Plant husbandry – Receptacle for growing medium – Sectional construction
Reexamination Certificate
2000-05-23
2002-05-14
Jordan, Charles T. (Department: 3643)
Plant husbandry
Receptacle for growing medium
Sectional construction
Reexamination Certificate
active
06385903
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to devices used in the propagation of plants, and in particular to a device for use in germinating and growing plants.
In the horticultural industry, it is common practice to germinate seedlings or cultivate young plants in containers or trays having a plurality of like sized cavities or cells, each of which is dimensioned to receive a charge of plant growing material, such as peat moss, soil and the like, and one or more seeds or young plants. These trays, commonly referred to as “plug trays” within the industry, normally have the cells arranged in a closely packed, uniform spatial array such that a maximum number of plants may be grown within each tray. Once the seeds or young plants and the material necessary for growth are positioned within the cells, the plug tray is positioned in a designated area and exposed to environmental conditions necessary for expedient plant growth. Once the plants within the plug tray cells achieve a certain amount of growth, or have been positioned within the plug tray for a preselected period of time, the plants are removed from the plug tray and transplanted into larger containers.
Normally, both the placement of the seeds and growing material within the cells, and the transplantation of plants from the plug tray into larger containers, is accomplished by an automated process. In this automated process, the plug trays are placed in a contiguous end-to-end relationship along a conveying surface. The plug trays are filled with growing media as they move on a conveyor. An automated device, positioned above the plug trays, deposits one or more seeds into the cells, or removes the plants together with the “root plug” or “root system” contained within each cell and deposits the same in a larger container. The automated device is positioned overhead of the plug trays and is formed having a plurality of laterally extending fingers or guides which are moved into position below the top surface of the plug tray, and between the cells. These lateral guides align the plug tray below the automated device. The automated device is calibrated to descend upon a particular cell or cells within the plug tray based upon the center-to-enter distance between adjacent cells. Consequently, it is critical for the effective and efficient operation of this automated process that the center-to-center distances between adjacent cells of the plug trays is maintained.
In the past, it has been common practice to use a single plug tray in the deposition and transplantation processes. However, when using multiple plug trays, a difficulty encountered by the industry is the ineffective deposition into, and transplantation from, a series of plug trays due to the non-uniformity in the center-to-center distance between cells of adjacent plug trays. That is, at the intersection between two adjacent plug trays, the center-to-center distance between the cells of the last row of one plug tray and the first row of the second plug tray are not equal to the center-to-center distance between the remainder of the cells composing a particular plug tray. Consequently, when the automated device descends upon the first row of cells of a second plug tray, the automated device often fails to adequately align with the center of the cell. This lack of centering between the automated device and the cells of a plug tray results in the failure to deposit the seed within the cell, or in the case of transplantation, to adequately grasp the entirety of the plant and its root system. This in turn causes ineffective filling of the plug tray cells, and when transplanting, increases the likelihood of damage to the plants and/or plug tray, and reduces the efficiency of the transplantation process. Furthermore, the inefficiencies caused by non-uniform center-to-center distances between plug trays will continue until the automated device is shut down and the plug trays are repositioned.
Heretofore, the use of multiple plug trays in the automated processes previously described has required the plug trays to have vertical exterior walls in order to maintain a uniform distance between the cells of adjacent plug trays. Additionally, some plug trays are designed and manufactured to be reusable. One method commonly used to form a reusable plug tray having vertical exterior walls is injection molding. Injection molding is a relatively expensive molding process, and hence increases the manufacturing costs and can add complications to the plug growing process.
Reusing plug trays presents additional problems within the industry. Specifically, reusing plug trays exposes the second or successive batch of plants to potential disease from the previous plant batch. Thus, in many instances, to prevent transmission of plant diseases, the reusable plug trays are cleaned before accepting another batch of seed. Cleaning the plug trays is a cumbersome procedure which increases the complexity and costs of the plant cultivation procedure. Specifically, cleaning the plug trays requires the purchase of a relatively expensive cleaning/sterilizing apparatus.
Accordingly, there exists a need within the industry for a plug tray which overcomes the difficulties of the prior art by providing a uniform center-to-center distance between the cells of adjacent plug trays, which is sufficiently economical to manufacture so as to avoid the need for reuse, is recyclable, and exhibits the requisite strength and rigidity for both singular tray or multiple tray use, and especially with automated processes.
SUMMARY OF THE INVENTION
The present invention provides a plug tray having increased strength and rigidity which may be manufactured using the relatively inexpensive thermoforming process. By employing the thermoforming process, it becomes economically feasible to use the plug tray of the present invention in the cultivation of a single batch of seeds or young plants, whereafter the plug tray may be recycled. Providing an economical, single use plug tray reduces the potential for disease in successive batches of plants and eliminates the need to clean the plug tray subsequent to transplantation. Furthermore, the plug tray of present invention is configured having a uniform center-to-center distance between the cells of adjacent plug trays, which in turn maximizes the efficiency of the automated planting and transplantation processes.
According to an aspect of the invention, a plug tray for growing plants includes a surface member having formed in or therethrough a plurality of rows of inner cavities or cells, and a pair of rows of outer cells with each row of outer cells adjacent to an end of the surface member. Each cell is dimensioned to accept a charge of growing material, and at least one seed or young plant. A plurality of apertures are formed in the surface member to thereby provide aeration for plant growth. The apertures are formed in the surface member such that each aperture is separated from the cells by the surface member. Each inner and outer cell is at a preselected offset angle with respect to the major axis of the surface member. Offsetting the cells at a preselected angle yields a plug tray having greater strength and rigidity, and thus enables the plug tray to be manufactured using the less expensive method of thermoforming. Further strength is gained by forming the apertures such that the surface member surrounds the apertures and separates the same from the cells. Additionally, off-setting the cells at a preselected angle provides a centering effect which aids in the alignment of the plug trays during the automated deposition and transplantation processes. Due to the off-set angle, the lateral guides of the automated device extending below the top surface of the plug tray have less clearance between adjacent rows of cells, and thereby enables the lateral guides to achieve greater precision in aligning the plug trays.
In a preferred embodiment, the plurality of apertures are positioned in rows, such that each row of inner cells is bordered by a pair of rows of ap
Diller Calvin K.
Lercel Mark S.
East Jordan Plastics, Inc.
Jordan Charles T.
Nguyen Son T.
Van Dyke, Gardner, Linn & Burkhardt, LLP
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