A water and fertilizer management method for promoting root sprouting type alfalfa root sprouting

Abstract

The application provides a water and fertilizer management method for promoting root sprouting type alfalfa root system tillering, relates to the technical field of forage grass cultivation and water and fertilizer regulation, and comprises the following steps: obtaining the distribution positions of horizontal roots and root sprouting buds of the root sprouting type alfalfa, and selecting the horizontal roots with root sprouting bud distribution root segments and terminal extension root segments as target horizontal roots, wherein the terminal extension root segments are located on the side of the root sprouting bud distribution root segments away from the root neck of the mother plant. The water and fertilizer management method for promoting root sprouting type alfalfa root system tillering divides the soil corresponding to the target horizontal roots into a horizontal root extension area and a plurality of activation sub-areas by identifying the spatial distribution of the horizontal roots and root sprouting buds of the root sprouting type alfalfa, changes the water and fertilizer action positions before and after mowing, realizes the zoned and staged water and fertilizer regulation of the root sprouting occurrence area, and matches the water and nutrient supply of the root sprouting occurrence layer with the processes of root sprouting bud swelling, germination and new sprout formation.

Description

Technical Field

[0001] This invention relates to the field of forage cultivation and water and fertilizer management technology, specifically a water and fertilizer management method for promoting root tillering in alfalfa. Background Technology

[0002] Alfalfa is a common perennial leguminous forage grass, characterized by high yield, good nutritional value, and wide adaptability. In addition to taproots and lateral roots, root suckers also form horizontal roots that grow laterally. These horizontal roots bear root suckers. After sprouting, these suckers form new above-ground branches, promoting the plant's expansion and facilitating grassland renewal and long-term use. Current alfalfa cultivation primarily employs drip irrigation, sprinkler irrigation, or fertigation. Irrigation periods mainly include the greening stage, budding stage, before and after mowing, and before wintering. Fertilization is mostly done through a combination of basal and topdressing. Topdressing is often applied with irrigation water, primarily using nitrogen, phosphorus, and potassium fertilizers. Some cultivation methods also adjust the frequency and amount of irrigation, the depth of drip irrigation tape installation, and the timing of post-mowing topdressing to meet the needs of alfalfa greening, regeneration, and root growth.

[0003] Current water and fertilizer management typically treats the alfalfa root zone as a unified water and fertilizer supply area, without independently regulating the root tillering layer based on the distribution of horizontal roots and root suckers. Conventional irrigation and fertilization mainly meet the growth needs of the mother plant and root collar branches, making it difficult for the water and nutrient status of the root tillering layer to match the formation and germination process of root suckers, resulting in an unstable number of root suckers formed and new tillers emerging from the soil. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a water and fertilizer management method for promoting root tillering in alfalfa. The technical problem this invention aims to solve is: how to address the mismatch between the water and fertilizer status of the root tillering layer and the root tiller formation and germination process by using functional zoning based on the spatial distribution of horizontal roots and root tillers, horizontal root extension induction before mowing, and zone-by-zone water and fertilizer activation after mowing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a water and fertilizer management method for promoting root tillering in alfalfa, comprising: S1. Obtain the distribution location of horizontal roots and root suckers of root-tillering alfalfa, select horizontal roots with root sucker distribution segments and terminal extension segments as target horizontal roots, wherein the terminal extension segments are located on the side of the root sucker distribution segment away from the root neck of the mother plant; determine the soil corresponding to the root sucker distribution segment as the root sucker activation zone, determine the soil corresponding to the terminal extension segment and the adjacent soil outside the end of the target horizontal root as the horizontal root extension zone, and divide the root sucker activation zone into at least two activation sub-zones along the length direction of the target horizontal root; S2. Independently controllable water and fertilizer supply is implemented for the horizontal root extension zone and each of the activation sub-regions; S3. Before cutting the root-tiller type alfalfa, stop supplying water and fertilizer to each of the activation sub-zones, supply water to the horizontal root extension zone, and form an extension moist zone on the outer side of the end of the target horizontal root. The extension moist zone contacts the end extension root segment but does not enter the root-tiller activation zone. S4. After the root sucker alfalfa is cut, stop supplying water and fertilizer to the horizontal root extension zone. Supply water and fertilizer to each of the activated sub-zones in sequence, from the end of the target horizontal root to the root neck of the mother plant. Supply water and fertilizer to the current activated sub-zone to form an activated moist zone within the current activated sub-zone. The activated moist zone is confined to the current activated sub-zone and separated from the soil where the root neck of the mother plant is located. After the root suckers in the current activated sub-zone reach the preset swelling standard, start the next activated sub-zone located on the side of the current activated sub-zone closer to the root neck of the mother plant, until the water and fertilizer supply to each of the activated sub-zones is completed. S5. After the root suckers in any of the activated sub-regions emerge from the soil and form new suckers, water and fertilizer continue to be supplied to the activated sub-regions where the new suckers are formed until the new suckers form independent above-ground branches.

