METHOD FOR DETECTING ROOT RESURGENCE IN A PLANT

Abstract

The invention relates to a method for detecting root regrowth in a plant (1), characterized in that it comprises the following steps carried out using a central unit (2) consisting of retrieving soil water tension measurements (4) over time, determining if at least two successive soil water tension measurements are greater than a certain threshold water tension, calculating a rate of change in soil water tension, comparing the calculated rate of change in soil water tension with a threshold rate of change in soil water tension, creating a root activity detection data point if the calculated tensiometry rate of change is greater than the threshold rate for at least a first given period, and creating a numerical data point representing the detection of root regrowth if, during a period greater than the period, at least two root activities are detected.Figure to be published with the abbreviation: Fig.2.

Description

Title of the invention: METHOD FOR DETECTING ROOT RESURGENCE IN A PLANT technical field

[0001] The invention relates to the field of agronomy and more particularly to a method for detecting root regrowth in a plant and a measuring station for implementing such a root regrowth detection method. Prior art

[0002] It is now accepted that urban trees play a beneficial ecosystemic role on the environment and on human health through the elimination of air pollutants, the storage and sequestration of carbon, protection against storms, the mitigation of the impacts of runoff and flooding, the limitation of heat islands and even the improvement of cognitive development.

[0003] They are therefore considered among the best alternatives for adapting to the weather and climate changes experienced in our cities.

[0004] The first few years of a tree's life, also called the recovery period, are generally defined as the time it takes for a tree to regrow its root system and become capable of supporting aboveground growth. In other words, recovery is a biological process during which the transplanted tree becomes permanently established in its new environment and from which it can provide the expected ecosystem services. Indeed, newly transplanted trees suffer from "post-transplantation stress," characterized by altered physiological functions and reduced growth. Roots that grow from seeds develop naturally according to soil conditions and other parameters such as climate or species, whereas the roots of transplanted trees are forced to acclimatize to their new environment.In most cases of tree transplantation in urban areas, the trees come from nurseries and lose more than 70% of their root system, triggering "post-transplantation stress".

[0005] However, we are increasingly observing the decline and premature mortality of trees in cities. Indeed, they are often subjected to difficult growing conditions due to insufficient root space, soil compaction, unsuitable soils, severe water stress, poor post-transplantation management, and biophysical factors such as climate and extreme weather conditions.

[0006] There is therefore an essential need to know the state of root recovery of the plant to determine if it has properly established itself in its environment.

[0007] There are now processes that use physiological and morphological data from trees, such as the growth of shoots, leaves, trunk or stems.

[0008] Other methods are based on in vitro experiments to understand the phenomena of root growth, while others use imaging data capable of representing the architectural and functional structure of root development.

[0009] Root re-establishment can be partially deduced from observations of the aerial part of the plant by evaluating the growth dynamics of the plant's crown over time and by correlation to determine root re-establishment. This indirect method is not sufficiently reliable for evaluating and optimizing the tree's re-establishment in its environment.

[0010] Root regrowth can also be observed in the underground portion through root excavation, providing a precise indication of the extent of root regrowth. This more direct method generally results in the death of the plant and presents access difficulties on public roads in urban environments. Description of the invention

[0011] The objective of the invention is therefore to solve the aforementioned problems.

[0012] To this end, the invention relates to a method for detecting root regrowth in a plant, characterized in that it comprises the following steps carried out using a central unit and consisting of:

[0013] - record soil water tension measurements in the central processing unit's memory measurements taken over time using at least one moisture sensor placed in the soil along an estimated path of plant root growth,

[0014] - determine if at least two successive soil water tension measurements are above a certain threshold water tension, and in turn calculate a rate of change in soil water tension from the aforementioned at least two identified soil water tensions,

[0015] - compare the rate of change of the calculated soil water tension with a threshold rate of change in soil water tension,

[0016] - create a numerical data point representative of a root activity detection if the the rate of change of the calculated tensiometry is greater than the threshold rate for at least a first given period, and

[0017] - create a numerical value representing the detection of root regrowth if during a second given period longer than the first given period, at Two less root activities are detected.

[0018] The idea behind the invention is to measure the soil moisture level around the plant roots to determine root activity in real time and then to model a plant root dynamics representative of root recovery, ultimately allowing us to anticipate the chances of success of plant establishment in its environment.

