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April 11, 2026Crops0 citationsOpen Access

Grapevine Ecophysiology: Implications of N Fertilization, Deficit Irrigation, and Arbuscular Mycorrhiza on N Isotope Composition (δ15N)

DTDimitrios TaskosFederation of Greek Mariculture GDGeorgios DoupisMediterranean Agronomic Institute of Chania STSerafeim TheocharisInternational Hellenic University

Key Points

To assess the effects of nitrogen fertilization, deficit irrigation, and arbuscular mycorrhiza on nitrogen isotope composition in grapevines.
Conducted a randomized complete block field trial over two years in two vineyards.
Applied varying rates of ammonium nitrate and deficit irrigation.
Measured δ15N in leaves, berry juice, dormant cane, and roots at different growth stages.
Assessed arbuscular mycorrhizal fungal colonization in fine roots.
Fertilization increased δ15N in leaf blades and canes but had minimal effect on berry juice.
Irrigation slightly lowered cane δ15N, with variability observed across treatments and years.
δ15N indicated intravine discrimination, with enriched young berries and leaf blades and depleted roots.
Root δ15N responses varied by cultivar and were influenced by AMF colonization.
Higher leaf and cane δ15N correlated with vine nitrogen status and yield but negatively with agronomic efficiency.

Abstract

Over two years, a randomized complete block field trial tested deficit irrigation I: 70% ETc; NI and ammonium nitrate N0, N60, N120; 0, 60, 120 kg N ha−1 application in two northern Greece winegrape vineyards of cv. ‘Xinomavro’ (XM) and cv. ‘Cabernet Sauvignon’ (CS). Leaf-blade δ15N was measured at berry set, bunch closure, veraison, and technological maturity; berry-juice (must) δ15N at technological maturity and dormant cane δ15N in winter were also determined. In the first year, δ15N was additionally measured in petioles, unripe berries, trunks, and roots, along with arbuscular mycorrhizal fungal (AMF) colonization of fine roots. Fertilization increased δ15N in leaf blades and canes, whereas berry-juice δ15N responded weakly and inconsistently. Irrigation marginally lowered cane δ15N; cane δ15N varied between years, and berry-juice δ15N showed the highest variability across treatments. At berry set, intravine discrimination was evident: young berries and leaf blades were enriched, while fine roots and woody tissues were depleted. Root δ15N responses differed between cultivars and depended on AMF colonization in XM. Leaf and cane δ15N were positively related to vine N status, yield, and pruning weight but negatively to agronomic N-use efficiency indices. These findings indicate that δ15N serves as an integrative proxy of N cycling processes and fertilizer-use efficiency in vineyards, with potential implications for the assessment and optimization of sustainable vineyard management practices in the context of climate change.

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