1. Field of the Disclosure
The present disclosure relates to compositions and methods of making a rhizo signaling gel matrix that results in an engineered rhizosphere that alters a plant's water flow dynamics and increases plant drought tolerance. More particularly, the compositions and methods according to the present disclosure alter the rhizosphere rewetting and transpiration of plants.
2. Description of Related Art
Water scarcity is considered a major threat and challenge that must be overcome in the twenty-first century. Further, limited water supply is one of the largest impediments to crop production worldwide. For example, drought is a predominant cause of low crop yields. Increasing a plant's drought tolerance and improving the capacity of agricultural plants to extract water from soil are fundamentally imperative to sustaining a food supply that can meet the increasing food demand caused by modern population growth trends.
Soil drying and rewetting happen at various time intervals and with various degrees of volume or intensity. Wetting, as used herein, means providing water. Soil drying limits root water uptake and affects root synthesis of phytohormones and transport phenomena that regulate leaf growth and gas exchange. Consequently, without an abundant supply of water, crops suffer and yields are reduced.
Plants adapt to abiotic stress by undergoing diverse biochemical and physiological changes that involve hormone-dependent signaling pathways. One such hormone is Abscisic Acid (“ABA”). Exogenous ABA and its analogs have been used in foliar and soil directed spray applications to delay wilting and allow plants to survive short periods of severe drought as a means of maintaining marketability of horticulture and floriculture product and to extend shelf life. However, such sprays and topical applications of ABA do not alter the rhizosphere. The effect is limited over time and generally inconsistent and inefficient. Exogenous ABA has been shown to decrease yields of green and red lettuces. Concentrated exogenous abscisic acid drenches have been shown to reduce root hydraulic conductance and cause wilting in tomato. Other negative side effects include rate-dependent chlorosis of the lower leaves and leaf abscission.
In the face of growing populations and a shifting global climate, various production strategies have been developed to alleviate problems related to droughts and other shortages of water, but at the expense of crop yields. These strategies, which optimize the amount of crop production and water use, are crop specific and require exact knowledge of how a particular crop will respond. Further, these strategies may result in higher soil salinization which limits the effectiveness of such strategies and negatively impacts yield.
Attempts have also been made to use genetic modification to reduce water needs in plants and increase crop yields. However, there are countless concerns regarding genetically modifying crops, including unknown evolutionary consequences to crops and their ecosystem, safety for human consumption, and ethical concerns. Long term health effects in humans of consuming genetically modified crops are unknown.
There are important rhizosphere processes that regulate the availability of water to roots and other physiological and biochemical interactions that occur in the rhizosphere. There is a need to modify the ability of roots to extract water from the soil by managing the rhizosphere properties. Accordingly, there is a need for a system and method for targeted management of plant soil interactions, particularly modification of water dynamics in the rhizosphere and plant transpiration rates, that overcome these and other shortcomings.
The present disclosure provides a rhizo signaling gel matrix and method that modifies rhizosphere hydraulic properties, thereby providing faster and more uniform rewetting of the rhizosphere, increased initial water fluxes from the rhizosphere into the roots, reduced physiological recovery time of a plant after irrigation, and increased overall water availability to plants after irrigation.
The present disclosure provides a rhizo signaling gel matrix and method that engineers or modifies plant properties in the rhizosphere to reduce mucigel swelling and increase mucigel stability. A reduced swelling yields low saturated hydraulic conductivity. It is believed that a plant also senses a low level of water stress when the soil is wet.
The present disclosure provides a non-genetically modified organism approach to altering chemical and biological signaling in a plant. Such an approach increases plant water use efficiency and endogenous Abscisic Acid signaling efficiency. ABA is a plant hormone that functions in a plant's developmental processing. As an anti-transpirant, ABA induces stomatal closure, decreases transpiration to prevent water loss, inhibits fruit ripening, inhibits seed germination, regulates enzymes needed for photosynthesis, and prevents root growth when exposed to saline conditions.
The present disclosure provides a rhizo signaling gel matrix and method that increases a plant's tolerance to drought. This includes a reduction in transpiration when plants undergo repeated drying, wetting, and rewetting cycles. Further, the rhizo signaling gel matrix and method of the present disclosure induces a plant's stomates to partially close, thereby lowering transpiration rates while simultaneously increasing the duration of effective transpiration. Transpiration is unaffected when the soil remains wet; rather the drying/wetting cycle does not include a period of drought stress.
The presence of a rhizo signaling gel matrix according to the present disclosure in the rhizosphere increases a plant's water use efficiency.
The presence of a rhizo signaling gel matrix according to the present disclosure in the rhizosphere increases a plant's root biomass.
