Crop management

Abstract

An apparatus for crop management configured to be adjacent the root 602 of a plant 603, comprising a positive electrode 606, a negative electrode 607, and a power supply to generate an electric field

Description

FIELD The present disclosure relates to an apparatus and method for crop management. In particular, an apparatus and method are provided for protecting plant roots from electrotactic organisms. Electrotactic organisms include pathogens such as microorganisms (e.g. oomycete zoospores) or animals (e.g. nematodes). Further, an apparatus and method are provided for controlling electrotropic plant roots. BACKGROUND Increasing food production to meet the demands of the rising world population requires the introduction of novel crop protection strategies. Billions of dollars are lost annually to crop infection and chemical solutions are slowly becoming obsolete due to environmental consciousness and a rise in pathogen resistance. There are required new ways to address pathogen resistance. Furthermore, there is a general desire in crop management to control the direction of root growth. The disclosure herein is directed to addressing these issues. SUMMARY The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. According to a first aspect, there is described an apparatus for crop management. The apparatus is configured to be positioned adjacent to the root of a plant. The apparatus comprises a positive electrode configured to be in contact with a first area of soil and / or a liquid medium and a negative electrode configured to be in contact with a second area of soil and / or a liquid medium. The apparatus further comprises a power supply electrically connected to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism and / or an electrotropic plant root. According to a second aspect, there is described a method. The method comprises providing an apparatus for crop management. The apparatus is configured to be positioned adjacent to the root of a plant and comprises a positive electrode, a negative electrode and a power supply. The method further comprises configuring the positive electrode to be in contact with a first area of soil and / or a liquid medium and configuring the negative electrode to be in contact with a second area of soil and / or a liquid medium. The method further comprises electrically connecting a power supply to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism and / or an electrotropic plant root. The electrotactic organism may comprise an electrotactic pathogen. The electrotactic pathogen may comprise an oomycete zoospore. The oomycete zoospore may be Phytophthora palmivora. The plant may be one of the following: a cocoa plant, a coconut plant, a palm oil plant, a papaya plant or a rubber tree. The electric field may be tuneable to have the substantially same electric field profile as the adjacent plant root. The electric field may be tuneable to have an electric field profile that is attractive to the electrotactic organism. The electrotropic plant root may be adjacent to the apparatus. The electrotactic organism may be a nematode. The electric field may be tuneable to have an electric field that is attractive to the nematode. The apparatus may further comprise a housing configured to be positioned adjacent to a root of a plant. The positive electrode and negative electrode may be attached to the housing. The housing may comprise a column for insertion into the soil and / or liquid medium. The positive electrode may be positioned on a first area of the column. The negative electrode may be positioned on a second area of the column. The electric field may be located adjacent to or surrounding the column. The electric field may be parallel to the root of the plants or perpendicular to the root of the plants depending on the placement of the positive and negative electrode. The housing may comprise a frame for holding the soil and / or liquid medium. The positive electrode may be positioned along a top portion of the soil and / or liquid medium and the negative electrode may be positioned along a bottom portion of the soil and / or liquid medium, where the top portion is above the bottom portion. Alternatively, The positive electrode may be positioned on a first side of the box adjacent to a root of a first plant and the negative electrode may be positioned on a second side of the box adjacent to a root of a second plant. The electric field may be located in an area between the root of the first plant and the root of the second plant. The strength of the electric field may be between 0.1 V / cm to 10 V / cm. The current of the electric field may be between 100 pA to 1000 pA. The power supply is a renewable power supply source. The housing may be 3D printed. The tuneable electric field may be applied for a period of 2 hours. The tuneable electric field is applied at a 45 mm range from the root of the plant. BRIEF DESCRIPTION OF THE FIGURES Embodiments of the invention will now be described by way of example only with reference to the figures, in which: FIG. 1A shows, by way of example, the life cycle of a zoospore. FIG. 1B shows, by way of example, a plant root and its natural ionic flows in the surrounding zone. FIG. 2 shows, by way of example, a perspective view of an apparatus for insertion into the soil. FIGS. 3A to 3D show, by way of example, different views of the column of FIG. 2. FIG. 4 shows, by way of example, a first housing according to the present disclosure. FIGS. 5A to 5D show, by way of example, different views of the first housing of FIG. 4. FIG. 6 shows, by way of example, a second housing according to the present disclosure. FIGS. 7A to 7D show, by way of example, different views of the second housing of FIG. 6. FIGS. 8A to 8C show, by way of example, distracting pathogens from a plant root using a local and global electric field. FIGS. 9Aand 9B show, byway of example, graphs of the efficacy of global and local electric field application. FIGS. 10A and 10B show, by way of example, graphs which compare placement of a local electric field. FIGS. 11Aand 11Bshow, by way of example, graphs which compare pathogen biomass with respect to the different type of configuration (e.g. local vs global). FIGS. 12A and 12B show, by way of example, graphs which compare root growth and gravitropism response angle for an applied electric field. FIGS. 13A, 13B and 13C show, by way of example, graphs to compare fresh weight, dry weight and leaf number of plant biomass for an applied electric field. FIG. 14 shows, by way of example, a method according to the present disclosure. DETAILED DESCRIPTION The disclosure herein has several applications. A first application of the disclosure herein is for use in protecting the roots of crops from electrotactic organisms, which include electrotactic soil pathogens (e.g. oomycete zoospores and nematodes). Initially the first application will be discussed. A second application of the disclosure is for controlling an electrotropic plant root. An organism is herein defined as any living thing that functions as an individual. An organism has autonomous reproduction, growth, and metabolism. An organism is herein defined to include soil pathogens. Soil pathogens include microorganisms (e.g. oomycete zoospores) and animals (e.g. nematodes). Electrotactic organisms are organisms which navigate or swim towards a positive or negative charge when exposed to an electric field in vitro. A microorganism, also known as a microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. A microorganism may include any microscopic organism, such as an oomycete, bacterium, virus, or fungus. Electrotactic microorganisms are microorganism which navigate or swim towards a positive or negative charge when exposed to an electric field in vitro. An electrotactic organism may include, but is not limited to, an electrotactic soil pathogen such as an electrotactic nematode. The first application of the disclosure herein protecting the roots of crops from electrotactic organisms, such as electrotactic pathogens. The disclosure