[0019] The method for measuring the root activity of the plant according to the invention may also include the following steps:

[0020] - calculate the number of root activities during the second given period, plus the the number of root activities in the said second given period being high and the more the plant shows a significant level of root recovery and in turn create a numerical data representative of a level of root recovery;

[0021] - calculate the number of days during which the plant is in root activity during said second given period, the higher the number of days during said second given period and the more the plant shows a significant intensity of root recovery and in turn creates a numerical data representative of a certain intensity of root recovery;

[0022] - calculate a first average rate of change of soil water tension during the said first given period and create in return a numerical data representative of an average intensity of root activity during the said second given period Atl;

[0023] - calculate a second average rate of change of soil water tension during said second given period and create in return a numerical data representative of an average intensity of root activity during said second given period;

[0024] - define a certain root recovery efficiency, said recovery efficiency root being determined by a correlation between the level of root recovery and the intensity of root recovery such that the greater the level of root recovery and the greater the intensity of root recovery are during the second given period and the greater the efficiency of root recovery and in turn create numerical data representative of a certain efficiency of root recovery during the second given period;

[0025] - calculate a duration during which the soil water tension measured by said The humidity sensor is constant, then compare said calculated duration with a constant soil water tension threshold duration beyond which the plant is considered not to be in root activity, then create a numerical data representing an absence of root activity if the calculated duration is greater than said threshold duration.

[0026] The invention also extends to a measuring station for detecting root regrowth in a plant, comprising at least one sensor designed to measure soil water tension and a central unit configured to implement the method according to the invention, and a display screen. The central unit is designed to display said numerical data representing the detection of root regrowth in several categories on the display screen.

[0027] The categories may also be displayed as color code on the display screen and / or as icons. Brief description of the drawings

[0028] The present invention will be better understood and other advantages will become apparent upon reading the detailed description of the embodiment taken by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0029] [Fig-1] - [Fig.1] is a diagram representing the different stages of the process according to the invention for detecting root regrowth;

[0030] [Fig.2] - [Fig.2] is a schematic representation of a measuring installation according to the invention using a measuring station according to the invention to implement the root regrowth detection method according to the invention. Detailed description of the invention

[0031] The invention here relates to a method for detecting root regrowth in a plant 1.

[0032] The term "plant" according to the invention extends to any type of plant intended to be Planted in the ground as perennial or annual crops and capable of developing a root system, such as trees, shrubs, crops, lawns, etc. It is understood that the plant is relatively isolated from other plants at the time of transplanting (from 30 cm for annual plants up to 1m for trees) so that their root systems are not or only slightly entangled.

[0033] The terms "root recovery" of a plant according to the invention represent a certain periodicity of root activity of the plant which corresponds to a state of implantation of the plant in its environment.

[0034] The term "root activity" according to the invention represents a drying of the soil attributed to the action of the plant's roots at a given moment. In other words, root regrowth according to the invention corresponds to a certain dynamic of root activity.

[0035] The root recovery detection method according to the invention therefore comprises several steps carried out using a central unit 2 and at least one moisture sensor 3 placed in the soil 4 on an estimated path of root growth 5 of the plant 1.

[0036] The central unit 2 is then configured to retrieve soil water tension measurements taken over time by said at least one moisture sensor 3.

[0037] It will be understood that several moisture sensors 3 can be arranged on the estimated growth path of the roots 5 of the plant 1 such as for example, a first moisture sensor 3a arranged as close as possible to the roots in the root ball of the plant 1, a second moisture sensor 3b far from the first moisture sensor 3a on a horizontal plane and a third moisture sensor 3c far from the second moisture sensor 3b on a vertical plane.

[0038] Said at least one humidity sensor 3 according to the invention is herein designed to measure water content or water tension, herein referred to as water tension. The conversion from water content to water tension and vice versa is possible thanks to a suitable soil transfer function. Furthermore, the measured water content or water tension data are always converted into absolute values ​​to facilitate data reading. For example, when the humidity sensors measure water tension, the measured data are expressed in ohms, then converted into mbar, for example, between 0 and 2000 mbar, and finally converted into absolute values.

[0039] The soil water tension measurements can be recorded in a database 6, such that the database 6 contains, for each moisture sensor 3, a plurality of water tension measurements taken over time. Indeed, the plant 1 that has just been transplanted has roots 5 only at the level of its root ball, roots 5 which will tend to develop horizontally and then vertically in relation to the root ball.

[0040] Root activity can therefore evolve at the level of sensors 3 according to their position relative to the root ball.

[0041] Also, in addition to the humidity data measured by the humidity sensors 3 in real time, the database 6 according to the invention includes, for each plant 1 monitored, at least one or more of the following distinctive criteria: the type of species of the plant (for example its essence, genus, etc.), the climatic region in which the plant is located, the texture of the root ball, the year of planting, the planting context (soil-stone mixture, open ground or planting pit) and the geographical coordinates of the plant.

[0042] The central unit 2 according to the invention can then be parameterized to determine if at least two successive soil water tension measurements, from the same moisture sensor 3, are greater than a certain threshold water tension a.

[0043] The threshold water tension a according to the invention corresponds here to the minimum tensiometry value taken into account to be able to determine root activity. This means that below the threshold water tension a, no root activity can subsequently be determined.

