Modelling crop yield and harvest index: the role of carbon assimilation and allocation parameters

Abstract Crop yield improvement during the last decades has relied on increasing ratio of economic organ to total aboveground biomass, known as harvest index (HI). In most crop models, HI is set a parameter; this empirical approach does not consider that only depends plant genotype, but also affected by environment. An alternative simulate allocation mechanistically, in LPJ-GUESS model, which simulates based daily growing conditions and development stage. Simulated critical for agricultural research due its importance, it can validate robust representation production processes. However, there challenge constrain parameter values globally Therefore, paper aims evaluate sensitivity wheat maize simulated with eight allocation-related parameters identify suitable global simulations. The nitrogen demand reduction after anthesis, minimum leaf carbon (C:N) range C:N strongly assimilation yield, while retranslocation labile stem grains rate from vegetative organs anthesis mainly influenced HI. A database observed both crops was compiled reference simulations before calibrating against data. Two high- low-yielding cultivars emerged calibration, whilst spring winter were found appropriate wheat. calibrated version improved simulation at scale crops, providing basis future studies exploring under different climate management scenarios.