EP2066599A2

EP2066599A2 - Nutrient feed solution

Info

Publication number: EP2066599A2
Application number: EP07805213A
Authority: EP
Inventors: Jens Ernest Bahne Jacobsen; Rita Louise Jacobsen
Original assignee: Carbon Stimulated Growth (Propriety) Ltd
Current assignee: Carbon Stimulated Growth (Propriety) Ltd
Priority date: 2006-09-27
Filing date: 2007-07-24
Publication date: 2009-06-10
Also published as: IL197855A0; AP2009004828A0; WO2008038165A2; MA30812B1; BRPI0715281A2; WO2008038165A3

Abstract

This invention relates to a method for providing nutrients to a plant, a nutrient feed solution containing such nutrients, and a process and composition for obtaining the nutrient feed solution. In particular, the invention provides a nutrient feed solution, particularly a dilute inorganic acid solution, for application to the aerial parts of a plant, wherein the nutrient feed solution comprises nutrients having molecules that are sufficiently small to pass rapidly through a plant cuticle.

Description

NUTRIENT FEED SOLUTION

BACKGROUND TO THE INVENTION

This invention relates to a method of providing nutrients to a plant, a nutrient feed solution containing such nutrients, and a process and composition for obtaining the nutrient feed solution.

Foliar feeds are conventionally applied as solutions of dissolved salts to the plant leaves. Recent research has demonstrated that, initially, the feed moves mainly through the stomata, while later on, penetration across the cuticle is the primary pathway. The foliar feed solution contains both positively charged cations and negatively charged anions, which enter the plant through stomata, found mostly on the undersides of the leaves. The stomatal pores are the main route for the entry of carbon dioxide (CO₂) into the plant and the exit of water vapour from the plant. Once the plant surface has been hydrated, the main entry of dissolved salts into the leaf is via the cuticle and its polar pores; the smaller molecules entering faster than the larger ones.

A problem with the conventional application of foliar feeds is that the initial uptake of the dissolved salts into the plant is dependent on the regulation of the opening of the stomatal pores. At least two mechanisms trigger the opening or closing of stomatal pores. Firstly, in most plants the stomata are closed at night and the CO₂ is depleted during the dark phase of photosynthesis. At dawn, light triggers the stomata to open and resume CO₂ uptake. Secondly, when the amount of water entering the leaf via the roots is less than the amount of water exiting the leaf in the form of water vapour, such as would occur in hot weather, the stomatal pores close in order to protect the leaf from further dehydration. Thus it is essential to apply the foliar feed to the plant's leaves at specific times in the day when the stomatal pores are open for efficient uptake of the nutrients by the plant. However, water deficiency and temperature can cause the stomata to close during the day, and thus it is not guaranteed that the stomatal pores will be fully open when the foliar feed is applied to the leaves. In addition, the time of application for optimal uptake of the foliar feed by the leaves is not always predictable. This is problematic as it can result in wastage of the foliar feed together with increased costs. Feed solution settling on astomatous parts of the plant may enter the plant by penetrating the waxy covering (cuticle), either directly through the matrix or via the cuticular micropores. These openings in the cuticle are several orders of magnitude smaller and vastly more numerous than stomatal openings cf 20,000 stomata to 10 billion micropores. The majority of dissolved salts in conventional feed solutions have large molecules and therefore, typically, slow penetration of the dissolved salt molecules occurs through the cuticle. Once the plant surface has dried, penetration of dissolved salts through the cuticle ceases. This results in a greater loss of feed solution containing large molecules, than that with small molecules.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, a method of providing nutrients to a plant primarily through the cuticle of the plant includes contacting the plant cuticle, typically on the leaves and stems, with a source of nutrients comprising molecules that are sufficiently small to pass through the cuticle, in particular a dilute inorganic acid solution comprising the nutrients.

The dilute inorganic acid solution may be selected from a group including nitric acid, sulphuric acid, carbonic acid, phosphoric acid, phosphorous acid, boric acid, molybdic acid and silicic acid, and mixtures thereof.

The concentrations of the individual elements in the dilute inorganic acid solution are typically between 0.001 ppm and 150ppm.

