A method for identifying heat tolerance at flowering stage in rice

Abstract

The application provides a method for identifying heat tolerance of rice in flowering period, comprising the following steps: staggered sowing of rice, so that each rice germplasm is in the same period of heading and flowering; when the rice enters the heading and flowering period, artificially heating the canopy of the rice before the daily flowering of the rice, and stopping the artificial heating of the canopy of the rice after the rice closes the glume; recording the first flowering date and the end date of flowering of each rice germplasm when the rice enters the flowering period, and monitoring and recording the canopy air temperature of each rice germplasm; after the rice matures, calculating the daily average high temperature stress accumulated temperature encountered by the rice in the flowering period and calculating the heat tolerance value of each rice germplasm in the flowering period; and judging the heat tolerance of the rice in the flowering period by comparing the heat tolerance values of each rice germplasm. The application uses the balanced high temperature stress intensity and the empty grain rate to calculate the heat tolerance value, avoids the deviation of a single index, and the greater the heat tolerance value, the stronger the heat tolerance, and the smaller the heat tolerance value, the weaker the heat tolerance.

Description

Technical Field

[0001] The invention belongs to the technical field of rice heat resistance, and in particular relates to a method for identifying heat resistance of rice during the flowering period. Background Art

[0002] Heat damage has become a major natural disaster threatening the safe production of rice and other crops. Rice is most sensitive to heat damage during its flowering period, and this is also the period when heat damage most severely limits rice yield. If rice, especially indica rice, experiences temperatures exceeding 35°C for three consecutive days during its flowering period, it inhibits spikelet opening, anther dehiscence, and pollen shedding, compromising pollination and fertilization and significantly reducing spikelet fertilization rates. Even a single day of heat damage during the flowering period can increase the number of sterile spikelets to varying degrees. The longer the overlap between the flowering period and high temperatures, the greater the yield loss.

[0003] The rice flowering and pollination process is highly sensitive to its environment. Besides ambient temperature, light intensity, air humidity, carbon dioxide concentration, photoperiod, field water holding capacity, wind speed and direction, and mechanical damage can all interfere with normal rice flowering and pollination. The adverse effects of these environmental factors, similar to the damage to rice flowering and pollination caused by high temperatures and heat damage, produce the same result: spikelet sterility. These adverse effects can interfere with research on heat tolerance during the flowering period. Therefore, using artificial climate chambers or greenhouses to simulate high temperatures to study rice heat tolerance often yields significantly different conclusions when applied to the field. Using artificial climate chambers or greenhouses to simulate high temperatures and heat damage to study rice heat tolerance during the flowering period also presents challenges, such as uneven temperatures within the chamber or greenhouse, and limited experimental space, making it difficult to process multiple samples simultaneously. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a method for identifying the heat tolerance of rice during the flowering period, which aims to solve the problems mentioned in the background technology and improve the accuracy and feasibility of the test. The method of the present invention is easy to implement and has low manufacturing cost.

[0005] The present invention provides a method for identifying heat tolerance of rice during flowering period, comprising the following steps:

[0006] Step S1: staggering rice sowing so that all rice germplasms can head and flower at the same time;

[0007] Step S2: When the rice enters the heading and flowering stage, the rice canopy is artificially heated before the rice blooms every day, and the artificial heating of the rice canopy is stopped after the rice glume closes;

[0008] Step S3: When the rice enters the flowering period, the flowering start date and flowering end date of each rice germplasm are recorded, and the canopy air temperature of each rice germplasm is monitored and recorded;

[0009] Step S4: After the rice matures, the paddy plot is sampled using the 5-point method; after the rice is threshed, the total number of spikelets and the number of sterile spikelets of each rice plant are investigated, and the empty shell grain rate of each rice plant is calculated;

[0010] Step S5: taking the duration of rice flowering each day as the effective accumulated temperature as the total accumulated temperature during the flowering period, and the number of days from the beginning to the end of rice flowering as the number of days during the flowering period; calculating the average daily high temperature stress accumulated temperature encountered by the rice during the flowering period;

[0011] Step S6: Calculating the heat tolerance value of each rice germplasm during the flowering period based on the empty shell rice rate and the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period;

[0012] Step S7: evaluating the heat tolerance of rice during the flowering period by comparing the heat tolerance values ​​of various rice germplasms during the flowering period.

