Apparatus for growing crops in a greenhouse

Abstract

Apparatus for growing crops in a greenhouse, comprising a holder for holding therein a growth medium for growing the crops therein. The holder has an at least partially open upper side, via which a crop portion of the crops which is located outside the growth medium can be exposed to air and light in the greenhouse. The apparatus further comprises airflow guiding means for guiding an airflow coming from an underside of the holder to a crop space directly above the at least partially open upper side of the holder, such that the airflow on a lateral side of the crop portion is oriented toward a medial side thereof.

Description

[0001] Apparatus for growing crops in a greenhouse

[0002] The present invention relates to an apparatus for growing crops in a greenhouse. The apparatus comprises a holder for holding therein a growth medium for growing the crops therein. The holder has an at least partially open upper side, via which a crop portion of the crops which is located outside the growth medium can be exposed to air and light in the greenhouse.

[0003] A known advantage of growing crops in a greenhouse is that the properties of the climate in which the crops are located can thereby be controlled. Cultivation in a greenhouse however requires a considerable investment. The greenhouse must be built, and controlling the climate properties consumes a great deal of energy since the air must be heated, cooled, humidified and dehumidified, all this depending on the properties of the air outside the greenhouse.

[0004] In known apparatuses for growing crops use is made of a so-called cultivation gutter in which can be arranged a growth medium, such as water or a growth substrate, in which the crop can be grown. It is possible here to distinguish between so-called closed gutters and open gutters, inter alia in cultivation of for instance leafy vegetables. Closed gutters have on the upper side thereof a series of holes through which the crop can grow, while open gutters have a wholly open upper side. The air in the vicinity of the crops is usually conditioned by supplying conditioned air from below the cultivation gutter to an area in the vicinity of the crops, for instance by means of an air distribution hose provided with air outlet openings. A significant advantage of supplying the air from below is that incidence of light from above onto the crop is not impeded by the air distribution system. Although these measures have a proven positive effect on the growth of the crops, the average quality of cultivated crops leaves something to be desired at times.

[0005] It is therefore an object of the present invention to provide an apparatus for growing crops whereby a higher and / or better crop yield can be obtained in an efficient manner.

[0006] The present invention provides for this purpose an apparatus according to the type stated in the preamble with the special feature that the apparatus comprises airflow guiding means for guiding an airflow coming from an underside of the holder to a crop space directly above the at least partially open upper side of the holder, such that the airflow on a lateral side of the crop portion is oriented toward a medial side thereof. This has the particular advantage that the airflow travels through the crop portion, which reduces the chances of any plant diseases and also results in increased crop growth and / or crop growth of better quality. In this way an airflow as occurs regularly in crop cultivation outside in a field, particularly when it is windy, is in fact simulated. A microclimate is as it were created in and around each plant, which microclimate can be adjusted and be kept continuous for optimal crop growth by means of adjusting a speed of the airflow and / or properties of the air of the airflow. Owing to the highly targeted ventilation in and around the crop portion, the amount of supplied air can be reduced, this resulting in an energy saving. The optimization of the crop growth in turn as the result that the growth time can thereby be reduced by several days. A higher crop yield can therefore be obtained with the apparatus according to the present invention, while the average quality of the cultivated crops has also increased.

[0007] The apparatus is preferably also provided with water channels or water chambers on one side or both sides of the growth medium, which are configured such that the growth medium can be provided with water in controlled manner. As a result of water being supplied to the growth medium in controllable manner the use of water can be drastically reduced, particularly such that only 10% of the supplied water must be discharged as residual water.

[0008] The growth medium preferably comprises water and / or a growth substrate.

[0009] In a preferred embodiment the holder comprises a holder wall defining the holder and having an outer surface which is formed such that it guides the airflow from the underside of the holder to the crop space, and here forms the airflow guiding means or at least a part thereof.

[0010] The holder wall is preferably formed such that an outer contour of the holder wall has a convex form, as seen in cross-section. Owing to the convex form, the airflow coming from the underside of the holder follows the holder wall, such that a laminar flow along the holder wall is brought about. This laminar flow enables the air coming from the underside to reach the crop space directly above the at least partially open upper side of the holder more easily.

