NL2022188B1

NL2022188B1 - A method for growing seedlings during seed germination and/or seedling growth.

Info

Publication number: NL2022188B1
Application number: NL2022188A
Authority: NL
Inventors: Van Egmond Albrecht Sr
Original assignee: Van Egmond Lisianthus Holding B V
Priority date: 2018-12-12
Filing date: 2018-12-12
Publication date: 2020-07-02

Abstract

A method for growing seedlings, comprising a providing of a matrix (1) of seedling containers (2, 6) with seedlings therein, comprising multiple rows of seedling containers, 3 providing of weight sensors (11), in which the weight sensors are smaller in number than the seedling containers, a measuring of weights of the seedling containers with the weight sensors, a providing of a control unit (14) that receives the measured weights, compares them to predefined threshold weight values and produces control signals corresponding to said comparison, and finally, the seedlings are watered by opening a watering system (15) based on said control signals. According to the inventive thought, each seedling container comprises a multiplicity of growing positions, the weight sensors are fixedly positioned and dedicated to measure the weights of specific seedling containers, wherein the control signals are based upon the measured weights, and wherein the seedlings are watered based on the control signals.

Description

P33523NLO0/RR Title: A method for growing seedlings during seed germination and/or seedling growth. The invention relates to a method for growing seedlings and a seedling watering control system for providing water to seedlings. In particular the invention relates to such a control system comprising weight sensors, a control module, and a watering system used in conjunction to determine water requirements of said seedlings and providing water as required. Previously this was done mainly by using expert knowledge of a seedling grower, mostly one of the owners of a seedling growing greenhouse company or someone who has been working there for years, and who was able to take into account the appearance of the seedlings (colour, shape) and the look and feel of substrates they were growing in. Day in day out, the expert grower had to walk along long matrixes of containers each filled with large numbers of the seedlings a few times a day in order to be able to decide upon a suitable watering regime for that specific time of the day to render a commercially viable product. This required manually sampling the soil humidity, carefully observing the seedling stems and leaves, and forming an opinion about the water requirements.

This approach leaves to be improved. For instance, it is inconvenient that the expert grower then always needs to be around, and for example never can be sick or on holidays. It would not be the first time that the expert grower would be unable to reach the growing area on time and that someone else had to take over, for example due to a delayed airplane on one side and a traffic jam on the other, and that things then went wrong. In one event, it has even occurred during a leave of the expert grower that the seedlings were supplied with too much water which resulted in an outbreak of algae and fungi. In another event, also during a leave of the expert grower, it has occurred that the water supply was too limited for too long and that many of the seedlings died. The other side of the coin is that this manual approach puts a large burden on the expert growers private life. As they find themselves unable to be absent from the workplace for consecutive periods, it is difficult to live up to expectations that follow from other aspects of life.

In order to provide some kind of more reliable monitoring, the expert grower sometimes would sample one or more of the containers with seedlings out of the matrixes at random in order to weigh them and then decide upon the suitable watering regime for that specific time of the day.

This however requires taking those to-be-weighed ones of the seedling containers out of the matrixes and putting them on a weighing scale. Ergonomically this approach is unfavourable, while these containers typically weigh several kilograms and need to be lifted

-2- from knee-high. Another downside of this approach is that it is very cumbersome. Firstly, the grower needs to be constantly up and about to check the seedlings, secondly, in order to obtain representative samples, the grower must go to extreme lengths to pick out containers with seedlings from both an inner and outer area of the matrix. As the containers are tightly packed together in the matrix to maximize floor usage, this then may even require to first move neighbouring ones of the containers before being able to lift up an aimed container for weighing. The expert grower then for example must fiddle out a row of tightly packed containers to provide a pathway to the centre area, carry a container to the weighing scale, perform the measurement, and finally carry all containers back to their location. Besides being a hassle to the expert grower, this also agitates the seedlings excessively. To make matters even worse, this process demands an accurate and reliable weighing scale to be carried along by the expert grower when walking along the matrixes. The expert grower can also make a choice for pushing a cart with an expensive weighing scale around, or to make use of a fixed weighing scale, and carry the to be weighed containers towards that fixedly located weighing scale, To summarize, the current approach for growing seedlings is suboptimal regarding product quality, sampling reliability, ergonomics and large dependency on expert growers.