[0013] Furthermore, the rice is sown at a different time in step S1, specifically:

[0014] Step S11: Each rice germplasm is planted in more than two rice field plots, each of which has a width of 1 meter and a field enclosure and temperature-increasing device is installed outside the rice field plot;

[0015] Step S12, the field enclosure heating device includes a support frame, a highly transparent film, an automatic lifting cable, a remote control motor and a timing relay; the support frame is inserted around the rice field area, and the top corners of the support frame are provided with an automatic lifting cable. The highly transparent film is installed on the automatic lifting cable, and the highly transparent film is driven by the automatic lifting cable to form a closed enclosure space that can be automatically raised and lowered around the rice field area. A timing relay is installed on the top support frame to realize the timed opening and closing of the automatic lifting cable. At the same time, a remote control motor is installed on the top support frame, and the running time of the automatic lifting cable is manually remotely controlled to control the height of the high-transparent film enclosure driven by the automatic lifting cable;

[0016] Step S13, determining the height of the automatically raise / lowerable closed high-transparency film enclosure based on the temperature at 1.5 meters above the ground around the rice paddy area;

[0017] Step S14: The rice paddy plot is routinely fertilized and watered, and pests and diseases are controlled, and unified cultivation management is performed.

[0018] Furthermore, in step S13, the temperature at 1.5 meters near the ground around the rice field area determines the height of the automatically rising and falling closed high-transparent film enclosure, specifically:

[0019] When the height of the automatically rising and falling high transparent film enclosure is within the range of 1.2 to 1.8 meters and the temperature at 1.5 meters near the ground around the rice paddy plot is between 30.0 and 36.0 degrees Celsius, the canopy temperature of the rice paddy plot is expressed by the formula:

[0020] Y=19.85·ln(H+0.5)+T-8.53 (1);

[0021] Among them, Y is the canopy temperature of the rice field; H is the height of the automatically rising and falling high-transparent film enclosure; T is the temperature 1.5 meters near the ground around the rice field; the coefficient 19.85 and the constant 8.53 are obtained by fitting the field test data.

[0022] Furthermore, in step S2, the rice canopy is artificially heated before the rice flowers bloom each day, and the artificial heating of the rice canopy is stopped after the rice glume closes; specifically,

[0023] Step S21: A 10 cm gap is maintained between the automatically elevating high-transparent film enclosure and the ground of the rice paddy plot, and the area directly above the rice paddy plot is not enclosed;

[0024] Step S22: Before the rice flowers bloom each day, the temperature at 1.5 meters above the ground around the rice paddy plot is monitored using an automatic temperature monitoring recorder. The height of the automatically adjustable high-transparent film enclosure is calculated using a formula for the canopy temperature of the rice paddy plot.

[0025] Step S23: manually remotely controlling the motor and adjusting the automatically elevating high-transparent film enclosure using the automatic elevating cable to ensure that the canopy temperature of the rice field is controlled at a preset target value;

[0026] In step S24, the automatic temperature monitoring recorder feeds back the temperature data 1.5 meters near the ground around the rice field area in real time to the remote control motor, dynamically adjusts the high-transparent film enclosure that can automatically rise and fall, and controls the automatic lifting cable to achieve artificial heating of the canopy temperature and stop artificial heating.

[0027] Furthermore, in step S3, the canopy air temperature of each rice germplasm is monitored and recorded; specifically:

[0028] The monitoring step length is 1 time / min. After the rice flowering period is over, the canopy temperature data of the test rice germplasm from the start date to the end date of flowering are retrieved; after the flowering period is over, the field enclosure and warming device of the rice plot are removed.

