Abstract
(Englisch)
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The aim of this work was to determine specific physiological parameters for the discrimination between tolerant and susceptible varieties of spelt and wheat with respect to early flooding tolerance, a prerequisite for the adaptation to cold and wet environmental conditions. Based on these parameters, simple, fast and cheap germination tests were developed. The results of these tests were used for the calculation of quantitative trait loci (QTL) for flooding tolerance.
The reaction in the field was observed and the experimental conditions were adjusted according to the field conditions. A field trial with eight sowing dates showed that the most important factor for the yield reduction was the low number of plants surviving the winter period. Under growth chamber conditions, two days of flooding after 0 or 4 days of growing at 20°C resulted in a good differentiation between tolerant and susceptible lines. After this optimisation part additional varieties were tested and the physiological reactions of the plants were investigated. Under optimal conditions for cereals, spelt (cv. Oberkulmer) germinated faster and showed a faster seedling growth than wheat (cv. Forno). Under flooding stress between imbibition and begin of root growth, spelt consumed less oxygen than wheat. Spelt adapted better, presumably because the maintenance of the integrity of the cell membranes. The leakage of metabolites was less and the rate of survival was higher for spelt. When flooding occurred four days after sowing, the faster coleoptile elongation of spelt was probably part of an avoidance strategy. Spelt showed better growth and produced less ethanol, indicating that it was less affected by the hypoxia stress. Survival of flooding just after imbibition and faster coleoptile elongation are indicators for the better adaptation of spelt to temporary flooded soils. In cooperation with Dr. M. Messmer (FAL, SESA partner 15) a wheat x spelt population (F5 RILs of FO x OK) was used to conduct a genetic analysis of flooding stress reactions in the early phase of germination. The tolerance to 48 h of flooding just after imbibition was negatively correlated (r = -0.79) with the leakage of metabolites in the soil solution, indicating that the plants which could preserve their membrane integrity survived better. Five QTL explaining 40.6 % of the phenotypic variance for survival were found, and localised on the chromosomes 2B, 3B, 5A, and 7S. The tolerance to 48 h of flooding four days after sowing showed the highest correlation with the germination rate (r = 0.8), indicating that the plants with a fast coleoptile growth were less susceptible to flooding. Ten QTL were found explaining 35.5 % of the phenotypic variance for seedling growth index, and were localised on chromosomes 2A, 2B, 2D, 3A, 4B, 5A, 5B, 6A, and 7S.
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