The presence of a rhizo signaling gel matrix in the rhizosphere according to the present disclosure increases a plant's root to shoot ration, thereby yielding a more robust plant.
The present disclosure provides a rhizo signaling gel matrix that acts as an interconnected networked linkage between a plant's roots and soil particles, thereby enabling a more efficient uptake of water and mineral nutrients by roots in dry soils.
The present disclosure further provides a rhizo signaling gel matrix and method that increases rhizosheath mass and extension. Thus, larger, enhanced, and more stable rhizosheaths are possible without the need for genetic modification.
The present disclosure provides a rhizo signaling gel matrix that can be used to control the water relations of root and mucigel in the rhizosphere. Rhizoligands increase the wetting kinetics of the rhizosphere, as well as the uniformity of the rhizosphere rewetting. This results in faster root rehydration upon irrigation as well as to a higher volume of water available to the plant. Remarkably, the higher water volume is also used more slowly, as the plant transpiration is suppressed. Rhizoligands also affect the swelling and viscosity of mucigel exuded by roots. By modifying the mucigel swelling, the hydraulic connectivity between soil and roots is controlled. Specifically, mucigel swelling decreases after drying and treatment with rhizoligands and therefore limits the diffusion of mucigel away from the roots. The suppressed mucigel swelling also results in decreased hydraulic conductivity of the rhizosphere, which induces moderate water stress, thereby reducing transpiration in plants that have undergone drying/wetting cycles, with important consequences like increased water use efficiency and increased root to shoot ratio, without genetic modification.
The faster rhizosphere rewetting in the samples irrigated with rhizo signaling gel matrix 10 results in a pulse of ABA from the roots to the shoot, which temporarily limits the opening of stomata and consequently limits transpiration.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee
Referring now to the drawings and, in particular,
Rhizosphere 60 is a thin layer of soil adjacent to a root, directly influenced by root exudation, and whose physical, chemical and biological properties are different from those of bulk soil. The rhizosphere begins at the root surface and extends into the soil over a distance of up to about 30 mm, preferably up to about 5 mm, and most preferably about 1 mm, and any subranges therebetween.
Rhizoligand 40 is a compound that complexes plant and microbial exudates (polysaccharides with lipophilic components) stabilizing them to the form a rhizo signaling gel matrix. Rhizoligand 40 also indirectly affects the duration and longevity of mucigel.
The rhizo signaling gel matrix is a complex net of soil particles, root and microbial exudates including mucigel, dead root cells and fungal hyphae bound together by the rhizoligand.
Mucigel 20 is a slimy substance that covers a rootcap 52 of the roots 50 of a plant 12. It is known to be a highly hydrated polysaccharide. Mucigel 20 is secreted from the epidermal cells of rootcap 52. Formation occurs in the Golgi bodies. Secretion is known as exocytosis. Mucigel is excreted from a plant root, but mucigel and mucigel-like derivatives can also be synthesized and/or formulated.
Mucigel 20 has numerous functions, including protecting the rootcap 52 and preventing desiccation, lubricating the rootcap 52 to allow the root to efficiently and effectively penetrate the soil, and creating symbiotic environments for soil microorganisms.
Again, the layer of microorganism-rich soil immediately surrounding the mucigel and that is impregnated with the mucigel is rhizosphere 60. Distinguishable therefrom and adjacent rhizosphere 60 is root zone 62. As water is absorbed, rhizosphere 60 expands, and as the plant transpires, rhizosphere 60 contracts. Root zone 62 contains root zone soil 63, which is the volume of soil that is penetrated by plant roots 50 during growth. Root zone 62 is not part of rhizosphere 60, but rather, lies just outside the rhizosphere. Beyond root zone 62, is a third zone 66 containing bulk soil 67. Bulk soil refers to soil that is not penetrated by plant roots 50 and that is not modified by the roots.
In the top row, there are shown two soil particles 30 near a normal root (not shown) being irrigated with water 14 in an unmodified environment. The pore space between two soil particles 30 covered with dry mucigel 20 is illustrated during rewetting. Dry mucigel 20 is hydrophobic and temporarily limits the soil rewetting shown at t1. As mucigel 20 starts to adsorb water, soil 50 rewets at t2. The soil's hydraulic conductivity increases as the mucigel hydrates at t3. Notably, there is large expansion of rhizosphere.
In contrast to the unmodified environment, a modified rhizosphere with rhizo signaling gel matrix 10 is shown in the bottom row. There is a reduction of the contact angle and quicker rewetting of the soil at t1. As mucigel 20 swells, at t2, the soil hydraulic conductivity decreases. Rhizoligand 40 acts to decrease mucigel 20 swelling. Mucigel 20 does not fully expand resulting in a reduced soil hydraulic conductivity at t3. Stated another way, the rhizoligand 40 in rhizo signaling 10 creates an interconnected linkage between plants roots and soil particles.