herein aims to use external electric fields to divert electrotactic organisms away from a plant root thus acting as a crop protection system. A soil pathogen is a disease-causing agent which lives both in soil and in a plant host, and which will tend to infect undiseased plants which are grown in that soil. Common soil borne pathogens include Fusarium, Pythium, Rhizoctonia, Phytophthora, Verticillium, Rhizopus Thielaviopsis, and nematodes including Meloidogyne. A particular soil pathogen investigated with respect to the disclosure is Phytophthora palmivora. Some soil pathogens such as Phytophthora palmivora are known to be electrotactic. Phytophthora palmivoral is an oomycete. Other important pathogenic oomycete known to be electrotactic are Phytophthora infestans and Pythium aphanidermatum which are known for attacking soybeans, beets, peppers, chrysanthemum, cucurbits, cotton and turf-grasses. C. elegans are a type of nematode soil pathogen that has been shown to be electrotactic. Other electrotactic nematodes are Meloidogyne javanica and Meloidogyne hapla. A further application of the disclosure herein is for controlling an electrotropic plant root. Root electrotropism, also known as galvanotropism, is the ability of plant roots to sense and grow toward or away from electric charges, or to align with local electric fields and ionic currents. Several types of cells such as nerve cells, muscle cells, fibroblasts, epithelial cells, green algae, spores, and pollen tubes, among others, have been already reported to respond by either growing or migrating in a preferential direction when exposed to an electric field. First recorded in 1882 (Elfving F (1882) Ueber eine Wirkung des galvanischen Stromes auf wachsende Wurzeln. Bot Zeit 40: 257-264) and rediscovered at the start of the 20th century (Ewart AJ, Bayliss JS (1905) On the nature of the galvanotropic irritability of roots. Proc R Soc Lond Ser B 77: 63-66), root electrotropism has been studied sporadically in maize (Zea mays), peas (Pisum sativum), and bean (Vigna mungo) but with contradicting results (Wolverton C, Mullen JL, Ishikawam H, Evans ML (2000) Two distinct regions of response drive differential growth in Vigna root electrotropism. Plant Cell Environ 23: 1275-1280). Crucially, the anatomical and molecular details of sensing electric fields are still largely unknown in roots. However, it is known that electric fields may also dictate the direction of plant root growth. This type of movement results in a curvature of the root. As such the proposed apparatus may be used to control the direction of root growth. Benefits of controlling the direction of root growth include protection of underground infrastructures such as water or gas pipes, houses and roads by guiding plant root growth in the opposite direction and control of root-root competition between nearby plants and optimization of crop field layouts. According to the Food and Agriculture Organization of the United Nations and World Health Organisation, the lack of global food security, or the insufficient availability of safe and nutritious food worldwide is a major crisis. A primary contributor to food scarcity is the continuous reduction in crop yields due to pests and pathogens. They cause up to 40% loss in annual yield worldwide, which costs over USD 220 billion each year. Unfortunately, there is currently no prevention plan in place, highlighting the urgent need for an effective solution. One example pathogen which will be discussed herein, is Phytophthora palmivora, an oomycete pathogen, which affects many plantation crops. Phytophthora palmivora produces motile zoospores that respond to weak electric fields. Phytophthora palmivora is a hemibiotrophic oomycete pathogen endemic to tropical areas. It infects over 200 species of plants and causes up to 90% yield loss at an average annual cost of over USD 1 Billion to plantation crops such as cocoa, coconut, oil palm, papaya and rubber trees. The main symptoms consist of fruit and root rot and no preventative crop protection strategy is currently available. Establishing an effective preventative method is therefore urgent. Phytophthora palmivora infestation of plantations occurs mostly in the rainy season or during irrigation. This is because infection is initiated by motile zoospores that require a liquid substrate to swim towards and attach to plant roots. This is followed by germination and the growth of a mycelium inside the host tissue. The cycle is completed when the oomycete’s fruiting body (sporangium) develops and releases more zoospores. A remarkable characteristic of Phytophthora palmivora zoospores is their electrotactic behaviour when exposed to a weak electric field the spores accumulate at the positive electrode and germination rates increase. Zoospore electrotaxis assumes relevance when considering that plant roots exhibit an endogenous bioelectric field generating external ionic currents between the apical root meristem (more negatively charged) and the proximal elongation zone (more positively charged). Interestingly, plant endogenous bioelectric fields are involved in a variety of biotic interactions, and it has been shown that Phytophthora palmivora zoospores preferentially attach to the positively charged zone of cocoa roots. The disclosure herein uses artificial electric fields to perturb the natural bioelectric interaction between zoospores and roots, to divert zoospores away from plant roots and thus acting as a crop protection system. Set-ups are described to perform and quantify Phytophthora palmivora root infections in hydroponics in the presence of external electric fields. By way of example, the effect of different external electric field intensities and configurations can be shown on different stages of Arabidopsis thaliana and Medicago truncatula root infections. FIG. 1A shows, by way of example, a phytophthora palmivora zoospores 101 lifecycle 100. Phytophthora palmivora infection begins at a plant root 102 when zoospores 101 locate, swim towards and attach to the plant root 102, as shown in FIG. 1 A. The zoospores 101 swim towards the plant root 102, which they recognize through different environmental cues including its endogenous electric field. Once in contact with the plant root 102 surface, zoospores 101 encyst by losing their flagella and adheres to the plant root 102 surface. They then germinate and form an appressoria that penetrates the plant root 102 surface to form an intracellular infection vesicle. Intercellular hyphae then develop into a complex mycelial network. This is followed by the formation of sporangia, which burst when in contact with water thus releasing the next generation of zoospores. Some pathogens, such as phytophthora palmivora zoospores, are electrotactic. Electrotactic zoospores are zoospores which swim towards a positive or negative charge when exposed to an electric field in vitro. Such phenomenon is discussed in Morris BM, Reid B, Gow NAR. “Electrotaxis of zoospores of Phytophthora palmivora at physiologically relevant field strengths”, Plant, Cell &Environment 1992. Morris BM, Gow NAR, “Mechanism of Electrotaxis of Zoospores of Phytopathogenic Fungi”, 1993, further defines the range of electric fields and currents at which the zoospores are responsive as well as described the population movement. Moratto E, Rothery S, Bozkurt TO, et al, “Enhanced germination and electrotactic behaviour of Phytophthora palmivora zoospores in weak electric fields”, Phys Biol 2023, further shows that electric fields increase zoospore germination. Many plant roots produce endogenous electric fields, as shown in FIG. 1B. FIG. 1B shows a plant root 102 with a meristematic zone (i.e. root tip) 103 which is negatively charged and an elongation zone 104 which is positively charged. Electrotactic zoospores use the electric field produced by a plant root 102 to guide the zoospore to the root. As such, a plant root’s 102 endogenous electric field consists of a negatively charged meristematic zone 103 and a positively charged elongation zone 104. Plant endogenous electric fields are involved