[0006] Preferably, the distribution positions of the horizontal roots and the root suckers are obtained by a transparent root window set outward along the root neck of the mother plant. The position of the root suckers is determined based on the root image collected by the transparent root window, and the continuous non-budding root segment between the root sucker closest to the end of the target horizontal root and the end of the target horizontal root is determined as the terminal extension root segment.

[0007] Preferably, the root suckers are divided into at least two root sucker groups according to their arrangement from the end of the target horizontal root to the root neck of the mother plant. Each root sucker group includes one or more consecutively arranged root suckers, and each root sucker group corresponds one-to-one with each activation sub-region. The boundary between two adjacent activation sub-regions is located at the midpoint between the two root suckers that are closest to each other in the two adjacent root sucker groups along the extension path of the target horizontal root.

[0008] Preferably, water and fertilizer delivery branch pipes are provided in the horizontal root extension area and each of the activation sub-areas, and each water and fertilizer delivery branch pipe is connected to an independent control valve. Each independent control valve controls the opening or closing of the corresponding water and fertilizer delivery branch pipe. The water and fertilizer outlet of each water and fertilizer delivery branch pipe is located in the corresponding horizontal root extension area or the corresponding activation sub-area, and the center burial depth of each water and fertilizer outlet is between the minimum and maximum burial depth of the target horizontal root in the corresponding area.

[0009] Preferably, each of the activated sub-regions has a soil moisture monitoring point located at the midpoint of the target horizontal root along its length, at one end near the root collar of the mother plant, and at one end away from the root collar of the mother plant. The burial depth of each soil moisture monitoring point is between the minimum and maximum burial depth of the target horizontal root within the corresponding activated sub-region. When the soil moisture content measured by the soil moisture monitoring point located at the midpoint of the current activated sub-region reaches the preset midpoint moisture content, and the soil moisture content measured by the soil moisture monitoring points located at both ends of the current activated sub-region is lower than 60% of the field capacity of the soil in the current activated sub-region, the supply of water and fertilizer to the current activated sub-region is stopped. The preset midpoint moisture content is 70%-85% of the field capacity of the soil in the current activated sub-region.

[0010] Preferably, the operation of stopping the supply of water and fertilizer to each of the activated sub-zones and supplying water to the horizontal root extension zone begins 5-10 days before harvesting and continues until harvesting; when the operation begins, the soil moisture content of each of the activated sub-zones is 40%-55% of the field capacity of the corresponding soil, and during the operation, the soil moisture content of the horizontal root extension zone is maintained at 65%-80% of the field capacity of the corresponding soil.

[0011] Preferably, the boundary of the extended moistening zone on the side away from the root neck of the mother plant along the length direction of the target horizontal root is located 5cm-20cm away from the root neck of the mother plant at the end of the target horizontal root; the boundary of the extended moistening zone on the side near the root neck of the mother plant is located in the soil corresponding to the terminal extended root segment, and the distance between it and the boundary of the root sucker activation zone on the side away from the root neck of the mother plant is 2cm-10cm.

[0012] Preferably, the water and fertilizer supply to the currently activated sub-region includes a first supply of clean water, a first supply of fertilizer solution, and a second supply of clean water in sequence, wherein the mass ratio of nitrogen, phosphorus pentoxide, and potassium oxide in the first fertilizer solution is 1:(1.5-3):(1-2).

[0013] Preferably, the preset enlargement standard is determined based on root images acquired through the transparent root window before and after water and fertilizer are supplied to the current activated sub-region. The root images acquired before and after water and fertilizer supply have the same imaging ratio and are sized. The preset enlargement standard is as follows: the maximum transverse diameter of the same bud in the current activated sub-region increases by no less than 20% after water and fertilizer supply compared to the maximum transverse diameter before water and fertilizer supply, and the number of buds with a maximum transverse diameter increase of no less than 20% accounts for no less than 60% of the total number of buds in the current activated sub-region determined before water and fertilizer supply.

[0014] Preferably, the formation of independent above-ground branches by the new tillers means that the vertical height from the position of emergence to the apical growth point of the new tillers is not less than 10cm, and that they form no less than 3 fully unfolded trifoliate leaves.

[0015] This invention provides a water and fertilizer management method to promote root tillering in alfalfa. It has the following beneficial effects:

[0016] This water and fertilizer management method for promoting root tillering in alfalfa identifies the spatial distribution of horizontal roots and root tillers in alfalfa, divides the soil corresponding to the target horizontal roots into horizontal root extension zones and multiple activation sub-zones, and changes the location of water and fertilizer application before and after harvesting. This achieves zoned and phased water and fertilizer regulation of the root tillering area, matching the water and nutrient supply of the root tillering layer with the process of root tiller swelling, germination, and new tiller formation.