Without wishing to be bound by a particular theory, it is believed that rhizo signaling gel matrix 10 causes recognition phenomenon in a plant to occur or causes a change in water gradient which triggers production of ABA, influences microbial populations, and plant biochemical responses.
Root water uptake generates a gradient in soil water potential and soil water content toward the roots. The gradients become steeper when the soil dries. When the water potential at the root surface decreases below a critical value, such as −1.5 MPa, roots send a signal to the leaves to close the stomata or ABA production is increased, travels by transpiration to the stomata, to signal the closing thereof. The lower hydraulic conductivity from rhizo signaling gel matrix 10 may signal inducing enhanced ABA production, stomatal closure and transpiration reduction. At this point both transpiration and photosynthesis decrease.
Rhizo signaling gel matrix 10 unexpectedly alters the water dynamics in rhizosphere 60 and creates interconnected linkages between the soil particles and an interface between the rhizosphere and plant root to increase biological and chemical communications. During drying rhizosphere 60 is wetter than bulk soil 67 and soil in root zone 62. Because of rhizo signaling gel matrix 10, the hydraulic connection between rhizosphere soil and roots is maintained. The region around the roots becomes hydrated and conductive. Root hydration is defined as root swelling. Contact between roots and soil, necessary for nutrient uptake, is maintained. High levels of microbial activity result thereafter. Moreover, a region for active communication between plants and the rhizomicrobiome, i.e., the root associated microbes, is established.
Without rhizo signaling gel matrix 10, after drying, the rhizosphere becomes water repellent (at most 25% moisture, preferably between about 5 and 20%, most preferable between 10 and 20%). Upon wetting or after irrigation, the bulk soil is wettable, but the rhizosphere is not. water depletion around the root occurs. Root water uptake cannot be sustained by the soil alone. The result is soil hydraulic failure, and as such, the plant dehydrates. As a plant dehydrates, roots shrink and lose contact with the soil. A gap results. There is additional resistance. Stated another way, continuity between the water and the root surface is interrupted without rhizo signaling gel matrix 10.
Without rhizo signaling gel matrix 10, mucilage expands, becomes less viscous, and it diffuses into the bulk soil. As it dries, it becomes hydrophobic.
Rhizo signaling gel matrix 10 and in particular, rhizoligand 60, instead result in a more viscous and more hydrated rhizosphere 60, with less swelling and less diffusive mucilage. Rhizosphere 60 stays closely appressed to the root, i.e., without a gap. Also, rhizosphere 60 quickly rewets after being treated with the rhizoligand. A continuous interface between the rhizosphere and a plant root is maintained, even as the plant root dries and shrinks, because rhizoligand maintains the rhizosphere appressed to the root.
The interconnected linkages created within rhizo signaling gel matrix 10, as described above, produce a physiological response in the plant such that the plant responds as if under a water deficit. The linkage creates an interface for nutrient uptake, improves cationic exchange capacity, and stimulates production of ABA that is transported to the shoot.
The increase in water flux into the roots is a short term pulse. Even though the rhizo signaling gel matrix is less conducive to flow, it leads to a seven times faster pulse of water to the shoot, after irrigation The faster pulse is explained by the faster rehydration of the rhizo signaling gel matrix. Because of rhizo signaling gel matrix 10, rewetting the rhizo signaling gel matrix results in the flow of water across the root-soil interface and to the shoot during the first 1-2 hours after irrigation, enhancing the transport of ABA to the shoot, i.e., an ABA pulse after irrigation.
Transpiration and stomatal conductance are controlled by root-shoot signaling and by the hormone ABA. High ABA concentration in the xylem results in transpiration reduction. ABA is a phyto-hormone regulating stomatal opening/closing, thereby affecting transpiration. It is also involved in drought and salinity tolerance
Plants treated with rhizoligands transpire less than not treated plants. It is well accepted that higher ABA concentration impacts guard-cells of stomates, resulting in partial, if not full, stomatal closure. In this case, stomatal closure is better regulated (partial closure). The reduced transpiration occurs during dry-down periods between irrigation. Some degree of water stresses are needed to reduce transpiration and induce ABA production. A drying cycle initiates the effect.
Rhizoligands, such as certain surfactants, reduce mucigel swelling and increase its viscosity. The rhizoligand prevents mucigel expanding or diffusing away from the root surface or outside the rhizosphere, and maintains a higher concentration of mucigel near the root surface. This has additional positive implications for the activity of microorganisms in the rhizosphere and results in a more effective symbiotic relationship between rhizosphere microorganisms and plants. Because there is lower mucigel swelling, there is also a low saturated hydraulic conductivity of the rhizosphere.
