Method for identifying temperature sensitivity of indoor rice

Abstract

The invention discloses a method for identifying the temperature sensitivity of indoor rice, and relates to evaluation of the temperature sensitivity of different rice varieties by using physiological experiments in breeding. Rice is cultivated in a plant greenhouse with different temperature control and light control modes, agronomic characters such as flowering time, the number of grains per ear, tillering, primary branches and secondary branches of the rice are detected, and the influence of temperature on growth and development of the rice is qualitatively described. The correlation between agronomic traits and temperature is established by identifying the temperature sensitivity of the rice, and the temperature sensitivity of the rice variety is evaluated. In global climate change, rice temperature sensitivity identification is beneficial to breeding of heat-resistant varieties and latitude adaptability selection, breeding is guided and accelerated, and grain safety is guaranteed.

Description

Technical Field

[0001] The invention relates to a method for identifying the temperature sensitivity of indoor rice. Background Art

[0002] Temperature is the main factor affecting plant growth and development. For crops, high or low temperatures are not conducive to growth and development. Global climate change not only increases the frequency of extreme temperatures, but also leads to global warming. Therefore, changes in environmental temperature not only affect the metabolism, growth and development of crops, but also cause the abandonment of original crop planting areas and expansion to high-latitude areas. For rice breeding, it will affect the flowering period of rice, and hybrid rice seed production will suffer significant losses.

[0003] As a major food crop, rice is sensitive to temperature. Its average optimum growth temperature is around 28℃ (day) / 22℃ (night). Too high or too low ambient temperature can inhibit rice growth and development (Wheeler et al., 2007). During the vegetative growth process, abnormally high temperatures at the budding stage may lead to a serious reduction in germination rate and whitening of seedlings; high temperatures at the seedling stage may cause wilting or death of seedlings; high temperatures at the tillering stage will directly affect the accumulation of nutrients during the vegetative growth stage, affecting plant height, tiller number, dry matter weight and root development, and ultimately causing a reduction in rice yield and quality in the later stage. Compared with the above stages, rice is extremely sensitive to temperature during the budding and heading stages (i.e., 10 days before and after heading). During the period from rice heading to fruiting, if the temperature continues to exceed the upper limit of the normal growth temperature of rice, it will affect normal pollination and filling, resulting in a decrease in fruiting rate and an increase in the empty grain rate, ultimately resulting in a reduction in yield or even a total loss of yield. Under high temperature stress, the increase in the empty shell rate of rice is largely due to the irreversible damage of high temperature to the fertility of spikelets, which is mainly manifested in the four factors of pollen cracking, pollen grain fertility, stigma pollen germination rate and pollen tube elongation (Zhang et al., 2020, Jagadish et al., 2007).

[0004] Global warming has caused the temperature in different latitudes to rise to a certain extent, resulting in the extension of the growing season of the original crop planting areas and the northward shift of the crop planting areas, affecting the yield of crops. Therefore, it is necessary to adjust the planting frequency and farming pattern of crops so that the growth period of crops matches the local farming season to maximize the utilization of light energy resources, which requires the selection of the latitude adaptability of crops (Wang et al., 2022). Among the factors affecting the latitude adaptability of crops, the most critical are day length and temperature. When producing hybrid rice seeds, the flowering period of the parents is affected by temperature. If the flowering period is not met, it will cause a devastating blow to the sowing in the new year and threaten food security.

[0005] Artificial light plant factory is a type of facility that relies on artificial light sources to provide the light required for plant growth and can precisely adjust the plant growth environment. Using plant factories to identify the temperature sensitivity of rice has the advantages of stable environment, no seasonal restrictions and batch operation.

[0006] Rice is the main food crop in my country, with a long history of cultivation, rich germplasm resources and a wide planting area. The rice planting area in my country spans a wide range, forming many local specialty varieties. The natural field environment changes with the change of latitude, and the day length changes and the day and night temperatures in the north and south are quite different. Summary of the invention

[0007] The purpose of the present invention is to improve the above-mentioned deficiencies existing in rice variety breeding technology and provide a method for identifying the temperature sensitivity of rice.

