Sara Crespo-Martínez

Evaluating graft quality in grapevine grafted plants is challenging because structural differences at the graft union are mostly internal. Conventional nursery assessments rely on external inspection, which provides limited information on vascular reconnection. This study applied two complementary approaches to characterise graft union quality: histological observations of callus and vascular development, and hydraulic conductance measurements. Trials were conducted in 2020 and 2021 with Tempranillo grafted onto 110 Richter. Five bench grafting methods were tested: omega with completely aligned cambium (OM-CA), omega with partially aligned cambium (OM-PA), V-shape (V), full cleft (FC), and hand-made whip and tongue (WTh). Histological analysis based on phenotyping of graft union vascular development were done at two time points, after the callusing phase and after field rooting, and hydraulic conductance was measured in one-year-old potted plants using a gravimetric flow–pressure method. Omega grafts, despite shorter contact surfaces, generally produced higher callus and a greater proportion of plants with complete vascular connection. OM-CA reached the most advanced vascular developmental categories, whereas V and WTh remained in intermediate stages and FC showed variable results. Hydraulic conductance did not differ among methods, although OM-CA displayed the highest and most uniform values. These results indicated that grafting efficiency depended more on cambial alignment and tissue differentiation than on the length of cambium surface. Combining scalable histological and hydraulic measurements offered a practical framework to assess graft quality in nursery trials and complemented advanced imaging approaches.

OBJECTIVES/BACKGROUND: Climate change has raised concerns about the imbalance between anthocyanin and sugar levels in grapevines. High temperatures tend to reduce anthocyanin content by inhibiting its synthesis and increasing degradation, while simultaneously enhancing sugar accumulation. The application of elicitors, which promote the anthocyanin biosynthetic pathway, may help alleviate this imbalance. METHODS: To investigate this, a four‐year field trial was conducted on Vitis vinifera cv. Tempranillo to assess the effects of four commercial products: two natural‐based (an antioxidant‐mannitol and an alginic acid‐mannitol products) and two phytohormone‐based (an abscisic acid and an ethephon‐based products). The study evaluated the effect of these treatments on the phenyl propanoid pathway gene expression, various yield parameters, and the content of primary and secondary metabolites. RESULTS: Although none of the treatments consistently increased anthocyanin levels across seasons, the results varied depending on the year. Two products influenced some parameters in specific seasons: the ethephon‐based product, which influenced the anthocyanin‐to‐sugar ratio through the reduction of TSS and induced the expression of key anthocyanin genes, and the natural‐based antioxidant‐mannitol product, which transiently increased the expression of some phenylpropanoid genes. CONCLUSIONS: None of the treatments increased anthocyanin levels across seasons. Ethephon (Fruitel) showed greater effectiveness under temperature stress and reduced sugar accumulation, which may be advantageous in a warming climate. Natural elicitors like antioxidant–mannitol elicitor (Vitalfit) had short‐term effects on gene expression but no lasting impact on anthocyanins. Further research is needed to assess their influence on other polyphenols and their potential for commercial use. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Viral diseases in grapevine cause large economic losses due to decreased irregular yield and unbalanced ripening, and can even lead to plant mortality. There is a large number of grapevine viral agents, and a few of them have a prominent impact due to their worldwide distribution, virulence, and incidence. Although previous research has evaluated variations in viral load between organs and time since infection, there is still a lack of knowledge on how the viruses are transported toward developing tissues. In this work, we present the results of two experiments that contribute to understanding the spread dynamics of four major grapevine viruses (GFLV, GFkV, GLRaV-1, and GLRaV -3). Bud and leaf tissues were sampled from shoots obtained from cv. ‘Garnacha’ cuttings known to be infected with one of these viruses. Bud samples taken at early development stages were used to understand short-distance transport, while leaves taken from young shoots represented long-distance transport, driven mainly through the phloem. Our results show that all viruses were able to invade tissues from the beginning of development. The dissemination ability of GFLV was considerable, as the viral load detected in young organs was as high as in the dormant shoot. Furthermore, for GFLV and GFkV, it was shown that the viral load in young shoots does not follow the general assumption of older tissues accumulating a higher viral load but, conversely, a higher viral load closer to the shoot tip might be driven by the sink strength.