Abstract:
A method for securing seeds in an automatic seeding process is provided wherein: (A) a plurality of individual seeds are each placed in a selected location on a horizontal surface of a growth medium; and (B) a gel film is provided over each said seed to thereby secure each said seed in position on said horizontal surface of said growth medium. said gel film being provided by contacting said gel precursor with said gelling agent substantially in the presence of said seed.

Description:
BACKGROUND  
       [0001]     1. Field  
         [0002]     The present invention relates to seeding systems. More particularly, the present invention relates to automated seeding methods and systems wherein a seeding machine sows seeds in growth medium in trays that are then transported to greenhouses for germination encouraged by moisture and warmth.  
         [0003]     2. Background Information  
         [0004]     Automated seeding and systems are used, for example, in the forest industry for efficient seeding operations. Generally speaking, in an automated seeding method or system, a plurality of trays are carried by a conveyor belt under a seeding machine. Each tray carries a plurality of individual containers and each container has a cavity that contains a growth medium such as vermiculite or peat. When each container is passed under the seeding machine, each seed is accurately placed in the growth medium. The trays are then transported to greenhouses that provide a warm, moist environment for germination of the seeds. However, the transportation of the trays, whether manual or automated, often dislodges and misplaces a substantial number of the seeds. Misplaced seeds are commonly referred to as “off-centers” or “drop-offs” and reduce the efficiency of the process.  
         [0005]     It is known to cover seeds with a small amount of vermiculite or grit for keeping moisture around the seed. This technique offers protection against seed desiccation but fails to secure the seeds in place. There remains a need for an improved method of reducing the number of seeds that are dislodged in order to improve the efficiency of automatic seeding operations.  
         [0006]     The present invention provides improved efficiency for automated seeding systems. This and other advantages will be appreciated from the following disclosure wherein all parts and percentages are by weight unless otherwise indicated.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with the present invention, a method for securing seeds in an automatic seeding process is provided wherein: 
        (A) a plurality of individual seeds are each placed in a selected location on a horizontal surface of a growth medium; and     (B) a gel film is provided over each said seeded location to thereby secure each said seed in position on said horizontal surface of said growth medium. 
 
 said gel film being provided by contacting a gel precursor with a gelling agent over each seeded location.
       
 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a somewhat schematic view illustrating a preferred system of the present invention; and  
         [0011]      FIG. 2  is a block diagram setting forth the method steps of a preferred embodiment of the present invention;  
         [0012]      FIG. 3  is a cross-sectional view, broken away, illustrating a seed, which has been bound by film on a peat pellet in accordance with a preferred embodiment of the present invention.  
     
