Resource capture and use in intercropping: solar radiation

Abstract

A more-efficient use of resources is a major reason advanced for the advantage of intercropping over alternative cropping systems. This paper reviews the interception and utilization of solar radiation in intercropping systems. To achieve this, a framework is presented on radiation interception and use in sole crops and elements of this framework are subsequently extended to intercropping systems. Improved productivity per unit incident radiation could be achieved by the adoption of an intercropping system that either increases the interception of solar radiation and/or has greater radiation-use efficiency. Minimizing the proportion of radiant energy reaching the ground is a simple means of promoting efficient utilization of incident solar radiation. Examples are discussed where advantages acrued from intercropping short- and long-duration species due to enhanced radiation capture over time. Frequent confounding with plant density effects has meant that the evidence for intercropping to enhance radiation capture in space is equivocal. Examples are also presented, demonstrating improved utilization of radiant energy, once intercepted, either by more-efficient production of biomass or increased proportion of biomass partitioned to yield. The potential variety and complexity of intercropping systems, means that recommendations on how to optimise radiation capture and use in intercrops could not readily be determined. Attempts to quantify and predict intercrop performance are examined and dynamic simulation models considered to offer a means by which intercrop performance could be optimised.