[0029] Furthermore, in step S4, the empty shell grain rate of each rice plant is calculated; it can be expressed as follows:

[0030] Empty kernel rate = number of sterile spikelets / total number of spikelets.

[0031] Furthermore, in step S5, the duration of rice flowering per day is taken as the effective accumulated temperature as the total accumulated temperature during the flowering period, and the number of days from the beginning of rice flowering to the end of flowering is taken as the number of days in the flowering period; the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period is calculated; specifically:

[0032] The average daily effective accumulated temperature of each rice germplasm high temperature treatment group and normal temperature control group was calculated; the average daily effective accumulated temperature of the high temperature treatment group and the average daily effective accumulated temperature of the moderate temperature control group were expressed by the formula:

[0033] The average daily effective accumulated temperature of the high temperature treatment group = the total accumulated temperature of the high temperature treatment group during the flowering period / the number of days of the high temperature treatment group during the flowering period;

[0034] Average daily effective accumulated temperature of the optimal temperature control group = total accumulated temperature of the optimal temperature control group during flowering period / number of days of flowering period of the optimal temperature control group;

[0035] The intensity of high temperature stress was determined by the difference between the average daily effective accumulated temperature of the high temperature treatment group and the average daily effective accumulated temperature of the suitable temperature control group, and was expressed by the formula:

[0036] The average daily accumulated temperature of high temperature stress during the flowering period = the average daily effective accumulated temperature of the high temperature treatment group - the average daily effective accumulated temperature of the suitable temperature control group.

[0037] Furthermore, in step S6, the heat tolerance value of each rice germplasm during the flowering period is calculated based on the empty shell kernel rate of the rice and the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period. The formula is expressed as:

[0038] Heat resistance value = × Average daily accumulated temperature of high temperature stress during flowering period.

[0039] The present invention has the following beneficial effects: it can effectively identify the heat resistance of rice during the flowering period under natural field conditions, overcoming the problem that existing field identification relies on occasional high temperature weather and the shortcomings of artificial climate chamber identification methods, such as small test space and unnatural test environment, and improving the accuracy and feasibility of the test. At the same time, it provides a new approach for screening heat-resistant germplasm materials in agricultural breeding processes and has broad application prospects. It can accurately assess the heat resistance of rice during the flowering period in the natural environment of the field, breaking through the limitation of traditional field identification relying on occasional high temperature weather, and solving the problems of small space, uneven temperature, and unnatural growth conditions in artificial climate chambers. It has the advantages of a simple and efficient warming device, precise temperature control, and reliable identification results. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0041] Figure 1 It is a schematic diagram of the field enclosure warming device of the present invention. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs; the terms used herein are only for the purpose of describing specific embodiments rather than limiting the present invention.

[0044] The present invention is achieved by providing a method for identifying heat tolerance of rice during the flowering period, comprising the following steps:

[0045] Step S1: staggering rice sowing so that all rice germplasms can head and flower at the same time;

[0046] Step S2: When the rice enters the heading and flowering stage, the rice canopy is artificially heated before the rice blooms every day, and the artificial heating of the rice canopy is stopped after the rice glume closes;

[0047] Step S3: When the rice enters the flowering period, the flowering start date and flowering end date of each rice germplasm are recorded, and the canopy air temperature of each rice germplasm is monitored and recorded;

[0048] Step S4: After the rice matures, the paddy plot is sampled using the 5-point method; after the rice is threshed, the total number of spikelets and the number of sterile spikelets of each rice plant are investigated, and the empty shell grain rate of each rice plant is calculated;

[0049] Step S5: taking the duration of rice flowering each day as the effective accumulated temperature as the total accumulated temperature during the flowering period, and the number of days from the beginning to the end of rice flowering as the number of days during the flowering period; calculating the average daily high temperature stress accumulated temperature encountered by the rice during the flowering period;

[0050] Step S6: Calculating the heat tolerance value of each rice germplasm during the flowering period based on the empty shell rice rate and the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period;

[0051] Step S7: evaluating the heat tolerance of rice during the flowering period by comparing the heat tolerance values ​​of various rice germplasms during the flowering period.

