Drought is a major stress that hinders plant growth and causes water stress, posing a significant threat to global food security. While nanotechnology, particularly the use of nanoparticles such as TiO₂, offers a promising solution by enhancing plants’ resilience to drought stress, improving nutrient absorption, and promoting growth under adverse conditions, its application in viticulture remains underexplored. The objective of this research was to investigate the effects of titanium dioxide nanoparticles (TiO₂-NPs; 100, 10, 1, and 0 ppm (control)) on various physiological, biochemical, and morphological parameters in grapevine saplings. Three different rootstock varieties, 41 B/Crimson Seedless (CS), 1103 P/CS, and 5 BB/CS, were included in the experiment to assess how rootstock variety influences the response of grapevine saplings to TiO₂-NPs under drought stress (40–50%) and well-irrigated (90–100%) conditions. Young vines grown in pots under greenhouse conditions were used in this study. Applications of 10 ppm TiO₂-NPs improved growth parameters and the SPAD index and enhanced stomatal conductance, relative water content, and protein content in grapevine saplings under both drought and well-irrigated conditions. Conversely, oxidative stress parameters, including the membrane damage index, hydrogen peroxide, drought index, and lipid peroxidation levels, were significantly reduced following 10 ppm TiO₂-NP applications under drought conditions. Furthermore, total phenolic content, proline content, and ascorbate peroxidase, catalase, and superoxide dismutase activities, which increased significantly with drought stress, were reduced to lower levels, paralleling the alleviation of drought-induced oxidative stress. Our results suggest that the primary role of TiO₂ nanoparticles in enhancing drought tolerance is due to their beneficial effects in alleviating damage caused by drought stress. This finding applies not only to grapevines but may also be relevant for other agricultural crops.

Although plant‐derived smoke solutions (SSs) have exhibited growth‐promoting properties in various plant species, their potential role in mitigating heavy metal stress, specifically in grapevines, has remained unexplored and unreported. This knowledge gap prompted the present study to evaluate the efficacy of foliar application of SSs derived from vineyard pruning waste at concentrations of 0%, 0.5%, 1%, and 2% in mitigating Cadmium (Cd) phytotoxicity in grape saplings. In our study, cadmium stress was induced by applying 10 mg/kg CdCl₂ to the root area of the saplings, in conjunction with fertilizers. Our findings showed that exposure to Cd toxicity impeded the growth of grapevine saplings, adversely affecting shoot and root length, as well as fresh weight. Furthermore, it resulted in a reduction in chlorophyll content, stomatal conductance, and leaf water content while significantly increasing membrane damage and lipid peroxidation. Notably, the application of 0.5% SS enhanced grapevine sapling growth and alleviated Cd stress‐induced damage by more effectively regulating physiological and biochemical responses compared to the control and other concentrations. Based on our results, under Cd stress conditions, the application of 0.5% SS effectively increased chlorophyll content, relative water content (RWC), stomatal conductance (1.79 mmol.m⁻².sn⁻¹), and total phenolic content (1.89 mg.g⁻¹), whereas it significantly reduced malondialdehyde (MDA) levels and membrane damage (1.35 nmol.g⁻¹). Additionally, it significantly elevated the activities of antioxidant enzymes, including superoxide dismutase (SOD) (2.16 U.mg⁻¹), catalase (CAT) (1.55 U.mg⁻¹), and ascorbate peroxidase (APX) (3.03 U.mg⁻¹). The study demonstrated that plant‐derived SS mitigates Cd stress in grapevines by enhancing antioxidative defence mechanisms.

Grapes and grape products are rich in secondary metabolites such as phenolic compounds and anthocyanins, which have antioxidant properties. These compounds possess health-promoting attributes, including cardioprotective, antimicrobial, and anticancer effects. In recent years, biotechnological methods have been employed to produce high quantities and purity of secondary metabolites under in vitro conditions, aiming to elucidate their complex functions and optimize production methods. However, the potential effects of harpin proteins on the accumulation of secondary compounds in callus cultures have not been investigated thus far. Harpin proteins, encoded by the hrp gene clusters in Gram-negative phytopathogens, are known to trigger defense responses in various plant species by promoting the accumulation of secondary compounds. These findings suggest that harpin proteins may have the potential to enhance secondary metabolite accumulation in callus cultures. This study therefore investigated the potential of applying different concentrations of harpin protein (0, 0.1, 1, 10, and 100 ppm) to increase secondary metabolite production in calluses derived from petioles of the “Horoz Karası” grape cultivar. Our findings revealed that 1 and 10 ppm harpin treatments resulted in the highest anthocyanin accumulations, with 17.21 and 16.57 CV/g, respectively, representing 1.95- and 1.87-fold increases compared to control treatments, respectively. Total phenolic content peaked at 0.39 mg GAE g⁻¹ FW with the 1 ppm harpin treatment, representing a 4.33-fold increase over the control. Total flavanol levels reached their highest levels at 0.027 mg CE g⁻¹ FW with 1 and 10 ppm harpin concentrations, resulting in a 2.25-fold increase compared to the control. The highest averages for total flavonol content were recorded at 0.024 and 0.021 mg RE g⁻¹ FW with 1 and 10 ppm harpin concentrations, respectively, representing 1.5- and 1.3-fold increases over the control. Principal component analysis (PCA) corroborated the results obtained from the heatmap analysis, indicating that harpin applications at 1 and 10 ppm were the most effective concentration range for maximizing secondary metabolite synthesis, while very low or high concentrations diminished these effects. These findings offered valuable insights for optimizing the production of high-value bioactive compounds, which can be utilized in various fields such as medicine, pharmaceuticals, food, and cosmetics. These results are expected to serve as a valuable reference for elucidating the mechanisms by which harpin proteins, rarely used in vitro, exert their effects on grapevine calluses, contributing to the literature in this domain.