EP12715283 discloses a system and method for providing controlled soil moisture conditions within potted plants in a large-scale, automated gravimetric screening system, typically located in a greenhouse. The system comprises a stationary platform, a plurality of potted plants or seeds to be measured and watered, and a movable gantry located below the platform. The system furthermore comprises a controller, programmed to determine the water requirements based on the weights of the individual pots, and a water supply, comprising flow control valves that can adjust water throughput per individual pot based on control signals.

The stationary platform is provided with a plurality of through holes arranged in rows and columns, and the pots are suspended in said holes. The movable gantry comprises a set of load cells that are aligned with a row of potted plants. The system of EP12715283 cycles through the plurality of rows with pots, by repeating the following cycle: moving the gantry to the next row, lifting the gantry so that the pots get fully supported by the weighing scales thereby becoming free from the platform, performing a weighing measurement, determining the water requirements, and subsequently supplying each individually weighed pot with the required water, after which the pots are lowered again by the ganiry.

A disadvantage of this system and method is that, considering its size and amount of moving parts, it is relatively expensive with regards to purchase and maintenance. Another disadvantage is that with the system from EP12715283, no redundancy with respect to the water supply is present. When for instance one of the load cells malfunctions, a whole line of pots gets deprived of water. Furthermore, the individual pots are only usable for growing up

-3- seedlings to large sizes. Using such a system for growing truly large amounts of seedlings to relative small sizes and in relative small amounts of substrates would require large amounts of load cells with vulnerable accuracies that would render this system too expensive. Finally, each individual pot in this system gets agitated during the picking and placing with the gantry before being supplied with water. For tender organisms such as seedlings, this is suboptimal, and may well lead to a damaging of the vulnerable plants.

The present invention aims to at least partly overcome those disadvantages or to provide a usable alternative.

In particular the invention aims to provide an affordable, reliable and user friendly method for germinating seeds and/or facilitating initial seedling growth.

According to the invention this aim is achieved by means of the method according to claim 1. This method for growing seedlings, comprises a step of providing a matrix of seedling containers for growing seedlings therein, wherein the matrix comprises a multiplicity of rows of seedling containers, a step of providing a number of weight sensors, in which the number of weight sensors is smaller than the number of seedling containers, and a step of measuring of weights of the seedling containers with the weight sensors. The method furthermore comprises a step of providing a control unit that is configured to receive the measured weights from the weight sensors, to compare the measured weights with predefined threshold weight values that correspond to growing phases of the seedlings; and to produce watering control signals corresponding to outcomes of the comparisons between the measured weights and the predefined threshold weight values. The seedlings in the seedling containers are then watered by opening a watering system to extents that correspond to the produced watering control signals. According to the inventive thought, each of the seedling containers comprises an array of growing positions for growing a multiplicity of seedlings per seedling container, the number of weight sensors are positioned at fixed positions and are dedicated to measure the weights of a limited number of specific to-be-weighed ones of the seedling containers during the growing phases, wherein the produced watering control signals are based upon the measured weights of the respective to-be-weighed ones of the seedling containers, and wherein the seedlings in both the to-be-weighed and not-t0-be-weighed ones of the seedling containers are watered with amounts of water that correspond to the produced watering control signals.

This approach has proven to vield better production results, namely more and healthier seedlings. Partly this is due to the fact that this method is completely static. This avoids the need for agitating the seedling containers during service, rendering improved product quality.

-4- Another important advantage is that no moving parts are required to obtain a representative weighing samples for all seedling containers. Besides resulting in a more cost effective design, the overall system is also more reliable.

The seedling containers each comprise an array of growing positions with small amounts of substrate having seedlings growing therein. The weight of the whole seedling container, including the total of the small amounts of substrate and the large number of seedlings growing therein, is weighed together. Thus the measurement per seedling in effect is averaged. This decreases the effect of measuring errors, and avoids the need for excessively accurate weight sensors. The present invention is thus also expected to be more reliable because of reduced measuring error. This benefits the product quality by means of a more optimal growth process, and by reducing the formation of algae, fungi and insects. By providing the seedlings each time, for example one or more times a day, with optimal amounts of water, the method also reduces the environmental impact of the growth process. Compared to the conventional expert grower dependent approach as described for the state of the art applied by the inventor, it now advantageously has appeared possible to reduce the water consumption during the entire growing process with more than 25%.

The fact that water is provided to a large quantity of seedling containers, based on merely a static weighing of merely a limited number of containers, makes that the supply of water in the present invention has a better redundancy than the closest prior art. Even when one of the weight sensors malfunctions, the seedlings would still remain being supplied with water.