[0052] Further, such as Figure 1 As shown, the rice is sown at different times in step S1, specifically:

[0053] Step S11: Each rice germplasm is planted in more than two rice field plots, each of which has a width of 1 meter and a field enclosure and temperature-increasing device is installed outside the rice field plot;

[0054] Step S12, the field enclosure warming device includes a support frame 1, a highly transparent film 2, an automatic lifting cable 3, a remote control motor 4 and a timing relay 5; the support frame 1 is inserted around the rice field area, and the top corner of the support frame 1 is provided with an automatic lifting cable 3, and the highly transparent film 2 is installed on the automatic lifting cable 3. The highly transparent film 2 is driven by the automatic lifting cable 3 to form a closed enclosure space that can be automatically lifted around the rice field area. A timing relay 5 is installed on the top support frame 1 to realize the timed opening and closing of the automatic lifting cable 3. At the same time, a remote control motor 4 is installed on the top support frame 1. The running time of the automatic lifting cable 3 is manually remotely controlled to control the height of the high-transparent film enclosure driven by the automatic lifting cable 3;

[0055] Step S13, determining the height of the automatically raise / lowerable closed high-transparency film enclosure based on the temperature at 1.5 meters above the ground around the rice paddy area;

[0056] Step S14: The rice paddy plot is routinely fertilized and watered, and pests and diseases are controlled, and unified cultivation management is performed.

[0057] Furthermore, in step S13, the temperature at 1.5 meters near the ground around the rice field area determines the height of the automatically rising and falling closed high-transparent film enclosure, specifically:

[0058] When the height of the automatically rising and falling high transparent film enclosure is within the range of 1.2 to 1.8 meters and the temperature at 1.5 meters near the ground around the rice paddy plot is between 30.0 and 36.0 degrees Celsius, the canopy temperature of the rice paddy plot is expressed by the formula:

[0059] Y=19.85·ln(H+0.5)+T-8.53 (1);

[0060] Among them, Y is the canopy temperature of the rice field; H is the height of the automatically rising and falling high-transparent film enclosure; T is the temperature 1.5 meters near the ground around the rice field; the coefficient 19.85 and the constant 8.53 are obtained by fitting the field test data.

[0061] Furthermore, in step S2, the rice canopy is artificially heated before the rice flowers bloom each day, and the artificial heating of the rice canopy is stopped after the rice glume closes; specifically,

[0062] Step S21: A 10 cm gap is maintained between the automatically elevating high-transparent film enclosure and the ground of the rice paddy plot, and the area directly above the rice paddy plot is not enclosed;

[0063] Step S22: Before the rice flowers bloom each day, the temperature at 1.5 meters above the ground around the rice paddy plot is monitored using an automatic temperature monitoring recorder. The height of the automatically adjustable high-transparent film enclosure is calculated using a formula for the canopy temperature of the rice paddy plot.

[0064] Step S23: manually remotely controlling the motor and adjusting the automatically elevating high-transparent film enclosure using the automatic elevating cable to ensure that the canopy temperature of the rice field is controlled at a preset target value;

[0065] In step S24, the automatic temperature monitoring recorder feeds back the temperature data 1.5 meters near the ground around the rice field area in real time to the remote control motor, dynamically adjusts the high-transparent film enclosure that can automatically rise and fall, and controls the automatic lifting cable to achieve artificial heating of the canopy temperature and stop artificial heating.

[0066] Furthermore, in step S3, the canopy air temperature of each rice germplasm is monitored and recorded; specifically:

[0067] The monitoring step length is 1 time / min. After the rice flowering period is over, the canopy temperature data of the test rice germplasm from the start date to the end date of flowering are retrieved; after the flowering period is over, the field enclosure and warming device of the rice plot are removed.

[0068] Furthermore, in step S4, the empty shell grain rate of each rice plant is calculated; it can be expressed as:

[0069] Empty kernel rate = number of sterile spikelets / total number of spikelets.