High lime content in agricultural soils poses a significant challenge to crop production, particularly in viticulture. Due to the persistent and detrimental effects of lime stress on plant growth, the present study investigated the potential of iron oxide nanoparticles (Fe₃O₄-NPs) to mitigate lime-induced stress in 1103 Paulsen American grapevine rootstock. We examined the effects of Fe₃O₄-NPs (0, 0.01, 0.1, and 1 ppm) under varying lime stress conditions (0%, 20%, 40%, and 60% CaCO₃). Our findings revealed that increasing lime content progressively inhibited grapevine growth, with significant reductions in shoot fresh weight, root fresh weight, shoot length, and leaf number. Fe₃O₄-NP application demonstrated pronounced protective effects: 0.1 ppm Fe₃O₄-NPs optimized growth under non-stressed conditions, while 1 ppm Fe₃O₄-NPs significantly improved plant performance under 60% lime stress. Notably, nanoparticle treatments mitigated oxidative stress by reducing membrane damage, lipid peroxidation, and leaf temperature while maintaining photosynthetic efficiency and osmotic balance. Fe₃O₄-NPs demonstrated significant potential in mitigating lime-induced stress in grapevines, with optimal concentrations of 0.1 ppm for low–moderate lime environments and 1 ppm for high lime content areas. These findings provide a targeted nanobiotechnological approach to enhance grapevine resilience in calcareous soils, advancing sustainable viticulture strategies.

Climate change and drought are increasing soil lime content globally, a major threat to crop productivity and quality, especially for viticulture. High lime concentrations disrupt nutrient uptake, leading to chlorosis and reduced growth in plants. While exogenous putrescine applications have shown potential in enhancing plant defense responses against various environmental stresses, their efficacy in modulating lime stress has not been previously explored. In this regard, we studied the effects of putrescine on grapevine saplings under varying lime conditions. The experiment used the Karaerik grape variety, an economically important indigenous cultivar from Eastern Black Sea Region of Turkey, grafted onto three American rootstocks with different lime tolerances: Fercal (high), 5 BB (moderate), and 3309 C (low). These were tested under four lime levels (0%, 20%, 40%, and 60% CaO) and treated with different putrescine concentrations (0, 0.05, 0.1, and 0.2 mM) to examine their morphological, biochemical, and physiological responses under lime stress conditions. The results indicated that lime stress adversely affected the growth and development of grapevine saplings by reducing growth parameters, SPAD index, stomatal conductance, and relative water content (RWC), while increasing membrane damage and malondialdehyde (MDA) content. However, different rootstock/cultivar combinations exhibited distinct strategies to cope with lime stress. The highly tolerant Fercal/KE combination maintained higher chlorophyll content, better RWC, and stomatal conductance, supported by increased production of protective enzymes, along with higher proline and protein accumulation, ultimately leading to improved growth and development under lime stress. Exogenous putrescine applications effectively improved plant performance across all rootstock/cultivar combinations, with different concentrations showing optimal results for each combination. The 0.2 mM putrescine treatment significantly enhanced growth parameters, chlorophyll content, stomatal conductance, RWC, and protective enzyme levels while reducing membrane damage and lipid peroxidation in 3309 C/KE combination, which typically shows low lime tolerance. For the moderately tolerant 5 BB/KE, 0.1 mM putrescine was most effective, while the already lime-tolerant Fercal/KE responded best to 0.05 mM putrescine applications. These optimized concentrations demonstrated that putrescine can effectively enhance lime stress tolerance, particularly in more sensitive rootstock/cultivar combinations. This study demonstrated that exogenous putrescine applications effectively mitigated lime stress effects in grapevine saplings by improving physiological parameters and reducing oxidative damage, with optimal concentrations varying according to rootstock tolerance levels (0.2 mM for 3309 C/KE, 0.1 mM for 5 BB/KE, and 0.05 mM for Fercal/KE). The findings revealed that putrescine’s protective effects were most pronounced in lime-sensitive rootstock combinations, suggesting its potential as a protective compound for improving lime stress tolerance in grapevine cultivation.