September is a beautiful month, but the climate is a challenge for the propagation of tomatoes. "The moisture content is tricky and will rise sharply, especially in the early morning," Hans Van Heck (pictured below) of Communication Solutions shared in the Communication Update.
Planting of crops ignited by humidity levels continues until approximately mid-October. The age of the plants (standard plant types) caught on the second leaf is usually around 53-56 days, so they grow particularly well in September and October. Hans: "These months are characterized by wet mornings and it takes a long time for the sun to be strong enough to evaporate the moisture. This usually only happens after 10 o'clock. In addition, the radiation is much weaker than in July and August, The maximum power in Northwestern Europe is 450-500 watts. Therefore, water is drained more slowly from the greenhouse and plants tend to grow vegetatively. This in turn can lead to poor quality clusters, stretched stems (especially single heads) or second More leaves on a leaf between trusses 1 and 2 clamp the plant."
Nevertheless, the outdoor temperature at night is mainly maintained above 12 degrees Celsius, so the air will be filled with more moisture (= lower humidity is insufficient). Hans: "This is also not good for reproduction. In this case, it is a compact plant with sufficient energy. If, like the Benelux, people have to use shading screens to prevent glowing, then it is possible that they are plant-like. (Elongation, poor quality clusters) Of course it is a problem!"
5-6 days before delivery: The goal is a vigorous compact plant with strong generating capacity
The answer to these communication questions is activity in the greenhouse climate. According to Hans, this term is comprehensive and easy to explain. "There are several terms hidden in it, such as ventilation, temperature accumulation, plant density, and minimum ducts." Hans passed through them below.
Ventilation It is important to keep the ventilation line, the Lea side and the wind side close to the heating line. In the past, especially the wind side was chosen generously, that is, at 1 degree Celsius or higher. This creates a humid and inactive climate, which is detrimental to the reproductive development of plants. It is best to set the leeward side to 0.2 degrees Celsius and the windward side to 0.5 degrees Celsius so that they can react quickly. It is not enough to use P-band control, which will have an unstable effect on the ventilation, which will affect the temperature.
In addition, there should be a rain opening on the lea side to keep it as active as possible. It should not rain indoors, but despite the rain, the outdoor temperature usually remains the same.
The temperature structure is the best with radiation control and climate control. When the sun is shining, the temperature must rise. Therefore, the "increase" of temperature is indispensable and greatly stimulates plants. In terms of temperature within 24 hours, the "pyramid" shape is ideal. Tomato plants are "colored" in this way, which means that they will grow dark green leaves with many bubbles (=assimilates) on the leaves, purple on the stems, and a nicely curved truss; in other words , A generative contact!
Cluster bent before delivery
Plant density/square meter The final distance of the plant that is about to bloom is very low; 4-5 blocks/square meter is normal for plants that are squeezed. Therefore, the middle distance is very wise, but the best practice is to start at a short distance, starting with the transplant.
When the plants are transplanted, the blocks are completely saturated. This is necessary to achieve unhindered growth. However, when these blocks are placed next to each other, they also create a very humid microclimate. The solution to this problem is to separate them by 1-2 cm so that the wind can dissolve the humid microclimate and keep the plants compact. The most practical way is to allow the blocks to be picked up mechanically.
Soon after pruning, up to 3-4 days later, the plants must be moved to the next stage. This is not necessarily the final distance; the intermediate distance is a good choice.
However, it is important that the plants are guided to produce reproductive capacity. Excessive water content is still a threat because the plants themselves are evaporating more and more. Larger temperature difference between day and night is necessary, 22-23 degrees Celsius during the day, the lowest 15 degrees Celsius (depending on the species). When the night before use or cool morning, the 24-hour temperature is usually set to 17.5 – 18 C.
By combining the number of plants/blocks per square meter with significant differences in temperature, generative growth can be quickly promoted, thereby improving the quality of the cluster. The factory is also kept compact, which is of course also the wishes of the customers. Varieties with larger tomatoes (> 120 g/fruit) benefit greatly from this, and smaller tomatoes (such as cherries) usually already have this naturally.
Leave a little distance for compactness and generative contact, it's time for the next stage
The smallest tube is of course a big energy consumer, but it is very convenient. A 45 degree Celsius tube has reduced radiation from one hour before sunrise to 2 hours after sunrise. It is a great instrument! In reproduction, in order to drain water, this seems to be inevitable. One solution is to "lift" the smallest tube during the day, which does not cost any extra energy, because the tube temperature is needed to reach the temperature anyway, and it can remove the morning coolness at the same time. Will not exceed 45-50°C. Let it in slowly (2 hours), and then keep it for 2-3 hours, otherwise it will not affect the moisture. Starting from 175 watts, the light can be quickly reduced.
Lighting during the spread (HPS / LED) Lighting at this time of year has the opportunity to increase the length of the day to more than 12 hours, thus creating a long day, and Hans continues his renewal. It also provides additional assimilation, so that plants have a large amount of assimilation. "Growers can use these to speed up crop growth after planting. Focusing on clusters is the best way to balance crops."
Hans knows that more and more people are studying the possibility of LED in the spread. "Growers usually order a plant that is almost flowering, or the first flower to open around the planting date. These plants have a cane of 50-60 cm, have a large leaf area and occupy all of the square when propagating Meters, especially in the "last 10 days." This is a vegetable again. Plants can only grow into the air. "
Hans pointed out that the advantage of HPS lamps is that they can also bring heat into the greenhouse. "Of course, the degree depends on the concentration. If these lights are turned on late at night or late at night, they will bring some activity. With LED lighting, this must be compensated by the radiant heat of the tube. This situation continues until the end of the growing period. By Mobile heating systems can compensate for this well, thereby bringing radiant heat closer to plants. From an energy point of view, this is also very attractive!"
According to Hans, it is clear that LED lights provide more energy for plants. "The establishment of assimilation is stronger."
Growing tomatoes in a greenhouse with 100% LED (100 micromolar)
Nursery irrigation Control irrigation is of course very important, because water can ensure vegetative growth. Hans said that since almost all tomatoes are grafted, this is even more important because rootstocks can benefit greatly from moisture and nutrients. "Control is best when the plant is small, and then dry culture with high EC is very important. When the plant is almost ready for delivery, the block volume slowly becomes too small for a large plant, so the maneuverability disappears In short, you do need irrigation."
Conclusion To cultivate plants that are almost flowering for growers, plant propagators face considerable challenges in September and October. As Hans explained above, they must be very concerned about the moisture content in the greenhouse. Insufficient activities caused by ventilation, temperature, density, or minimal ducts can easily cause problems in cluster formation and cluster startup. But undesirable stem elongation is also problematic for growers to handle plants and also makes them difficult to transport. "Lighting and irrigation certainly also play a role in this and need to be well coordinated," he concluded.
For more information: Hans van Herk Propagation Solutions 31 (0)6 20 91 81 00 hans@propagationsolutions.nl
Publication date: Tuesday, October 19, 2021 © HortiDaily.com / Contact
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