[0017] The method involves supplying water to the horizontal root extension zone before cutting and then supplying water and fertilizer to each zone in sequence from the end of the horizontal root towards the root neck of the mother plant after cutting. This allows each activated sub-zone to form an independent activated and moist zone. The next activated sub-zone is activated based on the swelling state of the root suckers, reducing the diffusion of water and fertilizer into the soil where the root neck of the mother plant is located. This method plays a role in directionally activating root suckers, stabilizing the number of new suckers emerging from the soil, and maintaining the subsequent growth of new suckers. Attached Figure Description

[0018] Figure 1 This is the overall flowchart of the management method of the present invention; Figure 2 This is a schematic diagram of the horizontal root partition and equipment layout of the present invention; Figure 3 This is a flowchart of the water and fertilizer regulation process before harvesting according to the present invention; Figure 4 This is a flowchart of the activation and switching process for each zone after reaping according to the present invention; Figure 5 This is a flowchart illustrating the process from the emergence of new tillers to their independent branching in this invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 like Figure 1-5 As shown, this embodiment of the invention provides a water and fertilizer management method for promoting root tillering in alfalfa, comprising: S1. Obtain the distribution location of horizontal roots and root suckers in alfalfa with root sucker distribution. Select horizontal roots with root sucker distribution segments and terminal extension segments as target horizontal roots. The terminal extension segment is located on the side of the root sucker distribution segment away from the root neck of the mother plant. Define the soil corresponding to the root sucker distribution segment as the root sucker activation zone, and define the soil corresponding to the terminal extension segment and the adjacent soil outside the end of the target horizontal root as the horizontal root extension zone. Divide the root sucker activation zone into at least two activation sub-zones along the length of the target horizontal root. The distribution location of horizontal roots and root suckers is obtained through a transparent root window set outward from the root neck of the mother plant. Determine the attachment position of root suckers based on the root image acquired through the transparent root window, and define the continuous non-budding root segment between the root sucker closest to the end of the target horizontal root and the end of the target horizontal root as the terminal extension segment. Root suckers are divided into at least two groups according to their arrangement from the end of the target horizontal root towards the root collar of the mother plant. Each root sucker group includes one or more consecutively arranged root suckers, and each root sucker group corresponds one-to-one with each activation sub-region. The boundary between two adjacent activation sub-regions is located at the midpoint between the two closest root suckers in the two adjacent root sucker groups along the extension path of the target horizontal root.

[0021] S2. Independent water and fertilizer supply is implemented for the horizontal root extension zone and each activation sub-zone. Water and fertilizer delivery branch pipes are installed within each horizontal root extension zone and each activation sub-zone. Each water and fertilizer delivery branch pipe is connected to an independent control valve, which controls the opening or closing of its corresponding water and fertilizer delivery branch pipe. The water and fertilizer outlet of each water and fertilizer delivery branch pipe is located within the corresponding horizontal root extension zone or the corresponding activation sub-zone. The center burial depth of each water and fertilizer outlet is between the minimum and maximum burial depth of the target horizontal root within the corresponding area.

[0022] S3. Before harvesting root-tiller alfalfa, stop supplying water and fertilizer to each activated sub-zone, and supply water to the horizontal root extension zone. Create an extended moist zone on the outer side of the end of the target horizontal root, ensuring the extended moist zone contacts the terminal extended root segment but does not enter the root tiller activation zone. The operation of stopping water and fertilizer supply to each activated sub-zone and supplying water to the horizontal root extension zone should begin 5-10 days before harvesting and continue until harvesting. At the start of the operation, the soil moisture content of each activated sub-zone should be 40%-55% of the corresponding soil field capacity. During the operation, the soil moisture content of the horizontal root extension zone should be maintained at 65%-80% of the corresponding soil field capacity. The boundary of the extended moist zone, along the length of the target horizontal root, away from the root neck of the mother plant, should be located 5cm-20cm from the end of the target horizontal root away from the root neck of the mother plant. The boundary of the extended moist zone on the side near the root neck of the mother plant is located in the soil corresponding to the terminal extended root segment, and the distance between it and the boundary of the root sucker activation zone on the side away from the root neck of the mother plant is 2cm-10cm.

