Non-invasive pressure probes magnetically clamped to leaves to monitor the water status of wheat

Being able to monitor the hydration status of a plant would be useful to breeding programs and to providing insight into adaptation to water-limited environments, but most current methods are destructive or laborious. We evaluated novel non-invasive pressure probes (commercial name: ZIM-probe) for their potential in monitoring the water status of wheat (Triticum aestivum L.) leaves. The probes consist of miniature pressure sensors that clamp to the leaves via magnets and detect relative changes in hydration status. Probes were clamped to leaves of six individual plants of the cultivar Wyalkatchem at the stem elongation stage and compared against traditional plant water relations measurements. Output from the probes, called patch-pressure (P (p) ), correlated well with leaf water potential and transpiration of individual plants. Variation between plants in the original clamp pressure exerted by the magnets and leaf individual properties led to variations in the amplitude of the diurnal P (p) profiles, but not in the kinetics of the curves where P (p) responded simultaneously in all plants to changes in the ambient environment (light and temperature). Drying and rewatering cycles and analysis of the curve kinetics identified several methods that can be used to test comparisons of water status monitoring of wheat genotypes under water deficit.