Nitrogen isotope ratio (δ15N) as a tool to trace the major nitrogen source in vineyards

Detailed geological analyses of a plot belonging to the « AOC Gaillac » area have been carried out. This plot belongs to the left bank terraces of the Tarn River which coinciding with one of the three main terroirs of the AOC area. It is localised on the rissian-aged (≈ 200 000 yrs B.P.)

Each grapevine variety has a specific water use regulation response under drought, and it is still unclear whether this regulation results from innate genotypic behavior (iso- and anisohydric), or is a response to environmental factors, namely recurrent water stress priming effects. In the present work, we explored the influence of the field-grown genotypes’ drought memory in the drought-response phenotype of their vegetative progenies, in Trincadeira (isohydric) and Castelão (anisohydric) varieties under a drought event followed by recovery in a glasshouse. Cuttings from both cultivars subjected to full irrigation (FI) and non-irrigation (NI) treatments for 5 consecutive years were used.

Context and purpose of the study. Climate change is already threatening California vineyards, as they grapple with increasing extreme weather events and drier growing seasons.

I performed my PhD in grapevine physiology under the supervision of Dr. H. Medrano, standing in the vineyards from pre-dawn to sunrise during many hot, wet and sunny days with my colleagues J.M.E. and J.B. I also spent many days and nights facing ticks year-round working in Mediterranean macchias with J.Gu. and M.M. Later I was able to supervise PhD students on grapevines – like A.P. and M.T. – and on Mediterranean vegetation – like J.Gal. With the incorporation to the group of M.R.-C. ‘the puzzle’ was completed and, combining the aforementioned studies, we could conclude (more than 20 years ago) things like: (1) stomatal conductance is the best proxy for ‘water stress’ in studies on photosynthesis; (2) steady-state chlorophyll fluorescence retrieves photosynthesis under saturating light; (3) photoinhibition is not a major photosynthetic limitation under water stress; (4) mesophyll conductance instead is; and (5) mesophyll conductance is a major driver of leaf water use efficiency.

En vue d’une production économique de qualités des raisins optimales une connaissance des informations les plus différentes est importante. Les nouvelles technologies, telles qu’un SIG permettent de réunir les informations sur le terrain, la nature du sol, le danger d’érosion, le climat, la végétation, l’hydrographie, l’apparition de nuisible et de maladies, etc. Sur la base de cartes topographiques un SIG permet une vaste analyse, une appréciation des rapports complexes ainsi qu’une représentation cartographique. Sur la base de modélisations en trois dimensions du terrain avec le SIG, les ensembles de données saisies ainsi que leur classification au niveau local peuvent être utilisés dans la production de zonages régionaux.