[0011] In a preferred embodiment the airflow guiding means comprise a first air guiding wall which, as seen in cross-section of the apparatus, is situated adjacently of the holder and extends from a position at a distance from the holder to the holder substantially toward the medial side of the crop portion. The first air guiding wall has a first free outer end which faces toward the medial side and is situated close to the lateral side of the crop portion. The first air guiding wall thereby guides the airflow coming from the underside of the holder, which airflow is oriented substantially vertically, toward the medial side of the crop portion.

[0012] In a preferred embodiment a horizontal component of an extending direction of the first air guiding wall is greater than a vertical component of said extending direction, as seen in cross-section of the apparatus. In other words, the first air guiding wall extends substantially horizontally. The vertical component is preferably oriented upward, so that an upward directed component of the airflow coming from the underside of the holder is at least partially maintained when the airflow is guided along the first air guiding wall.

[0013] In a further preferred embodiment the first air guiding wall extends substantially horizontally. A horizontally extending air guiding wall ensures that the airflow on the lateral side of the crop portion is oriented sufficiently toward the medial side. In a preferred embodiment the first free outer end lies higher than a plane defining the at least partially open upper side of the holder. The first free outer end preferably does not lie above the at least partially open upper side of the holder.

[0014] In a preferred embodiment the airflow guiding means further comprise a second air guiding wall which, as seen in cross-section of the apparatus, is situated lower than the first free outer end adjacently of the holder on the side of the holder where the first air guiding wall is also situated, extends from a position adjacently of the holder in a direction away from the holder, and has a second free outer end which is situated close to the first outer end at a position lower than a position of the first free outer end. An underside of the second air guiding wall here guides the airflow coming from the underside of the holder, which airflow is oriented substantially vertically, toward the first air guiding wall. An upper side of the second air guiding wall furthermore contributes to a guiding toward the medial side of the crop portion of the airflow being guided toward the medial side by the first air guiding wall.

[0015] In a further preferred embodiment the second free outer end of the second air guiding wall is situated directly below the first air guiding wall, such that a lower surface of a first portion of the first air guiding wall and an upper surface of a second portion of the second air guiding wall which overlaps the first portion forms an air guiding channel through which the air of the airflow is guided toward the medial side.

[0016] In a preferred embodiment the second air guiding wall extends obliquely upward. Owing to this extending direction of the second air guiding wall, a vortex is created on the upper side of the second air guiding wall, which vortex contributes to the guiding of the airflow being guided toward the medial side of the crop portion by the first air guiding wall.

[0017] In a preferred embodiment a horizontal component of an extending direction of the second air guiding wall is greater than a vertical component of said extending direction, as seen in cross-section of the apparatus.

[0018] In a preferred embodiment the airflow guiding means further comprise a third air guiding wall which, as seen in cross-section of the apparatus, is situated lower than the second air guiding wall adjacently of the holder on the side of the holder where the first and the second air guiding wall are also situated, extends from a position adjacently of the holder in a direction away from the holder, and has a third free outer end which is situated at a horizontal distance from the holder which is at least substantially equal to a horizontal distance from the holder at which the second free outer end is situated. Instead of the underside of the second air guiding wall, the underside of the third air guiding wall guides the airflow coming from the underside of the holder, which airflow is oriented substantially vertically, toward the first air guiding wall. In addition, the second and the third air guiding wall bound an intermediate space lying therebetween, wherein the second and third air guiding wall cause in said intermediate space an air vortex which contributes to the guiding of the airflow between the first and the second air guiding wall toward the medial side of the crop portion. In a preferred embodiment the third air guiding wall extends substantially horizontally.

[0019] In a preferred embodiment a wall part extending downward, preferably vertically, is provided on the second free outer end and a wall part extending upward, preferably vertically, on the third free outer end, as seen in cross-section of the apparatus.

[0020] In a further preferred embodiment outer ends of the downward extending wall part at the second free outer end of the second air guiding wall and the upward extending wall part at the third free outer end of the third air guiding wall are directed toward each other.

[0021] In a preferred embodiment the holder comprises a first holder and a second holder disposed adjacently of the first holder. Each of the holders is suitable for holding therein a growth medium for growing the crops therein. Each of the first holder and the second holder has an at least partially open upper side, via which a crop portion of the crops located outside the growth medium can be exposed to air and light in the greenhouse. The first air guiding wall is provided on one of the first and the second holder, as seen in cross-section of the apparatus, such that the first air guiding wall extends between the first holder and the second holder from said one of the first and the second holder toward the adjacent other of the first and the second holder. In this way the first air cooling wall provided on one of the holders directs the air of the airflow to the crop portion of crops being grown in the adjacent other of the holders.

