Combining pluriannual dynamics and Bayesian approach to analyze grapevine growth and storage as a function of nitrogen supply.

The effect of nitrogen (N) nutrition on grapevine carbon (C) production, allocation and storage has been well-studied at the annual scale, but poorly addressed at a pluriannual timestep. Also, the quantification of N supply on C functioning raises interesting questions from a statistics-based methodological point of view. The aim of this study was to quantify, in an integrated conceptual framework, the pluriannual effect of N nutrition on potted Sauvignon blanc grapevine growth and storage over two consecutive years. The consequences of using destructive measurements to address this issue was investigated using a hierarchical Bayesian model.The segmentation of leaf area dynamics with a period of growth followed by a plateau showed that leaf area growth rate and the duration of growth were both positively impacted by the chlorophyll content of the leaves measured by SPAD index. However, the initial carbohydrates had the opposite effect on leaf growth, raising a distortion in the estimation of initial reserves. The carbon production per unit of global radiation was mostly linked to the leaf area dynamics. The allocation of dry matter was highly reliant on the phenological stage, but it was poorly impacted by the total dry matter. The present study highlighted the importance of using appropriate statistical methods to overcome uncertainties due to destructive measurements. The genericity of the statistical approach presented may encourage their implementation in other agronomy studies. Based on our results, a simple ecophysiological conceptual framework of grapevine pluriannual growth under various nitrogen supplies was built. This latter provides a relevant basis for a future model of grapevine C and N balances and responses to N fertilization.