[0070] Furthermore, in step S5, the duration of rice flowering per day is taken as the effective accumulated temperature as the total accumulated temperature during the flowering period, and the number of days from the beginning of rice flowering to the end of flowering is taken as the number of days in the flowering period; the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period is calculated; specifically:

[0071] The average daily effective accumulated temperature of each rice germplasm high temperature treatment group and normal temperature control group was calculated; the average daily effective accumulated temperature of the high temperature treatment group and the average daily effective accumulated temperature of the moderate temperature control group were expressed by the formula:

[0072] The average daily effective accumulated temperature of the high temperature treatment group = the total accumulated temperature of the high temperature treatment group during the flowering period / the number of days of the high temperature treatment group during the flowering period;

[0073] Average daily effective accumulated temperature of the optimal temperature control group = total accumulated temperature of the optimal temperature control group during flowering period / number of days of flowering period of the optimal temperature control group;

[0074] The intensity of high temperature stress was determined by the difference between the average daily effective accumulated temperature of the high temperature treatment group and the average daily effective accumulated temperature of the suitable temperature control group, and was expressed by the formula:

[0075] The average daily accumulated temperature of high temperature stress during the flowering period = the average daily effective accumulated temperature of the high temperature treatment group - the average daily effective accumulated temperature of the suitable temperature control group.

[0076] Furthermore, in step S6, the heat tolerance value of each rice germplasm during the flowering period is calculated based on the empty shell kernel rate of the rice and the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period. The formula is expressed as:

[0077] Heat resistance value = × Average daily accumulated temperature of high temperature stress during flowering period.

[0078] The present invention provides a method for identifying heat tolerance of rice during the flowering period, comprising the following steps:

[0079] In some embodiments.

[0080] Example 1: Planting rice; Example 1 was carried out in an experimental field of a university in Nanchang in 2024. The test materials were: Zhenfu, Yuzhenxiang, IR64, Miyang 46, Meixiangzhan No. 2, Guangxinzhan, Qiyinzhan, Huasizhan, Nongxiang 39, Huazhan, Huangguangyouzhan, Jiangxi Ji'an Si Miao, a total of 12 rice germplasms. Each test rice germplasm was sown in two batches at different times. According to the sowing period of the test rice germplasm in Nanchang, Jiangxi over the years, the first batch was sown and planted at different times from May 5th to 17th, so that the test rice was concentrated in the same period of heading and flowering in early August as a high temperature treatment. The second batch was sown and planted at different times from June 11th to 20th, so that the test rice was concentrated in the same period of heading and flowering in mid-September as a suitable temperature control. Individual rice plants were transplanted to the field with a planting spacing of 16.5 cm per plant and 23.1 cm per row. Four plots were planted for each accession: two plots for the treatment and two for the control, with five rows of six plants per plot. After transplanting, fertilizer, water, and pest control measures were implemented according to local practices.

[0081] Install a field enclosure warming device; the device consists of a support frame, highly transparent film, automatic lifting cables, a remote-controlled motor, and a timer relay. To install the device, one day before rice flowering, insert the support frame into the four corners of the paddy plot to be warmed. Install the automatic lifting cables and timer relay on the support frame, and then attach the highly transparent film to the cables, creating a closed enclosure around the paddy plot that automatically rises and falls. A 10-centimeter gap is left between the bottom edge of the highly transparent film and the ground, leaving the area directly above the paddy plot open. This maintains air circulation within the paddy plot and prevents the formation of extremely high humidity in the rice canopy.

[0082] According to the definition of high temperature heat damage during the flowering period of rice: when the temperature reaches or exceeds 35.5°C during the flowering period of rice, it is considered to have suffered high temperature heat damage during the flowering period. Therefore, this experiment set 38±0.5°C as the high temperature stress temperature for the heat tolerance assessment of the test rice germplasm. That is, the field enclosure warming device of the present invention was used to raise the canopy temperature of the rice field plot to 38±0.5°C.

