FIELD OF THE INVENTION The present invention generally relates to reducing adverse affects of salt on plant growth and germination. More particularly, the present invention relates to coating seeds with an active ingredient that reduces salt stress dormancy in the seeds.

BACKGROUND OF THE INVENTION Plants that grow in saline environments and tolerate salt water irrigation (halophytes) may be useful for several reasons. For example, the halophytes may be used as food for humans and livestock, fuel, carbon sequestration, and revegetation of saline environments.

Accordingly, although halophytes are found growing in uncultivated areas, it may be desirable to plant and grow halophytes in a particular area for a particular purpose.

The term"halophyte"refers to a variety of plant species, ranging from grasses to trees, that are capable of growing in saline environments. Several of these plant species may be cultivated for a variety of reasons such as those noted above, and because salt water can be used to irrigate the halophyte seeds and plants, these plants can grow in arid and semi-arid areas as well as areas that are typically too salty for other types of plants to grow such as salt marshes and marine estuaries. In particular, Salicornia bigelovii Torr., an annual, leafless, succulent plant, may be grown to provide a suitable source of oilseed and forage in saline environments using seawater or brackish water irrigation (Riley, J et al., 273, Halophytes as a Resource for Livestock and Rehabilitation of Degraded Lands, Squires et al. ed., Kluwer Academic Publishers, 1994).

In general, halophyte seeds may be planted using conventional farming techniques.

More specifically, the seeds may be planted by preparing a plot of land for planting such as by plowing, distributing the seeds over the prepared land, and irrigating the planted seeds as necessary.

Although halophytes may suitably grow and thrive in saline environments, salt may nevertheless have a deleterious affect on, among other things, germination of halophyte seeds.

In particular, salinity is thought to negatively affect both the percentage of seeds that germinate and the rate at which the seeds germinate. Salt may, among other things, retard germination and reduce the number of seeds that germinate by affecting physiological factors such as gibberellins, affecting the osmotic potential of the seed (the seeds ability to imbibe water), or combinations thereof.

To compensate for relatively low germination rates and percentages of the halophyte seeds, farmers often plant an excess amount of halophyte seed to produce a suitable stand.

Planting an excess amount of seeds increases the cost of producing halophyte plants and may lead to varying amounts of halophytes throughout the stand (i. e., the stand may not have a uniform crop distribution). Non-uniform plant distribution may be problematic for farmers because water and chemicals, such as fertilizers, pesticides, and herbicides and the like, may be wasted if they are applied to regions where there is little to no plant growth. Also, the poor distribution can cause low crop yield per unit area and inefficiencies in harvesting.

Farmers may also choose to plant the halophyte seeds in areas having lower salt concentrations, such as on the side of a seed bed to increase the yield of the halophytes.

Planting the halophyte seeds on the side of seed beds may be advantageous because salts typically deposit out on the top of the seed bed and thus less salt reaches the planted seed.

However, special planting equipment and techniques are typically required to plant the seed on the side of a seed bed. Thus, planting halophyte seeds on the side of seed beds often increases costs associated with growing the halophytes.

For the reasons set forth above. improved methods and apparatus for planting and growing plants in a saline environment are desirable.

SUMMARY OF THE INVENTION The present invention provides improved method and apparatus for growing halophytes. While the ways in which the present invention addresses the drawbacks of the now-known techniques and apparatus used to grow such plants will be described in greater detail hereinbelow, in general, in accordance with various aspects of the present invention methods and apparatus are provided wherein the seed is provided with a coating that can enhance growth and germination of the seed. Methods for forming and planting the coated seed are also provided.

In accordance with an exemplary embodiment of the present invention, a seed is coated with material that encourages seed germination. In accordance with a further aspect of this

embodiment. the seed coating also includes an inert material, nutritional material or a combination of these materials.

In accordance with one embodiment of the present invention, a method for coating seeds is disclosed wherein the seeds are coated by forming a compound of an active ingredient and inert material. and coating the seeds by mixing the compound with seeds.

