Terroir 2020 banner
IVES 9 IVES Conference Series 9 Plant nitrogen assimilation and partitioning as a function of crop load

Plant nitrogen assimilation and partitioning as a function of crop load

Abstract

Aims: The optimization of nitrogen use efficiency (NUE, i.e. uptake, assimilation and partitioning) is a solution towards the sustainable production of premium wines, while reducing fertilization and environmental impact. The influence of crop load on the accumulation of N compounds in fruits is still poorly understood. The present study assesses the impacts of bunch thinning on NUE and the consequences on the free amino N (FAN) profile in fruits.

Methods and Results: A large crop load gradient was imposed by bunch thinning (0.5 to 2.5 kg m–2) in a homogeneous plot of 225 vines. Isotope-labelled foliar urea (10 atom % 15N) was applied on the canopy of the fertilized treatment at veraison. The plants were excavated at four phenological stages over the two seasons (bud burst, flowering, veraison and harvest) and were individually split into five plant parts (roots, trunk, canopy, pomace and must). Total nitrogen and its stable isotope composition were determined in each part, with the aim of monitoring NUE as a function of crop load and fertilization.

The N concentration in fruits either at veraison or at harvest was not related to crop load variation. N concentration was maintained in the must to the detriment of N content in the roots. The root dry weight was 15 % lower and the root N quantity 27 % lower under high yielding conditions (HYC, compared to low yielding conditions LYC). The fertilizer N uptake was 41 % higher under HYC than under LYC. Consequently, urea supply had a positive impact on the yeast assimilable N concentration in the must (+55 mg L-1) only under HYC. However, the must FAN profile was significantly affected by the crop load, suggesting a possible modification of the aroma potential, independently from fertilization and grape maturation.

Conclusion: 

Using a 15N-labeling method, we demonstrate that grapevine has a strong ability to regulate nitrogen uptake and reserve mobilization to maintain a constant fruit N concentration despite changes in crop load. Foliar-urea fertilization at veraison was more efficient under HYC and helped to fulfill grape N demand, while limiting the mobilization of N reserves. However, the crop load affected the must FAN profile, inducing a possible modification of the fruit aroma. 

Significance and Impact of the Study: These findings highlight the great capacity of plants to adapt their N metabolism to constraints, e.g. bunch thinning in this case. These results are important to improve perennial fruit crop production through higher fertilization efficiency and lower environmental impact. Without fertilization, plant nutrition can be enhanced through the optimization of agricultural practices. The root activity appears to be key for understanding the mechanisms that balance N nutrition in plants

DOI:

Publication date: March 25, 2021

Issue: Terroir 2020

Type : Video

Authors

Thibaut Verdenal1, Vivian Zufferey1, Agnes Dienes-Nagy1, Olivier Viret2, Cornelis van Leeuwen3, Jorge Spangenberg4, Jean-Laurent Spring1

1Agroscope Institute, Av. Rochettaz 21, CH-1009 Pully, Switzerland
2Direction générale de l’agriculture, de la viticulture et des affaires vétérinaires (DGAV), Av. de Marcelin 29, CH-1110 Morges, Switzerland
3EGFV, Bordeaux Sciences Agro, INRAE, Univ. Bordeaux, ISVV, F-33882 Villenave d’Ornon, France
4Institute of Earth Surface Dynamics, University of Lausanne, CH-1015 Lausanne, Switzerland

Contact the author

Keywords

Nitrogen partitioning, crop load, isotope labelling, amino acids, vines

Tags

IVES Conference Series | Terroir 2020

Citation

Related articles…

Physiological and growth reaction of Shiraz/101-14 Mgt to row orientation and soil water status

Advanced knowledge on grapevine row orientation is required to improve establishment, management and outcomes of vineyards on terroirs with different environmental conditions (climate, soil, topography) and in view of a future change to more extreme climatic conditions. The purpose of this study was to determine the combined effect of row orientation, plant water status and ripeness level on the physiological and viticultural reaction of Shiraz/101-14 Mgt.

Effects of mechanical leafing and deficit irrigation on Cabernet Sauvignon grown in warm climate of California

San Joaquin Valley accounts for 40% of wine grape acreage and produces 70% of wine grape in California. Fruit quality is one of most important factors which impact the economical sustainability of farming wine grapes in this region. Due to the recent drought and expected labor cost increase, the wine industry is thrilled to understand how to improve fruit quality while maintaining the yield with less water and labor input. The present study aims to study the interactive effects of mechanical leafing and deficit irrigation on yield and berry compositions of Cabernet Sauvignon grown in warm climate of California.

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Application of a fluorescence-based method to evaluate the ripening process and quality of Pinot Blanc grape

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Different yield regulation strategies in semi-minimal-pruned hedge (SMPH) and impact on bunch architecture

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.