Most models use carbon allocation assumptions, which ignore the effects of different potential allocation strategies between leaves and roots on growth and how cellular processes such as photosynthesis and respiration alter this. However, any strategy for increasing productivity must balance the allocation of carbon to the growth of source and sink tissues.
A new paper published in in silico Plants explores the effects of varying the source-sink allocation ratio on plant growth by analyzing the sensitivity of a simple carbon allocation model for vegetative and reproductive growth.
Bethany Holland of the University of Sheffield and her coauthors found that when maintenance costs are equal, leaves are much more beneficial for growth than roots in a framework which considers roots as carbon sinks. However, when leaves cost more to maintain than roots, the benefits of growing leaves and roots become more equal. This allows for a range of root:shoot ratios to produce the same final plant size. Interestingly, when leaf respiration is higher than root respiration, reallocating carbon away from leaves and toward the roots can improve plant growth.
Holland, B. L., Monk, N. A. M., Clayton, R. H., & Osborne, C. P. (2019). A theoretical analysis of how plant growth is limited by carbon allocation strategies and respiration. In Silico Plants, 1(1). https://doi.org/10.1093/insilicoplants/diz004