The presence of rhizo signaling gel matrix 10 reduces rhizosphere conductivity. The plant senses a low level water stress, even when the soil is wet. This leads to a partial closure of the stomata and to a moderate suppression of transpiration. The lower transpiration results in a saving water strategy. Plants consume a given amount of water in longer time. Low or reduced irrigation frequency techniques can be applied without a loss of yield. Consequent to the partial closure of the stomata, plant water use efficiency is also increased. Further, the root/shoot ratio is increased, which means more robust and drought tolerant plants.
In some embodiments, suitable rhizoligands in accordance with the present disclosure include alkyl terminated block copolymers, alkylpolyglycoside, ethylene oxide, propylene oxide, polymers based on ethylene oxide, polymers based on propylene oxide, ethylene oxide/propylene oxide block copolymers, and combinations thereof. Suitable rhizoligands can be mixtures of compounds with different sugars comprising the hydrophilic end and alkyl groups of variable length comprising the hydrophobic end. Rhizoligands can also include ethoxylated aliphatic alcohol, carboxylic esters, polyethylene glycol esters, anhydrosorbitol ester and ethoxylated derivatives thereof, glycol esters of fatty acids, carboxylic amides, monoalkanolamine condensates, polyoxyethylene fatty acid amides, and combinations thereof.
The most preferred rhizoligands are ethylene oxide/propylene oxide block copolymers and alkyl terminated block copolymers.
In certain embodiments, rhizoligands have a hydrophilic/lipophilic balance (HLB) between about 4 to about 30, more preferably between about 6 to about 14, and most preferably between about 7 to about 9, and any subranges therebetween.
In preferred embodiments, rhizoligands are biologically compatible for food and/or have a low level of toxicity.
Rhizoligands in accordance with the present disclosure are present in rhizo signaling gel matrix 10, preferably at a concentration of about 1 μg/kg to about 10 g/kg, more preferably about 5 mg/kg to about 1 g/kg, and most preferably about 10 mg/kg to about 100 mg/kg, and any subranges therebetween.
Suitable rhizoligands have one or more of the following properties: contact angle in the rhizosphere, rewetting rate of the rhizosphere, limited swelling after mixing with mucigel, higher viscosity after mixing with mucigel, and water retention after mixing with mucigel.
By way of non-limiting example, the contact angle in the rhizosphere can be about 0° to about 120°, preferably about 0° to about 60°, with 0° to about 30° being most preferred, and any subranges therebetween.
By way of non-limiting example, the rhizosphere rewetting rate can be between about 1 minute to about 2 days, preferably between about 1 minute to about 60 minutes, with between about 1 minute to about 10 minutes being most preferred, and any subranges therebetween.
By way of non-limiting example, the maximum swelling of the rhizoligand mixed with mucigel can be between about 0 to about 1000 gram of wet gel per gram of dry gel, preferably about 100 to about 500 gram of wet gel per gram of dry gel, with between about 200 to about 300 gram of wet gel per gram of dry gel being most preferred, and any subranges therebetween.
Soil 30 can be wettable soil or non-wettable soil. A wettable soil is a soil that has the ability to intake water. A non-wettable soil is a water repellent soil that has waxy, hydrophobic organic compounds coating soil particles. Consequently, a non-wettable soil repels water. Water repellence is mostly associated with sandy-textured soils, but can affect some heavier textured soils (for example forest loamy gravels).
Water availability to plant roots is controlled by the hydraulic properties of the rhizosphere. As discussed above, rhizosphere is the thin layer of soil in intimate vicinity of the roots. Importantly, hydraulic properties of the rhizosphere differ from those of the bulk soil and root zone soil. The rhizosphere remains wetter than the bulk soil during drying. The rhizosphere remains markedly dry after irrigation and it can be rewetted in only a few days. Thus, water content is higher in the rhizosphere during drying and the rhizosphere has temporarily lower water content after irrigation. Mucigel is a hydrogel exuded by most of plants. Mucigel has a large affinity to water and at saturation it has water content up to about 500 times its dry weight or more. The rhizo signaling gel matrix is primarily polysaccharides and some lipids that make it hydrophobic upon drying.
It has been found by the present disclosure that rhizoligands modify the water dynamics in the rhizosphere and transpiration rates, among other functions. ACA3282 and ACA3276 (Aquatrols® Corp., Paulsboro, N.J., U.S.A.) were used as rhizoligands during experimentation. ACA3282 and ACA3276 are surfactants that are exemplary of suitable rhizoligands according to the present disclosure. ACA3282 and ACA3276 are rhizoligand 1 and rhizoligand 2, respectively
With rhizo signaling gel matrix 10, the rhizosphere is rewetted more quickly and more uniformly than with normal water.