According to a second aspect of the invention, there is provided a nutrient feed solution for application to the aerial parts of a plant, wherein the nutrient feed solution comprises, preferably consists essentially of, one or more nutrients having molecules that are sufficiently small to pass rapidly through the plant cuticle.

The nutrient feed solution is preferably a dilute inorganic acid solution. The molecules are preferably selected from inorganic anions such as nitrates, chlorides, sulphates, carbonates, bicarbonates, phosphates, phosphites, borates, molybdates and silicates, and mixtures thereof.

The sizes of the molecules are preferably less than 100 g/mol.

The pH of the nutrient feed solution may be between 2.6 and 3.5.

According to a further aspect of the invention, a process for producing a nutrient feed solution comprising one or more nutrients having molecules sufficiently small to pass rapidly through the plant cuticle, includes the step of passing an aqueous solution containing dissolved salts of the group comprising nitrates, chlorides, sulphates, bicarbonates, carbonates, phosphates, phosphites, borates, molybdates and silicates, and mixtures thereof, through a cation exchanger.

The cation exchanger is preferably a column comprising a cation exchange resin or a fibrous ion exchange medium. The cation exchange resin may consist of a gel resin, a macroporous type resin or a fabric type resin. The cation exchanger also may comprise a combination of cation and anion exchange resins with cation and anion fibrous ion exchange mediums that incorporate cathodes and/or anodes, and which separates the cations and anions in a process of electro-deionisation.

The invention extends to a composition consisting essentially of one or more salts selected from the group comprising nitrates, chlorides, sulphates, bicarbonates, carbonates, phosphates, phosphites, borates, molybdates and silicates and mixtures thereof, which composition is suitable for producing a nutrient feed solution having molecules sufficiently small to pass rapidly through the plant cuticle.

BRIEF DESCRIPTION OF ACCOMPANYING FIGURES

The invention will now be illustrated by way of non-limiting examples only, with reference to the accompanying Figures, in which :- Figure 1 shows the comparative growth of a lettuce leaf treated with the nutrient feed solution of the present invention and the growth of an untreated lettuce leaf (control);

Figure 2 shows the comparative growth of lettuce plants treated with the nutrient feed solution of the invention and the growth of untreated lettuce plants (control);

Figure 3 shows the comparative growth of tomato plants treated with the nutrient feed solution; and

Figure 4 shows the comparative growth of strawberry plants treated with the nutrient feed solution of the invention and the growth of un-treated strawberry plants (control).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is aimed at providing nutrients that move rapidly through the waxy plant cuticle that typically covers all aerial parts of a plant.

The method of providing nutrients to a plant in accordance with the invention is preferably carried out by applying a dilute inorganic acid solution, such as nitric acid, sulphuric acid, carbonic acid, phosphoric acid, phosphorous acid, boric acid, molybdic acid and silicic acid, or mixtures thereof, to the aerial parts of the plant, wherein the inorganic acid molecules move into the plant primarily through the plant cuticle. The solution is typically applied as a liquid spray from above, usually to saturate the aerial parts of the plant with the solution. Transport of the molecular nutrients through the cuticle and subsequently into the plant is dependent on the molecules being small enough to move rapidly through the cuticle via hydrophilic and lipophilic pathways. Water has uncharged molecules that pass singly through the amorphous phase of cuticular wax via the lipophilic pathway, i.e. lipid loving. Water diffuses through polar pores such as the cuticular micro-pores, which are typically less than 1 nanometer in size, and/or directly through the matrix of the cuticle. The inorganic acid solution of the invention is able to pass through the cuticle by way of the cuticular micro-pores and micro-channels filled with water.

Furthermore, as the surface of the cuticle is acidic and would therefore facilitate penetration of acidic nutrient solutions through the cuticle, it is important that the nutrient feed solution of the invention has a sufficiently low pH, as foliar feeds are typically taken up more effectively by the plant in low pH regimes.

