Nitrogen (N) is a major fertilizer for vine and an important nutrient for yeast in the must. Identification of spatial variation patterns will be determinant for technicians to understand the effects of soil, climate and topography in order to establish decision rules to manage nitrogen inputs. Such decision rules would be useful to winegrowers to succeed in homogenizing the N status within a plot. The determination of variation patterns can indeed lead to the implementation of inputs management such as differential winter pruning or fertilizer rate. Recently, a vehicule-mounted optical sensor, Multiplex®, was introduced to estimate the nitrogen status of grapevine leaves. The measuring principle of this proximal sensor is based on chlorophyll fluorescence screening. The aim of the present study was to correlate nitrogen contents to the Nitrogen Balance Index (NBI) measured with the Multiplex on leaves.

Multiplex measurements on leaves were recorded for each main stage during the growing seasons 2010 and 2011 on Plumecoq (Chouilly, France), the experimental vineyard of the Champagne Committee. The experimental plot was composed of three grape varieties (Chardonnay, Pinot noir and Meunier) planted in a Latin square pattern to minimize soil and microclimate effects. The Multiplex was mounted on a small caterpillar and connected to a DGPS. It provided NBI with high resolution. After two years of measurement, reliable correlations were obtained between the NBI in leaves, Nitrogen in the must, wood pruning and leaves biomass.