The coated seeds of the present invention may be planted in saline environments using conventional planting and farming equipment. However, in accordance with an exemplary embodiment of the present invention, a stand of halophytes is grown by sorting the halophyte seeds by size into at least two groups, applying a compound including gibberellic acid to at least some of the smaller seeds, and planting the large and small seeds to form the stand.

BRIEF DESCRIPTION OF THE DRAWING A more complete understanding of the present invention may be derived by referring to the detailed description and claims, considered in connection with the drawing figures. wherein like reference numbers refer to similar elements throughout the figures, and: Figure 1 is a cut-away view of a coated seed in accordance with the present invention; Figure 2 is a schematic representation of a seed planting process in accordance with the present invention; and Figure 3 is a graph representing the effects of gibberellic acid on the germination of Salicornia bigelovii Torr. seeds.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS The present invention generally relates to improved methods and apparatus for reducing deleterious effects of salt on seed germination.

A coated seed 100 in accordance with the present invention is illustrated in Figure 1.

Coated seed 100 generally includes seed 110 and coating 120. Although seed coating 120 may be used in connection with a variety of seeds, the present invention will conveniently be described below in connection with halophyte seeds, and more particularly to Salicornia bigelovii Torr. seeds. It should be recognized, however, that other seeds and the planting thereof may be advantageously improved using the teachings set forth herein. For example, Salicornia bigelovii Torr. seeds tend to be very small, and as a result, germination may be easily impacted by a variety of things, such as salinity of the environment in which the seed is planted. Moreover. handling of the seed, due to its size. can be difficult. Coating 120 tends

to minimize these disadvantages, as will be discussed hereinbelow in greater detail.

Seed 110 may be selected by sorting the seeds according to size because, in general, larger seeds tend to be more robust and accordingly in accordance with certain embodiments of the present invention may not be treated with coating 120. Applying coating 120 only to those seeds that are most likely to be affected by coating 120 may reduce farming costs associated with growing plants from seed 110. In general, however, seed 110 may be of any size or type.

Coating 120 generally comprises a material that enhances growth and/or germination of seed 110. For example, coating 120 may be selected and applied to seed 110 in a manner that tends to mitigate certain deleterious effects of a saline environment on the germination of a halophyte seed. Alternatively, coating 120 may comprise a plant-growth additive as an active ingredient.

In addition to an active ingredient, coating 120 may suitably include inert materials, nourishing materials, and binder materials. In particular, coating 120 may include an inert material such as diatomaceous earth; a binder such as a polymeric-based dispersing, thickening, or sticking agent, e. g., Rhoplex B-15J (8) manufactured by Rohm and Hass; nourishing materials such as fertilizers, insecticides, fungicides, selective herbicides; any combination of these materials; and the like.

In accordance with an exemplary embodiment of the present invention, coating 120 includes a plant-growth promoting hormone such as gibberellic acid (C, 9H2206) as an active ingredient. Gibberellic acid is a tetracyclic dihydroxylactonic acid that occurs naturally in plants and can be synthesized. The acid is commercially available from, among others, Sigma Chemical Company of St. Louis, MO.

At least some halophytes, for example, such as Salicornia bigelovii Torr., are believed to suffer from salt stress dormancy when planted in or exposed to a saline environment. The salt stress dormancy is believed to be due, at least in part, to low growth regulator production, a rapid turnover in gibberellins (plant growth hormones), or the like. Accordingly, in accordance with this aspect of this embodiment of the present invention, coating 120 preferably includes an active ingredient that reduces or counteracts the negative effects of the saline environment on the seed by affecting the growth hormones or regulators of the seed.

When applied to seeds, gibberellic acid may regulate plant germination. Germination generally includes imbibition of water by the seed to activate the embryo of the seed. In particular. the water reactivates proteins that became inactive as the seeds matured. The plant

hormones then regulate enzymes to facilitate digestion of the seed material and the growth of the plant. Several plant hormones regulate the growth process. Of particular interest in the context of this aspect of the present invention are gibberellins, e. g. hormones that regulate protein synthesis and plant growth. Gibberellic acid is a gibberellin that occurs naturally in some plants, and may be added to plants to control plant development.