in a variety of biotic interactions. The disclosure herein aims to use external electric fields to divert zoospores or nematodes or other pathogens away from a plant root thus acting as a crop protection system. Furthermore, the same principle may be used control the plant root itself. The principle may be used to control other roots in area nearby to a specific plant root, such that completion for resources can be controlled and the specific plant root be protected. In this case of attracting a nematode, some nematodes are attracted to a plant root by using the electric field of the plant root to guide the nematodes. Such nematodes are capable of sensing electric fields and using them to guide their motion of travel. Therefore, a mock electric field may be generated to distract or guide a nematode. In the case of controlling the root of plant, some plant roots guide the direction of their growth based on electric fields present in the soil. For example, some plant roots may be attracted towards a positive or negative charge in the soil. Such plant roots are capable of sensing electric fields and using them to guide their direction of growth. Therefore, a mock electric field may be generated to guide the direction of growth of a plant root. Apparatus There are envisioned to be multiple ways to generate an external electric field for the above identified purposes. A global electric field may be used or a local electric field, both providing viable options for diverting zoospores away from the root of a plant and for controlling nematodes and the direction of plant growth. A global electric field is herein defined as an electric field between a positive and negative electrode which span an entire region where the roots are, so that the roots are immersed in the electric field and in the resulting ionic currents. The global electric field typically covers a relatively larger area. For example, a global electric field may cover multiple plants and plant roots over an extensive area. The global electric field may envelop multiple plant roots. A local electric field is herein defined as by a positive electrode and a negative electrode that are in a ‘mock root’ configuration and generate a smaller electric field which does not include the plant roots.. The local electric field, typically covers a relatively smaller area than the global electric field. For example, a local electric field may be generated by a ‘mock root’ arrangement whereby an apparatus is used to generate an electric field which is either substantially identical to or closely resembles a plant root to which it is to be located next to. Both examples of apparatus’ for generating a local electric field (see FIGS. 2 to 5) and for generating a global electric field (see FIGS. 6 to 7) will be discussed herein. There is herein provided an apparatus for crop management. The apparatus includes a housing configured to be positioned adjacent to a root of a plant. The housing may be any element capable of supporting an electrode and the example disclosures herein are not in any way intended to limit the scope of the term ‘housing’. Indeed, a housing may refer to any structural component which may be inserted into a soil or other liquid medium to allow an electric field to be applied across the soil or liquid medium. In some embodiments, the housing may be a ‘mock root’ configuration. In other embodiments the housing may support both a positive electrode and a negative electrode in the soil. In another embodiment, separate housing may be used to support each of a positive and negative electrode in the soil. In some scenarios, the housing may not be required at all and the positive and negative electrode may be inserted into the soil or liquid medium without a housing structure present. In some scenarios the housing may be designed to be large to cover an area adjacent to multiple plant roots and / or the roots of several different plants. In some scenarios the housing may be smaller and may only cover one or a small number of roots. The housing may be designed to cover the roots of only one plant. The housing being positioned adjacent to a root of a plant may mean that the housing is directly next to a root of the plant, touching the root of a plant or within a predetermined distance from the root of the plant. The predetermined distance may for example be in the range of 0 to 10 millimetres, 0 to 100 centimetres or within a range of 1-5 meters. In some embodiments, the housing may be 3D printed according to a specification. The apparatus further includes a positive electrode attached to the housing and configured to be in contact with a first area of soil or a liquid medium and a negative electrode attached to the housing and configured to be in contact with a second area of soil or a liquid medium. Positive and negative electrode may be in contact with soil in the situation where the root of a plant is planted in soil. Alternatively or additionally, the positive and negative electrode may be in contact with a liquid in the situation where the root of a plant is suspended in a liquid medium such as in a laboratory or in a hydroponic situation where a plant root is cultivated in a liquid medium. As such the liquid medium may be water or a water-based solution. The apparatus further includes a power supply electrically connected to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode. The power supply may be a solar power supply, connected to mains power, a battery supply or any other form of renewal power generation. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism (e.g. soil pathogen) and / or an electrotropic plant root. The term tuneable electric field is herein defined to mean an electric field that may be adjusted to vary the intensity or profile of the electric field (including the intensity of the force of the electric field, direction of the field and overall geometric profile of the field in three dimensions) according to the desire outcome of the apparatus. The electric field may be tuned by controlling the power output by the power supply, or by a control system which is configured to vary the intensity or geometry of the electric field. The control system may be configured to be input with information by a user via a graphical user interface (GUI) to adjust the electric field. The electric field may be tuned prior or during to positioning of the apparatus next to a plant root or after the apparatus has been positioned. In the situation where the electric field is configured to attract an electrotactic organism (e.g. soil pathogen), the electric field may be tuned to mimic the electric field profile of an adjacent root, such that the electric field of the apparatus distracts a electrotactic organism away from the plant root and instead the pathogen is attracted towards the local or global electric field. Alternatively, the electric field may be tuned to m im ic an electric field that is especially attractive to a particular species of nematode and as such the nematode may have a more powerful attraction to the mock electric field than any nearby electric fields generated by plant roots or otherwise. As such, the migration of nematodes through soil may be achieved by use of the mock electric field generated by the apparatus. In the situation where the electric field is configured to attract the root of a plant, the electric field may be tuned to be an electric field profile that is especially attractive to a particular species of plant and thereby plant root, and as such the plant root may have a more powerful attraction to the mock electric field than any nearby electric fields present in the general vicinity of the plant root. Therefore, the direction location of the plant root in the soil and / or liquid medium may be varied by applying the mock electric field. This may be obtained by controlling the direction of growth or movement of the plant root. The apparatus may be suitable for all of the above described uses and the electric field may therefore be varied by a user according to the present intended use of the