title: Totomatix: a novel automatic set-up to control diurnal, diel and long-term plant nitrate nutrition.
abstract: BACKGROUND
  Stand-alone nutritional set-ups are useful tools to grow plants at defined nutrient availabilities and to measure nutrient uptake rates continuously, in particular that for nitrate. Their use is essential when the measurements are meant to cover long time periods. These complex systems have, however, important drawbacks, including poor long-term reliability and low precision at high nitrate concentration. This explains why the information dealing with diel dynamics of nitrate uptake rate is scarce and concerns mainly young plants grown at low nitrate concentration.
  
  
  METHODS
  The novel system detailed in this paper has been developed to allow versatile use in growth rooms, greenhouses or open fields at nitrate concentrations ranging from a few micro- to several millimoles per litres. The system controls, at set frequencies, the solution nitrate concentration, pH and volumes. Nitrate concentration is measured by spectral deconvolution of UV spectra. The main advantages of the set-up are its low maintenance (weekly basis), an ability to diagnose interference or erroneous analyses and high precision of nitrate concentration measurements (0·025 % at 3 mm). The paper details the precision of diurnal nitrate uptake rate measurements, which reveals sensitivity to solution volume at low nitrate concentration, whereas at high concentration, it is mostly sensitive to the precision of volume estimates.
  
  
  CONCLUSIONS
  This novel set-up allows us to measure and characterize the dynamics of plant nitrate nutrition at high temporal resolution (minutes to hours) over long-term experiments (up to 1 year). It is reliable and also offers a novel method to regulate up to seven N treatments by adjusting the daily uptake of test plants relative to controls, in variable environments such as open fields and glasshouses.
authors: INRA, UR 1115 Plantes et Systèmes de culture Horticoles, F-84000, Avignon, France. stephane.adamowicz@avignon.inra.fr
authors: Stéphane
authors: S
authors: Adamowicz
authors: Jacques
authors: J
authors: Le Bot
authors: Ruth
authors: R
authors: Huanosto Magaña
authors: José
authors: J
authors: Fabre
mesh_terms: D001331:Automation; D001692:Biological Transport; D002940:Circadian Rhythm; D018527:Hydroponics / Q000379:methods*; D009566:Nitrates / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism*
chemical_list: D009566:Nitrates