Gradual responses of grapevine yield components and carbon status to nitrogen supply

Abstract

Aim: Nitrogen is a major element conditioning grapevine growth, yield and aromatic profiles of berries and wines. Different tools can be used in order to detect differences in N status of the plant, including direct measurements of soil, plant nitrogen status (eg. petiole; must), or indirect observations of plant nutritional status such as leaf transmittance or reflectance (eg. SPAD; NDVI). However, the relationships between these indicators of nitrogen status and the overall plant functioning over vintages remain poorly known. The present study aimed at quantifying key vegetative and reproductive responses to plant nitrogen status over two successive seasons under different nitrogen supply levels.Methods and results: Potted plants of Sauvignon Blanc grafted onto SO4 were grown outdoors in 2017 and 2018 with no water limitation. Four mineral nitrogen fertilization levels (equivalent to 0 kg of N ha-1 or 0U, 20U, 40U, 80U) and one organic nitrogen fertilization level (40U) were imposed in 2017. These treatments were doubled in 2018 to increase the degree of nitrogen supply and consequently, the range of observed effects on plant growth and yield. Plant nitrogen status (SPAD) was monitored weekly during both growing cycles. Yield components were determined over the two seasons. Lastly, plant carbon status was addressed through dynamic measurement of plant development and photosynthesis, and destructive measurement of dry matter accumulation and carbon storage in annual and perennial organs at flowering, veraison and harvest.The SPAD values progressively decreased under lower N supply (0N) during the first year (from 31 to 16) and they were more than halved between the maximum and the minimum N treatments straight after budburst in year two (40 for 160N and 19 for 0N). Then, the differences in SPAD values among treatments were maintained up to harvest (2018). The gradient of N status resulted in a gradient of berry numbers per inflorescence (from 180 to 34 berries/inflorescence for 80N and 0N, respectively in 2018) and of individual berry dry matter at harvest (from 0.13 to 0.41 g for 160N and 0N, respectively in 2018). Quantitative relationships between N status and the relative reductions (% of reduction per %SPAD decrease) in terms of C gain (leaf area, photosynthesis), C growth (shoot, berry, trunk and root dry matter) and C storage (trunk and root) were fitted at flowering, veraison and harvest. The reduction in C gain under lower N supply was mainly related to the decrease in total leaf area before flowering (-1.64%). Although the photosynthesis rate tended to decrease under N deficiency over the season, it only poorly contributed to the reduction in C gain. The whole plant C growth was inhibited when N status decreased (-1.13% at harvest), due to the inhibition of shoot dry matter before veraison (-1.81%) and to a lower extent, to the lower dry matter in berries (-0.80%), trunks (-0.42%) and roots (-0.84%) at harvest. Part of the reduction in root dry matter was related to the lower starch reserves (-0.31%) at harvest. Interestingly, starch reserves tended to be higher under organic N supply than mineral N supply.Conclusion: The present results provided a general framework of carbon gain and use over time (within and between seasons) as impacted by N supply levels and form. Such a framework will be useful when building a model of the pluri-annual dynamics of carbon balance related to yield elaboration in grapevines.

Understanding and managing nitrogen nutrition in grapevine: a review

“…Examples of hand-held chlorophyll meters used for diagnosis purposes are the N-Tester (Yara, Oslo, Norway), SPAD 502 (Konica Minolta, Nieuwegein, Netherlands) and Dualex (Force A, Orsay, France). Chlorophyll meter readings reflect the intensity of the green colour of the foliage, and are thus wellcorrelated with leaf chlorophyll and N concentrations (Spring and Zufferey, 2000;Cerovic et al, 2015;Aranguren et al, 2018;Vrignon-Brenas et al, 2019). Therefore, chlorophyll content can be used to diagnose plant N status, making such readings effective tools for N monitoring.…”

Cover Crop and Pruning Residue Management to Reduce Nitrogen Mineral Fertilization in Mediterranean Vineyards

“…Subsequently, vines replenish their N reserves mostly post-harvest, actively absorbing N from the soil [36,48,49]. This last intense root activity preceding vine dormancy [50] leads to the soil N reserve depletion observed in winter. In the case of temporary winter cover cropping, as in our case, this intense N absorption is a little or not influenced by cover crop competition.…”

“…Bud fertility and grape yield increased when cover crop and vine pruning residue burial were combined (CC + PR), regardless of the adoption of chemical fertilization. However, the combination of urea fertilization with the spring burial of cover crop plus vine pruning residues (CC + PR) and the parallel high N amount detected in the aerial biomass resulted in a further increase in vine shoot vigor that may not be necessarily favorable to a balanced relationship between vegetative and productive grapevine activities [20,34,50].…”

“…Both N deficiency and N excess affect grapevine performance, including must properties ( [50] and references therein). Vegetative growth, photosynthetic activity, and N content in berries (and related wine fermentability and quality) are inversely correlated with N deficiency [52].…”

Biochemical and Proteomic Changes in the Roots of M4 Grapevine Rootstock in Response to Nitrate Availability

“…In this view, the tight relationship between the rootstock/scion combination and N availability is emerging [ 7 , 8 , 9 ]. The N status of grapevine, like other perennial crops, depends on many factors, such as the acquisition of N from the soil, its distribution among annual organs and its reallocation from annual growth parts into both fruits and woody tissues [ 10 , 11 , 12 , 13 , 14 ]. In this context, the N content in grape berries, lost from the vineyard each year, has been estimated to be 2–3 kg of N per ton of fruit matter [ 2 ].…”