apparatus. The electric field profile may comprise a particular spatial pattern (for example, a geometric configuration, horizontal, vertical, etc) and / or temporal pattern (sequence of on / off, intermittent, variable intensities, etc). The spatial pattern and temporal pattern may be varied to tailor the electric field to attract a desired organism. By way of example, the strength of the electric field may be in the region of between 0.1 V / cm to 10 V / cm. By way of example, the current of the electric field may be in the region of between 100 pA to 1000 pA. In particular, such a n electric field strength may be useful for plant species such as tests performed on Phytophthora palmivora root infections. Other plant species (e.g. tree’s roots) might require stronger fields to work. A relatively low current is useful for capturing soil pathogens without killing them or the plants themselves which it is aimed to protect. It is useful to capture soil pathogens for further biological analysis. As such, it is not the strength of the electric field that is important but instead the idea of applying these electric fields to distract electrotactic organisms and control electrotropic path roots. Example apparatus for crop management according to the disclosure herein are shown in FIGS. 2 to 7. FIGS. 2 to 5 show examples of apparatus for applying a local electric field and FIGS. 6 and 7 shows examples of apparatus for applying a global electric field. The global electric field surrounds the plant roots with the positive electrode located further away from the roots and is designed to cover a larger area of plant roots. Whereas the local electric field is placed to the side of the plant roots and may be immediately adjacent to the plant root. FIG. 2 shows an apparatus 200 with a housing 201 configured to be positioned adjacent to a root of a plant. The housing 201 may comprise a column 202 for insertion into the soil or liquid medium (as shown in FIG. 2) which provides a local electric field designed to emulate a plant root, in other words to generate a ‘mock root’. The apparatus 200 further comprises a positive electrode (not shown) attached to the housing 201 and / or column 201 and configured to be in contact with a first area of soil and / or a liquid medium. The positive electrode may be positioned on a first area of the column 201. The apparatus further comprises a negative electrode (not shown) attached to the housing 200 and / or column 201 and configured to be in contact with a second area of soil and / or a liquid medium. The negative electrode may be positioned on a second area of the column 201. The first area and second area of the column may be opposite sides of the column 201, such as either side of a cylindrical portion of the column 201 or located at the top and bottom of the column respectively. A power supply (not shown) is electrically connected to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode. The electric field may be generated in the area surrounding or adjacent to the entire apparatus 200. The profile of the electric field will depend on where the positive and negative electrode are located on the apparatus 200. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism (e.g. soil pathogen) and / or an electrotropic plant root. The column may be referred to as a ‘mock root’ as it is designed to emulate the electric field properties of adjacent plant roots. FIGS. 3A-3D show example perspective views of the apparatus of FIG. 2. FIG. 3A shows a vertical side profile view of the column 201. The column 201 includes a bottom tip 202 which may be located at the bottom of the column 201 when the 12 apparatus is placed into the soil and / or liquid medium. The column 201 also includes a top 203 which may be located at the top of the column 201 when the apparatus is placed into the soil and / or liquid medium. The column may also include a window 204 which may be configured to hold a portion of soil or the liquid medium to which the column is to be inserted. The window 204 may also be configured to help position the positive and negative electrode and / or to hold the power supply for the electrodes. Alternatively, the power supply may be located external to the column 201. For example, the column 201 may be inserted into the soil or liquid medium whilst a power supply can be located above the surface of the soil or liquid medium. This is especially helpful in the scenario where the power supply is solar powered such that the suns ray can protrude onto the surface of a solar panel. FIG. 3B shows a perspective view of the column 201. FIG. 3C shows a top 203 view of the column 201. FIG. 3D shows a horizontal side profile view of the column 201. Protrusions 205 from the column 201 may be seen in FIG. 3D which may align with the window 204 of the column 201. The protrusions 205 may allow the column 201 to grip and embed into the soil or may be used to hold or grip the positive or negative electrode. The shape of the apparatus 200 shown in FIG. 3A-3D is by way of example only and in no way limiting on proposed design of the apparatus. FIG. 4 shows an apparatus 400 with a housing 401 configured to be positioned adjacent to a root 402 of a plant 403. The housing 401 may comprise a box 405 (with a frame-like structure) for holding the soil or liquid medium which supports the roots 402 of the plant 403. The apparatus 400 provides a local electric field designed to emulate a plant root. The apparatus 400 further comprises a positive electrode 406 attached to the housing 401 and / or box 405 and configured to be in contact with a first area of soil and / or a liquid medium. The positive electrode 406 may be positioned on a first side of the box adjacent to a root of a first plant. The apparatus 400 further comprises a negative electrode 407 attached to the housing 400 and / or box 405 and configured to be in contact with a second area of soil and / or a liquid medium. The first area and second area of soil and / or liquid medium may be substantially the same area of soil and / or liquid medium. As such the positive electrode 406 and negative electrode 407 may be located very close to each other. The negative electrode 407 may be positioned on the same first side of the box 405 as the positive electrode 406 adjacent to the root of the first plant. As such, a column like structure similar to the structure shown in FIG. 2 may be formed, however, the column like structure is supported by 13 the box 405 to provide integrity to the apparatus 400. A power supply (not shown) is electrically connected to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode. The electric field may be generated in the area surrounding or adjacent to the entire apparatus 400. The profile of the electric field will depend on where the positive electrode 406 and negative electrode 407 are located on the apparatus 400. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism (e.g. soil pathogen) and / or an electrotropic plant root. The configuration of FIG. 4 may be referred to as a ‘mock root’ which is designed to emulate the electric field properties of adjacent plant roots. A local electric field is generated in a small area surrounding where the positive electrode 406 and negative electrode 407 are located. FIGS. 5A-5D show example perspective views of the apparatus of FIG. 4. FIG. 5A shows a top profile view of the apparatus 400. The apparatus includes a frame 409 for supporting the soil and / or liquid medium and the positive electrode 406 and negative electrode 407. The frame 409 may also support the plant and plant roots themselves. The top view of FIG. 5A of the apparatus shows holes 408 for positioning plants 403 and the positive electrode 406 and negative electrode 407. FIG. 5B shows a bottom perspective view of the apparatus 400. FIG. 5C shows a first side view profile of the apparatus 400. FIG. 5D shows a second side profile view of the apparatus 400. The shape of the apparatus 400 shown in FIG. 5A-5D is by way of example only and in no way limiting on proposed design of the apparatus. FIG. 6 shows an apparatus 