Nitrogen isotope ratio (δ15N): a nearly unexplored indicator that provides useful information in viticulture

The study of the natural abundance of nitrogen-stable isotopes is an aspect of viticulture research that has received limited attention. While stable isotopes of carbon, oxygen and hydrogen have received significant attention, nitrogen isotope ratio (S15N) 15 N) remains a less studied yet potentially informative parameter. This paper explores the implications of S15N 15 N measurements in grapevines, shedding light on its utility as an indicator for nitrogen sources, plant water status, and within-field variability. The study examines the influence of nitrogen sources, dose, and sampling organs on S15N 15 N values, revealing distinct trends in petioles, berries, and seeds. Organic fertilisers led to higher S15N 15 N values compared to inorganic sources, while increasing nitrogen doses exhibited a much weaker effect on S15N. 15 N. Moreover, S15N 15 N values vary spatially within vineyards, associating with its topography and potential soil composition, soil management and water availability. Our results highlight the importance of considering S15N 15 N in viticulture, suggesting its integration with S13C 13 C for comprehensive insights into nitrogen cycling and soil management practices. The findings advocate for further research to harness the full potential of 15 N as a valuable tool in viticultural studies.