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Introduction to plant modelling. Phenology Most important stages: Sowing, Flowering & Maturity. Each phase develops through cumulative thermal time, can include photoperiod & vernalisation responses. Photosynthesis Potential Growth= f(cover, radiation, rue) ∆DM = RUE x radn x cover
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Phenology Most important stages: Sowing, Flowering & Maturity. Each phase develops through cumulative thermal time, can include photoperiod & vernalisation responses.
Photosynthesis Potential Growth= f(cover, radiation, rue) ∆DM = RUE x radn x cover RUE = f(water, N, P, T, CO2) cover = 1 - e-k x LAI (Beer-Lambert law) RUE – radiation use efficiency. (grams biomass / MJ) K – extinction coefficient; crop specific, affected by row spacing. Water limited growth = sw supply * TEC / VPD TEC = Transpiration efficiency coefficient. Actual growth = minimum of potential and water limited growth.
Biomass production • Partitioning to leaf, stem, ear/pod and root is stage dependant. • Grain filling takes priority during reproductive growth. • Sink size is determined by one of • Harvest Index, • Grain number/size • Grain cohorts (ears).
Stress affects different processes in different ways • SW: • Reduced availability slows dm production • FX photosynthesis & phenology via supply:demand ratio • FX leaf-expansion & nitrogen fixation via fr_asw • N • Reduction of RUE • Grain N content • Phenological development • Frost, Age • Leaf senescence
N fixation ‘Magic’ supply of N to maintain concentration in all plant organs Extra N in the system comes from roots & surface residues that are returned at maturity
Root development Constant (~20mm/day) in wet soil layers, slows down as layer dries Can be further delayed by XF
Why does my crop die? • Look in the summary file: • Was it ever sown? At the right time? • Did it get a reasonable peak LAI? • Did it encounter stress?
Why does my crop die? • Look in the summary file: • Was it ever sown? At the right time? • Did it get a reasonable peak LAI? • Did it encounter stress?
Why does my crop die? • Look in the summary file: • Was it ever sown? At the right time? • Did it get a reasonable peak LAI? • Did it encounter stress?