600 with a housing 601 configured to be positioned adjacent to a root 602 of a plant 603. The housing 601 may comprise a box 605 (with a frame-like structure) for holding the soil or liquid medium which supports the roots 602 of the plant 603. The apparatus 600 provides a global electric field designed to generate an electric field in the vicinity of the apparatus 600. The apparatus 600 further comprises a positive electrode 606 attached to the housing 601 and / or box 605 and configured to be in contact with a first area of soil and / or a liquid medium. The apparatus 600 further comprises a negative electrode 607 attached to the housing 600 and / or box 605 and configured to be in contact with a second area of soil or a liquid medium. In a configuration as shown in FIG. 6, the positive electrode may be positioned along a top portion 608 of the soil and / or liquid medium and the negative electrode may be positioned along a bottom portion 609 of the soil and / or liquid 14 medium, where the top portion 608 is above the bottom portion 609. In such a configuration, the electric field located in an area between the top portion 608 and bottom portion 609. In an alternative configuration, the positive electrode 606 may be positioned on a first side of the box adjacent to a root of a first plant. The negative electrode 607 may be positioned on a second side of the box adjacent to a root of a second plant. The first area and second area of soil and / or liquid medium may be located in different areas of soil and / or liquid medium. An area between the root of the first plant and the root of the second plant, may comprise a root of a third plant or multiple other plant roots. The electric field may be parallel to the root of the plants or perpendicular to the root of the plants depending on the placement of the positive and negative electrode. The positive electrode 606 and negative electrode 607 may be located relatively far apart from each other. The negative electrode 607 may be positioned on the first side or top of the box 605 as the and the positive electrode 606 may be located on the second side or bottom of the box 605. As such, a global electric field may be generated which extends across the entire apparatus. A power supply (not shown) is electrically connected to the positive electrode 606 and the negative electrode 607, such that an electric field is generated between the positive electrode and the negative electrode. The electric field may be generated in the area surrounding or adjacent to the entire apparatus 600. The profile of the electric field will depend on where the positive electrode 606 and negative electrode 607 are located on the apparatus 600. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism (e.g. soil pathogen) and / or an electrotropic plant root. The configuration of FIG. 6 may be referred to as a global electric field extending across a range of plant and plant roots as the apparatus generates a larger electric field than the mock plant root. FIGS. 7A-7D show example perspective views of the apparatus of FIG. 6. The structure of the apparatus shown in FIGS. 7A-7D is similar the structure of the apparatus shown in FIGS. 5A-5D however it is slightly modified to better suit the global electric field scenario. FIG. 7A shows a top profile view of the apparatus 600. The apparatus includes a frame 609 for supporting the soil and / or liquid medium and the positive electrode 606 and negative electrode 607. The frame 609 may also support the plant and plant roots themselves. The top view of FIG. 7A of the apparatus shows holes 608 for positioning plants 603 and the positive electrode 606 and negative 15 electrode 607. FIG. 7B shows a bottom perspective view of the apparatus 600. FIG. 7C shows a first side view profile of the apparatus 600. FIG. 7D shows a second side profile view of the apparatus 600. The apparatus may incorporate a groove rail610 which extends around the frame 609 of the apparatus 600 to accommodate a flat electrode. The shape of the apparatus 600 shown in FIG. 7A-7D is by way of example only and in no way limiting on proposed design of the apparatus. Applications The described apparatus may have the applications as previous discussed, including for use in distracting pathogens from soil roots to protect crops. The pathogen comprises an electrotactic pathogen, such as Phytophthora palmivora zoospores. Phytophthora palmivora zoospores are pathogens for plants such as a cocoa plant, a coconut plant, a palm oil plant, a papaya plant or a rubber tree. FIGS. 8A-8C show how the proposed apparatus may work for distracting pathogens away from the roots of plants, such as in the example of Phytophthora palmivora zoospores. FIG. 8A shows an example of a control system 801 including a plant 802 with roots 803 where no electric field is applied. Pathogens 804 exist in soil surrounding the plant roots 803 and are evenly distributed throughout the soil. FIG. 8B shows an example of a system 810 which is similar to the control system 801 where a local electric field 811 is applied. The local electric field 811 is applied to the left hand side of the system 810 and the pathogens 804 are attracted towards the local electric field. This means that there are fewer pathogens 804 surrounding the plant roots 803. The electric field may be parallel to the root of the plants (as shown in FIG. 8B) or perpendicular to the root of the plants depending on the placement of the positive and negative electrode. FIG. 8C shows an example of a system 820 which is similar to the control system 801 where a global electric field 821 is applied. The global electric field 821 is applied to the bottom of the system 820 and the pathogens 804 are attracted towards the positive charge of the global electric field. Other example pathogens could be attracted to a negative electric charge. There are fewer pathogens 804 surrounding the plant roots 803. Both the global and local electric fields may act as means to distract the pathogens from the plant roots and thereby limit the damage caused by pathogens to the plant roots. The electric field is tuneable such that it may have substantially same electric field profile as the adjacent plant root in order to mimic the plant root closely. In some embodiments, a further feature may be applied to the apparatus to kill or denature the pathogens such that once they enticed away from the plant root they are unable to reproduce or re-enter the vicinity of the plant root. A stronger, localised, electric field could be used to kill the pathogens. Alternatively, the mock root could contain non-diffusible chemicals to kill locally the pathogen. Furthermore, trapping and recovering alive pathogens might be useful for identification of what species are living in that soil and what their level of virulence is since some biological tests require the sample to be alive. A further application of the disclosure is for controlling an electrotropic plant root. Root electrotropism, also known as galvanotropism, is the ability of plant roots to sense and grow toward or away from electric charges, or to align with local electric fields and ionic currents. Several types of cells such as nerve cells, muscle cells, fibroblasts, epithelial cells, green algae, spores, and pollen tubes, among others, have been already reported to respond by either growing or migrating in a preferential direction when exposed to an electric field. Some multicellular organisms such as some nematodes have been shown as electrotactic. Electric fields may also dictate the direction of plant root growth. This type of movement results in a curvature of the root. Although the mechanism of root electrotropism is not entirely known, it is clear that different root regions have different behaviours in response to electricity. Furthermore, plants treated with an electric field are able to uptake water and nutrients differently, leading to differential plant growth in electric field conditions. As such the proposed apparatus may be used to control the direction of root growth. The mechanism includes applying