Plant husbandry – Mulching
Reexamination Certificate
1999-08-20
2002-01-22
Jordan, Charles T. (Department: 3644)
Plant husbandry
Mulching
Reexamination Certificate
active
06339898
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to plant treatment materials used to promote growth, and development of cultivated plants.
BACKGROUND ART
One approach to promoting plant growth and development is to place ground covers over the ground adjacent or near to the plant. These covers have been made with a variety of materials such as paper, plastic and organic plant materials e.g bark or straw. The materials may contain in addition to the base material, compounds such as pigments and dyes that also impart specific properties to the materials. Use of such covers gives a number of benefits including conserving soil moisture and controlling weed growth. Also, depending on the nature of the covers, light useful to the plants' environment may be reflected back upwards to the plant.
2. Description of the Prior Art
Currently known important ground covers are as follows:
Clear unpigmented plastic ground cover; Black pigmented plastic ground cover; Brown pigmented plastic ground cover; Green pigmented plastic ground cover;
Red pigmented plastic ground cover;
White pigmented plastic ground cover; White unpigmented plastic ground cover;
Silver pigmented plastic ground cover; Silver metallised plastic ground cover;
The clear, black, brown and green plastic ground covers warm the soil.
The red pigmented ground cover is designed to influence plant phytochromes that influence plant morphology.
The white pigmented and unpigmented plastic ground covers look to increase reflected light into the plant canopy. White pigmented ground covers are produced from plastic polymer pigmented with the white titanium dioxide pigment. Unpigmented white ground covers are produced by flattening many microfibres into a continuous sheet.
The silver pigmented and metallised plastic ground covers look to increase reflected light into the plant canopy. Silver pigmented ground covers are typically made from metal particles (commonly aluminium) placed into or onto plastic polymer. Silver metallised ground covers are produced from depositing a thin layer of metal (commonly aluminium) onto a plastic film or sheet, in a vacuum—vacuum metallising.
Paper or wood fibre based ground covers are based on their weed suppression and moisture retention properties, and are not highly reflective.
Generally in the design of a specific ground cover for a certain situation the greater the number and degree of the influences the ground cover can have on the plant or crop environment, the greater the total benefit or performance of the ground cover.
The crop species and variety, the plant component intended for harvest, the plant's physical environment and the plant's biological environment all influence the type of ground cover most preferred for a specific cropping situation. For example if soil warming is a limiting growth factor, then ground cover that assists soil warming will be preferred, or if production of anthocyanins for fruit coloration is critical then reflection of light of the correct wavelengths to increase anthocyanin production will be preferred.
In many cases to achieve one of the preferred benefits with known ground covers requires the compromise of another possible benefit. The applicant has now found that by using ground covers with particular reflectance and transmission properties unexpectedly good performance may be obtained.
SUMMARY OF THE INVENTION
It is an object of the invention to provide plant treatment materials and/or methods giving an enhanced environment for the plant leading to improved plant production and/or quality or at least to provide the public with a useful choice.
In accordance with one aspect of the invention there is provided a reflective plant treatment material comprising, at least one pigment and having high reflectance of UV (280-400 nm), visible (400-700 nm) and near infrared (700-800 nm) radiation, but allowing at least part transmission of radiation of 800-2500 nm. Preferably the material allows at least part transmission of radiation of most of the wavelength range 200-25000 mm including all of the range 4100-6100 nm. The material has a reflectance of at least 11% over the range 280-400 nm, of at least 15% over the visible wavelengths and at least 10% over the range 700-800 nm. In addition it has a transmittance of at least 4% over the range 1001-1650 nm, at least 2% over the range 1651-2500 nm and at least 1% over the range 4100-6100 nm.
For many preferred plant materials, more preferred plant materials and most preferred plant materials the reflectance and transmittance values are as in the relevant columns of Tables 1 and 2 respectively.
TABLE 1
REFLECTANCE VALUES OF PREFERRED PLANT TREATMENT MATERIALS
Total Reflectance
More
Especially
Most
Most Especially
Wavelength (nm)
Preferred
Preferred
Preferred
Preferred
Preferred
280-300
13-86%
23-86%
27-86%
37-86%
37-80%
301-360
12-90%
23-90%
33-90%
41-90%
41-83%
361-380
13-90%
23-90%
37-90%
51-90%
51-84%
381-420
17-90%
29-90%
43-90%
51-90%
51-84%
421-700
37-90%
37-90%
44-90%
54-90%
54-84%
701-1000
25-89%
29-89%
40-89%
47-89%
47-82%
1001-1640
24-90%
30-90%
35-90%
42-90%
42-80%
1641-2200
15-93%
18-93%
24-93%
24-93%
24-76%
2201-2500
5-96%
10-96%
15-96%
17-96%
17-72%
TABLE 2
TRANSMITTANCE VALUES OF PREFERRED PLANT TREATMENT MATERIALS
Transmittance
More
Especially
Most
Most Especially
Wavelength (nm)
Preferred
Preferred
Preferred
Preferred
Preferred
280-300
0-87%
0-77%
0-75%
0-63%
0-63%
301-360
0-88%
0-77%
2-67%
2-59%
3-59%
361-380
0-87%
0-77%
5-63%
5-49%
8-49%
381-420
0-83%
0-71%
6-57%
6-49%
11-49%
421-700
7-63%
7-63%
9-56%
9-46%
12-46%
701-1000
9-75%
9-71%
11-60%
11-53%
14-53%
1001-1640
7-76%
7-70%
10-65%
10-58%
17-58%
1641-2200
4-85%
4-82%
7-76%
7-76%
12-76%
2201-2500
1-95%
1-90%
1-85%
1-83%
4-83%
4100-6100
1-95%
1-95%
1-95%
1-95%
1-90%
8100-10100
1-95%
1-95%
1-95%
1-95%
1-90%
For the purposes of this specification reflectance and transmittance properties of a plant treatment material are as determined for the material before any field use and the reflectance values are for material without any air gaps, holes, slits or openings greater than 0.8 mm in or between the material. The reflectance and transmittance values occur at each wavelength at 1nm intervals across all of the range of wavelengths listed unless otherwise specified.
Reflectance and transmittance values are those obtainable when measured as detailed in Example 28 for reflectance and transmittance as specified in System One and transmittance in System Three.
Preferably the plant treatment material is a ground cover in the form of a sheet e.g. sheets prepared from extruded film. One preferred form is a sheet formed from woven tapes. Preferably the sheets do not have gaps, holes, slits or openings greater than 5 mm in or between the material so as to minimise unwanted plant growth through the sheets of material.
Preferably the plant treatment material comprises a plastic (including plastic polymers derived from cultivated plant materials) more preferably polyolefins such as polyethylene, polypropylene or mixtures thereof. Ethylene alpha-olefin and polyolefin elastomers are also preferred. Certain plastics are particularly useful when present as minor components. Ethylene vinyl acetate (EVA), Ethylene butyl acrylate (EBA) and Ethylene methyl acrylate (EMA) are useful for imparting elasticity. Polyesters may be present as a UV absorbing component and Polystyrene, Styrene-butadiene (SB), Acrylonitrile-butadiene-styrene (ABS), Styrene-acrylonitrile (SAN), Polyethylene terephthalate (PET), Polymethylmethacrylate (PMMA) and polycarbonate are useful as dye carriers. These plastics are also useful in other aspects of the invention. Starch and other plant polymers are often useful components to increase biodegradability.
Alternatively the plant treatment material may comprise paper, wood or cellulose fibre, starch based polymers, casein, latex or in any combination of the above and/or with petroleum derived plastic polymers.
In accordance with a second aspe
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