Plants absorb forms of copper both through leaves and roots, although the needs are always small as it is an essential micronutrient. In plants, copper activates certain enzymes involved in lignin synthesis, which is key for various enzymatic systems. It is also necessary in the process of photosynthesis, fundamental for plant respiration and aiding plants in carbohydrate and protein metabolism. Moreover, copper helps to intensify the flavour and colour of vegetables and flowers.
One of the functions of copper in agriculture is to correct phytopathological problems associated with fungal diseases such as: mildew, leaf spot, anthracnose, monilia, etc.
Excessive use of formulations with high concentrations of Cu has led to the accumulation of high levels in soils, even in the deepest layers. That is why its use in organic farming is currently limited with a gradual reduction in levels of Cu from 6 kg/ha to 4 kg/ha (Implementing Regulation (EU) No 540/2011 Organic Farming).
Optimising formulations that successfully maintain the effectiveness of conventional formulations while reducing the levels of copper added to the crop is essential.
Traditional copper fungicides are preventive and act by contact, while modern copper complexes have systemic properties.

Total systemics
- TRICOPPER® is easily absorbed through the roots and transported to the rest of the plant (through the xylem and phloem). Total ascending and descending systemics allows the active components to be quickly mobilised towards the most sensitive tissues.
- TRICOPPER® corrects copper deficiencies, providing a high-value, fast-absorbing organic nutrient, suitable for organic farming.

Copper heptagluconate is a compound characterised by the high absorption and diffusion of copper on the plant, and it is safer for the environment compared to other traditional inorganic copper-based fungicides.

In order to verify this dual systemics of copper in the form of gluconates and heptagluconate, a trial was carried out on the “San Pedro” tomato variety under controlled conditions. To do so, a single application of copper was carried out with leaf and root treatments and the plants were analysed over time to determine the persistence of copper.
All treatments provided the same amount of mineral copper to the crop.

In plants where the treatment was carried out through the roots, it was observed that copper absorption was slower than through the leaves, with a significant increase in the metal after 8 days of application.
In this case of copper in the form of heptagluconate, its absorption lasts longer, thus covering nutritional needs for more time.
After 14 days of application, the concentration of copper gluconate decreases in the roots. Both formulations are equal after 14 days, although it is unknown whether the persistence of heptagluconate could be greater since the trial was concluded.

The bars indicate average values of milligrams per kilogram of dry matter of copper from the plant roots where the different treatments were applied. Analysis of variance (p<0.05) and subsequent Duncan’s multiple range test.
In plants where the treatment was carried out through the leaves, it was observed that copper absorption was quicker than through the roots, where the treatment with TRICOPPER® (Heptagluconate) exhibits values that are higher 8 days after application. Both formulations were equal 14 days after application.

The bars indicate average values of milligrams per kilogram of dry matter of copper from the plant leaves and stem where the different treatments were applied. Analysis of variance (p<0.05) and subsequent Duncan’s multiple range test.
In the analysis of copper in the roots and at the leaf level 14 days after application, systemics of the element is observed both at an ascending and descending level, since copper content was detected at the root level in the treatments that were carried out through the leaves and vice versa. Therefore, it can be deduced that copper can be absorbed by the leaf and reach the roots, as well as be absorbed by the root and reach the leaves. This is how the dual systemic effect of these formulations described by several authors makes contact (Vršič et al., 2023, González, 2019, Zhang et al., 2013 and Kurnik et al., 2012).

The bars indicate average values of milligrams per kilogram of dry matter of copper from the plant roots, stem and leaves where the different treatments were applied. Analysis of variance (p<0.05) and subsequent Duncan’s multiple range test.
CONCLUSIONS
- At the leaf level, it is absorbed more quickly and in a greater proportion than conventional gluconate.
- It is assimilated by the root progressively, covering nutritional needs for longer.
- Dual systemics demonstrated through trials.

REFERENCES
- Kurnik, V., Gaberšek, V., Unuk, T., Tojnko, S., Vogrin, A., Vajs, S., & Lešnik, M. (2012). Influence of alternative copper fungicide formulations on copper content in apple fruits. erwerbs-Obstbau, 54(4), 161-170.
- Vršič, S., Gumzej, M., Lešnik, M., Perko, A., & Pulko, B. (2023). Patterns of Copper Bioaccumulation and Translocation in Grapevine Grafts Depending on Rootstocks. Agriculture, 13(9), 1768.
- González Hernández, A. I. (2019). New approaches to control Pseudomonas syringae disease in tomato plants.
- Zhang, Y., Mao, R., Zheng, J., Xiao, Y., Tang, M., & Quan, J. (2013). Laboratory bioassay and field evaluation of copper gluconate as a new potential bactericide against Xanthomonas campestris pv. citri (Hasse) dye. Journal of Agricultural Science, 5(12), 23.
- Moraga, D. S., & Boix, L. R. (2015). Evaluación de la Toxicidad Y de la Bioacumulación Del Cu en Un Cultivo Acumulador (Lactuca Sativa L.) Y Otro No-acumulador (Solanum Lycopersicum L.) en Suelos Agrícolas Mediterráneos Representativos, Como Base Para La propuesta de Estrategias de Gestión (Doctoral dissertation, Universitat de València, Facultat de Ciències Biològiques).
To find out more about what biotechnology is, its types and applications, the AgroTech and BioTech projects that we carry out at Fertiberia, and the biotechnological products that we develop, visit our specific section with related information.