a weak electric field, such as an electric field of between 0.5 and 2.5 V / cm to plants and a change in the direction of root growth is observed. In such a scenario, the electric field may be tuned to be the intensity and profile (including spatial pattern and temporal pattern) that is most attractive (or repellent) to a plant root in order to control the plant root at the fastest rate. There may be a range of desired intensities that may be used for controlling the plant root. An example application of the disclosure is for controlling a nematode (which is a type of electrotactic organism). Certain nematodes are known for being guided by electric fields. Some nematode larvae have been found to "surf" electric fields generated by insects since they are able to sense the electric field. This allows them to leap into the air and land on passing insects, using them as a mode of transportation. Furthermore, some parasitic nematodes have been shown to use static 17 electricity to their benefit. They can be attracted to the electric charge on insects, increasing their chances of latching onto a suitable host. Therefore the electric field generated by the proposed disclosure may be used to attract nematodes. This is helpful for deterring parasitic nematodes. In such an application, the electric field is tuneable to have an electric field that is attractive to the nematode. This may depend on the type of nematode. Example Experiments By way of example only, the disclosure herein has been tested on exposed the roots of two plant species, Arabidopsis thaliana and Medicago truncatula (hereafter referred to as Arabidopsis and Medicago) for the pathogen phytophthora palmivora, to an external electric field in the local electric field configuration and the global electric field configuration. The plant roots were exposed the electric field for a period of 2 hours, however, a longer or shorter timeframe could be used depending on the requirement of the plant species being protected by the proposed solution. The number of spores attached to each root were counted to observe the effect of the electric field on the early stages of infection. Wild-type Arabidopsis thaliana (Col-0) and wild-type Medicago truncatula (DZA315) were used in the present examples. Arabidopsis seeds were imbibed in water and kept in the dark for 2 days at 4°C to synchronize germination. All seeds were surface sterilized using 50% Haychlor bleach and 0.0005% Triton X-100 for 3 minutes and then rinsed 6 times with sterilized Milli-Q water. Seeds were germinated and grown in nurseries. Briefly, seeds were sown individually inside tubes filled with a gel medium and the tubes had their end cut out to allow the root to grow through, and placed in a boxes. These “germination” or “nursery” boxes were placed in a growth chamber at 23 °C, with a 16 h / 8 h light / dark photoperiod and light intensity of 120 pmol / m2s. For Medicago truncatula (DZA315), seeds underwent initial scarification using sandpaper, followed by a thorough 90-second wash with 12% bleach. The treated seeds were subsequently rinsed six times with sterilized Milli-Q water. After this process, the seeds were plated onto 0.8% agar plates and kept in darkness at 4°C for three days. The seeds were later sown on a 1 MS plate and maintained at 22°C with 16 h / 8 h light / dark photoperiod and light intensity of 120 pmol / m2s. All experiments were conducted with primary roots of seedlings 5-8 days post-germination. For the global electric field configuration, two long foil electrodes were immersed in the medium and placed underneath (positive electrode) and above the 18 roots (negative electrode) as shown in FIG. 6. For the local EF configuration, a 3D printed cylindrical support mock root was used with two short foil electrodes as shown in FIG. 2. The mock root is slotted in the box next to the plant roots as shown in Fig. 4. In both cases, the electrodes are connected to a power supply to generate an electric field and an ionic current parallel to the growing roots. Apparatus generation The apparatus used was generated by CAD software and printed using a 3D printer. The artificial root was designed and printed in the same way. For the global electric field configuration, three platinum-iridium foils with 5 perforations were slotted in the top electrode compartment, and three more were clipped in the bottom one with the file clip. For the local electric field configuration, two platinum-iridium foils were cut to size and slotted in the two compartments of the artificial root. The ‘mock root’ was then inserted in the apparatus. The system is enclosed in a glass jar containing 2L of 1 / 500 liquid medium and wired to a power supply. Electric field tolerance assay For the root electric field tolerance assay in hydroponics, each tube containing a single 7 to 10-day-old seedling was transferred to the box. The plantlets were then exposed to 250 pA for 24h and plated on agarose plates placed vertically. Images were taken 48h later and root growth and gravitropic response angles were measured using Imaged. For the root electric field tolerance assay in soil, Arabidopsis and Medicago were transplanted to a soil-vermiculate mixture. Arabidopsis seedlings were placed in groups of 16 per pot, while Medicago seedlings were placed in groups of 7 per pot. Artificial roots were inserted into the corners of the pots. Following a two-week growth period, data were collected for leaf count, fresh weight, and dry weight. Dry weight was determined through freeze drying. Root infection assay and confocal microscopy For infection assays, each tube containing a single 7 to 10-day-old seedling was transferred to the V-box and 1 mL of spore solution (50000 spores / mL) was pipetted after the electric field was turned on. The roots were then removed after 2h for live confocal imaging or and 24h for biomass quantification. Infected plantlets were mounted on slides using water and the coverslip adhered using surface tension. Leica TCS SP5 resonant inverted confocal microscope was used for the visualization with the 10x dry and 63x water immersion 19 lenses. The number of zoospores attached to the root were counted using the cell counter tool in Imaged software and is calculated as follows: sr ^norm ""~ Jmax where sris the number of spores attached to the root of interest with r = {1; 2; 3; 4; 5} and sma^is the maximum number of spores attached to a root within the same technical repeat. Example test results A test was applied to determine the efficacy of global and local electric field application. To show that an external electric field can affect early-stage root infection, the global configuration was used to expose roots to nominal EFs known to cause P. palmivora zoospore electrotaxis at electric field strengths of 0.5 V / cm, 0.7 V / cm and 1.0 V / cm, with the corresponding current and current density measured in the system (Error! Reference source not found.). After 2h exposure, when zoospore attachment and germination had taken place, the roots were observed under a confocal microscope and calculated a spore attachment index normalised to take into account variation in total spore numbers within each replicate. Nominal EF Current (mean Current density (mean ± (V / cm) ± s.e.m.) s.e.m.) 0.5 V / cm 134 ±20 pA 0.2 ± 0.03 pA / mm2 0.7 V / cm 253 ± 53 pA 0.4 ± 0.09 pA / mm2 1.0 V / cm 309 ± 63 pA 0.5 ±0.10 pA / mm2 Table 1 Average electrical currents and current density measured for each global nominal electric field applied. Then the effect of the local EF configuration was shown on spore attachment to Arabidopsis roots, applying 6.0 V / cm to obtain a current -250 pA through the mock root. With this experiment, we aimed to match the lowest best-performing current produced by the global configuration (Table 1). As in the case of the global configuration, confocal imaging showed a statistically significant reduction of spores attached to roots in the presence of the local EF when compared to the control without electric field. It was found that both the global electric field configuration and the