[0083] The timing relay automatically lowered the high transparent film enclosure before the rice flowers bloomed every day to raise the temperature of the test plot. After the rice glume closed, the high transparent film enclosure was automatically retracted to return to the natural state of the field. At the same time, the height of the high transparent film enclosure was adjusted according to the temperature data 1.5 m near the ground in the field when the test rice germplasm flowers. The purpose was to increase the temperature in the plot to the preset Y = 38 ± 0.5 ° C after adjusting the height of the high transparent film enclosure, thereby ensuring that the different genotypes of rice germplasm were subjected to the preset high temperature stress temperature when flowering (the warming effect is shown in Table 1).

[0084] Table 1 Statistical table of the effects of warming treatment during rice flowering period

[0085]

[0086] When the height of the automatically rising and falling high transparent film enclosure is within the range of 1.2 to 1.8 meters and the temperature at 1.5 meters near the ground around the rice paddy plot is between 30.0 and 36.0 degrees Celsius, the canopy temperature of the rice paddy plot is expressed by the formula:

[0087] Y=19.85·ln(H+0.5)+T-8.53 (1);

[0088] After the rice flowering period, the field enclosure and warming device are removed.

[0089] Monitoring of Rice Canopy Temperature: One day before rice flowering, a temperature probe from the farmland climate monitoring system was placed in the middle of the rice panicle to monitor and record the rice canopy temperature at a monitoring step of 1 time / min. The start and end dates of flowering for each test rice accession were also recorded. After the rice flowering period ended, canopy temperature data for each rice accession from the start to the end of flowering were retrieved from the farmland climate monitoring system. The canopy temperature data for the high-temperature treatment (Table 1) were used to calculate the accumulated temperature from the start to the end of flowering for the high-temperature treatment, while the canopy temperature data for the suitable temperature control (Table 2) were used to calculate the accumulated temperature from the start to the end of flowering for the suitable temperature control.

[0090] Table 2 Statistics of temperature during the flowering period of rice in the suitable temperature control group

[0091]

[0092] Data collection and processing: After the rice matures, 5 plants are sampled in each paddy field using the 5-point method. After threshing, the individual plants are transplanted and the number of sterile spikelets and the total number of spikelets of each plant are counted.

[0093] Based on the temperature values ​​recorded by the farmland climate monitoring system, the rice canopy air temperature data were collected from the beginning to the end of flowering. The empty-shelled grain rate of rice was calculated according to the formula: empty-shelled grain rate = number of sterile spikelets / total number of spikelets (the calculation results are shown in Table 3).

[0094] Table 3 Accumulated temperature during the flowering period of rice in 2024 and calculation results of heat tolerance value

[0095]

[0096] The duration of rice flowering per day was taken as the effective accumulated temperature and the total accumulated temperature during the flowering period. The number of days from the beginning to the end of rice flowering was taken as the number of days during the flowering period. The average daily accumulated temperature of high temperature stress encountered by rice during the flowering period was calculated (the calculation results are shown in Table 3). Specifically:

[0097] Based on the above steps and methods, the factors affecting the heat tolerance of rice germplasm are: the empty shell rate of the control under suitable temperature, the empty shell rate of the high temperature treatment, and the average daily high temperature stress accumulated temperature during the flowering period. The higher the value of and the higher the average daily high temperature stress accumulated temperature during the flowering period, the better the heat tolerance of the rice germplasm, and vice versa. To ensure the comparability of heat tolerance among different rice germplasms, the formula is used:

[0098] Heat resistance value = × Daily average accumulated temperature of high temperature stress during flowering period;

[0099] Calculate the heat tolerance value of each rice accession at the flowering stage. By comparing the heat tolerance values ​​of different rice accessions at the flowering stage, the larger the heat tolerance value, the stronger the heat tolerance, and the smaller the heat tolerance value, the weaker the heat tolerance (see Table 3 for calculation results).