[0023] S4. After cutting the root-sprouting alfalfa, stop supplying water and fertilizer to the horizontal root extension zone. Supply water and fertilizer sequentially to each activated sub-zone, following the order from the end of the target horizontal root towards the root collar of the mother plant. Supplying water and fertilizer to the current activated sub-zone creates an activated moist zone within it, confined to the current activated sub-zone and separated from the soil containing the root collar of the mother plant. Once the root suckers in the current activated sub-zone reach the preset swelling standard, start the next activated sub-zone located on the side of the current activated sub-zone closer to the root collar of the mother plant, until the sequential water and fertilizer supply to each activated sub-zone is completed. Each activated sub-zone has soil moisture monitoring points at the midpoint of the target horizontal root's length direction, at the end closer to the root collar of the mother plant, and at the end away from the root collar of the mother plant. The burial depth of each soil moisture monitoring point is between the minimum and maximum burial depth of the target horizontal root within the corresponding activated sub-zone. When the soil moisture content measured at the soil moisture monitoring point located at the midpoint of the current activated sub-region reaches the preset midpoint moisture content, and the soil moisture content measured at the soil moisture monitoring points at both ends of the current activated sub-region is lower than 60% of the field capacity of the soil in the current activated sub-region, the supply of water and fertilizer to the current activated sub-region will be stopped. The preset midpoint moisture content is 70%-85% of the field capacity of the soil in the current activated sub-region. The water and fertilizer supply to the current activated sub-region includes a first supply of clean water, a first supply of fertilizer solution, and a second supply of clean water in sequence. The mass ratio of nitrogen, phosphorus pentoxide, and potassium oxide in the first fertilizer solution is 1:(1.5-3):(1-2). The preset enlargement standard is determined based on root images collected through a transparent root window before and after the supply of water and fertilizer to the current activated sub-region. The root images collected before and after the supply of water and fertilizer have the same imaging scale and are sized. The preset expansion standard is: the maximum transverse diameter of the same bud in the current activated sub-region increases by no less than 20% after water and fertilizer supply compared to the maximum transverse diameter before water and fertilizer supply, and the number of buds with a maximum transverse diameter increase of no less than 20% accounts for no less than 60% of the total number of buds in the current activated sub-region determined before water and fertilizer supply.

[0024] S5. After the root suckers in any activated sub-zone emerge from the soil and form new suckers, continue to supply water and fertilizer to the activated sub-zone where the new suckers are forming until the new suckers form independent above-ground branches. The formation of independent above-ground branches by new suckers means that the vertical height from the position of emergence to the apical meristem of the new sucker is not less than 10cm, and that it forms no less than 3 fully unfolded trifoliate compound leaves.

[0025] This invention employs a zoned water and fertilizer regulation method based on the spatial distribution of horizontal roots and root suckers, allowing the horizontal root extension zone and the root sucker activation zone to receive different water and fertilizer treatments before and after mowing. This avoids the overlap of water and fertilizer action ranges caused by overall irrigation of the root zone and enhances the matching between the water and fertilizer supply location and the development stage of the root suckers.

[0026] This invention initiates water and fertilizer supply in stages based on the actual swelling state of the root suckers, and uses the boundaries of local humid areas and soil moisture content monitoring to limit the spread of water and fertilizer to adjacent areas and the root collar of the mother plant. This helps to improve the controllability of the root sucker activation process and maintain a continuous supply of water and fertilizer after the new suckers emerge from the soil.

[0027] Example 2 This embodiment is used to verify the effect of forming an extended moist zone on the outer side of the horizontal root tip before cutting, which is separate from the root sucker activation zone, on isolating the target horizontal root tip extension and root sucker distribution area from water.

[0028] 1. Experimental materials and grouping The experimental material was three-year-old root-tillering alfalfa from the same clonal line. The soil in the experimental site was sandy loam, and the field water holding capacity (DBC) of the 0-30 cm soil layer was 22.8%. The DBC was measured by taking undisturbed soil samples with a ring sampler, allowing them to absorb saturated water, and then allowing them to drain freely for 48 hours. The percentage of DBC mentioned below is the ratio of soil volumetric water content to 22.8%.

[0029] Twenty plants with similar growth vigor were selected and paired according to the initial length of the target horizontal root and the number of root suckers. They were then randomly divided into an extension induction group and a uniform water supply group, with 10 plants in each group. The initial length of the target horizontal root in the extension induction group was 89.6±4.3 cm, and the number of root suckers was 16.0±1.1. The initial length of the target horizontal root in the uniform water supply group was 89.1±4.0 cm, and the number of root suckers was 15.8±1.0.

[0030] Each experimental unit containing a plant was surrounded by a 60cm deep waterproof barrier, and the distance between adjacent experimental units was 1.5m. During the experiment, a mobile rain shelter was used to prevent natural rainfall from entering the experimental units, consistent with other field management practices.

[0031] 2. Target horizontal root location and functional zoning A transparent root window was installed 12cm from the root collar of the mother plant. The transparent root window was 100cm long and 40cm high, with an opaque cover on the outside. After installation, the plant recovered for 25 days, and root images were taken using a fixed shooting position and a fixed focal length. A millimeter ruler was placed in the images for size calibration.