[0022] In a preferred embodiment the first air guiding wall is provided on a first side wall of said one of the first and the second holder, and extends from the first side wall toward an opposite, second side wall of the adjacent other of the first and the second holder.

[0023] In a preferred embodiment the second air guiding wall is provided on the other of the first and the second holder, as seen in cross-section of the apparatus, such that the second air guiding wall extends between the first holder and the second holder from said other of the first and the second holder toward said adjacent one of the first and the second holder.

[0024] In a preferred embodiment the second air guiding wall is provided on said second side wall and extends from the second side wall toward the opposite, first side wall.

[0025] In a preferred embodiment the third air guiding wall is provided on the other of the first and the second holder, as seen in cross-section of the apparatus, such that the third air guiding wall extends between the first holder and the second holder from said other of the first and the second holder toward said adjacent one of the first and the second holder.

[0026] In a further preferred embodiment the third air guiding wall is provided on said second side wall and extends from the second side wall toward the opposite, first side wall.

[0027] In a preferred embodiment each of the first and the second holder has, as seen in cross section, two mutually adjacent holder parts, each of which is suitable for holding therein a growth medium for growing the crops therein, wherein each of the two holder parts has an at least partially open upper side via which a crop portion of the crops located outside the growth medium can be exposed to air and light in the greenhouse, wherein the second holder parts are mutually connected on their underside by means of a lower wall extending between the holder parts. An advantage of a first and second holder consisting of two mutually adjacent holder parts is that the first and second holder have a greater width, as seen in cross-section, whereby the first and second holder have more stability. This is particularly advantageous in cultivation of crops that, during growth, expand in the transverse or width direction of the gutter, such as heads of lettuce.

[0028] In a preferred embodiment at least one opening is provided in the lower wall for the purpose of allowing passage therethrough of air of the airflow coming from the underside of the holder, such that air of the airflow can flow between the holder parts, and wherein a fourth and a fifth air guiding wall is provided on opposite side walls of the holder parts, between which flows the air which is allowed to pass through the at least one opening, in a configuration similar to that of the first and the second guiding wall. Via the at least one opening crops in one of the adjacent holder parts of one of the first and second holder can be provided with sufficient air by means of the fourth and fifth air guiding wall, while the crops in the other of the holder parts of said one of the first and the second holder are provided with sufficient air by the first air guiding wall, and optionally the second and the third air guiding wall, of the adjacent other of the first and the second holder.

[0029] In a preferred embodiment the holder is an elongate holder and said medial side of the crop portion is situated close to the median plane or the median planes of respectively a portion of the holder holding growth medium or portions of the holder holding growth medium.

[0030] The holder preferably comprises a cultivation gutter.

[0031] The present invention is further elucidated with reference to the following figures, which show preferred embodiments of the apparatus according to the present invention and are not intended to limit the scope of protection of the invention in any way, wherein: figure 1 is a cross-sectional front view of an apparatus according to the prior art; figure 2 is a cross-sectional front view of a preferred embodiment of the apparatus according to the present invention; figure 3 is a cross-sectional front view of a preferred embodiment of the apparatus according to the present invention differing from figure 2; figures 4-7 are cross-sectional front views of a preferred embodiment of the apparatus according to the present invention differing from figures 2 and 3, wherein a growth stage of the crop and an intermediate space between holders of said apparatus differ from each other in each of the figures 4-7; figure 8 is a perspective view of a portion of the apparatus shown in figures 4-7; figure 9 is a cross-sectional front view of a preferred embodiment of the apparatus according to the present invention differing from figures 2-8; figure 10 is a perspective view of a portion of the apparatus shown in figure 9. An outer contour 2 of a cross-section of a conventional cultivation gutter 1 according to the prior art is generally rectangular in shape (see figure 1). As a result, an airflow 4 coming from the underside 3 of the cultivation gutter is disrupted by comer points 5 of the cultivation gutter wall 6 of cultivation gutter 1, such that the airflow 4 moves substantially along the crop space 7 above the at least partially open side 8 of cultivation gutter 1, whereby the air from airflow 4 does not come into direct contact with the crops present in the cultivation gutter, or hardly so.