It can be appreciated that the rate of transport of the nutrients through the cuticle is dependent on the molecular size/weight of the molecules of the inorganic acid nutrients. The smaller the molecules, the easier the passage of those molecules into the plant via the cuticle. The rate of transport through the cuticle falls exponentially as the molecular size/weight increases. Preferably the size of the molecules is less than 100 g/mol. The dilute inorganic acids of the invention, for example nitric, sulphuric, carbonic, phosphoric, phosphorous, boric, molybdic and silicic acids, and mixtures thereof, have molecules, for example inorganic anions such as nitrate, chloride, sulphate, carbonate, bicarbonate, phosphate, phosphite, borate, molybdate, silicate ions, or mixtures thereof, which are small enough to move rapidly through the cuticle into the plant.

Thus, it will be appreciated that it is important to produce a nutrient feed solution that consists of molecules that are small enough to facilitate rapid and easy movement of the molecules through the cuticular matrix and/or cuticular pores, and which have a sufficiently low pH that is conducive to optimal penetration of the molecules into the plant. The applicant has found that for optimal penetration, the pH of the nutrient feed solution should be between 2.6 and 3.5.

The nutrient feed solution is produced by way of a cation exchange process, preferably involving a cation exchanger. There are many different types of cation exchangers that could be used, including a cation exchange resin or a fibrous ion exchange medium. A cation exchange resin is particularly preferred. The resin may be in the form of a gel resin, a macroporous resin or a fabric type resin. It will, however be appreciated that the cation exchanger also may comprise a combination of cation and anion exchange resins with cation and anion fibrous ion exchange mediums that incorporate cathodes and/or anodes, and which separate the cations and anions in a process of electro- deionisation.

An aqueous solution containing dissolved salts, such as nitrates, sulphates, carbonates, bicarbonates, phosphates, phosphites, borates, molybdates and silicates is passed through a cation exchange resin where the cations are removed from the feed solution. The resin preferably contains negatively charged hydroxide ions to attract and hold/retain the positively charged cations. The removal of cations is facilitated by the exchange of hydrogen ions for the cations in the aqueous salt solution. The hydrogen ions then combine with the remaining anions in the feed solution to form dilute inorganic acids.

The transport of the acids through the cuticle makes various nutritional elements available to the plant for production of increased plant mass. The concentration of the individual elements in the dilute inorganic acid solution are typically between 0.001 ppm and 150 ppm, the preferred concentration range of each element being :-

Element Preferred Concentration Ranqe (ppm)

C 50 - 150

N 5 - 20

Si 10 - 40

P 10 - 35

S 10 - 25

B 0.01 - 0.1

Mo 0.001 - 0. 01

The nutritional elements include nitrogen, phosphorus, carbon, boron, molybdenum, silica and sulphur. Effective permeability of the cuticle is typically higher for sulphuric acid than for nitric acids. The inclusion of sulphates in the feed solution leads to the formation of dilute sulphuric acid in the product, which accelerates the transport of the nutrients through the cuticle. The inclusion of nitric acid provides a source of nitrogen for enhanced growth. Phosphorus is included as a vital source of the ATP molecule required for energy production. The uptake of phosphorus by the plant from conventional foliar feeds is extremely slow, and this element is often unavailable in soils through unfavourable soil conditions. Boron is important in sugar transport, cell division, and synthesizing certain enzymes. Increasing the sugar formation necessitates increasing boron for sugar transport. Molybdenum is a cofactor to enzymes important in building amino acids, and is needed with the increased catabolism.

The introduction of carbon into the plant is typically via the carbonic acid, which dissociates in the plant into carbon dioxide (CO₂) and water. The CO₂ is assimilated into carbohydrate during photosynthesis. The carbohydrates in turn are used to form proteins, lipids, nucleic acids etc with the aid of the other elements that are present in the nutrient solution. This leads to enhanced yield of plant material.

Figures 1 to 4 illustrate one of the effects that the nutrient solution has on the growth of a plant, namely increased size. In Figure 1 , the size of a lettuce leaf that has been treated with the nutrient solution of the present invention is compared to the size of an untreated leaf (control). It can be seen that the treated leaf is much larger in size than the untreated leaf. This increase in plant growth is essential for numerous reasons including the fact that it results in the production of a better product for consumers, and earlier harvesting. The maturation is shortened by between 10 and 14 days, thus allowing for additional harvested crops per annum. Similarly, in Figure 2, the increased growth of lettuce plants that have been treated with the nutrient solution when compared to untreated plants (control) is illustrated.

