The response of sugarcane canopy development to water stress

Water stress is a common occurrence in dryland crop production, including sugarcane production. A good understanding of how crops respond to water stress is a prerequisite for choosing the best cultivar and management practices to optimally exploit natural resources. One aspect of sugarcane growth and development that has not been investigated thoroughly is how canopy development is affected by water stress. The aim of this study was to gain a better understanding of the effect of water stress on various canopy development processes and interception of radiation. An experiment was conducted on a rainshelter facility at Mount Edgecombe, South Africa. The crop was planted and grown to four months age under optimal conditions. Subsequently, water was withheld from one half of the experiment for a period of 42 days. Soil water content for the stressed plots decreased from a field capacity of 26% at the start of drying to 15% on day 15 and a permanent wilting point of 10.5% at approximately day 40. Shoot and leaf development and interception of radiation were measured and related to soil water content, leaf water potential and stomatal conductance. Leaf senescence responded the most to drying (220% increase in leaf senescence rate as RSWC dropped from 0.7 to 0.3), followed by leaf appearance (96% decrease) and shoot senescence (113% increase for N22 and no response for NCo376). Cultivar NCo376 was able to maintain canopy development processes longer under conditions of increasing water stress than N22, at least initially. This was evidenced by lower rates of shoot senescence and leaf senescence (initially). NCo376 also maintained high stomatal conductance and leaf water potentials for longer during the drying process and at lower soil water content values than N22. The information obtained in this study should assist in simulating canopy responses in a more mechanistic way. (c) 2005 Elsevier B.V. All rights reserved.