    
     DESCRIPTION OF THE INVENTION  
       [0013]     Now referring to  FIG. 1 , a somewhat schematic diagram showing a system of a preferred method of the present invention is illustrated and indicated generally by the numeral  10 .  
         [0014]     As shown in  FIG. 1 a  plurality of trays  12  are carried by conveyor belt  14  for seeding at station  16  by seeding machine  18 . Each tray  12  carries a plurality of peat pellets  20  comprising a growth medium for seeds  22 . Seeding machine  18  is a conventional seeding machine and has a plurality of tubes  24  which serve to place each individual seed  22  in a selected location on peat pellet  20 . It will be appreciated by those skilled in the art that in some cases it may be desirable to place a plurality of seeds, for example, a pair of seeds together in each location and that peat pellets  20  may be carried directly on trays  12  or each pellet may be itself carried by a container which is carried by a tray  12 . Furthermore, it will be appreciated that peat pellets  20  may be comprised of alternative suitable growth medium such as vermiculite.  
         [0015]     After seeding station  16 , trays  12  are passed through an optional watering station  26  and then to fixing station  28 . At fixing station  28  a gel film  30  is applied over seeds  22  to secure seeds  22  to peat pellets  20 . As illustrated in  FIG. 1 , fixing station  28  has a first spray nozzle  32  and a second spray nozzle  34 . First spray nozzle  32  applies an aqueous solution of a gel precursor onto the selected locations of seeds  22  on peat pellets  20 . Then second spray nozzle  34  applies a gelling agent onto the selected locations whereupon the gelling agent comes in contact with the gel precursor solution and interacts therewith to form a gel film  30  over peat pellets  20  and seeds  22  thereby “fixing” seeds  22  onto peat pellets  20 . The resulting product is shown in Figure that illustrates in cross-section a peat pellet  20  with seed  22  fixed thereon by gel film  30 . Gel film  30  helps retain moisture around the seed, thereby potentially increasing the germination rate.  
         [0016]     Suitable gel precursors include high molecular weight molecules that can be cross-linked to form a gel. The gel precursors are natural based polymeric compounds, synthetic polymeric compounds, or a mixture thereof. Exemplary of natural based polymeric compounds are latex natural rubber, polypeptides (i.e., proteins) and polysaccharides (i.e., alginate). Exemplary of synthetic gel precursors that are normally solutions are polyacrylic acid, copolymers of maleic anhydride, methyl vinyl ethers, polyvinyl pyrrolidone, polyvinyl alcohol. Exemplary of synthetic gel precursors that are normally emulsions or dispersions are polyvinyl acetate, and latex rubbers (i.e. styrene-butadiene with a small percentage of a carboxyl group). Suitable gelling agents are well known, and include calcium ions which can be provided as calcium nitrate, calcium citrate or calcium chloride. Of course, other polyvalent ions, such as Al +3  and B +3  may be suitable depending upon the particular gel precursors. Polyvinyl alcohol or polyvinyl acetate can be cross-linked with borax solution. Polypeptides can be cross-linked by metals or other functional molecules, where the metal interacts with the electronegative functional groups, such as hydroxyl groups, carboxyl groups, and amines. In cases where the gel precursor is an emulsion or dispersion, gelling can be affected through the application of compounds that disrupt the surface tension, causing the micelles to coalesce. Coalescing agents such as ethylene/diethylene glycol 2-ethylhexyl ether can be added to quicken the process.  
         [0017]     Alternatively, the aqueous solution of gelling agent may be applied before the gel precursor solution or the gelling agent and the gel precursor may be applied at the same time. Also alternatively, either one of the gelling agent or gel precursor may be applied to the peat pellet in dry form with the other of the gelling agent or gel precursor being applied in aqueous solution. Also alternatively, both the gelling agent and the gel precursor may be applied in dry form and then contacted with water to provide a gelled film over the seed  22  to fix it to peat pellet  20 .  
         [0018]     Now referring to  FIG. 2 , the method steps of a preferred embodiment of the present invention are broadly set forth in block diagram. Thus, seeds are first sown in peat pellets or other growth medium by selectively placing each seed on an exposed surface of the peat pellet. Then, a gel film and gelling composition are commingled or otherwise mixed and placed in contact with each other in film relationship on the surface of the seed and peat pellet. A gel film is thereby formed over the seed and peat pellet surface to fix the seed thereon. Then the peat pellet with fixed seed thereon is ready for transport to a greenhouse or the like.  
         [0019]     Further understanding of the present invention will be had from the following examples.  
       EXAMPLE 1  
       [0020]     An aqueous pre-gel solution is made of the following ingredients:  
                                                   ingredient   amount                           alginate (Protonal LF20/40   2%           from FMC Biopolymers)           sugar (dispersant)   8           sodium benzoate (preservative)   0.1           potassium sorbate (preservative)   0.1           water   89.9                      
 
 All of the above dry ingredients are combined and mixed and dissolved in the water to form an aqueous pre-gel solution. The solution is then further diluted 1:20 to form a 0.1% aqueous solution which is then used in the fixing station and sprayed onto seeds on peat pellets. An aqueous solution of 2% calcium nitrate is sprayed onto the pre-gel solution to form a thin gel film over the seed and peat pellet. 
 
       EXAMPLE 2  
       [0021]     The following ingredients are mixed together:  
                                                                 ingredient   amount                                        Protonal LF20/40   41.2%           citric Acid (anhydrous)   29.4           potassium carbonate (anhydrous)   29.4                      
 
 The effervescent components act both as a diluent and a dispersant. 
 
       EXAMPLE 3  
       [0022]     The following dry ingredients are mixed together:  
                                                   ingredient   amount                           Protonal LF20/40   1%           citric acid   8.5           potassium carbonate   8.5           calcium nitrate   2           vermiculite   80                      
 
 The mixture is placed on the seed dry and then sprayed with water after the seed is sown on the peat pellet. The dry ingredients dissolve in the water and effervesce to disperse the alginate around the seed and vermiculite. The calcium ion (in solution) gels the alginate. This formulation enjoys the advantage that there is no need to mix the product on site and does not use any special equipment to spray the solutions. The product can be applied using the equipment that is already used to apply the vermiculite.