[0100] According to the definition of heat damage to rice, when the maximum daily temperature reaches or exceeds 35.5°C, rice is considered to have suffered heat damage. This experiment used 38±0.5°C as the preset temperature for the enclosure to assess the heat tolerance of the tested rice germplasm during the flowering period. Based on the preset canopy temperature of 38±0.5°C within the enclosure and the temperature 1.5 meters above the ground in the field, the corresponding enclosure height can be derived using the formula:

[0101] 38±0.5℃=19.85·ln(H+0.5)+T-8.53;

[0102] It can be seen from Table 3 that according to the heat resistance values ​​of the tested rice germplasms in Table 3, they are sorted from small to large. The larger the heat resistance value, the stronger the heat resistance of the rice during the flowering period, and the smaller the heat resistance value, the worse the heat resistance of the rice during the flowering period.

[0103] The above results show that the field enclosure warming device involved in the present invention can effectively increase the canopy temperature in the rice field area to a preset temperature under the natural field environment, so that each test rice germplasm is subjected to a preset canopy high temperature stress temperature of 38±0.5℃ during the flowering period, thereby identifying the heat resistance of rice during the flowering period, overcoming the problem that the existing field identification relies on occasional high temperature weather and the shortcomings of the artificial climate chamber identification method with a small test space and an unnatural test environment; the heat resistance value quantification method involved in the present invention can effectively evaluate the heat resistance of rice germplasms of different genotypes during the flowering period, providing a new idea for variety selection in the agricultural breeding process, and has broad application prospects.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for identifying heat tolerance of rice during the flowering period, characterized by: The following steps are involved: Step S1: staggering rice sowing so that all rice germplasms can head and flower at the same time; Step S2: When the rice enters the heading and flowering stage, the rice canopy is artificially heated before the rice blooms every day, and the artificial heating of the rice canopy is stopped after the rice glume closes; Step S3: When the rice enters the flowering period, the flowering start date and flowering end date of each rice germplasm are recorded, and the canopy air temperature of each rice germplasm is monitored and recorded; Step S4: After the rice matures, the paddy plot is sampled using the 5-point method; after the rice is threshed, the total number of spikelets and the number of sterile spikelets of each rice plant are investigated, and the empty shell grain rate of each rice plant is calculated; Step S5: taking the duration of rice flowering each day as the effective accumulated temperature as the total accumulated temperature during the flowering period, and the number of days from the beginning to the end of rice flowering as the number of days during the flowering period; calculating the average daily high temperature stress accumulated temperature encountered by the rice during the flowering period; Step S6: Calculating the heat tolerance value of each rice germplasm during the flowering period based on the empty shell rice rate and the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period; Step S7: evaluating the heat tolerance of rice during the flowering period by comparing the heat tolerance values ​​of various rice germplasms during the flowering period; The rice is sown at different times in step S1, specifically: Step S11: Each rice germplasm is planted in more than two rice field plots, each of which has a width of 1 meter and a field enclosure and temperature-increasing device is installed outside the rice field plot; Step S12, the field enclosure heating device includes a support frame, a highly transparent film, an automatic lifting cable, a remote control motor and a timing relay; the support frame is inserted around the rice field area, and the top corners of the support frame are provided with an automatic lifting cable. The highly transparent film is installed on the automatic lifting cable, and the highly transparent film is driven by the automatic lifting cable to form a closed enclosure space that can be automatically raised and lowered around the rice field area. A timing relay is installed on the top support frame to realize the timed opening and closing of the automatic lifting cable. At the same time, a remote control motor is installed on the top support frame, and the running time of the automatic lifting cable is manually remotely controlled to control the height of the high-transparent film enclosure driven by the automatic lifting cable; Step S13, determining the height of the automatically raise / lowerable closed high-transparency film enclosure based on the temperature at 1.5 meters above the ground around the rice paddy area; Step S14: routine fertilization and watering, pest and disease control, and unified cultivation management are carried out in the rice field plot; In step S13, the temperature at 1.5 meters near the ground around the rice field area determines the height of the automatically rising and falling closed high-transparency film enclosure, specifically: When the height of the automatically rising and falling high transparent film enclosure is within the range of 1.2 to 1.8 meters and the temperature at 1.5 meters near the ground around the rice paddy plot is between 30.0 and 36.0 degrees Celsius, the canopy temperature of the rice paddy plot is expressed by the formula: Y=19.85·ln(H+0.5)+T-8.53 (1); Where Y is the canopy temperature of the rice paddy plot; H is the height of the automatically raised and lowered high-transparent film enclosure; T is the temperature 1.5 meters above the ground around the rice paddy plot; the coefficient 19.85 and the constant 8.53 are obtained by fitting the field test data; In step S2, the rice canopy is artificially heated before the rice flowers bloom each day, and the artificial heating of the rice canopy is stopped after the rice glume closes. Specifically, Step S21: A 10 cm gap is maintained between the automatically elevating high-transparent film enclosure and the ground of the rice paddy plot, and the area directly above the rice paddy plot is not enclosed; Step S22: Before the rice flowers bloom each day, the temperature around the rice paddy plot at a height of 1.5 meters from the ground is monitored using an automatic temperature monitoring recorder. The height of the automatically adjustable high-transparent film enclosure is calculated using a formula for the canopy temperature of the rice paddy plot. Step S23: manually remotely controlling the motor and adjusting the automatically elevating high-transparent film enclosure using the automatic elevating cable to ensure that the canopy temperature of the rice field is controlled at a preset target value; In step S24, the automatic temperature monitoring recorder feeds back the temperature data 1.5 meters near the ground around the rice field area in real time to the remote control motor, dynamically adjusts the high-transparent film enclosure that can automatically rise and fall, and controls the automatic lifting cable to achieve artificial heating of the canopy temperature and stop artificial heating.