The method according to the invention advantageously no longer has to be dependent on the expert grower, and thus may help to make the life of the expert grower somewhat easier. The expert grower no longer needs to be around all the time, and for example can safely go on holidays. Outbreaks of algae and fungi or a dying of large numbers of the seedlings can now be reliably prevented. Furthermore the invention makes it possible to further automate the growing process of the seedlings and even have it controlled from a distance, for example towards other parts of the world.

All in all the method according to the invention is significantly cheaper, more environmentally friendly, more reliable and better adapted to the tender nature of seedlings than existing methods.

In a preferred embodiment, the step of providing the number of weight sensors can be executed by providing at least one set of the number of weight sensors of which set the weight sensors are structurally and/or electrically connected. This approach aids workers during the setup process, by reducing the time required for installation, and more importantly reducing the chance of errors during installation.

-5- In addition thereto, the step of providing the number of weight sensors can be executed by arranging the number of weight sensors in sets of four adjacent weight sensors. An advantage of this, is that this facilitates the option of being able to make use of existing software (like for example software used in weighing bridges for large obstacles) for the control system, rendering a cheaper apparatus.

In another preferred embodiment, the step of providing multiple weight sensors can be performed by positioning each weight sensor to measure only a single seedling container comprising an array of growing positions with small amounts of substrate having seedlings growing therein. An advantage of this, is that each weight sensor then gets fully dedicated to measure a start weight and perform subsequent weight measurements of a same single dedicated to-be-weighed one of the seedling containers during the respective growth phases.

In another preferred embodiment, the step of providing a control unit can be executed with the control unit being configured to furthermore apply an averaging method to one or more of the measured weights of the to-be-weighed ones of the seedling containers. This averaging may help to reduce possible measuring errors, and therefore indirectly improve the product quality and environmental friendliness of the method.

In another preferred embodiment, the step of measuring the weights of the to-be- weighed ones of the seedling containers may comprise at least a measuring of the weights of the seedling containers in a first area of the matrix, and at least a measuring of the weights of the seedling containers in a second area of the matrix , wherein the location of the second area differs from the location of the first area. In particular those to-be weighed ones of the containers in the first and second areas may lie in different ones of the rows of the matrix. Those to-be-weighed ones of the containers in the first and second areas may however also lie in a same one of the rows at different positions of this row. An advantage of this, is that these measurements can be used to determine differences in weight between the seedling containers in different areas of the matrix, for example caused by increased evaporation in certain areas of the matrix. This information then can be used to differentiate the water supply between those areas.

In another preferred embodiment, the step of measuring the weights of the to-be- weighed ones of the seedling containers can be performed for those seedling containers that lie at least 5 meters, in particular at least 10 meters, preferably about 15 meters, away from head ends of the matrix. An advantage of this, is that the effect on the measurements of increased evaporation at said ends is reduced.

-6- In another preferred embodiment, the step of measuring the weights of the to-be- weighed ones of the seedling containers may be performed at least 4 times per day, in particular at least 12 times per day, more in particular at least 24 times per day. This results in a more accurate weight characteristic, increasing the effectiveness of the control system.

In another preferred embodiment, the step of providing the matrix of the seedling containers furthermore comprises leaving spacings between to-be-weighed ones of the seedling containers and not-to-be weighed ones of the seedling containers. This will prevent the occurrence of friction between the to-be-weighed and not-to-be weighed ones of the seedling containers, increasing the measuring accuracy.

In another preferred embodiment, the step of providing the matrix of the seedling containers may comprise positioning said seedling containers in an elevated plane above a support surface, in particular by placing the not-to-be weighed ones of the seedling containers onto support legs that are distributed along said support surface, and by placing the to-be- weighed ones of the seedling containers onto their corresponding weight sensors. Owing to this, the weight sensors can be placed directly underneath their seedling containers which benefits the compactness of the growing method and helps to minimize undesired shadowing for the seedlings. Vice versa, this enables the seedling containers to be placed onto the weight sensors, which makes it possible to execute the step of providing the seedling containers more continuously, by placing the weight sensors together with the support legs.

In addition yet another embodiment, the step of providing the number of the weight sensors can be executed with the weight sensors being placed on the support surface while reaching to a same height as the support legs. This benefits the homogeneity of incidence regarding water and light onto the seedlings.

The invention also relates to a seedling watering control system, according to one of claims 12-15.

Further preferred embodiments are stated in the dependent sub claims.

