Optimizing development for improved yield and yield quality in the perennial bioenergy crop Miscanthus
Student thesis: Doctoral Thesis › Doctor of Philosophy
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Miscanthus genotypes exhibit key characteristics that make it an excellent sustainable source of biomass. Miscanthus is perennial, requiring few inputs for growth and thus has a highly favourable energy ratio and produces biomass yield for up to 20 years. Miscanthus is typically propagated clonally via rhizome which is expensive, and it is difficult to scale up existing and new varieties to plant large areas rapidly. Propagation by glasshouse raised plug plants from seed is a new alternative but requires optimisation from growth in plugs to field establishment and senescence. This study focussed on the optimisation of the first year of a seeded Miscanthus stand, from germination and seedling phase to harvest the following spring. Germinating seedlings under mulch film in the glasshouse improved seedling vigour and germination rate, leading to larger plants at field planting, but the larger plants did not reliably yield higher biomass production at harvest, leading to further experimentation for the optimum seedling morphology and growth conditions. Combinations of plug design and planting date were tested. Establishment success in field was more likely in warmer, wetter conditions earlier in the season, as opposed to dry, summer conditions which increased the risk of plug desiccation, especially under mulch film. Planting environment and post planting care had a significant effect on overall yield, whereas initial plug morphology did not. Increasing glasshouse module sizes from 35cm3 of soil to 45cm3 improved plug plant development and planting time flexibility. Experimentation with different seedling morphologies concluded that larger plants with strong root biomass were more likely to survive planting into the field, but correlations with yield were less significant, suggesting that increased establishment percentage should be the first priority when growing seeded Miscanthus. The study concluded that individual plant growth over the season is extremely difficult and complex to predict or influence due to a multitude of interacting environmental and physiological factors. Finally, plant growth regulators were investigated to encourage senescence in a hybrid that had previously failed to successfully overwinter in the UK. Applications of exogenous ethephon at 480g/L stock solution greatly altered leaf colouration in treated plants, suggesting this approach has potential for commercial application; however, the consequences of the induced senescence need further investigation.
Thesis, 9.96 MB, PDF
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Thesis, 9.96 MB, PDF
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