1. BACKGROUND
Deciduous fruit tree producers across Europe continue to experience negative campaigns due to the lack of chilling hours for most of these species, which do not reach the minimum required to ensure proper hormonal regulation and guarantee normalized and homogenized flowering and fruiting processes.
It should be noted that for the crop to properly self-regulate, the number of hours below 7 degrees must be reached, within a range close to December through mid-February. A more common practice is to count these hours from the time the trees shed their first leaves until the phenological phase known as swollen bud.
However, the outlook for this campaign is for frequent daytime temperatures of 20°C and not excessive drops at night across the vast majority of the peninsula.
2. DERIVED FROM THE CURRENT SITUATION
Lack of chilling hours leads to the appearance of what are known as "blind buds," causing partial, irregular, and uneven sprouting, which makes efficient crop management difficult. Buds formed in very warm springs with low relative humidity will require a longer dormancy period, potentially increasing by up to 50%.
Delayed bud break, especially in vegetative organs (lateral buds). Excessive bud break on terminal buds, with greater vigor and final growth compared to the rest. Excessive vegetative growth. Delayed onset of tree production. Delayed and prolonged flowering period, with early shoots versus annual branches (later). Flower buds open before vegetative buds. Imbalance in reserves (early fruit drop due to nutrient deficiency). In young trees, bud break may occur less, but those that do emerge will be more vigorous, delaying the plant's precocity. In species such as peach, bud drop has been reported. Small, low-quality fruit. Irregular ripening. Impaired storage potential.
3. UNDERSTANDING THE PROCESSES DERIVED FROM SELF-REGULATION BASED ON TEMPERATURE AND LIGHT
In this sense, there are formulations that try to alleviate the lack of these cold hours, by influencing the so-called ENDODORMANCE, which is controlled by the conditions of the bud itself and prevents it from sprouting (recess), being dependent on Exogenous or Environmental signals of a normalized cycle and having as bases of this process the phytochrome (p730) that acts as a biological light switch and the characteristic thermoperiod of the year.
In this regard, the increase in short days has a negative effect on the synthesis of phytochrome P730, located in the chloroplasts of the leaves. When this decreases, growth processes also decrease. When growth decreases, the synthesis of auxins, cytokinins, and FAs
Regarding the thermoperiod, this will be the most important external signal for deciduous species in our latitudes. The drop in temperatures at the beginning of autumn results in a generalized reduction in plant metabolism, which can be summarized as: reduced enzymatic activity / reduced respiratory intensity / reduced photosynthetic activity / reduced transpiration activity (influence of ABA) / decreased rate of water and nutrient absorption / low assimilation of nitrogenous substances and low assimilation of P and K.
At the hormonal level, there is a reduction in the synthesis of auxins, cytokinins, and FAs, which shifts the balance in favor of ethylene and ABA, triggering senescence processes (leaf abscission, decreased respiration rate, metabolic stasis, etc.). ABA, as in seeds, is responsible for keeping the buds dormant, protecting them from low temperatures until sprouting conditions are adequate.
4. FUNCTIONAL BASES OF A COLD HOURS COMPENSATOR
We are aware after what has been explained that, although dormancy is related to environmental conditions, this phenomenon is of endogenous origin, that is, it is closely related to a progressive decrease in growth promoters (auxins, gibberellins and cytokinins) and a progressive increase in inhibitors (abscisic acid). When the concentration of these plant hormones is reversed, i.e., when the endogenous promoter content increases and the inhibitor level decreases, dormancy is broken and the bud sprouts. In this sense, the use of artificial substances known as “cold compensators" or currently “sprouting stimulators”, They aim to activate the enzymatic reactions involved in the synthesis of plant growth hormones that promote bud sprouting.
The function of a cold hour compensator is to stimulate Chemical reactions in the yolks that did not occur naturally due to the lack of low temperaturesThe effect of compensators is not widespread throughout the tree, as each bud typically has a different dormant state, depending on its position (terminal or lateral) and type (vegetative or floral). The application of these chemicals has three purposes:: accelerate flowering, make flowering uniform and stimulate bud sprouting.
5. CULTIFORT SOLUTIONS.
CULTIFORT offers a strategy with proven results that compensates for cold hours or stimulates sprouting.
This strategy is based on the combination of BVC EVOLUTION y FASKOLOR.
BVC EVOLUTION It is a biostimulant with a joint action of specifically selected amino acids, nitrogen and reducing sugars, to have a multi-purpose effect on different phenological phases, promoting the self-synthesis of natural substances (proteins, peptides, amino acids, phytohormones such as cytokinins) and improving the profiles of active substances (polyphenols, essential oils, alkaloids, vitamins, etc.).
Its cytokinin-promoting activity will favor, among other variables:
- Promoting the onset of plant physiological activity.
- Stimulation of the formation of leaves and flowers.
- It will improve the quality of the fruits.
- It will promote precocity in the ripening phase.
- It will increase resistance to low temperatures and adverse weather conditions, a key factor for setting and fruiting phenologies.
Meanwhile FASKOLOR, incorporates organic acids and peptide complexes that exert a physiological action y non-hormonal on the culture that acts directly on the chloroplast, maintaining the structure and function of the thylakoid membranes and regulating the level of oxidation products and redox balances.
6. RESULTS OF THE PROPOSED STRATEGY.
- Number of applications: 3 applications distributed.
- A first application on pink bud (BVC EVOLUTION foliar + FASKOLOR root).
- A second application between 75-85% open flower (BVC EVOLUTION foliar + FASKOLOR root).
- Third application at the beginning of fruit set. (BVC EVOLUTION FOLIAR + FASKOLOR root application).
Dosage: 300 cc/hL (3 foliar applications) of BVC EVOLUTION + 5 L/ha of FASKOLOR as indicated (3 root applications)
Producer management
- Uniformity in Sprouting: BVC EVOLUTION It provides buds with the metabolites necessary to overcome dormancy, ensuring uniform bud opening along the branches and complete activation. The product is applied to wood and penetrates the interior of the dormant bud, transporting nutrients that activate enzymatic processes and create the energy needed for meristematic tissues to sprout and develop evenly and regularly.
- FASKOLOR offers homogeneity of maturation and uniformity of size: : the homogeneous opening of the buds favors a homogeneous and uniform ripening of the fruit by reducing apical dominance.
- Greater profitabilityThe strategy applied achieves results in fruit reaching commercial maturity sooner, with larger size, better color, and optimal organoleptic qualities. Improved fruit productivity and quality.
- Savings in labor costs during harvestingIts use allows for lower costs and more profitable harvests due to their more grouped nature.
- Return on investment per hectare taking into account the variables of price for precocity and increase in productive yield, in terms of the percentage of set fruit and total weight of +- 9 %.