[0044] The central unit 2 is then parameterized to calculate in return a rate of change of the soil water tension at the level of each sensor from said at least two soil water tensions identified and to compare the rate of change of the calculated soil water tension with a threshold rate of change [3 of the soil water tension.

[0045] The threshold speed [3 of evolution of water tension according to the invention corresponds here to the value of the minimum water tension evolution speed of the soil from which it is possible to determine root activity.

[0046] The threshold velocity [3] was determined in advance by carrying out an in situ analysis on a large number of plants (trees, shrubs, etc.). Plants planted simultaneously were dug up successively over several years in order to observe the evolution of the roots.

[0047] The threshold speed [3 according to the invention will for example be between 0.1 and 10 mbar / hour depending on the choice of the different distinctive criteria listed above.

[0048] The threshold rate [3 of evolution of the water tension therefore corresponds to a certain rate of decrease of soil moisture 4 above which the decrease of soil moisture 4 is attributed to the presence and activity of roots 5. We can therefore consider that a rate of decrease of soil moisture 4 below the threshold rate [3 corresponds substantially to a low rate of drying of the soil 4, by evaporation for example.

[0049] It is understood that if several moisture sensors 3 are used, each sensor will use its own successive water tension measurements to calculate the rate of change of soil water tension at the level of said sensor. The central unit 2 may also calculate the rate of change of soil water tension at several sensors at different or identical time intervals, as required.

[0050] It is also understood that different threshold speeds [3 of evolution of water tension may be used depending on the depth at which the moisture sensor is positioned, the type of soil, the type of plant being monitored, etc.

[0051] The central unit 2 according to the invention will also be parameterized to create a numerical data representative of a root activity detection if the rate of evolution of the calculated tensiometry is greater than the threshold rate [3] for at least a first period Atl, then to create a numerical data representative of the detection of a root recovery if during a second period At2 greater than the first period Atl, at least two root activities are detected.

[0052] The Atl period is defined in advance and can be entered in the parameterization of the central unit 2. For example, a certain number of days, for example between 1 and 7 days, preferably 3 days, can be taken as the first Atl duration.

[0053] The second period At2 will necessarily be longer than the first period Atl and may last, for example, several days, weeks, months or even several years in depending on the plant to be monitored, for example here 1 year for a fruit tree.

[0054] In addition to being able to detect root regrowth of the plant, the method according to the invention also makes it possible to determine indicators providing additional information on root regrowth.

[0055] Among these indicators, the method according to the invention makes it possible to characterize a certain level of root establishment, consisting of calculating, using the central processing unit 2, the number of root activities during the period At2. The central processing unit is then parameterized to create a numerical value representing a certain level of root establishment, such that the higher the number of root activities in said period At2, the greater the level of root establishment of the plant 1. In other words, the higher the number of root activities in said period At2, the better established the plant 1 will be in the soil 4.

[0056] Another indicator according to the invention corresponds to a certain intensity of root recovery calculated using the central unit 2 and corresponding to the number of days during which the plant 1 is in root activity during said second given period At2. The central unit 2 is then parameterized to create a numerical data representative of said intensity of root recovery such that the higher the number of days during said second given period At2 and the greater the intensity of root recovery of the plant 1 will be.

[0057] The method according to the invention also makes it possible to produce an indicator corresponding to an average intensity of root activity during said first given period Atl. For this purpose, the central unit is parameterized to calculate a first average rate Vml of evolution of the soil water tension 4 during said first given period Atl and then to create in return a numerical data representative of an average intensity of root activity during said second given period Atl.

[0058] Another indicator according to the invention can be determined by the central unit 2 and corresponds to an average intensity of root activity during said second given period At2. The central unit 2 will in this case be parameterized to calculate a second average rate Vm2 of evolution of the soil water tension during said second given period At2 and then to create in return a numerical data representative of an average intensity of root activity during said second given period At2.

[0059] Another indicator according to the invention corresponds to a certain root recovery efficiency. For this purpose, the central unit 2 will be parameterized to correlate the level of root recovery with the intensity of root recovery, such that the greater the level of root recovery and the greater the intensity of root recovery during the given period At2, the greater the root recovery efficiency will be. The unit central unit 2 will in turn produce numerical data representative of said certain root recovery efficiency during the given period At2.

[0060] The central unit 2 according to the invention can also be configured to provide an indicator of the absence of root activity. For this purpose, the central unit 2 will be configured to calculate a duration At3 during which the soil water tension measured by said moisture sensor is constant, to compare said calculated duration At3 with a threshold duration y of constant soil water tension beyond which the plant is considered not to be in root activity, and to create a numerical value representing an absence of root activity if the calculated duration is greater than said threshold duration.

[0061] The implementation of the method according to the invention for detecting root regrowth shall comprise the following successive steps:

[0062] At a step 100, each moisture sensor 3 takes measurements of water tension in the soil 4 and feeds the database 6 in the central unit's memory.