Referring now to
In
To quantify the root swelling, the focus was on the upper part of the tap root. The tap root shrinks up to 25% during severe drying, corresponding to a decrease in diameter of 0.3 mm. The swelling of the upper part of the tap root was used as a proxy for the root tissue rehydration. The changes in the diameter of the taproot are calculated from the neutron radiographs according to the following method: the intensity of the neutron beam transmitted behind the sample depends on the thickness and composition of the sample. More specifically, in each pixel of the image the logarithm of the ration between the transmitted and incident beam, divided the neutron attenuation coefficient of water, gives the thickness of water in each point of the sample. The resulting changes in root diameter are plotted in
One of the challenges in estimating the root swelling from
Further experiments were conducted to demonstrate the effect of rhizo signaling gel matrix 10 on soil water availability. In this experiment, ACA3282 and ACA3276 were used as rhizoligands for root water uptake of lupine and maize during repeated drying/wetting cycles. Ten lupines were planted in containers of 12×12×1 cm filled with sandy soil. The samples were grown in a climate chamber with day/night temperature of 24/19° C., humidity 60%, photoperiod of 14 hours. The plants were kept irrigated by capillary rise from the bottom (1 cm water table) for two weeks. After two weeks the water at the bottom of the sample was removed and the samples were allowed to dry. When the plants showed wilting symptoms, the samples were irrigated again by immersing the samples in 1 cm water table for one hour. Half of the samples were used as a control. Then, the water at the bottom was removed and another drying cycle was repeated. In total, there were 6 drying cycles. During the drying/cycles we measured transpiration rate by weighing the samples at regular intervals.
An image of the plants at day 4 is shown in
Transpiration was measured gravimetrically. Transpiration rates over time are plotted in
The experiments were repeated with maize instead of lupine. The transpiration curves were similar to those of lupines. Transpiration rates were also reduced in maize having rhizo signaling gel matrix 10 after repeated drying/wetting cycles. The results are shown in
Additional experiments were conducted to measure root and shoot biomass. Again, control samples having only water and tests samples having ACA3282 as the rhizoligand of rhizo signaling gel matrix 10 were used. Plants with rhizo signaling gel matrix 10 had a higher biomass and significantly higher root/shoot ratio compared to the control samples. The results are shown in
The above described experiments were repeated with lupines and ACA3276 instead of ACA3282 as the rhizoligand in rhizo signaling gel matrix 10. Lupines were grown in the same conditions as in the experiments described above. Two weeks after planting the samples were allowed to dry until they showed initial wilting symptoms. Then, the plants were irrigated by capillary rise (as described above). Half of the plants were control samples, and half had rhizo signaling gel matrix 10. ACA3276 at a concentration of 0.005% was used. The changes in water content during three drying cycles are shown in
Experiments were again repeated, but the soil kept wet. Every morning at 07:00 water or rhizo signaling gel matrix 10 that was lost by evapotranspiration during the day was replaced. ACA3276 was added at a concentration of 0.005%. In this way, the soil water content varied between 20% and 15%. At the end of the day, the samples with rhizo signaling gel matrix 12 were slightly drier than the control samples, as shown in
Without wishing to be bound by a particular theory, it is believed that suppression of transpiration upon irrigation with rhizo signaling gel matrix 10 was caused by a reduction of the hydraulic conductivity in the rhizosphere. The rhizoligands, which in the experiments were nonionic surfactants (i.e. ACA3282 and ACA3276) affect the maximum swelling rate and viscosity of gels containing hydrophobic components. At specific concentrations, nonionic surfactants decrease the swelling and increase the viscosity of gel containing hydrophobic components.
To test the effect of ACA3282 and ACA3276 on mucigel, mucilage (a type of mucigel) from chia seeds was used. Mucilage from chia seeds has similar physical and chemical properties to that of maize. A maximum swelling of mucilage was measured by immersing a given amount of dry mucilage into 6 ml of water, ACA3282 (0.1%) and ACA3276 (0.1% and 1%). Results are shown in
To upscale the effects of the rhizoligand interactions in the rhizosphere, a mixture of mucilage and soil was used. Mucilage was mixed with a sandy soil and then was let dry. Cylinders of 2 cm in diameter were filled with 10 g of dry mucilage-soil mixture and were saturated in water and ACA3276 (0.1%). The saturated hydraulic conductivity of the soil samples was estimated by imposing a constant difference in pressure head between the top and bottom of the sample and measuring the water outflow from the samples. It was found that mucilage decreased the saturated hydraulic conductivity of the soil. See
Also found was that at high mucilage concentrations, rhizoligands further decreased the soil hydraulic conductivity. It is believed that this reduction in conductivity with surfactants was caused by the lower swelling of mucilage with surfactants and the consequent higher viscosity of the mucilage. The higher mucilage viscosity is expected to limit the diffusion of mucilage away from the rhizosphere. Consequently, it has been found that rhizoligands increase the mucilage concentration near the root surface. This has an additional effect in reducing the hydraulic conductivity of the rhizosphere.
