Dissertation
EFFECT OF FOLIAR NITROGEN APPLICATION ON GRAPEVINE GROWTH, YIELD, NUTRIENT STATUS, AND FRUIT COMPOSITION
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2025
DOI:
https://doi.org/10.7273/000007356
Abstract
This study evaluated the effect of foliar nitrogen application in grapevines through three complementary experiments. A field trial with Syrah assessed the impact of foliar nitrogen on vine nutrient status and yeast assimilable nitrogen (YAN), in comparison to varying soil nitrogen rates. A pot experiment with Cabernet Sauvignon examined the effects of soil-applied nitrogen at bloom and foliar-applied nitrogen at veraison on fruit phenolic composition, with nitrogen partitioning tracked during the second year. A stable isotope (15N) labeling experiment with pot-grown Riesling determined the fate of nitrogen applied to leaves and fruit.
Across all experiments, foliar nitrogen application at veraison consistently increased YAN more effectively than soil-applied nitrogen at bloom, without affecting yield or vegetative growth. Nitrogen-deprived vines responded more strongly to foliar application, showing marked increases in YAN in the year of application. The following season, these N-deprived vines exhibited larger canopies and higher tissue nitrogen concentrations, supporting early growth. When nitrogen was applied to fruit, over 80% remained in the fruit, while leaf-applied nitrogen was largely translocated to and stored in perennial organs. Foliar nitrogen slightly reduced anthocyanin and tannin concentrations in grape skins, but not in seeds.
Foliar nitrogen appears to be a valuable tool for vineyard management, particularly as a supplement to low soil-applied nitrogen at bloom. This strategy has the potential to reduce totalnitrogen inputs while improving vine nitrogen status and boosting fruit YAN, contributing to more sustainable viticulture. The effectiveness of foliar sprays was strongly influenced by the vine’s nitrogen status, suggesting this approach may be especially beneficial in vineyards with variable vigor. Future research should investigate the impact of foliar nitrogen on wine composition, particularly whether reduced phenolic content affects sensory properties, and explore how environmental factors during the year, and application timing during ripening influence outcomes.
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Details
- Title
- EFFECT OF FOLIAR NITROGEN APPLICATION ON GRAPEVINE GROWTH, YIELD, NUTRIENT STATUS, AND FRUIT COMPOSITION
- Creators
- Pierre Davadant
- Contributors
- Markus Keller (Chair)Amit Dhingra (Committee Member)James Harbertson (Committee Member)Lee Kalcsits (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Horticulture
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 317
- Identifiers
- 99901220326801842
- Language
- English
- Resource Type
- Dissertation