The invention will be described in more detail below with reference to the accompanying drawings, in which: - Fig. 1 shows a schematic perspective view of the system according to the invention inside a greenhouse area;

-7- - Fig. 2 shows an enlarged view of three adjacent rows of seedling containers in fig. 1, with sets of weighing sensors placed under one of the rows; - Fig. 2a, 2b, 2c and 2d, show enlarged partial views of fig. 2, with respectively empty containers, containers filled with substrate and seeds, containers comprising seedlings just protruding above the substrate surface, and containers comprising seedlings in a further growing phase; - Fig. 3 shows a side view of a part of fig. 2; - Fig. 4 shows a schematic top view of fig. 3; and - Fig. 5 shows a schematic view of a weight curve of the system of fig. 1-4 when the method according to the invention is applied to a set of to-be-weighed ones of the seedling containers.

In figure 1-4 a greenhouse is shown wherein Lisianthus seedlings are typically grown.

A floor surface (9) is spanned with roofing structures (3), two for each of the three greenhouse segments depicted.

In this embodiment, the shown seedling watering control system comprises three adjacent matrices (1) of seedling containers (2, 6), and each matrix comprises forty three rows of twelve seedling containers (2, 6). Before the start of a new grow cycle, the floor surface (9) is empty.

A grower typically starts by (re)distributing support legs (8), embodied in figure 2 by plant pots turned upside down, onto the floor surface.

In this embodiment, the support legs (8) are distributed to each support a corner of at least a single one of not-to-be weighed ones (2) of the seedling containers, depending on the position of the support leg within the formation.

In a further step, sets of four adjacent weight sensors (11) mounted onto horizontal support beams (10) are placed in between the support legs on the floor surface.

In the embodiment shown in figure 1, two rows of each matrix of seedling containers are provided with three adjacent sets of four weight sensors.

Figure 2 shows that each of the weight sensors (11) is wired to a control unit (14). The seedling containers (2) as depicted in figure 2, are rectangular, made from Styrofoam, and comprise growing positions embodied by rectangular cavities (7). In figure 2a, a detailed view of the seedling container {2}, along with empty cavities (7) is depicted.

In a parallel process not depicted here, the seeds are planted into seedling containers (2) by filling the cavities (7) with substrate and one or more seeds.

See figure 2b for a depiction of the result of this process.

Once the seedling containers have been provided with substrate and seeds, they are placed onto the support legs (8) or onto the weight sensors (11). In the embodiment shown here, spacing (12) is left between to-be-weighed ones (6) of the containers (the containers placed on the weight sensors) and the not-to be-weighed ones (2) of the containers (the

-8- containers placed on the support legs). In the embodiment shown in figure 1, each matrix has two areas of to-be-weighed seedling containers (6, 6’). The first area of to-be-weighed containers (6) is embodied by row eight (when counting from left to right in figure 1), the second area of to-be-weighed containers (6') is embodied by row twenty-six. Figure 1 further depicts that both the containers in the first area (6) and in the second area (6’) are more than 5 meters away from head ends (16) of the matrices.

In the embodiment shown in figure 1, the watering system comprises six watering tubes (4) which are suspended below each of the roofing structures (3) and above each of the matrices (1) of the seedling containers (2, 6). The watering tubes (4) are provided with holes, nozzles, or the like distributed along their length at a bottom portion of their circumference. The watering tubes (4) are connected to a watering system (15), comprising one or more electronically controllable valves, and the holes, nozzles, or the like are designed for letting water gently and evenly distributed descend on the seedling containers (2, 6) below. A movable watering trolley (5), suspended and guided along said watering tubes (4), is present to provide additional means of watering.

When all of the elements of the seedling watering control system have been provided, connected and/or switched on, a growing cycle and method according to the invention may commence. In the embodiment shown here, a weight measurement is performed by each of the weight sensors (11) every 60 minutes. Each measurement marks the beginning of a new control loop for each of the matrices (1) of seedling containers (2, 6). During each control loop in figure 1: the weight measurements of the to-be-weighed ones (6) of the containers within a matrix are received by the control unit (14) through a wired transfer of a sensor signal, the control unit (14) applies an averaging method to said weight measurements, resulting in a single averaged value for each row of to-be-weighed ones (6) of the seedling containers, the control unit (14) compares the averaged value to a predefined threshold corresponding to the seedling growth phase, and finally, the control unit (14) produces a control signal corresponding to the difference between the averaged value and the threshold value. Per matrix and per control loop therefore, the weights of two rows of twelve containers are measured, resulting in twenty four weight measurements. For these twenty four weight measurements, a single averaged value and a single watering control signal is produced. Each one of the watering control signals produced in a control loop, is received by the watering system (15), and used to open the watering system to extents that correspond to the respective watering control signals. In this embodiment, the watering system (15) comprises a single watering control valve (not shown here) for every matrix (1) of seedling containers (2, 6). In this embodiment, the water is supplied to the seedling containers in a stepwise manner, by having the watering system provide water recurrently during intermittent periods. This