The concentration of gibberellic acid present in coating 120 may vary from application to application and may, as described in greater detail below, depend on seed size. However, when used as part of a seed coating for Salicornia bigelovii Torr. that have been sorted to a size of less than about 1.5 mm, the concentration of gibberellic acid is preferably about 0.0001 to about 1 molar and more preferably about 0.001 to about 0.1 molar. In a particularly preferred embodiment of this aspect of the present invention, coating 120 includes 0.01 molar gibberellic acid. Of course, it should be appreciated that in certain applications and for certain seeds other acids or varying concentrations of acid may be desirably incorporated into coating 120.

Seed 110 may be coated using a variety of methods now known or hereafter developed.

For example, various materials may be applied to the seed by spraying the seeds, dipping the seeds in the material, dusting the seeds, applying powder to the seeds, and the like. However, in accordance with preferred aspects of the present invention, the seeds are coated by using a slurry seed treater such as a Panogen 9 manufactured by R & B Metal Company of Woodstock, Illinois. In this case, materials comprising the seed coating are mixed together to form the slurry. A predetermined amount of slurry is then added to an amount of seed. The seed and slurry are then mixed to form coated seed 100. The amount of active and inert ingredients applied to the seed may be manipulated by adjusting the concentration of the ingredients in the slurry, by adjusting the amount of slurry mixed in with the seed, or combinations thereof.

Coating 120 may be any suitable thickness. Preferably, coating 120 is sufficiently sized to enable the advantageous effects of the active ingredient contained therein to be realized, but not so big as to inhibit seed maturation.

While, in general, seeds 110 of varying sizes may be coated as described herein, in certain contexts it may be desirable to coat only certain seeds of a particular lot. For example, in accordance with an exemplary embodiment of the present invention. the seeds may be prepared for planting according to process 200, which is schematically illustrated in Figure 2.

In general, process 200 includes a sorting step 210, a coating step 220, and a planting step

230. Process 200 may also suitably include a threshing step 240 and a seed cleaning step 250.

Sorting step 210 generally includes separating seeds that are likely to timely germinate in the growth (e. g., saline) environment from seeds less likely to timely germinate in the environment. For example, seeds may be separated according to size: larger seeds being typically more likely to germinate more readily without assistance in harsh environments than smaller seeds. In accordance with one embodiment of the present invention, when seed 110 comprises Salicornia bigelovii Torr. seeds, such seeds are sorted according to size. The seeds may be sorted by, for example, using a metal screen with openings of a predetermined size.

In accordance with a preferred aspect of the present invention, the seeds are sorted using a metal screen having openings of about 1.5 mm. such that seeds having a longest dimension of less than 1.5 mm pass through the mesh and seeds having a longest dimension greater than 1.5 mm do not pass through the mesh.

After the seeds have been sorted, a portion of the seeds (i. e., those selected or sorted seeds) are coated in step 220. In accordance with various aspects of the present invention, seeds that are less likely to germinate and seeds that are likely to take longer to germinated (e. g., Salicornia bigelovii Torr. having a longest dimension less than about 1.5mm) may be coated in step 220. In this manner use of the inventive coating described herein enables the planting of both the smaller and larger seeds together, this tending to minimize variable plant distribution throughout a stand due to typical size or other seed germination variations. That is, typically small uncoated seeds may exhibit no or late plant growth while the larger seeds planted in the same area may thrive. Such inequalities can be minimized in accordance with various aspects of the present invention.

Seed coating 120 may include several components that may be applied to the seeds in a variety of ways. For example, step 220 may suitably include substeps configured to mix the components of coating 120. Alternatively, coating 120 may include a plurality of substances that are applied to seed 110 in a series of coating steps. <BR> <BR> <BR> <BR> <P> After the seeds have been coated, they are ready to be planted according to step 230.<BR> <BR> <BR> <BR> <BR> <BR> <P>Step 230 may include any seed planting methods now know or hereafter devised.