[0063] At a step 200, the central unit 2 determines whether at least two successive soil water tension measurements 4 are greater than a certain threshold water tension (a), and calculates, at a step 300, in return a rate of evolution of the soil water tension from the said at least two soil water tensions 4 identified.

[0064] At a step 400, the central unit 2 compares the rate of change of the calculated soil water tension with a threshold rate of change [3 of the soil water tension.

[0065] At a step 500, the central unit creates a numerical data representative of a root activity detection if the rate of evolution of the calculated tensiometry is greater than the threshold rate (|3) for at least a first given period Atl.

[0066] And finally, at a step 600, the central unit creates a numerical data representative of the detection of a root recovery if during a period At2 greater than the period Atl, at least two root activities are detected.

[0067] The invention also extends to a measuring station 7 designed to detect root regrowth of a plant 1. The measuring station 7 according to the invention shall comprise at least one moisture sensor 3 designed to measure soil moisture tension 4, a display screen 8, and a central processing unit 2 configured to implement the method according to the invention and display said numerical data representing the detection of root regrowth in several categories. A first category may, for example, represent the detection of root regrowth, a second category may, for example, represent the level of root regrowth, a third category may, for example, represent the intensity of root regrowth, and a fourth category may represent a certain average intensity of root regrowth.

[0068] Each category may include subcategories to represent the upward or downward trends in root recovery.

[0069] Without restricting the scope of the invention, the categories may be displayed in the form of color code on the display screen 8 and / or in the form of icons.

Claims

Claims

1. Method for detecting root regrowth of a plant (1), characterized in that it comprises the following steps carried out using a central unit (2) and consisting of: - recording (100) in the memory of the central unit measurements of soil water tension (4) over time carried out using at least one humidity sensor (3) arranged in the soil on an estimated path of growth of the roots (5) of the plant, - determining (200) whether at least two successive soil water tension measurements are greater than a certain threshold water tension (a), and calculating (300) in return a rate of change of the soil water tension from said at least two identified soil water tensions, - comparing (400) the calculated rate of change of the soil water tension with a threshold rate of change (|3) of the soil water tension,- create (500) a digital data item representing a detection of root activity if the rate of change of the calculated tensiometry is greater than the threshold rate (|3) during at least a first given period (Atl), and - create (600) a digital data item representing the detection of root recovery if during a second given period (At2) greater than the first period (Atl), at least two root activities are detected.,

2. Method for detecting root recovery of a plant according to claim 1, characterized in that it comprises a step consisting of calculating the number of root activities during the second given period and in that the higher the number of root activities in said second given period, the more the plant shows a significant level of root recovery and in that it comprises a step consisting of creating in return a digital data item representative of a level of root recovery.

3. Method for detecting root recovery of a plant according to claim 1, characterized in that it comprises a step consisting of calculating the number of days during which the plant is in root activity during said second given period and in that the higher the number of days during said second given period, the more the plant shows a significant intensity of root recovery and in that it includes a step consisting of creating in return a digital data representative of a certain intensity of root recovery.

4. Method for detecting root recovery of a plant according to any one of the preceding claims, characterized in that it comprises a step consisting of calculating a first average speed (Vml) of evolution of the water tension of the soil during said first given period and in creating in return a digital data item representative of an average intensity of root activity during said first given period.

5. Method for detecting root recovery of a plant according to any one of the preceding claims, characterized in that it comprises the step of calculating a second average speed (Vm2) of evolution of the water tension of the soil during said second given period and to create in return a digital data item representative of an average intensity of root activity during said second given period.

6. Method for detecting root recovery of a plant according to claims 4 and 5, characterized in that it comprises a step consisting of defining a certain efficiency of root recovery, said efficiency of root recovery being determined by a correlation between the level of root recovery and the intensity of root recovery so that the higher the level of root recovery and the greater the intensity of root recovery during the given period At2 and the greater the efficiency of root recovery and to create in return digital data representative of a certain efficiency of root recovery during the given period At2.

7. Method for detecting root recovery of a plant according to claim 1, characterized in that it comprises the steps of calculating a duration (At3) during which the water tension of the soil measured by said humidity sensor is constant, comparing said calculated duration with a threshold duration (y) of constant water tension of the soil beyond which it is considered that the plant is not in root activity, then creating digital data representative of an absence of root activity if the calculated duration is greater than said threshold duration.

8. Measuring station (7) designed to detect root recovery of a plant, comprising at least one sensor designed to measure soil water tensions and a central unit configured to implement the method according to any one of the preceding claims, characterized in that the station comprises a display screen (8) and in that the central unit is designed to display said digital data representative of the detection of root recovery in several categories on the display screen.

9. Measuring station according to claim 8, characterized in that the categories are displayed in the form of color code on the display screen and / or icons.

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