[0032] An outer contour 2 of a cross-section of an underside (and sides) of the holder or cultivation gutter 1 according to a preferred embodiment of apparatus 10 according to the present invention however has a convex form (see figure 2). Such a convex form has the result that an airflow 4 coming from the underside of cultivation gutter 1 moves along an outer surface of the cultivation gutter wall 6 of cultivation gutter 1 in laminar manner, whereby air of the upward airflow 4 is able to reach the crop space 7 immediately above the at least partially open side 8 of cultivation gutter 1, whereby this air comes into contact with the crops present in cultivation gutter 1. This has the advantage that the air close to the leaves and / or fruits can be refreshed and / or conditioned, this benefitting the quality and / or the speed of the crop growth.

[0033] In the preferred embodiment of the apparatus 10 according to the present invention shown in figure 3 a cultivation gutter wall 6 of each of the cultivation gutters 1 has on the underside thereof a convex form and on an upper side of one of the side walls 9 thereof an air guiding wall 11 which is oriented obliquely upward and which ensures that an airflow 4 coming from the underside is guided to the crop space 7 above the open side 8 of the immediately adjacent cultivation gutter 1. The side wall 9 and the obliquely upward oriented air guiding wall 11 of the one cultivation gutter 1 provided thereon thus provide for ventilation in and around the crops 12 in the immediately adjacent cultivation gutter 1. As can be seen in figure 3, the holders or cultivation gutters 1 are configured such that they can hold a growth medium or growth substrate 13 therein in supporting manner. Situated under the growth medium or growth substrate 13 is a chamber 14 for water and / or nutrients for the roots in and / or under the growth medium or growth substrate 13.

[0034] In the preferred embodiment of the apparatus 10 according to the present invention shown in figures 4-7 side walls 20, 21 of each cultivation gutter 1 are provided with air guiding walls 22, 23, 24. These air guiding walls 22, 23, 24 are arranged such that an airflow 4 coming from the underside of cultivation gutters 1 is efficiently guided such that there is an airflow on the lateral side 15 of the crop portion 16 protruding above the growth medium 13 that moves toward the median plane 17 of each cultivation gutter, such that the air moves through lateral parts of crop portion 16 toward the medial side 19 of crop portion 16. The air guiding walls comprise a first air guiding wall 22 which is provided on the upper side of the left-hand side wall 21 of each cultivation gutter 1. The first air guiding wall 22 here extends substantially horizontally toward the median plane 17 of the adjacent cultivation gutter 1 and has a free outer end 25 that faces toward the medial side 19 and is situated close to the lateral side 15 of crop portion 16.

[0035] The air guiding walls further comprise two air guiding walls or fins 23, 24 which extend substantially laterally and which are provided on the right-hand side wall 21 of each cultivation gutter 1. An upper fin 23 of the two fins is situated below the first air guiding wall 22, such that the first air guiding wall 22 and the upper fin 23 together form an air guiding channel or air guiding passage 26, depending on the mutual interspace between the cultivation gutters 1 (compare each of the figures 4- 7). The channel or the passage 26 together ensure that the air moves sufficiently in horizontal direction toward the median plane 17 of the cultivation gutter 1 in question. A lower fin 24 of the two fins forms together with the upper fin 23 a chamber 27 which lies between the fins and in which an air vortex 28 is caused by the fins 23, 24. For this purpose each of the lower fin 24 and the upper fin 23 has mutually facing wall parts 29, 30. Said vortex 28 contributes to the guiding of the airflow between the upper fin 23 and the first air guiding wall 22 toward the medial side 19 of crop portion 16. The upper fin 23 extending obliquely upward furthermore provides together with an upper portion of the right-hand side wall 21 of each cultivation gutter 1 for a vortex 31 on the upper side of the upper fin 23. This vortex 31 contributes to the guiding of the airflow, which is already being guided toward median plane 17 by the first air guiding wall 22, to the median plane 17 of cultivation gutter 1.

[0036] Each cultivation gutter 1 further comprises a portion for holding a growth medium or growth substrate 13 therein in supporting manner. Situated under each growth medium or growth substrate 13 is a relatively large space 33 for allowing growth therein of the roots of the crops 12 to be grown in the cultivation gutters 1. This space 33 is provided with water and / or nutrients in controlled and preferably continuous manner by means of water and / or nutrient chambers 34, 35 on either side of growth medium 13. The underside of each cultivation gutter 1 is provided with a chamfered wall part close to each side wall 20, 21. These chamfered wall part 36, 37 ensure that the airflow 4 coming from the underside is guided to the space 38 between the cultivation gutters 1. An upright connecting wall 41, which prevents torque of the cultivation gutter 1, is moreover situated between the lower wall 39 of space 33 and the lower wall 40 of the cultivation gutter 1, which is advantageous since such cultivation gutters can become relatively top-heavy due to the size of the crops 12 to be grown therein.

