooding of wheat (Triticum aestivum)
Vejleder: Prof Ole Pedersen, Biologisk Institut, UCPH
Censor: Prof Morten Foldager, RUC
Flooding of wheat is a serious issue with 15-20% of the worlds wheat cropping area being affected yearly. This study enlightens a seldomly studied type of flooding in between waterlogging and complete submergence, partial submergence where some of the shoot is under water but there is still plenty of atmospheric contact. There was a decreasing amount of oxygen in the root aerenchyma with increasing flooding depth, to almost 0% oxygen left when half of the shoot was submerged, with large drop offs when the ligules were submerged. The ligules were shown to be cut offs to the internal oxygen flow. During long term flooding (43 days), there seemed to be less severe consequences from partial submergence than the oxygen measurements would indicate. There was no significant difference between waterlogged and partially submerged plants in survival or chlorophyll content of new leaves. Survival rates showed that both waterlogged and partially submerged plants survived the entire period and chlorophyll content of newly formed leaves showed that both kept producing new viable leaves. The only significant difference, found between waterlogged and partially submerged plants, were biomass where partially submerged plants had a lower biomass than waterlogged plants. This study indicates that overall partial submergence may not be very much worse than waterlogging. However, it identifies a very significant limitation in the internal oxygen transport of wheat at the ligules. Further work, may show this limitation having a more severe impact than in this study.