GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 GiESCO 2019 9 Sensitivity of vis‐nir spectral indices to detect nitrogen deficiency and canopy function in cv. Barbera (Vitis vinifera L.) Grapevines

Sensitivity of vis‐nir spectral indices to detect nitrogen deficiency and canopy function in cv. Barbera (Vitis vinifera L.) Grapevines

Abstract

Context and purpose of the study ‐ Precision nutrient management in viticulture can be addressed on the basis of a spatial characterization of within‐vineyard vine nutritional status derived from proximal or remote spectral observations. However, a key challenge is the discrimination between mineral deficiencies and water stress related issues, often coexisting under low vigor conditions. In addition several mineral disorders are associated to a decrease in chlorophyll concentration in leaves resulting in a wide array of symptoms classified as chlorosis. Despite clearly associated to their origin, visible symptoms appear too late for supporting an efficient mineral management; thus, non‐destructive early detection of either asymptomatic excess or deficient status become a challenging task of precision viticulture. This work evaluates the Vis‐NIR reflectance spectra and the sensitivity of the derived‐spectral indices to detect nitrogen deficiency in grapevines.

Material and methods ‐ Well N‐fertilized vs. unfertilized vines were compared over two seasons (2016 and 2017) on Vitis vinifera L. cv. Barbera potted vines. For each treatment, 24 leaves from eight representative vines were tagged in order to collect, at different phenological stages, contact Vis‐NIR spectra and perform physiological measurements. The performance of several spectral vegetation indices sensitive to different biophysical (i.e. chlorophyll and carotenoids content, leaf area index) and physiological parameters (light use efficiency) was measured by means of a sensitivity (signal to noise ratio) analysis. Leaf greenness index was monitored with a handheld chlorophyll meter SPAD 502 whilst single‐leaf gas exchanges were assessed by using a handheld analyzer. Multispectral analysis was associated to a rigorous ground‐truthing as it concerns shoot growth, yield, fruit composition and pruning weight.

Results – In both years the differential fertilization increased leaf N concentration of N+ vines at veraison. Vine performance varied according to plant vigor and nutritional status. N+ increased canopy growth, vine productivity, and bunch compactness whilst N0 enhanced the proportion of shot berries and reduced titratable acidity and malate in juice. N deficiency resulted in lower SPAD readings and assimilation rates as compared to well N‐fertilized vines. N0 vs N+ contact Vis‐NIR spectra differed in Green and Red‐edge regions with faster responses on basal leaves. Data were associated to a different sensitivity of Vis‐NIR spectral indices specially when based on the Red‐edge bands showing higher efficiency in detecting leaf N concentration since early stages of canopy growth.

DOI:

Publication date: June 22, 2020

Issue: GiESCO 2019

Type: Article

Authors

Matteo GATTI (1,2), Alessandra GARAVANI (1,2), Alberto VERCESI (1), Cecilia SQUERI (1), Michele CROCI (1,2), Ferdinando CALEGARI (2), Massimo VINCINI (2), Stefano PONI (1,2)

(1) DIPROVES Università Cattolica del Sacro Cuore, Via E. Parmense 84, I-29122 Piacenza, Italy
(2) CRAST Università Cattolica del Sacro Cuore, Via E. Parmense 84, I-29122 Piacenza, Italy

Contact the author

Keywords

Mineral nutrition, Visual symptoms, Leaf age, Assimilation, Yield components, Phenotyping

Tags

GiESCO 2019 | IVES Conference Series

Citation

Related articles…

Under-vine management effects on grapevine production, soil properties and plant communities in South Australia

Under-vine (UV) management has traditionally consisted of synthetic herbicide use to limit competition between weeds and grapevines. With growing global interest towards non-synthetic chemical use, this study aimed to capture the effects of alternative UV management at two commercial Shiraz vineyards in South Australia, where the sole management variables were UV management since 2016. In adjacent treatment blocks, cultivation (CU) was compared to spontaneous vegetation (SV) in McLaren Vale (MV), and herbicide was compared to SV in Eden Valley (EV). Soil water infiltration rates were slower and grapevine stem water potential was lower in CU compared to SV in MV, with the latter having a plant community dominated by soursob (Oxalis pes-caprae) during winter; while in EV, there was little separation between the treatments. Yields were affected at both sites, with SV being higher in MV and HE being higher in EV. In MV, the only effect on grape must was a lower 13C:12C isotope ratio in CU, indicating greater grapevine water stress. In the grape must at EV, SV had higher total soluble solids, total phenolics, anthocyanins, and yeast available nitrogen; and lower pH and titratable acidity. Pruning weights were not affected by the treatments in MV, while they were higher in HE at EV. Assessments revealed that the differing soil types at the two sites were likely the main determinants of the opposing production outcomes associated with UV management. In the silty loam soil of MV, the higher yields in SV were likely due to more plant-available water, as a potential result of the continuous soil bio-pores formed by winter UV vegetation. Conversely, in the loamy sand soils of EV with a lower cation exchange capacity, the lower yields and pruning weights in SV suggest the UV vegetation competed significantly with the grapevines for available water and nutrients.

Long-term sensorial and compositional effects of copper fining on the wine containing ‘reductive’ and ‘tropical’ volatile sulfur compounds

The aim of this study was to investigate long-term sensorial and compositional effects of copper addition to the white wine naturally high in varietal thiol levels, with added volatile sulfur compounds

Terroir valorization strategies in a reformed denomination area: the Prosecco case study

Aims: This work summarizes some of the upmost recent studies and valorization strategies concerning the Prosecco wine production area. After the geographical denomination Prosecco (DO) was strongly reformed in 2009, the newborn DOCG (controlled and guaranteed DO) and DOC (controlled DO) areas have required different and specific strategies to promote and protect the value of their production.

Sustainable management of grapevine trunk diseases

Grapevine trunk diseases (GTD) occur wherever grapes are grown and are considered the main biotic factor reducing yields and shortening vineyards’ lifespan. Currently, no product is available to eradicate GTD once grapevines are infected. Therefore, prophylactic strategies based on pruning wound protection and ‘remedial surgery’, the only eradication method based on the elimination of infected wood and renewal of the vine by means of new canes or suckers, are the only effective strategies available. The Canadian grape and wine industry focusses on a sustainable production and thus, looking for alternatives to chemicals for disease management is a top priority.

Prefermentative CO2 saturation of grape must to obtaining white wines with low SO2 content

The objective this work has been study the possibility of partially or completely replacing sulphur in the winemaking of white wines through the use of the prefermentative saturation of musts with CO2.