[0037] The preferred embodiment of the apparatus 10 according to the present invention shown in figure 9 consists of two mutually adjacent cultivation gutter assemblies 100, each with two mutually adjacent cultivation gutters 1, each cultivation gutter 1 of which is suitable for holding growth medium 13 therein for the purpose of growing the crops therein. Each of the two cultivation gutters 1 are mutually connected on their underside by means of a connecting wall 42 extending between the cultivation gutters 1. An advantage of this embodiment is that the cultivation gutter assemblies 100 have a greater width, giving them more stability. This is particularly advantageous in cultivation of crops that, during growth, expand in the transverse or width direction of the gutter, such as heads of letuce. The connecting wall 42 is further provided with an opening 43 for allowing passage therethrough of air of an airflow coming from the underside of the cultivation guter assembly 100. Air of this airflow can then flow between the cultivation guters 1. Provided on opposite side walls of cultivation guters 1, between which flows the air which is allowed to pass through the opening 43, in a configuration which is similar to that of the first air guiding wall 22 and the upper fin 23 are intermediate air guiding walls 44, 45. Via the opening 43 crops in one of the adjacent cultivation guters 1 of one of the two cultivation guter assemblies 100 can be provided with sufficient air by means of the intermediate air guiding walls 44, 45, while the crops in the other of the cultivation guters 1 of said one of the two cultivation guter assemblies 100 are provided with sufficient air by the first air guiding wall 22 and the two fins 23, 24 of the adjacent other of the two cultivation guter assemblies 100.

[0038] The present invention is not limited to the shown embodiments but also extends to other embodiments falling within the scope of protection of the appended claims.

Claims

Claims1. Apparatus for growing crops in a greenhouse, comprising a holder for holding therein a growth medium for growing the crops therein, wherein the holder has an at least partially open upper side via which a crop portion of the crops located outside the growth medium can be exposed to air and light in the greenhouse, characterized in that the apparatus comprises airflow guiding means for guiding an airflow coming from an underside of the holder to a crop space directly above the at least partially open upper side of the holder, such that the airflow on a lateral side of the crop portion is oriented toward a medial side thereof.

2. Apparatus according to claim 1, wherein the holder comprises a holder wall defining the holder and having an outer surface which is formed such that it guides the airflow from the underside of the holder to the crop space and here forms the airflow guiding means or at least a part thereof.

3. Apparatus according to claim 2, wherein the holder wall is formed such that an outer contour of the holder wall has a convex form, as seen in cross-section.

4. Apparatus according to any one of the claims 1 - 3, wherein the airflow guiding means comprise a first air guiding wall which, as seen in cross-section of the apparatus, is situated adjacently of the holder and extends from a position at a distance from the holder to the holder substantially toward the medial side of the crop portion and has a first free outer end which is directed toward the medial side and is situated close to the lateral side of the crop portion.

5. Apparatus according to claim 4, wherein a horizontal component of an extending direction of the first air guiding wall is greater than a vertical component of said extending direction, as seen in cross-section of the apparatus.

6. Apparatus according to claim 5, wherein the first air guiding wall extends substantially horizontally.

7. Apparatus according to any one of the claims 4 - 6, wherein the first free outer end lies higher than a plane defining the at least partially open upper side of the holder.

8. Apparatus according to claim 7, wherein the first free outer end does not lie above the at least partially open upper side of the holder.

9. Apparatus according to any one of the claims 4 - 8, wherein the airflow guiding means further comprise a second air guiding wall which, as seen in cross -section of the apparatus, is situated lower than the first free outer end adjacently of the holder on the side of the holder where the first air guiding wall is also situated, extends from a position adjacently of the holder in a direction away from the holder, and has a second free outer end which is situated close to the first outer end at a position lower than a position of the first free outer end.

10. Apparatus according to claim 9, wherein the second free outer end of the second air guiding wall is situated directly below the first air guiding wall, such that a lower surface of a first portion of the first air guiding wall and an upper surface of a second portion of the second air guiding wall which overlaps the first portion forms an air guiding channel through which the air of the airflow is guided toward the medial side.

