Exploiting resource use efficiency and resilience in ancient wheat species.
PhD thesis, University of Nottingham.
Modern bread wheat (Triticum aestivum) initially derived from wild progenitors which underwent hybridisation and domestication events. It is hypothesised that modern plant breeding has reduced the genetic variation among modern cultivars (Sparkes, 2010). Ancient wheat species form a conduit between wild ancient wheat and cultivated Triticum species, and may harbour the genetic variation required to supplement the modern bread wheat gene pool. The current work investigated a range of morphological and physiological aspects of several ancient species including several representatives of spelt, emmer and einkorn. These were compared to modern bread wheat in two field and three glasshouse experiments with the aim to investigate their resource use efficiency, where radiation use and water use formed the crux. The main components of the current work relate to 1) canopy interception characteristics 2) leaf photosynthetic capabilities and 3) water use. Spelt genotypes demonstrated increased WUE and green area longevity compared with modern bread wheat. Emmer displayed increased WUE, assessed on three scales using instantaneous transpiration efficiency (ITE), biomass to water uptake ratios, and carbon isotope discrimination (Δ13C). In addition, the mechanisms whereby emmer, einkorn and spelt maintained ITE appeared to differ. Emmer was observed to increase photosynthetic rates, whereas spelt maintained low transpiration as a result of low stomatal conductance. Einkorn however, maintained ITE through an intermediate of both of these mechanisms. This was further supported by species differences for maximum photosynthetic rates (Asat) which, for emmer and einkorn, were comparable with modern bread wheat. Investigation of WUE through Δ13C and biomass production to water uptake ratios ranked species similarly, showing emmer and spelt to have superior WUE during grain filling. Additionally, spelt was observed to produce biomass comparable to modern bread wheat, thought to be due to enhanced RUE (observed in one field trial) or increased green area longevity rather than increased assimilation capability. In field experiments, biomass production and light interception was relatively high for einkorn species, however this was believed to derive from excessive tiller production due to poor emergence. Overall, ancient species did partition a larger proportion of assimilates toward tillers. Modern bread wheat produced fewer tillers, but directed more biomass towards the ear, and therefore had greater harvest indices (HI) compared to all ancient species. Despite this broad analysis, further investigation of the mechanisms responsible for these traits is required. This research therefore indicates that there is sufficient variation for traits, which could be used to improve radiation and water use efficiency, and therefore warrants further exploration. With further investigation, resource capture and utilisation efficiency, and the morphological traits that confer these advantages in these genotypes, genetic markers could be identified with the aim to introduce valuable traits for the production of novel modern bread wheat varieties. The differences observed between these ancient wheat species and modern bread wheat provide an opportunity through which modern wheat gene pools may be improved to stabilise yields, particularly in sub-optimal environmental conditions, thus increasing biomass production per unit resource, thereby enhancing the productivity and the efficiency of crop systems.
Thesis (University of Nottingham only)
||Ancient wheat, Triticum monococcum, Triticum dicoccum, Triticum spelt, modern bread wheat, physiology, canopy architecture, resource use efficiency, water use efficiency, stay green, drought, yield, biomass.
||S Agriculture > SB Plant culture
||UK Campuses > Faculty of Science > School of Biosciences
||25 Feb 2015 09:51
||13 Oct 2016 17:37
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