[0032] For each plant, select one horizontal root with a burial depth of 17cm-23cm, a continuous visible length of no less than 80cm, and no mechanical damage as the target horizontal root. Root suckers are mainly distributed in root segments 24cm-64cm away from the root neck of the mother plant. The soil within a range of 6cm on both sides of the center line of the corresponding root segment, and 5cm above and below it, is defined as the root sucker activation zone.

[0033] The average length of the continuous non-budding root segment from 64cm from the root collar of the mother plant to the end of the target horizontal root is 25.6cm. The soil within 15cm outside the continuous non-budding root segment and the end of the target horizontal root, extending 6cm to both sides of the root segment's centerline and 5cm above and below it, is defined as the horizontal root extension zone.

[0034] The root sucker activation zone is divided into three activation sub-zones according to the arrangement of the root suckers. The three activation sub-zones contain an average of 5, 6, and 5 root suckers, respectively. The boundary between adjacent activation sub-zones is located at the midpoint between the two closest root suckers in two adjacent groups of root suckers.

[0035] 3. Water supply equipment and monitoring methods A water and fertilizer delivery branch pipe is buried in each of the horizontal root extension zone and the three activation sub-zones. Each branch pipe is connected to an independent control valve, the center burial depth of the water and fertilizer outlet is 20cm, and the rated flow rate is 1.2L / h.

[0036] Soil moisture sensors were installed at the midpoint and both ends of the three activation sub-regions. Monitoring points were set at the end of the target horizontal root, 10 cm outside the end, and near the boundary of the root tiller activation zone in the horizontal root extension zone. Before installation, the sensors were calibrated using the oven-drying method with soil from the test site, and the calibration determination coefficient was not less than 0.98.

[0037] Temporary moisture content measuring points are set every 2 cm along the direction of the target horizontal root extension. The soil area with a relative field capacity of 60% or more and which is continuous is defined as the moist zone, and the outermost measuring point with a relative field capacity of 60% is designated as the boundary of the moist zone.

[0038] 4. Pre-harvesting extension induction Seven days before mowing, the control valves of the three activation sub-zones in the extension induction group were closed, and water was supplied only to the horizontal root extension zone. At the start of treatment, the relative field capacity of the three activation sub-zones were 46.7%, 48.3%, and 49.5%, respectively.

[0039] The horizontal root extension zone was initially irrigated with 2.2L of water. Subsequently, soil moisture content was recorded daily at 8:00 AM. Water was replenished when the relative field capacity fell below 68%, maintaining the horizontal root extension zone at 68%-76%. Watering was conducted three times over seven days, with a cumulative water supply of 4.8L per plant.

[0040] The uniform water supply group receives the same total amount of clean water at the same time point. 4.8L of clean water is evenly distributed to the entire root zone corresponding to the target level root, without limiting the water supply location.

[0041] The extended moist zone formed by the extension induction group contacted the extended root segment at its tip. The boundary on the side away from the mother plant's root collar was located 11.4cm-14.2cm outside the target horizontal root tip, while the boundary on the side closer to the mother plant's root collar maintained a distance of 3.1cm-5.2cm from the root sucker activation zone. During the treatment, the relative field capacity of the three activated sub-zones was 45.2%-53.8%.

[0042] The relative field capacity of the root segments in the uniformly watered group was 67.5%-73.8%, and the target level root tip area and the root and shoot distribution area formed a continuous moist range.

[0043] 5. Post-harvest irrigation and fertilization The cutting height is 6cm from the ground. Stop watering the horizontal root extension zone 36 hours after cutting, and then supply water and fertilizer sequentially to the activation zone closest to the end of the target horizontal root, the activation zone in the middle, and the activation zone near the root collar of the mother plant.

[0044] Each activation sub-zone is supplied with 0.7L of clean water, 0.5L of fertilizer solution, and 0.4L of clean water sequentially. The mass ratio of nitrogen, phosphorus pentoxide, and potassium oxide in the fertilizer solution is 1:2.2:1.4. The next activation sub-zone is initiated once the number of root suckers with a maximum transverse diameter increase of at least 20% in the current activation sub-zone reaches 60% of the total number of root suckers before treatment.

[0045] After the new tillers emerge, maintain the relative field water holding capacity of the corresponding activated sub-zone at 65%-75% until the new tillers reach a vertical height of 10cm and form no less than 3 fully unfolded trifoliate leaves.

[0046] 6. Measurement Results The root images were registered using the same imaging ratio. The bifurcation point of the target horizontal root 7 days before mowing was used as a fixed reference point, and the extension length of the target horizontal root end was measured along the root axis centerline.

[0047] The terminal extension length of the extension induction group was 6.4±1.1 cm within 7 days, while that of the uniform water supply group was 2.6±0.8 cm. None of the 10 plants in the extension induction group entered the root sucker activation zone, while 8 plants in the uniform water supply group formed a continuous moist area extending from the target horizontal root tip area to the root sucker distribution area.

