Within the physiological phases or stages that a crop goes through, flowering can be considered one of the most important and sensitive, since it greatly determines the quality of the final harvest and production.
Basically, 3 criteria have to be met for the success of this operation, the first being correct pollination (either self-pollination, by means of animals, wind, water, etc.), climatic characteristics and nutrition . In the case of this, if the minimum requirements are not met, the flower will not have the minimum characteristics for the first step to take place, which is conditioning the attractiveness of the flower (size, color and smell) and the quality of the pollen ( if it is viable or not feasible).
NUTRITION IN FLOWERING: THE ROLE OF BORON AND MOLYBDENUM
For many years it has been a concept that micronutrients such as boron and molybdenum are designed to guarantee adequate pollination. However this is not entirely true. It is true that both micronutrients have a special relationship with the quality of the pollen, the increase in the size of the flowers and their opening and future germination, but not by providing more quantity will better results be achieved.
If adequate nutrition is carried out at all times, it will not be necessary to provide these microelements in greater quantity with extra contributions.
The contribution of boron together with molybdenum, in the days before the start of flowering, has only proven to be a practice that improves flowering and fruit set if previously the levels of these two elements in the plant were not satisfactory.
We can also say that a lack of calcium, phosphorus or another element at the time of flowering can cause a significant loss in the final production due to the same condition.
Let’s see the response of the coffee crop to the contribution of micronutrients such as boron:
As can be seen, boron is important only if the crop needs it and is not in sufficiency. In fact, production can go down due to excess boron, as can be seen in the productive yield by providing boron in pre-flowering.
However, the correct balance (providing before and after, and even with other microelements, such as zinc) leads to much more interesting productive results.
In any case, there are combinations of products that improve flowering based on correcting possible nutritional imbalances that the crop may have in the pre-flowering stages.
- Energetic biostimulants: amino acids (easy assimilation), contribution of nitrogen and sugars
- Hormonal activators: algae with contents of auxins, cytokinins, gibberellins, etc.
- Microelement correctors: contribution of boron, molybdenum, etc.
- Phosphorus contribution: phosphorus is involved in the production of sugars and energy by the plant, since it is an important part of the structure of ATP (adenosine triphosphate). That is why correcting defects in the assimilation of phosphorus or providing it in forms more available to the plant improves nutrition related to flowering.
There are flowering stimulators that combine all these conditions, including amino acids, organic matter (humic and fulvic acids), micronutrients and phosphorus. This is intended to cover all possible nutritional conditions that may reduce the quality of flowering. Then, of course, the atmospheric conditions that we will comment on below must be met.
Although there is the idea that nitrogen is counterproductive for flowering, it is only so in enormously abundant quantities, which hinder hormonal flow and the plant’s response to the activation of the generative phase of the crop (C / N ratio and production of sugars per plant).
In fact, an example made in Côte d’Ivoire for growing coffee, promoted by the fertilizer company Yara.
And here is the case of phosphorus:
As can be seen, if the contribution is continuous and balanced, the production reaches its maximum level for the cultivation of coffee from 150 kg / ha, but the yield drops again if the contribution is excessive. In the balance is success!
Often, we can observe in some horticultural flowering plants that they dry out before the fruit sets. This can be due to 2 reasons:
1: The flower has not been directly pollinated.
This can be of the anemophilic type, through the wind, hydrophilic, through water, or entomophilic, which is carried out by animals such as bees or bumblebees, among others. Almost 75% of the cultivated species in the world carry out this pollination through animals.
If we distributed this percentage among the different animals, the result would be as follows:
- Pollination by bees: about 73%
- Flies: 19%, They usually pollinate sugary fruits such as pear, cherries, apples, cocoa, etc.
- Butterflies: 4%
- Beetles: 5%, mostly pollinate palm species.
- Wasps: about 5%, crops like figs.
And as you know, right now there is great concern about the most important pollinating agents , which are bees, whose number of colonies and population is decreasing alarmingly due to a series of negative conditions in which the human being is 100% involved.
2. There are atmospheric conditions that cause flower wilting and abortion, without actually producing the fruit.
- Reduced lighting (cloudy days, whitewashed roof, green roofs, etc.)
- High / low temperatures: each type of flower needs a range of temperatures. Many times, due to excess or defect, the flower is unable to produce its structure, like pollen, correctly, so it is unviable and no matter how hard you try to pollinate, it cannot be obtained genetically.
- Low soil water potential.
One of the hormones that is most interesting in plant flowering is auxin . So that the fall of fruits or flowers does not occur, there must be a continuous current of this hormone through the petiole.
That is why, on the contrary, in the final stages of maturation or when the plant is subjected to stress (water, temperature, humidity, salinity, etc.), ethylene levels skyrocket and abscission of the fruit (because the auxin current in this case will be discontinuous).