Plant roots employ various mechanisms to increase their access to resources and tolerance to abiotic stress. This includes the production of root hairs, the development of appropriate root system architectures, the fostering of beneficial symbiotic associations and the improvement of physical and biological soil conditions in the rhizosphere.
These phenomena take place in a region known as the rhizosheath, which is operationally defined as the weight of soil that adheres strongly to roots on excavation. Root hairs increase rhizosheath formation. The present disclosure provides that application of rhizo signaling gel matrix 10 increases rhizosheath formation without the need for a plant genome modification approach.
Rhizosheath production is related to many factors, including: root hair length, density, and morphology, root and microbial mucilage, soil water content, soil texture, mycorrhizal fungi, and free living bacteria.
Both root hair length and rhizosheath production have been shown to influence water relations, to alleviate phosphorous (P) and zinc (Zn) deficiencies, and are involved in tolerance to hard soils, water deficit and aluminum (Al) induced acidity tolerance. Rhizosheaths are critical habitats/niches for soil microbes—especially plant growth promoting rhizobacteria. The more developed the rhizosheath is, the more beneficial it is to the bacterial rhizobiome. The bacterial rhizobiome is a population of specialized microorganisms that colonize the plant rhizosphere and endosphere.
Rhizoligands 40 of rhizo signaling gel matrix 10 stabilize the rhizosheaths and create a stable rhizo signaling gel matrix therein. Rhizoligands 40 bind together root exudates and the soil particles and increase the viscosity of the resulting gel, which remains concentrated close to the root, forming a viscous gel that connects the roots to the soil, as discussed above. Rhizoligands 40 increase the effective volume of the rhizosheath which in turn help plants to take up water and nutrients in dry soils.
The rhizoligands 40 in rhizo signaling gel matrix 10 also increase the zone of high soil organic matter and microbial activity
Rhizosheaths having rhizo signaling gel matrix 10 maintain the contact between soil and root and avoids that roots lose contact with the soil when they shrink in response to soil drying. Consequently such rhizosheaths facilitate water and nutrient uptake in dry soils
It has been found that rhizosheaths increase plant tolerance to water stress by limiting the development of air-filled gaps at the root-soil interface during wetting and drying cycles, as discussed above. Contact between soil and root in dry soils, when roots shrink, is maintained. The improved contact facilitates water and nutrient uptake from dry soils. Moreover, it has been found that the rhizosheath keeps the rhizosphere wetter than the bulk soil, making it more conductive to water flow and more diffusive for solutes.
Thus, rhizo signaling gel matrix 10, formed in the rhizosphere, is effective at maintaining optimal biological and biogeochemical processes in the rhizosphere.
Soil quality is also improved by rhizo signaling gel matrix 10 because of the resulting engineered rhizosphere. Effects on soil quality can be chemical, physical, or biological. Chemical effects include nutrient cycling, water relations, and buffering. Physical effects include physical stability and support, water relations, and habitat. Biological effects include biodiversity, nutrient cycling, and filtering.
Organic matter, or more specifically soil carbon, transcends all three soil quality indicator categories and has the most widely recognized influence on soil quality.
Organic matter is tied to all soil functions. It affects other indicators, such as aggregate stability (physical), nutrient retention and availability (chemical), and nutrient cycling (biological), and is itself an indicator of soil quality. Rhizo signaling gel matrix 10 which includes rhizoligand 40, increases soil organic matter.
Carbon concentration is 32.9% higher in the rhizosphere of plants having rhizo signaling gel matrix 10. As discussed above, rhizoligands 40 create a viscous matrix that keeps the root exudates which are a high source of soil organic matter, close to the root surface.
Moreover, the total carbon maintained in the rhizosphere having rhizoligands is even greater, because their rhizosheaths were higher in volume and mass.
Consequences of increased soil organic matter in the rhizo signaling gel matrix according to the present disclosure are critical. Soil organic matter is a source of sugars for soil microbes, provides a hydrated and connected environment for the microbiome, increases stability and maintains nutrients close to the roots (nutrients bound with organic matter), reduces nutrient leaching, promotes root growth and has positive effect on water uptake and nutrient acquisition, and increases longevity of enzymes
Enzymes are a biological indicator of soil quality. Enzyme as a free form in soil solution commonly degrade quickly. However, rhizo signaling gel matrix 10 increases enzyme availability in the rhizosphere.
