Frequent applications of copper (Cu)-based fungicides on vines causes the accumulation of this metal in vineyard soils, which can cause toxicity in young vines. However, liming may reduce these toxic effects. The present study aimed to evaluate the effects of Cu toxicity on the root anatomy of young vines and the alleviation of Cu toxicity by lime applications to contaminated sandy soil. The treatments consisted of the addition of lime (0.0, 1.5 and 3.0 Mg ha(-1)) and two Cu concentrations (0 and 50 mg kg(-1)) to Typic Hapludalf soil. Young vines 'Niágara Branca' (Vitis labrusca L.) were obtained by micropropagation and cultivated for 70 days. The young vines grown with Cu and without liming presented a disorganized root structure; reduced root cap size; increased diameter (47%), cortex area (128%), vascular cylinder area (93%), and number of cortical layers and cells containing phenolic compounds (132%); and reduced root (41%), stem (44%) and leaf dry mass (21%) and height increase (55%). Moreover, Cu exposure reduced Ca concentrations (13%) and increased Cu concentrations (371%) in the roots. Liming, primarily with the highest tested dose, increased the soil pH (from 4.4 to 5.4-6.1), decreased the Cu concentration in the soil (extracted by CaCl2), increased the calcium (Ca) and magnesium (Mg) uptake by plants, prevented root anatomical changes and benefited young vine growth in soil with higher Cu concentrations.

(1) Background: Arbuscular mycorrhizal (AM) fungi are symbiotic organisms that help plants acquire nutrients from the soil in exchange for photosynthetic carbon. Commercial AM fungal inoculants are widely available and are used extensively in agriculture including wine grape production. However, positive growth responses from inoculants are more consistent in the greenhouse compared to the field. (2) Methods: We grew three grapevine rootstocks with and without an AM fungal inoculant in the greenhouse for one year, then they were transplanted to the field for two years. To quantify the establishment of the inoculant, we analyzed root samples with a digital PCR assay. (3) Results: We show that AM fungal inoculation increased biomass production only in the greenhouse. After two growing seasons in the field, the commercial inoculant colonized roots but did not increase biomass production compared to uninoculated rootstocks. (4) Conclusions: This study highlights that AM fungal inoculants do not always promote growth of grapevines in the field. Future research should focus on inoculant strains designed for viticulture applications and take rootstock into consideration to maximize their efficacy.

This study examines the potential of 23 plant species, comprising 10 legumes, 9 grasses, and 4 forbs, as cover crops to enhance carbon (C) sequestration and soil nitrogen (N) in vineyards. After a 120-day evaluation period, cover crop biomass was incorporated into the soil, and grapevine seedlings were planted in its place. Among the established cover crops, the C input potential ranged from 0.267 to 1.69 Mg ha⁻¹, and the N input potential ranged from 12.3 to 114 kg ha⁻¹. Legume species exhibited up to threefold greater shoot dry weight (SDW) compared to grass species. Ladino white clover, Dutch white clover, and Clover blend were superior in SDW, total dry weight (TDW), total C content, and total N content. Legumes exhibited slightly higher root dry weight (RDW) than grasses, with the exception of Fall rye leading at 15 g pot⁻¹, followed by Ladino white clover and Dutch white clover at an average of 12 g pot⁻¹. Legumes, particularly clover blend and Alsike clover, displayed high shoot N concentration at an average of 2.95%. Root N concentration in Legumes (Fabaceae) were significantly higher at 1.82% compared to other plant families at 0.89%, while their root C/N ratio was lower at 18.3, contrasting with others at 27.7, resulting in a faster turnover. Biomass production exhibited a negative relationship (R² = 0.51) with soil residual NO₃⁻. Fall rye, Winfred brassica, and buckwheat had the highest N utilization efficiency (NU_tE) values (ava. 121 g g⁻¹). Alsike clover, Ladino white clover, and clover blend showed the highest N uptake efficiency (NU_pE) values (ava. 75%). The Readily Available N (RAN) Reliance Index (RANRI) is introduced as a novel indicator for quantifying the extent to which a plant relies on RAN for its total N requirement. The RANRI value represents the percentage of the plant’s total N sourced from RAN, ranging from 11% for legumes to 86% for grasses. This implies a substantial influx of nitrogen through a pathway independent of RAN in legumes. Grape shoot N concentration positively correlated with soil NO₃⁻ (R² = 0.31) and cover crop C/N ratio (R² = 0.17) but negatively correlated with cover crop TDW (R² = 0.31). This study highlights legume plants as more effective in C and N assimilation during establishment but cautions about potential soil mineral N depletion before reaching their full biological N fixation capacity.

Ciência e Técnica Vitivinícola, Journal of Viticulture and Enology