local electric field confirmation significantly reduced spore attachment in Arabidopsis and Medicago roots as shown in FIG. 9A and FIG. 9B. FIG. 9A shows that a global electric field is more effective at reducing spore attachment to Arabidopsis roots regardless of current intensity. Distributions of the proportion of spores on the surface of Arabidopsis roots exposed to 250 pA (left panel of FIG. 9A) and 550 pA (right panel of FIG. 9A) of current in the global and local electric field configurations. Each point marked on the graph represents the number of zoospores attached to one root each rep has 5 roots. FIG. 9B shows that global and local electric fields similarly reduce spore attachment to Medicago roots at 250 pA. Distributions of the proportion of spores on the surface of Medicago roots exposed to 250 pA in the global and local electric field configurations. Each point marked on the graph represents the number of zoospores attached to one root each rep has 5 roots. Therefore, in Medicago roots both configurations equally reduced spore attachment (FIG. 9B) while in Arabidopsis the global electric field always led to a greater reduction regardless of the current intensity (FIG. 9A). This is likely because the local electric field acts as a competitor to the plants’ endogenous electric field while the global configuration probably combines competition and camouflage by displacing the ionic currents around the plant roots. A further test was also applied to determine the ideal distance placement of a local electric field from a plant root. FIG. 10A shows that a local electric field significantly reduces spore attachment to all roots exposed. Distributions of the proportion of spores on the surface of Arabidopsis roots were exposed to 550 pA generated by the local electric field. Each point marked on the graph represents the proportion of zoospores attached to one root each rep has 5 roots. FIG. 10B shows a local electric field acts most effectively at a 45 mm range. Distributions of the proportion of spores on the surface of Arabidopsis roots were exposed to 550 pA generated by the local electric field. The x-axis of FIG. 10B describes the distance of the root from the local electric field. It is observed that, while the local electric field reduced overall spore attachment to all roots (FIG. 10 A) better protection is given to the root at a 45 mm distance from the local electric field (FIG. 10B). This indicates that a local electric field’s effectiveness is dependent on mock root distance from the plant. A further test was also applied to quantify the electric field effect on pathogen biomass after 24 h infection. It is shown that global and local electric fields generating a current of 225 pA significantly reduce P. palmivora biomass after 24h exposure. FIG. 11A shows biomass reduction of P. palmivora in Arabidopsis roots based on relative expression of P. palmivora housekeeping gene EF1a normalised on Arabidopsis 21 housekeeping gene atUBC21. FIG. 11B shows biomass reduction of P. palmivora in Medicago roots based on relative expression of P. palmivora housekeeping gene WS21 normalised on Arabidopsis housekeeping gene mtUBC21. It is observed that a significant reduction in biomass for both Arabidopsis and Medicago (FIGS. 11A and 11B) indicating that electric field exposure influences overall infection, not just spore attachment. A further test was also applied to expose Arabidopsis roots to a global electric field generating a current of 250 pA for 24h in hydroponic conditions. It is observed that there is no change in root growth or ability to respond to gravity (FIGS. 12A and 12B) suggesting electric field exposure causes no short-term damage to the plant. This is advantageous as it means that Arabidopsis is not susceptible to damage via the proposed solution and only the positive effects of pathogen elimination are obtained. FIG. 12A shows the distribution of root growth and FIG. 12B shows the gravitropism response of seedlings exposed to 250 pA produced by a global electric field for 24h. Each point of the graphs represents one root. A final test was also applied to expose Arabidopsis and Medicago roots to a current of 250 pA produced by a local electric field in soil for 14 days. It is observed that there are no changes in leaf number or plant biomass (fresh and dry weight) (FIGS. 13A, 13B, 13C) suggesting long-term exposure does not affect overall plant health. FIG. 13 shows the distribution of fresh weight (FIG. 13A), dry weight (FIG. 13.B) and leaf number (FIG. 13C) of seedlings exposed to 250 pA produced by a local electric field in soil for 14 days. Each point on the graph represents one root. Method FIG. 14 shows, by way of example, a flowchart of a method 400 according to example embodiments. Each element of the flowchart may comprise one or more operations. The operations may be performed in hardware, software, firmware or a combination thereof. For example, the operations may be performed, individually or collectively, by a means, wherein the means may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the performance of the operations. The method 1400 is performed by an apparatus. The apparatus may be the apparatus according to any of FIGS. 2 to 7. The method 1400 may comprise a first operation 1401 of providing an apparatus for crop management. The apparatus is configured to be positioned 22 adjacent to the root of a plant and comprises a positive electrode, a negative electrode and a power supply. The apparatus may also include a housing and the first operation 1401 may include positing the housing may be positioned in soil or the liquid medium adjacent to the root of a plant. Positioning of the housing may be carried out by a user of the apparatus of automatically by robotic machinery. The method 1400 may comprise a second operation 1402 of configuring the positive electrode to be in contact with a first area of soil and / or a liquid medium. The second operation 1402 may include attaching the positive electrode to the housing. The positive electrode may be attached to the housing prior to, during or after positioning of the housing adjacent to the plant. The positioning of the positive electrode may be modified or tweaked in order to tune the generated electric field. The method 1400 may comprise a third operation 1403 configuring the negative electrode to be in contact with a second area of soil and / or a liquid medium. The third operation 1403 may include attaching the negative electrode to the housing. The negative electrode may be attached to the housing prior to, during or after positioning of the housing adjacent to the plant. The positioning of the negative electrode may also be modified or tweaked in order to tune the generated electric field. The method 1400 may comprise a fourth operation 1404 of electrically connecting a power supply to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode. The electric field is tuneable and configured to attract at least one of the following: an electrotactic organism (e.g. soil pathogen) and / or an electrotropic plant root. The power supply may be attached to the housing prior to, during or after positioning of the housing adjacent to the plant. The power supply may be interchangeable, for example, to change the power supply from solar powered during the day to battery powered during the night. The method 1400 may optionally comprise a further operation of tuning the electric field to a desired intensity or profile. For example, the purpose of the electric field may be determined (e.g. to attract an electrotactic microorganism and / or an electrotropic plant root) and then the appropriate electric field may be chosen for that purpose. While the present invention has been described with reference to the exemplary embodiments thereof, it should be understood that the present invention is not limited thereto, and a person of ordinary skill in the art to which the present invention pertains 23 may make modifications and variations thereto, and such modifications or variations are within the scope of the appended claims.