β-Glucosidase is an enzyme that originates from plants and certain fungi involved in cellulose degradation and releasing of glucose. β-Glucosidase has a direct effect on the stabilization of soil organic matter. β-Glucosidase is an important indicator of the ability of a given soil ecosystem to degrade plant material and provide simple sugars for the microbial population. β-Glucosidase plays an important role in the soil organic carbon cycle.
Sulfatase is an enzyme produced by fungi and bacteria. Sulfatase transforms sulfur contained in organic forms to a form available for plant roots and microorganisms. Sulfatase is significantly correlated with soil organic matter and moisture.
Plants require sulfur for growth, in order to synthesize proteins and build stable photosynthetic complexes. Plants obtain this element from the soil as inorganic sulfate, but are also reliant on other forms of bound soil sulfur, including sulfate esters. However, plants cannot release sulfate esters from the soil themselves, and so they depend on interactions with bacteria that inhabit the rhizosphere. The bacteria, mobilize sulfur for plant uptake.
Bacteria, on the other hand, do not produce more sulfur than they need for themselves, and the sulfatase genes that are responsible for desulfurization of sulfate esters are normally switched off when bacteria are utilizing sulfate. Rhizo signaling gel matrix 10 overcomes this by stimulating the activity of bacterial sulfatases in the rhizosphere and inducing soil bacterial sulfatase gene expression.
In soils of the temperate, humid, and semi-humid regions, sulfur (S) occurs in organic forms, with organic sulfur accounting for >95% of the total sulfur. However, much of the organic sulfur in the soil remains uncharacterized. Organic sulfur generally becomes available to plants through mineralization to sulfate.
Phosphatase mainly originates from plant roots. Phosphatase catalyzes phosphorous containing compounds such as nucleotides and polyphosphates into a form available for root uptake.
Chitinase is an enzyme produced by bacteria and some fungi. Chitinase degrades chitin making carbon and nitrogen available for soil microorganisms and plants. Chitin is the second most abundant polysaccharide in the planet after cellulose. Chitin is a hard and inelastic polysaccharide is found in plants, fungi, yeast, algae, bacteria, insect, some animals. Certain plant disease causing fungi and fungus-like organisms are controlled by chitinolytic bacteria. Chitinases of soil-borne bacteria can decompose chitin of dead fungal hyphae and other resources, but they may also play a role in antagonistic activities against fungi by destroying the chitin in the fungal cell walls. Chitin also functions as a bioshield against plant pathogens and negatively affects soil-inhabiting insect pests.
Higher chitinase, sulfatase, and β-glucosidase in the rhizosphere containing rhizo signaling gel matrix 10 is explained by the higher soil organic matter and the consequent increase in microbial activity. Although phosphatase is not affected, the reason is that lupines are well known to exude large quantities of phosphatase (in particular by their cluster roots). Therefore it is possible that the potential benefit due to the rhizoligands is not detectable.
Nutrient uptake by plants having rhizo signaling gel matrix 10 in their rhizosphere was measured and is summarized in the tables that follow.
The observed increased B-glucosidase resulting from rhizo signaling gel matrix 10 indicates improved soil health.
The observed increased sulfatase resulting from rhizo signaling gel matrix 10 indicates better soil health as a consequence of enhanced soil microbial populations of beneficial bacteria, plant growth promoting rhizobacteria.
The observed increased chitinase resulting from rhizo signaling gel matrix 10 indicates increased plant growth promoting rhizobacteria populations enhancing “bioshield” protection suppressing plant pathogens and insect pests
The observed increased sulfatase and chitinase resulting from rhizo signaling gel matrix 10 are a result of an enhanced rhizobiome.
Among the several realized benefits and advantages of the present disclosure and rhizo signaling gel matrix 10 are enhanced nutrient uptake by plants. The ability of plant roots to take up nutrients from soils is affected by availability of nutrients in soil and transport of nutrients from soil to the root surface. Rhizo signaling gel matrix 10 affects both factors significantly. Specifically, rhizoligand 40 increases microbial activity, resulting in the production of enzymes which transform nutrients into plant available form. Rhizoligand 40 increases the concentration of root exudates and soil organic matter in the rhizosphere, increasing the cation exchange capacity and the adsorption of nutrients in the rhizosphere. These nutrients can be exchanged by organic acids released by the roots. Rhizoligand 40 maintains the rhizosphere hydrated and diffusive for a longer period of time than water alone. Rhizoligand 40 stabilizes the rhizo signaling gel matrix and maintain the connection between the root and soil.
