Cactus pear (Opuntia ficus-indica L. Miller) is a CAM plant with an extraordinary capacity to store water in its succulent stems (cladodes). However, the daily variations of cladode thickness is unknown. Studying cladode thickness fluctuations may be useful for the early prediction of plant dehydration stress. The objective of this study was to determine if age, water availability and temperature influence diel cladode shrinkage and enlargement dynamics in cactus pear. The experiment was conducted in a greenhouse from April to July 2014, using cactus pear plants, equally split into irrigated and unirrigated treatments, and unrooted cladodes detached from mother plants.
To date, the effect of drought stress on the physiological mechanisms leading to cladode growth in cactus pear has not been reported in the literature. The opportunity to study cladode enlargement and shrinkage and the relationship between cladode growth and environmental parameters is crucial to better understand the functioning of succulents. Diel fluctuations of cladode thickness may also represent an early indicator of the occurrence of dehydration stress. Eventually, acquisition of continuous measurements over a period of 24 h will allow the development of models useful for preventing the negative effects of drought on plant growth by real-time automated environmental control.