Claims

1. An apparatus for crop management configured to be positioned adjacent to the root of a plant, comprising:a positive electrode configured to be in contact with a first area of soil and / or a liquid medium;a negative electrode configured to be in contact with a second area of soil and / or a liquid medium; anda power supply electrically connected to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode;wherein the electric field is tuneable and configured to attract at least one of the following:an electrotactic organism and / or an electrotropic plant root.

2. The apparatus of claim 1, wherein the electrotactic organism comprises an electrotactic pathogen.

3. The apparatus of claim 2, wherein the electrotactic pathogen comprises an oomycete zoospore.

4. The apparatus of claim 3, wherein the plant is one of the following: a cocoa plant, a coconut plant, a palm oil plant, a papaya plant or a rubber tree.

5. The apparatus of any of any preceding claim, wherein the electric field is tuneable to have the substantially same electric field profile as the adjacent plant root.

6. The apparatus of any preceding claim, wherein the electric field is tuneable to have an electric field profile that is attractive to the electrotactic organism.

7. The apparatus of any preceding claim, wherein the electrotropic plant root is adjacent to the apparatus.

8. The apparatus of any preceding claim, wherein the electrotactic organism is a nematode.

9. The apparatus of claim 8, wherein the electric field is tuneable to have an electric field that is attractive to the nematode.

10. The apparatus of any of any preceding claim, further comprising:a housing configured to be positioned adjacent to a root of a plant; andwherein the positive electrode and negative electrode are attached to the housing.

11. The apparatus of claim 10, wherein:the housing comprises a column for insertion into the soil and / or liquid medium;the positive electrode is positioned on a first area of the column;the negative electrode is positioned on a second area of the column; andthe electric field is located adjacent to or surrounding the column.

12. The apparatus of any preceding claim, wherein the electric field is parallel to the root of the plants or perpendicular to the root of the plants.

13. The apparatus of claim 10, wherein:the housing comprises a frame for holding the soil and / or liquid medium;the positive electrode is positioned along a top portion of the soil and / or liquid medium;the negative electrode is positioned along a bottom portion of the soil and / or liquid medium, where the top portion is above the bottom portion; andthe electric field is located in an area between the top portion and bottom portion.

14. The apparatus of claim 10, wherein:the housing comprises a frame for holding the soil and / or liquid medium;the positive electrode is positioned on a first side of the box adjacent to a root of a first plant;the negative electrode is positioned on a second side of the box adjacent to a root of a second plant; andthe electric field is located in an area between the root of the first plant and the root of the second plant.

15. The apparatus of claim 14, wherein an area between the root of the first plant and the root of the second plant, comprises a root of a third plant.

16. The apparatus of any preceding claim, wherein the strength of the electric field is between 0.1 V / cm to 10 V / cm.

17. The apparatus of any preceding claim, wherein the current of the electric field is between 100 pA to 1000 pA.

18. The apparatus of any preceding claim, wherein the power supply is a renewable power supply source.

19. The apparatus of any of claims 10 to 14, wherein the housing is 3D printed.

20. A method, comprising:providing an apparatus for crop management, wherein the apparatus is configured to be positioned adjacent to the root of a plant and comprises a positive electrode, a negative electrode and a power supply;configuring the positive electrode to be in contact with a first area of soil and / or a liquid medium;configuring the negative electrode to be in contact with a second area of soil and / or a liquid medium;electrically connecting a power supply to the positive electrode and the negative electrode, such that an electric field is generated between the positive electrode and the negative electrode;wherein the electric field is tuneable and configured to attract at least one of the following:an electrotactic organism and / or an electrotropic plant root.

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