Rhizoligand 40 results in a rhizo signaling gel matrix that is more viscous, remains wettable, swells less, is less diffusive, and stays closely appressed to the root. The consequences are higher ABA transport and production, lower transpiration after drying events, larger, more stable, and longer wettable rhizosheaths, higher soil organic matter in the rhizosphere, higher enzyme activity in the rhizosphere, higher nutrient uptake in the rhizosphere, increased functionality and duration of root transport, and enhanced plant performance under abiotic stress conditions.
The higher viscosity and cation exchange capacity of the rhizosphere with rhizo signaling gel matrix 10, in part due to the interconnected linkages created by the rhizoligands, reduces the leaching of elements far from the rhizosphere. A stable rhizo signaling gel matrix will increase the retention of inorganic and organic compounds, including pesticides (insecticides, fungicides, miticides, nematicides, algaecides), plant growth regulators (including herbicides), and biostimulants.
Rhizo signaling gel matrix 10 can also be formulated to include pesticides, fertilizers, biostiumulants, bio-pesticidal bacteria and the like.
Rhizo signaling gel matrix 10 can also be formulated to also include bio organisms such as nitrogen fixing bacteria, fungi such as mycorrhizal fungi, phytohormones, and plant growth promoting rhizobacteria (naturally occurring or artificially introduced).
The plant growth promoting rhizobacteria (PGPR) should be proficient to colonize the root surface, survive, multiply and compete with other microbiota, and promote plant growth. Examples include Agrobacterium radiobacter, Azospirillum brasilense, Azospirillum lipoferum, Azotobacter chroococcum, Bacillus fimus, Bacillus licheniformis, Bacillus megaterium, Bacillus mucilaginous, Bacillus pumilus, Bacillus spp., Bacillus subtilis, Bacillus subtilis var. amyloliquefaciens, Burkholderia cepacia, Delfitia acidovorans, Paenobacillus macerans, Pantoea agglomerans, Pseudomonas aureofaciens, Pseudomonas chlororaphis, Pseudomonas fluorescens, Pseudomonas solanacearum, Pseudomonas spp., Pseudomonas syringae, Serratia entomophilia, Streptomyces griseoviridis, Streptomyces spp., Streptomyces lydicus and various Rhizobia spp.
Rhizo signaling gel matrix 10 can also be formulated to also include amino acids such as α-Alanine, β-alanine, asparagines, aspartate, cystein, cystine, glutamate, glycine, isoleucine, leucine, lysine, methionine, serine, threonine, proline, valine, tryptophan, ornithine, histidine, arginine, homoserine, phenylalanine, γ-Aminobutyric acid, and α-Aminoadipic acid; organic acids such as citric acid, oxalic acid, malic acid, fumaric acid, succinic acid, acetic acid, butyric acid, valeric acid, glycolic acid, piscidic acid, formic acid, aconitic acid, lactic acid, pyruvic acid, glutaric acid, malonic acid, tetronic acid, aldonic acid, and erythronic acid; sugars such as glucose, fructose, galactose, ribose, xylose, rhamnose, arabinose, desoxyribose, oligosaccharides, raffinose, and maltose; vitamins such as biotin, thiamin, pantothenate, riboflavin, and niacin; purines/nucleosides such as denine, guanine, cytidine, and uridine; and enzymes such as acid/alkaline-phosphatase, invertase, amylase, and protease.
A robust plant is one with a stable, hydrated rhizosphere, that allows the plant to remain healthy under water and nutrient stress—i.e. when the soil resources (water and nutrients) are scarce.
A stable, hydrated rhizosphere is obtained by rhizo signaling gel matrix 10 which has rhizoligands that interact with root exudates to form a viscous, stable and hydrated gel, which maintains root exudates and nutrients close to the root surface. The obtained rhizo signaling gel matrix enhances, soil organic matter, enzyme activity, and nutrient absorption. It also enhances soil microbes, important for mineralization (sulfur) and suppression of phytopathogens (chitinase) in the rhizosphere.
The rapid rewetting of the rhizosphere after drying obtained with rhizo signaling gel matrix 10 results in a pulse of ABA transported from the roots to the shoot, where it temporarily reduces stomata opening and transpiration. This results in a water saving strategy.
Rhizo signaling gel matrix 10 can be applied directly to a plant root. Rhizo signaling gel matrix 10 can alternatively be applied to the rhizosphere, or formulated therein.
It should be noted that where a numerical range is provided herein, unless otherwise explicitly stated, the range is intended to include any and all numerical ranges or points within the provided numerical range and including the endpoints.
It should also be noted that the terms first, second, third, upper, lower, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.
Although described herein with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation, construction, operation, or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the spirit and scope of the appended claims.
This application claims priority to U.S. Provisional Application No. 62/138,866, filed on Mar. 26, 2015, which is incorporated herein in its' entirety by reference thereto.
Number | Date | Country | |
---|---|---|---|
62138866 | Mar 2015 | US |