11. Apparatus according to claim 9 or 10, wherein the second air guiding wall extends obliquely upward.

12. Apparatus according to any one of the claims 9 - 11, wherein a horizontal component of an extending direction of the second air guiding wall is greater than a vertical component of said extending direction, as seen in cross-section of the apparatus.

13. Apparatus according to any one of the claims 9 - 12, wherein the airflow guiding means further comprise a third air guiding wall which, as seen in cross-section of the apparatus, is situated lower than the second air guiding wall adjacently of the holder on the side of the holder where the first and the second air guiding wall are also situated, extends from a position adjacently of the holder in a direction away from the holder, and has a third free outer end which is situated at a horizontal distance from the holder which is at least substantially equal to a horizontal distance from the holder at which the second free outer end is situated.

14. Apparatus according to claim 13, wherein the third air guiding wall extends substantially horizontally.

15. Apparatus according to any one of the claims 13 or 14, wherein a wall part extending downward, preferably vertically, is provided on the second free outer end and a wall part extending upward, preferably vertically, on the third free outer end, as seen in cross-section of the apparatus.

16. Apparatus according to claim 15, wherein outer ends of the downward extending wall part at the second free outer end of the second air guiding wall and the upward extending wall part at the third free outer end of the third air guiding wall are directed toward each other.

17. Apparatus according to any one of the claims 4 - 16, wherein the holder comprises a first holder and a second holder disposed adjacently of the first holder, each of which is suitable for holding therein a growth medium for growing the crops therein, wherein each of the first holder and the second holder has an at least partially open upper side via which a crop portion of the crops located outside the growth medium can be exposed to air and light in the greenhouse, wherein the first air guiding wall is provided on one of the first and the second holder, as seen in cross-section of the apparatus, such that the first air guiding wall extends between the first holder and the second holder from said one of the first and the second holder toward the adjacent other of the first and the second holder.

18. Apparatus according to claim 17, wherein the first air guiding wall is provided on a first side wall of said one of the first and the second holder, and extends from the first side wall toward an opposite, second side wall of the adjacent other of the first and the second holder.

19. Apparatus according to claim 17 or 18, to the extent dependent on any one of the claims 9 - 16, wherein the second air guiding wall is provided on the other of the first and the second holder, as seen in cross-section of the apparatus, such that the second air guiding wall extends between the first holder and the second holder from said other of the first and the second holder toward said adjacent one of the first and the second holder.

20. Apparatus according to claim 19, to the extent dependent on claim 18, wherein the second air guiding wall is provided on said second side wall and extends from the second side wall toward the opposite, first side wall.

21. Apparatus according to any one of the claims 17 - 20, to the extent dependent on any one of the claims 13 - 16, wherein the third air guiding wall is provided on the other of the first and the second holder, as seen in cross-section of the apparatus, such that the third air guiding wall extends between the first holder and the second holder from said other of the first and the second holder toward said adjacent one of the first and the second holder.

22. Apparatus according to claim 21, to the extent dependent on claim 20, wherein the third air guiding wall is provided on said second side wall and extends from the second side wall toward the opposite, first side wall.

23. Apparatus according to any one of the claims 17 - 22, wherein each of the first and the second holder has, as seen in cross-section, two mutually adjacent holder parts, each of which is suitable for holding therein a growth medium for growing the crops therein, wherein each of the two holder parts has an at least partially open upper side via which a crop portion of the crops located outside the growth medium can be exposed to air and light in the greenhouse, wherein the second holder parts are mutually connected on their underside by means of a lower wall extending between the holder parts.

24. Apparatus according to claim 23, wherein at least one opening is provided in the lower wall for the purpose of allowing passage therethrough of air of the airflow coming from the underside of the holder, such that air of the airflow can flow between the holder parts, and wherein a fourth and a fifth air guiding wall is provided on opposite side walls of the holder parts, between which flows the air which is allowed to pass through the at least one opening, in a configuration similar to that of the first and the second guiding wall.

25. Apparatus according to any one of the foregoing claims, wherein the holder is an elongate holder and wherein said medial side of the crop portion is situated close to the median plane or the median planes of respectively a portion of the holder holding growth medium or portions of the holder holding growth medium.

26. Apparatus according to any one of the foregoing claims, wherein the holder comprises a cultivation gutter.

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