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Advanced Plant-based, Internet-sensor Technology Increases Water Efficiency In Agriculture: A Proactive Response To Water Shortages And Climate Change

Congress: 2015
Author(s): Simon Rueger (Hennigsdorf, Germany)


Keyword(s): Sub-theme 10: Management of water resources,
AbstractIncreasing worldwide shortages of fresh water, the continuous increase in water consumption by agriculture due to climate changes, the increased demand for crop production to feed the world's increasing population and the progressive salinization of arable land provoked by irrigation are global concerns. The introduction of drip irrigation and other more sophisticated irrigation technologies have enabled a reduction of water consumption in agriculture with less soil salinization. A further step towards more efficient water use is expected from using new sensor technologies for monitoring water status of crops and scheduling the water supply accordingly. Optimum irrigation scheduling implies determining precisely both the timing of irrigation and the quantity of water to apply. Irrigation scheduling decisions are frequently based on the determination of soil moisture content or soil moisture tension. Local measurements of soil water status have, however, the drawback that they do not give direct information about the water needs of a plant. Further problems are the heterogeneity of water holding capacity of the soil and the large variations in plant /crop responses to water deficits. Therefore, plant-based sensing has many potential advantages over soil-based sensing. There are currently numerous techniques available for measuring water status in plants such as psychrometers, sap flow techniques, and stem dendrometers as well as infrared thermometers for measuring canopy and/or leaf temperature. Furthermore, leaf or stem water potential, measured with the pressure chamber at midday, have been proposed as standard methodologies to determine the plant water status for irrigation scheduling of fruit trees (Jones, 2004). Even though these techniques are very useful for studies of water relations of plants, practical difficulties of implementation have prevented the development of successful, user-friendly systems for routine field applications so far. Part of the classical techniques to measure water status of plant organs are very sophisticated, laborious, time-consuming and/or not robust under field conditions. They are very often unsuitable for monitoring fast occurring reactions in dynamically changing environments and difficult to conduct continuously due to their destructive character. Furthermore, many of these techniques are prone to large variations due to environmental factors and the person operating the equipment. The leaf patch clamp pressure probe (Yara ZIM-probe) has been developed to overcome these shortcomings of available technologies and thus to allow efficient irrigation control in commercial orchards (Zimmermann et al. 2008, Westhoff et al. 2009). The Yara ZIM probe technology measures the pressure transfer function through a patch of an intact leaf. The clamp pressure is generated by small magnets. High turgor pressure prevents pressure transfer through the leaf and, in turn, the output patch pressure measured by the probe is small. At very low turgor pressure the applied pressure is easily transferred to the pressure sensor and the patch pressure assumes a maximum value. Turgor pressure and patch pressure are inversely correlated with each other. The non-invasive Yara ZIM-probe can be applied to all leafy plant species and is characterised by high precision, operating convenience, automation suitability, robustness under field conditions and minimum costs. Data are sent wireless by telemetric units to a radio-controller which is linked to an Internet server via a mobile phone network. The plant signals are stored on a data bank and can be downloaded by smartphones, tablets or laptops. Thus, drought and irrigation effects on the plants are available for the grower in real time and the grower can make adequate irrigation decisions on an objective basis when they are needed. If desired, probes for ambient temperature, relative humidity and light irradiation close to the plant as well as soil temperature and moisture can also be connect to the transmitters thus giving a complete general view about the microclimate and the soil properties. However, measurement of turgor pressure is entirely sufficient for setting of irrigation thresholds, because the magnitude of turgor pressure is the result of water and solute uptake via the roots and transpirational water loss. Turgor pressure could not be measured non-invasively up to the present, but is one of the crucial parameters which dictate growth and productivity because many biophysical processes are turgor pressure dependent. For efficient growth and fruit production a turgor pressure of more than 100 -- 300 kPa is required over the entire vegetation period. In the last years the Yara ZIM-probe was tested successfully under laboratory, greenhouse and field conditions in many European countries, Australia, Africa, South America, Asia and the USA. Concomitant studies with other technologies currently used have shown the great potential of this novel water stress monitoring instrument in agricultural water management and reforestation. For some fruit trees water consumption could be reduced by up to 40% without adverse side effects on productivity, for some other crop and trees productivity could by increased by ca. 30% by optimisation of the irrigation regime. Adoption of smarter irrigation systems based on technologies such as Yara ZIM-probes are urgently required to increase agricultural production worldwide to feed the growing population under changing and variable climate. Acknowledgement The work presented here was supported by a grant of the Europäischer Fonds für regionale Entwicklung (EFRE 80145650; State Brandenburg) to ZIM Plant Technology GmbH. Jones, H.G. (2004) Irrigation scheduling: advantages and pitfalls of plant based methods. Journal of Experimental Botany 55, 2427–2436. Westhoff, M., Reuss, R., Zimmermann, D., Netzer, Y., Gessner, A., Geßner, P., Zimmermann, G., Wegner, L.H., Bamberg, E., Schwartz, A., Zimmermann, U.(2009) A non-invasive probe for online-monitoring of turgor pressure changes under field conditions. Plant Biology 11, 701–712. Zimmermann, D., Reuss, R., Westhoff, M., Geßner, P., Bauer, W., Bamberg, E., Bentrup, F.-W., Zimmermann, U. (2008) A novel, non-invasive, online-monitoring, versatile and easy plant-based probe for measuring leaf water status. Journal of Experimental Botany 59, 3157–3167.
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