[0048] Each plant was considered a biological replicate, and data are expressed as mean ± standard deviation. A two-tailed independent samples t-test was used when the two groups were normally distributed; the Mann-Whitney U test was used when they were not normally distributed. The significance level was set at 0.05. The inter-group comparison of the target level root tip extension length was P < 0.01.

[0049] Limiting water supply to the horizontal root extension zone before mowing maintains a low water content in the root sucker activation zone and blocks the continuous moist area between the horizontal root tip region and the root sucker distribution area. The extension length of the target horizontal root tip is higher than that under uniform water supply conditions in the root zone, indicating that the water action before mowing is concentrated near the terminal root extension segment, providing a root segment basis for the reverse zone-by-zone water and fertilizer supply after mowing.

[0050] Example 3 This study was used to verify the effect of supplying water and fertilizer in sequence from the root tip to the root collar of the mother plant after cutting on the swelling of root suckers, emergence of new suckers, and water restriction in the root collar area of ​​the mother plant.

[0051] 1. Experimental materials and control setup The experimental material was three-year-old root-tillering alfalfa from the same clone. The soil was loam with a field water holding capacity of 25.1%, and the measurement method was the same as in Example 2.

[0052] Twenty-four plants were selected and paired into blocks according to target horizontal root length, burial depth, and initial number of root suckers. Within each block, one plant was randomly selected to enter the phased activation group, and the other to enter the synchronous watering group, with 12 plants in each group. The initial target horizontal root length for the phased activation group was 101.8±5.2 cm, and the number of root suckers was 21.0±1.2. For the synchronous watering group, these figures were 101.1±5.0 cm and 20.8±1.3, respectively.

[0053] Each plant was equipped with an independent waterproof unit and a transparent root window. The conditions for waterproofing, rain protection, and image acquisition were the same as in Example 2. The cutting height for both groups was 6cm above the ground.

[0054] 2. Activate sub-region partitioning The average burial depth of the target horizontal roots in the zone-by-zone activation group was 22.6 cm. The root sucker distribution root segments were located 20 cm to 79 cm from the root neck of the mother plant, and the terminal extension root segments were located from 79 cm from the root neck of the mother plant to the end of the target horizontal root.

[0055] The root sucker activation zone was divided into four activation sub-zones based on the arrangement of the root suckers. Each activation sub-zone contained 4-6 root suckers, with a total of 19-23 root suckers per plant. Each root sucker was numbered according to its position in the transparent root window image.

[0056] Soil moisture sensors are installed at the midpoint and both ends of each activated sub-zone. The monitoring point at the root collar of the mother plant is located 5 cm outside the root collar, with the burial depth consistent with the average burial depth of the target horizontal roots. Continuous soil with a relative field capacity of 60% or more is defined as the activated moist zone.

[0057] 3. Moisture control before mowing Eight days before harvesting, stop supplying water and fertilizer to the four activated sub-zones and only supply water to the horizontal root extension zone. At harvesting time, the relative field capacity of each activated sub-zone is 45%-53%, and that of the horizontal root extension zone is 70%-78%.

[0058] The synchronized water supply group underwent the same pre-cutting treatment to ensure that both groups of plants had the same water baseline at the time of cutting. The control valve of the horizontal root extension zone was closed 36 hours after cutting.

[0059] 4. Water and fertilizer supply in each area The zone-by-zone activation group first activates the sub-zone closest to the target level root tip. A single water and fertilizer supply consists of 0.7L of initial clean water, 0.5L of initial fertilizer solution, and 0.4L of second clean water.

[0060] The first fertilizer solution was prepared using urea, phosphoric acid, and potassium sulfate, calculated based on their effective nutrient content. The mass ratio of nitrogen, phosphorus pentoxide, and potassium oxide was 1:2.2:1.4, and the total mass concentration of the three nutrients was 1.6 g / L. The same water source was used for both irrigations, and the conductivity of the irrigation water was 0.42 mS / cm.

[0061] When the relative field capacity at the midpoint of the current activated sub-region reaches 72%-82%, and both ends are below 60%, water and fertilizer supply should be stopped. Root system images should be collected every 24 hours before and after water supply, and the images should be calibrated using the same focal length, shooting distance, and size.

[0062] If the maximum transverse diameter of the same sucker increases by at least 20% after watering compared to before watering, it is considered to have reached the swelling standard. When the number of suckers that have reached the swelling standard accounts for at least 60% of the total number of suckers in the current activation sub-zone before treatment, the next activation sub-zone is started on the side closest to the root collar of the mother plant.

[0063] The synchronized water supply group and the paired zone-by-zone activation group received the same total amount of water and fertilizer on the same date. Each time, 1.6L of water and fertilizer was evenly distributed to the four activation sub-zones, and the water supply location was not changed according to the swelling status of root suckers. The cumulative water supply, total fertilizer nutrient content, and number of treatments were the same for each pair of plants.