In Figure 3, tomato plants that were treated with the nutrient solution are compared to those that were not treated (control). The tomato plants that were treated exhibited a greater growth than the untreated plants.

In Figure 4, strawberry plants that were treated with the nutrient solution are compared to those that were not treated (control). The strawberry plants that were treated had more vigorous growth than the untreated plants.

The net increase in plant biomass is the result of increased production of sugars, starch, cellulose, proteins, lipids and nucleic acids with the concurrent decrease in breakdown of metabolic products during respiration. The inclusion of silica salts in the feed solution gives rise to the formation of silicic acid in the product. Silica increases the cell wall strength and fungicidal property of the treated plant. The results lead to simultaneous stimulated growth and development, and enhanced fungicidal properties in the treated plants. Furthermore, the quality and shelf life of fruit produced by plants that are treated with the nutrient feed solution is improved.

Preliminary trials conducted in green houses and open fields have shown the following increases in plant yields of plants that have been treated with the nutrient feed solution of the invention:

Claims

1. A method of providing nutrients to a plant primarily through the cuticle of the plant includes contacting the plant cuticle, typically on the leaves and stems, with a source of nutrients comprising, preferably consisting essentially of, molecules that are sufficiently small to pass through the cuticle, in particular a dilute inorganic acid solution comprising the nutrients.

2. A method according to claim 1 wherein the dilute inorganic acid solution is selected from a group including nitric acid, sulphuric acid, carbonic acid, phosphoric acid, phosphorous acid, boric acid, molybdic acid and silicic acid, and mixtures thereof.

3. A method according to claim 1 wherein the concentrations of the individual elements in the dilute inorganic acid solution are typically between 0.001 ppm and 150ppm.

4. A nutrient feed solution for application to the aerial parts of a plant, wherein the nutrient feed solution comprises, preferably consists essentially of, one or more nutrients having molecules that are sufficiently small to pass rapidly through the plant cuticle.

5. A nutrient feed solution according to claim 4 wherein the nutrient feed solution is a dilute inorganic acid solution.

6. A nutrient feed solution according to claim 4 wherein the molecules are selected from inorganic anions such as nitrates, chlorides, sulphates, carbonates, bicarbonates, phosphates, phosphites, borates, molybdates and silicates, and mixtures thereof.

7. A nutrient feed solution according to claim 4 wherein the sizes of the molecules are less than 100 g/mol.

8. A nutrient feed solution according to claim 4 wherein the pH of the nutrient feed solution is between 2.6 and 3.5.

9. A process for producing a nutrient feed solution comprising one or more nutrients having molecules sufficiently small to pass rapidly through the plant cuticle, includes the step of passing an aqueous solution containing dissolved salts of the group comprising nitrates, chlorides, sulphates, bicarbonates, carbonates, phosphates, phosphites, borates, molybdates and silicates, and mixtures thereof, through a cation exchanger.

10. A process according to claim 9 wherein the cation exchanger is a column comprising a cation exchange resin or a fibrous ion exchange medium.

11. A process according to claim 10 wherein the cation exchange resin consists of a gel resin, a macroporous type resin or a fabric type resin.

12. A process according to claim 9 wherein the cation exchanger comprises a combination of cation and anion exchange resins with cation and anion fibrous ion exchange mediums that incorporate cathodes and/or anodes, and that separate the cations and anions in a process of electro- deionisation.

13. A composition consisting essentially of one or more salts selected from the group comprising nitrates, chlorides, sulphates, bicarbonates, carbonates, phosphates, phosphites, borates, molybdates and silicates and mixtures thereof, which composition is suitable for producing a nutrient feed solution having molecules sufficiently small to pass rapidly through the plant cuticle.

14. A method of providing nutrients to a plant primarily through the cuticle of the plant according to claim 1 substantially as herein described.

15. A nutrient feed solution for application to the aerial parts of a plant according to claim 4 substantially as herein described.

16. A process for producing a nutrient feed solution according to claim 9 substantially as herein described.

17. A composition according to claim 13 substantially as herein described.