Effects of Temperature and Atmospheric Carbon Dioxide on Source-Sink Relationsin the Context of Climate Change

This chapter concentrates on shoot-root relations to illustrate the effects of temperature and CO₂ concentration on carbon partitioning between plant organs. It explains how the major variables of climate change—temperature and atmospheric CO₂ concentration—affect source-sink relations, it is necessary to know the mechanisms by which source-sink and shoot-root balance are normally controlled, and the mechanisms by which temperature and CO₂ affect this balance. There are two cogent reasons for believing that plants respond to a change of temperature with a combination of short- and long-term effects. The number of lateral roots formed per soybean plant is unaffected by CO₂ concentration. Data from other species are consistent with a model whereby temperature directly affects metabolic rate of sinks, which in its turn results in changing size of sugar pools, and these than alter rates of import into sinks. The core of the model is the phloem transport system linking source and sink.