Nevertheless, in accordance with preferred aspects of the present invention, the seeds are planted by tilling the land, packing the land, and then planting the seed in the packed land.

As noted above, only a portion of the seeds may require coating to enhance probability and speed of germination. Accordingly, smaller seeds that were separated from larger seeds in step 210 and coated in step 220 may be combined with larger, non-coated seeds prior to

step 230. The smaller, coated and larger, non-coated seeds may simultaneously be planted accordingly to step 230.

Process 200 may also optionally include threshing step 240 to separate the seed from the rest of the plant. For Salicornia Bigelovii Torr., the seeds may suitably be removed from the flower spike using, for example, a combine or similar tool.

Process 200 may also include seed cleaning step 250. That is, in accordance with one aspect of the present invention, the seeds may be cleaned prior to coating. Cleaning may be done in accordance with any conventional process, for example, by passing the seeds over a screen or through any type of seed cleaning device. In the context of use of the screen, as the seeds pass over the screen. debris proximate or surrounding the seed falls through the openings and away from the seed. It should be appreciated that in accordance with various aspects of the present invention cleaning may take place before and/or after sorting step 210.

For example, it may be desirable in certain instances to both clean both the sorted seeds as well as the non-sorted seeds.

While various coatings may be applied to various seeds in the context of the present invention. coatings containing an effective amount of gibberlic acid used in connection with Salicornia bigelovii Torr. seeds are particularly preferred, particularly for smaller dimensional seeds of that type. In this regard, such coatings have been found to be particularly beneficial in enhancing small seed germination. Data representing the effects of gibberellic acid on the germination percentage of Salicornia bigelovii Torr. are represented in graph 300, shown in Figure 3. Graph 300 includes eight box plots 340,350, 360,370, and 380.

Each box plot 310-380 represents data for three replicates of the conditions listed below, with each replicate including fifty seeds belonging to the associated group. Box 310 represents a group of seeds that passed through a 1.5 mm screen that were grown in a saline environment including about 4.0% NaCI in water ; box 320 represents a group of seeds that passed through a 1.5 mm screen that were grown in a fresh water environment; box 330 represents a group of seeds that passed through a 1.5 mm screen that were grown in 4.0% NaCI environment and were treated with 0.01 M gibberellic acid; box 340 represents a group of seeds that passed through a 1.5 mm screen that were grown in a fresh water environment and treated with 0.01 M gibberellic acid; box 350 represents a group of seeds that did not pass through a 1.5 mm (i. e. * the seeds have a dimension greater than 1.5mm) screen which were grown in a saline environment including about 4.0% NaCI in water; box 360 represents a group of seeds that did not pass through a 1.5 mm screen which were grown in a fresh water environment ; box

370 represents a group of seeds that did not pass through a 1.5 mm screen which were grown in 4.0% NaCI environment and were treated with 0.001 M gibberellic acid; and box 380 represents a group of seeds that did not pass through a 1.5 mm screen which were grown in a fresh water environment and treated with 0.001 M gibberellic acid. Each box 310-380 includes a line (e. g., lines 312,322,332, 342, 352, 362, 372, and 382) representing the mean percentage germination for conditions listed above. As shown in graph 300, the addition of gibberellic acid to small seeds in the presence of a saline solution has a substantial effect on the percentage of seeds that germinate.

Although the present invention is set forth herein in the context of the appended drawing figures, it should be appreciated that the invention is not limited to the specific form shown. For example, while inventive methods and apparatus are conveniently described in connection with Salicornia bigelovii Torr. seeds sorted with a mesh size of about 1.5 mm, the inventive method and apparatus may be used in connection with alternative seeds and/or seed sizes. Various other modifications, variations, and ei-diancements in the design and arrangement of the methods and apparatus for reducing salt stress dormancy in plants as set forth herein may be made without departing from the spirit and scope of the present invention as set forth in the appended claims.