-9- ensures a gradual intake of water by the substrate, which reduces the risk of over-watering, and benefits the controllability and accuracy of the method. As time progresses, the control loop as described is executed consecutively.

Figure 5 shows a weight-time characteristic (13) that schematically represents the continuous alternation between an increase in weight due to the added weight of both the water from the watering system and the growing of seedlings, and a decrease in weight because of evaporation. Due to the incidence of light from the environment and/or supplementary indoor lighting, and due to the incidence of water from the watering system, the seedlings progress through several growing phases. In figure 2b, the seedling is still fully covered by the substrate. Figure 2c depicts seedlings that have just risen above the substrate. Figure 2d shows seedlings that have grown significantly, during the course of for example several weeks.

Besides the shown embodiments, numerous variants are possible. For instance the area of application of the method may be outside, underground, or on any floor level of multistory buildings. Also, the dimensions, material and shapes of the various control system components may differ. Instead of using rectangular Styrofoam containers, it is also possible to use other types of containers such as triangular, diamond shaped, or polygonal seedling containers made from other materials like wood, cardboard or pulp material. The substrate used can be soil, rock wool, efc., and the method could also be applied on other breeds than Lisianthus seedlings. Instead of arranging the seedling containers in rectangular matrices, they could form triangular, diamond shaped, polygonal, or circle shaped formations. Instead of placing the seedling containers on support legs, they could be placed directly on a support surface. In such an embodiment, the weight sensors could be placed in gutters sunk into the support surface. Said support surface could also comprise other kinds of protrusions, ridges or steps. In alternative embodiments, each one of the weight sensors could be placed at the edges or the corners of at least one of the seedling containers, and they could be round, square, or of another shape, as well as large enough to measure the weights of multiple seedling containers. Not all matrices of seedling containers may be provided with weight sensors. Instead, the weight sensors could be applied to one in two, three, or any other number of matrices, while the watering system could be used to supply all matrices with water based on the measurements of said weight sensors. The controller could comprise multiple (distributed) control units, dedicated to certain parts of the matrix or the larger area of application. Similarly, one averaged value could be determined for all weighed containers in the greenhouse, matrix, row, or on a set of weight sensors. The controller could also be connected to the weight sensors and watering system wirelessly. The watering system could

-10 - comprise for instance a flood system, or hydroponics instead of tubes suspended above the seedling containers. In another variant, the watering system could comprise a multiplicity of flow control valves, such as sprinklers or nebulizers, wherein said valves are comprised by either the static part of the watering system, the movable watering trolley of the watering system, or both, and wherein said valves can be individually or collectively controlled by the controller. Similarly, a single controllable valve could be present for all containers in the greenhouse, each ones of the matrices, each ones of the matrix areas, or each ones of the rows.

Thus according to the invention, a method and control system is obtained that makes it possible to grow seedlings of improved quality, at reduced costs, with increased reliability and then what has been disclosed in the closest prior art.

Claims

-11- CONCLUSIONS

A method of growing seedlings, comprising: - providing a matrix of seedling holders (2, 6) for growing seedlings, the matrix comprising multiple rows of seedling holders (2, 6); - providing a number of weight sensors (11), the number of weight sensors (11) being smaller than the number of seedling holders (2, 6); - measuring weights of the seedling holders (2, 6) with the weight sensors (11); - providing a control unit (14) adapted to: o receive the measured weights from the weight sensors (11) o compare the measured weights with set limit values for the weights corresponding to the growth stages of the seedlings; o produce watering control signals that correspond to the results of the comparisons between the measured weights and the set limit values for the weights; and - watering the seedlings in the seedling holders (2, 6) by opening a watering system (15) to an extent corresponding to the watering control signals produced, characterized in that each of the seedling holders (2, 6) has a series of cultivation positions (7) includes, for growing a plurality of seedlings per seedling holder (2, 6), the number of weight sensors (11) are fixed and dedicated to measure the weights of a limited number of specifically seedling holders (6) during the growth stages, where the produced watering control signals are based on the measured weights of the respective specific seedling holders (6) to be weighed, and the seedlings in both the specific weighing (6) and specific non-weighing (2) seedling holders are watered with quantities water corresponding to the watering control signals produced.