2. The method for identifying heat tolerance of rice during flowering period according to claim 1, characterized in that: In step S3, the canopy air temperature of each rice germplasm is monitored and recorded; specifically: The monitoring step length is 1 time / min. After the rice flowering period is over, the canopy temperature data of the test rice germplasm from the start date to the end date of flowering are retrieved; after the flowering period is over, the field enclosure and warming device of the rice plot are removed.

3. The method for identifying heat tolerance of rice during flowering period according to claim 2, characterized in that: Step S4, calculating the empty shell grain rate of each rice plant; expressed by the formula: Empty kernel rate = number of sterile spikelets / total number of spikelets.

4. The method for identifying heat tolerance of rice during flowering period according to claim 3, wherein: Step S5: Taking the duration of rice flowering each day as the effective accumulated temperature as the total accumulated temperature during the flowering period, and the number of days from the beginning of rice flowering to the end of flowering as the number of days during the flowering period, the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period is calculated; specifically: The average daily effective accumulated temperature of each rice germplasm high temperature treatment group and normal temperature control group was calculated; the average daily effective accumulated temperature of the high temperature treatment group and the average daily effective accumulated temperature of the moderate temperature control group were expressed by the formula: The average daily effective accumulated temperature of the high temperature treatment group = the total accumulated temperature of the high temperature treatment group during the flowering period / the number of days of the high temperature treatment group during the flowering period; Average daily effective accumulated temperature of the optimal temperature control group = total accumulated temperature of the optimal temperature control group during flowering period / number of days of flowering period of the optimal temperature control group; The intensity of high temperature stress was determined by the difference between the average daily effective accumulated temperature of the high temperature treatment group and the average daily effective accumulated temperature of the suitable temperature control group, and was expressed by the formula: The average daily accumulated temperature of high temperature stress during the flowering period = the average daily effective accumulated temperature of the high temperature treatment group - the average daily effective accumulated temperature of the suitable temperature control group.

5. The method for identifying heat tolerance of rice during flowering period according to claim 4, characterized in that: Step S6, calculating the heat tolerance value of each rice germplasm during the flowering period based on the empty shell rice rate and the average daily accumulated temperature of high temperature stress encountered by the rice during the flowering period, and the formula is expressed as: Heat resistance value = × Average daily accumulated temperature of high temperature stress during flowering period.

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