Abstract
Improving crop yield is essential to meet increasing global food demands. Boosting crop yield requires the coordination of carbon acquisition by leaves and carbon utilization by roots and seeds. Simple modelling approaches may be used to explain how this coordination is achieved within plant growth. Here, the limits to allocation strategies and the influence of maintenance costs are explored by analysing the sensitivity of a simple root–shoot carbon allocation model for vegetative and reproductive growth. The model is formulated based on fundamental constraints on plant growth and therefore can be applied to all plants. This general but quantitative approach shows that the relative costs of root and leaf respiration alter the relationship between carbon allocation and final plant size, enabling a range of allocation strategies to produce a similar total amount of plant material during vegetative growth. This plasticity is enhanced by increasing assimilation rate within the model. Results show that high leaf allocation during vegetative growth promotes early reproduction with respect to yield. Having higher respiration in leaves than roots delays the optimal age to reproduce for plants with high leaf allocation during vegetative growth and increases the restrictions on flowering time for plants with high root allocation during vegetative growth. It is shown that, when leaf respiration is higher than root respiration, reallocating carbon towards the roots can increase the total amount of plant material. This analysis indicates that crop improvement strategies should consider the effects of maintenance costs on growth, a previously under-appreciated mechanism for yield enhancement.
Highlights
Improving crop yield is considered vital for meeting increasing global food demands (Fischer et al 2009; Beddington et al 2011), and new approaches are needed to break through existing yield barriers
This paper explores the following questions: (i) How does varying the allocation of carbon for growth between leaves and roots alter total plant biomass during vegetative growth? (ii) How do the processes of respiration and photosynthesis constrain possible strategies of allocation between leaves and roots? (iii) Does increasing allocation towards the roots always lead to a decrease in overall plant size? (iv) How does varying allocation between leaves and roots during vegetative growth and lowering time alter reproductive output? These are addressed by analysing the sensitivity of a simple carbon allocation model for vegetative and reproductive growth
The aims of this paper were to understand the consequences of different allocation strategies and costs of maintenance respiration for plant growth in a general but quantitative manner, and to investigate any possible limitations to carbon allocation
Summary
Improving crop yield is considered vital for meeting increasing global food demands (Fischer et al 2009; Beddington et al 2011), and new approaches are needed to break through existing yield barriers. Where s is the amount of seed material, A is assimilation rate, l is leaf tissue, r is root tissue, and R1 and R2 are maintenance respiration for leaves and roots and seeds, respectively Within this framework, there are two decisions that a plant can make which alter potential seed yield: (i) The allocation strategy during vegetative growth; (ii) The developmental stage at which a plant reproduces. There is more available energy to grow; much more carbon needs to be allocated to the roots when growth stops in the model This means that the range over which inal plant size increases and decreases A plant must be more established in order to have the maximum energy available to reproduce (data not shown)
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