The method of claim 1, wherein the step of providing the plurality of weight sensors (11) is performed by providing at least one set of the plurality of weight sensors (11) whose weight sensors (11) are structurally and / or electrically connected to each other be connected.

-12-

The method of claim 2, wherein the step of providing the plurality of weight sensors (11) is performed by arranging the plurality of weight sensors (11) into sets of four adjacent weight sensors (11).

A method according to any preceding claim, wherein each weight sensor is arranged to measure a single specific seedling container (6) to be weighed.

A method according to any one of the preceding claims, wherein the step of providing a control unit is performed wherein the control unit is arranged to further apply an averaging method to one or more of the measured weights of the specific seedling containers (6) to be weighed .

Method according to one of the preceding claims, wherein the step of measuring the weights of the seedling holders to be specifically weighed (6, 8 ') comprises: - at least one measuring of the weights of the seedling holders in a first area (6 ) of the matrix; and - at least one measure of the weights of the seedling holders in a second region of the matrix (8 '), the location of the second region being different from the location of the first region.

A method according to any one of the preceding claims, wherein the step of measuring the weights of the seedling holders to be specifically weighed can be performed on those seedling holders which are at least 5 meters, in particular at least 10 meters, preferably about 15 meters , of head ends (18) of the matrix.

The method according to any of the preceding claims, wherein the step of measuring the weights of the seedling holders to be specifically weighed is carried out at least 4 times a day, in particular at least 12 times a day, more in particular at least 24 times a day.

The method according to any of the preceding claims, wherein the step of providing the matrix (1) of the seedling holders (2, 6) further comprises:

-13- leaving gaps between seedling holders specifically for weighing (8) and seedling holders not specifically weighing (2).

A method according to any preceding claim, wherein the step of providing the matrix {1} of the seedling holders (2, 6) comprises arranging the seedling holders (2, 6) in an elevated plane above a support surface, by place the specific non-weighing seedling holders (6) on support legs distributed over the supporting surface, and placing the specific seedling holders (2) on the weight sensors (11).

The method of claim 10, wherein the step of providing the plurality of weight sensors (11) is performed with the weight sensors (11) placed on the support surface (16) while reaching the same height as the support legs (8).

Seedling watering control system, in particular for use in the method according to the preceding claims, comprising: - a matrix (1) of seedling holders (2, 6) for growing seedlings therein, the matrix comprising a plurality of rows of the seedling holders ( 2, 6); - a number of weight sensors (11), the number of weight sensors (11) being smaller than the number of seedling holders (2, 6); - a control unit adapted to: o receive measured weights from the weight sensors (11); o compare the measured weights with set limit values for the weights corresponding to the growth stages of the seedlings; and o produce watering control signals that correspond to results of the comparisons between the measured weights and the set limit values for the weights, and - a watering system (15) designed to be opened to an extent corresponding to the produced watering control signal; characterized in that each of the seedling holders (2, 6) comprises a series of cultivation positions (7) for growing a plurality of seedlings per seedling holder (2, 6),

-14 - the number of weight sensors (11) are fixed and are dedicated to measure the weights of a limited number of specific seedling holders (6) to be weighed during the growth stages, with the control unit further arranged to base the watering control signals produced on the measured weights of the respective specific seedling holders (6), and wherein the watering system (15) is arranged to water the seedlings in both the specific weighing (6) and the specific non-weighing (2) seedling holders with quantities of water correspond to the watering control signals produced.

System according to claim 12, wherein the matrix of seedling holders (2) is provided with gaps between the specifically weighing seedling holders (6) and the specific non-weighing seedling holders (2).

A system according to any of the preceding claims 12-13, wherein the plurality of weight sensors (11) are provided in sets of four structurally and electrically connected adjacent weight sensors (11).

System according to any one of the preceding claims 12 - 14, wherein the matrix (1) of the seedling holders (2, 6) is arranged in an elevated plane above a supporting surface, wherein the specifically non-weighing seedling holders (2) and the specific seedling holders (6) to be weighed preferably reach the same height and are respectively placed on support legs (8) distributed over the support surface and on the weight sensors (11).