[0064] 5. Confirmation of new tiller source and nutritional continuity Only new suckers corresponding to the numbered root bud positions in the transparent root window are counted. After the new suckers emerge, the connection relationship is confirmed by continuous images of the underground buds, target horizontal roots, and above-ground emergence points. New suckers generated by branches directly forming from the root collar of the mother plant and other horizontal roots are not included in the results.

[0065] Soil moisture content in the activating zone for new tiller formation should be tested daily in the morning. When the relative field capacity is below 65%, 0.4L of clean water should be supplied, followed by 0.3L of fertilizer solution every 5 days. The mass ratio of nitrogen, phosphorus pentoxide, and potassium oxide in the fertilizer solution should be 1:0.6:1.0, with a total nutrient concentration of 1.2g / L. Water and fertilizer supply should cease after the new tillers reach a vertical height of 10cm and have formed 3 fully expanded trifoliate leaves.

[0066] The synchronous water supply group uses the same amount of clean water, fertilizer solution, and detection frequency, and distributes water and fertilizer evenly to the areas where new tillers have formed.

[0067] After the experiment, four plants from each group were randomly selected and their soil sections were dissected along the location where the new tillers emerged. The connection between the new tillers and the numbered root tillers was then verified. The results of the soil dissection were consistent with the records of the transparent root window images.

[0068] 6. Measurement Results The first to fourth activated sub-regions of the tiered activation group reached the swelling standard on the 3rd, 4th, 4th, and 5th days after water and fertilizer supply, respectively. The proportions of root suckers reaching the swelling standard were 80.0%, 60.0%, 66.7%, and 60.0%, respectively.

[0069] The first batch of new shoots appeared in the 7th day after mowing, and the new shoots in the four activated sub-regions emerged on the 19th day. The number of new shoots per plant was 13.2±1.5, of which 11.4±1.3 formed independent above-ground branches within 28 days after mowing.

[0070] The new shoots of the synchronously watered group emerged from the soil 10-17 days after cutting, with 9.1±1.4 new shoots per plant, of which 7.3±1.2 formed independent above-ground branches within 28 days after cutting.

[0071] During the zone-by-zone activation period, the relative field capacity at the midpoint of the currently activated sub-zone was 72.6%-82.1%, and at both ends it was 49.7%-58.6%, without forming a continuous moist zone spanning the boundaries of adjacent activated sub-zones. The average relative field capacity of the soil where the root collar of the mother plant is located was 51.8±2.7%, and for the synchronous water supply group it was 71.4±2.3%.

[0072] Each plant was considered a biological replicate, and the statistical methods were the same as in Example 2. The comparison results of the number of new tillers, the number of independent aboveground branches, and the soil moisture content of the root collar of the mother plant between the two groups were all P < 0.01.

[0073] By sequentially activating each sub-zone according to the swelling state of the root suckers, the location of water and fertilizer action can be moved along the target horizontal root from the tip to the root collar of the mother plant zone by zone. Compared with synchronous water supply of equal amount, the number of new suckers formed and the number of independent above-ground branches are greater under the zone-by-zone activation condition, and the soil moisture content in the root collar of the mother plant is lower. This indicates that zone-by-zone water and fertilizer supply can limit the diffusion of water and fertilizer to the root collar area of ​​the mother plant and establish a corresponding relationship between root sucker activation, new sucker emergence and subsequent water and fertilizer supply.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water and fertilizer management method for promoting root tillering in alfalfa, characterized in that, include: S1. Obtain the distribution location of horizontal roots and root suckers of root-tillering alfalfa, select horizontal roots with root sucker distribution segments and terminal extension segments as target horizontal roots, wherein the terminal extension segments are located on the side of the root sucker distribution segment away from the root neck of the mother plant; determine the soil corresponding to the root sucker distribution segment as the root sucker activation zone, determine the soil corresponding to the terminal extension segment and the adjacent soil outside the end of the target horizontal root as the horizontal root extension zone, and divide the root sucker activation zone into at least two activation sub-zones along the length direction of the target horizontal root; S2. Independently controllable water and fertilizer supply is implemented for the horizontal root extension zone and each of the activation sub-regions; S3. Before cutting the root-tiller type alfalfa, stop supplying water and fertilizer to each of the activation sub-zones, supply water to the horizontal root extension zone, and form an extension moist zone on the outer side of the end of the target horizontal root. The extension moist zone contacts the end extension root segment but does not enter the root-tiller activation zone. S4. After the root sucker alfalfa is cut, stop supplying water and fertilizer to the horizontal root extension zone. Supply water and fertilizer to each of the activated sub-zones in sequence, from the end of the target horizontal root to the root neck of the mother plant. Supply water and fertilizer to the current activated sub-zone to form an activated moist zone within the current activated sub-zone. The activated moist zone is confined to the current activated sub-zone and separated from the soil where the root neck of the mother plant is located. After the root suckers in the current activated sub-zone reach the preset swelling standard, start the next activated sub-zone located on the side of the current activated sub-zone closer to the root neck of the mother plant, until the water and fertilizer supply to each of the activated sub-zones is completed. S5. After the root suckers in any of the activated sub-regions emerge from the soil and form new suckers, water and fertilizer continue to be supplied to the activated sub-regions where the new suckers are formed until the new suckers form independent above-ground branches.

2. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: The distribution of the horizontal roots and the root suckers is obtained by a transparent root window set outward along the root neck of the mother plant. The location of the root suckers is determined based on the root image collected by the transparent root window. The continuous root segment without buds between the root sucker closest to the end of the target horizontal root and the end of the target horizontal root is defined as the terminal extension root segment.

3. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: The root suckers are divided into at least two root sucker groups according to their arrangement from the end of the target horizontal root to the root neck of the mother plant. Each root sucker group includes one or more consecutively arranged root suckers. Each root sucker group corresponds one-to-one with each activation sub-region. The boundary between two adjacent activation sub-regions is located at the midpoint between the two root suckers that are closest to each other in the two adjacent root sucker groups along the extension path of the target horizontal root.

4. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: Water and fertilizer delivery branch pipes are respectively provided in the horizontal root extension area and each of the activation sub-areas. Each water and fertilizer delivery branch pipe is connected to an independent control valve, and each independent control valve controls the opening or closing of the corresponding water and fertilizer delivery branch pipe. The water and fertilizer outlet of each water and fertilizer delivery branch pipe is located in the corresponding horizontal root extension area or the corresponding activation sub-area. The center burial depth of each water and fertilizer outlet is between the minimum burial depth and the maximum burial depth of the target horizontal root in the corresponding area.

5. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: Each of the activated sub-regions has a soil moisture monitoring point located at the midpoint of the target horizontal root along its length, at one end near the root collar of the mother plant, and at one end away from the root collar of the mother plant. The burial depth of each soil moisture monitoring point is between the minimum and maximum burial depth of the target horizontal root within the corresponding activated sub-region. When the soil moisture content measured by the soil moisture monitoring point located at the midpoint of the current activated sub-region reaches the preset midpoint moisture content, and the soil moisture content measured by the soil moisture monitoring points located at both ends of the current activated sub-region is lower than 60% of the field capacity of the soil in the current activated sub-region, the supply of water and fertilizer to the current activated sub-region is stopped. The preset midpoint moisture content is 70%-85% of the field capacity of the soil in the current activated sub-region.

6. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: The operation of stopping the supply of water and fertilizer to each of the activated sub-zones and supplying water to the horizontal root extension zone begins 5-10 days before harvesting and continues until harvesting; at the start of the operation, the soil moisture content of each of the activated sub-zones is 40%-55% of the field capacity of the corresponding soil, and during the operation, the soil moisture content of the horizontal root extension zone is maintained at 65%-80% of the field capacity of the corresponding soil.

7. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: The boundary of the extended moistening zone along the length of the target horizontal root, away from the root neck of the mother plant, is located 5cm-20cm away from the end of the target horizontal root on the side away from the root neck of the mother plant; the boundary of the extended moistening zone near the root neck of the mother plant is located in the soil corresponding to the terminal extended root segment, and the distance between it and the boundary of the root sucker activation zone away from the root neck of the mother plant is 2cm-10cm.

8. The water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: The water and fertilizer supply to the currently activated sub-region includes a first supply of clean water, a first supply of fertilizer solution, and a second supply of clean water in sequence. The mass ratio of nitrogen, phosphorus pentoxide, and potassium oxide in the first fertilizer solution is 1:(1.5-3):(1-2).

9. A water and fertilizer management method for promoting root tillering in alfalfa according to claim 2, characterized in that: The preset enlargement standard is determined based on root images acquired through the transparent root window before and after water and fertilizer are supplied to the current activated sub-region. The root images acquired before and after water and fertilizer supply have the same imaging ratio and are sized. The preset enlargement standard is as follows: the maximum transverse diameter of the same bud in the current activated sub-region increases by no less than 20% after water and fertilizer supply compared to the maximum transverse diameter before water and fertilizer supply, and the number of buds with a maximum transverse diameter increase of no less than 20% accounts for no less than 60% of the total number of buds in the current activated sub-region determined before water and fertilizer supply.

10. A water and fertilizer management method for promoting root tillering in alfalfa according to claim 1, characterized in that: The term "new tiller forming an independent above-ground branch" refers to a new tiller having a vertical height of not less than 10cm from its emergence point to its apical growth point, and having formed no fewer than 3 fully unfolded trifoliate compound leaves.

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