[0008] The technical solution of the present invention is as follows:

[0009] A method for identifying the temperature sensitivity of indoor rice comprises the following steps:

[0010] Step 1: During the growth period of rice, place the rice to be tested in an indoor environment;

[0011] Step 2: Using artificial light sources to set different temperature control and light control mode culture conditions, the artificial light sources are lights of different wavelengths and intensities;

[0012] Step 3: During the flowering period, before turning off the lights every day, count the flowering date of the rice and calculate the flowering time of the rice. After the seeds mature, count the number of grains per ear, tillers, primary branches, secondary branches and fruiting rate of the main ear;

[0013] Step 4: According to the result of step 3, the temperature sensitivity of the tested variety is obtained.

[0014] Furthermore, in step one, after germination, the rice seeds are transferred to a seedling tray and grown for 7 days, and seedlings with the same growth status are selected and transplanted into a hydroponic box, which is then placed in an indoor environment to begin testing.

[0015] Furthermore, in step 2, the culture was carried out in a greenhouse with different light control and temperature control modes for 28 days, with a photoperiod of 24 hours. Eight mature seedlings with consistent growth were selected under each condition and transferred to the hydroponic strips and cultured until harvest. During the growth period, 1 L of culture solution was added to each hydroponic strip every week, and the rest was supplemented with water.

[0016] Furthermore, in step 2, the lighting pattern includes a short-day lighting time of 10 hours and a long-day lighting time of 14 hours in a 24-hour day and night cycle.

[0017] Furthermore, the temperature control mode includes a 24h day and night cycle, in which the day temperature processing mode is that during the light time, the temperature is set to 25°C, 28°C, 31°C and 34°C respectively, and the night temperature is uniformly set to 25°C. The night temperature processing mode is that the night temperature is set to 17°C, 20°C, 25°C and 28°C respectively, and the day temperature is uniformly set to 31°C.

[0018] 6. A method for identifying the temperature sensitivity of indoor rice as claimed in claim 1, characterized in that in step 4, the temperature sensitivity of rice is determined based on the number of grains per ear, tillering, fruit setting rate, primary branches and secondary branches of the ear.

[0019] The present invention identifies the temperature sensitivity of rice in an indoor plant factory. Through a large number of experiments, it is found that under the condition of short-day 10h light control, day temperature treatment inhibits the flowering of rice, night temperature treatment promotes the flowering of rice, and high temperature affects the number of grains per panicle, tillering, fruit setting rate, primary branches and secondary branches of panicles of rice. Under the condition of long-day 14h light control, day temperature treatment promotes the flowering of rice. The method is easy to operate and has broad application space and market prospects in the fields of agricultural breeding and basic research.

[0020] The present invention uses indoor plant factories to identify temperature sensitivity without being restricted by seasonal conditions, and different day and night temperature modes can be set to comprehensively detect the temperature sensitivity of different varieties. According to the temperature response of different varieties, combined with the environmental changes at specific latitudes, it is possible to infer their suitable planting areas, and to quickly select varieties, avoiding multi-year multi-latitude field trials. Therefore, indoor identification of the temperature sensitivity of rice can be used as a solution for germplasm selection and grain production guarantee under the background of climate change. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 : Figure of the planting device of the present invention.

[0023] Figure 2 : Flow chart of the implantation technology of the present invention.

[0024] Figure 3 : Experimental light and temperature setting mode diagram of the present invention. Wherein, a is the day temperature control mode, and b is the night temperature control mode.

[0025] Figure 4:Evaluation of the effect of daily temperature on rice flowering time. Lowercase letters in the figure indicate significant differences. a Figure shows the planting pattern. b Flowering time phenotypes of DJ, hd1, dth8 and hd1dth8 under short-day daily temperature treatment. c Flowering of DJ, hd1, dth8 and hd1dth8 under long-day daily temperature treatment. Lowercase letters in the figure indicate significant differences. DJ is the wild type. hd1 (gene number Os06g0275000): Heading date 1 gene mutant, dth8 (gene number Os08g0174500): nucleartranscription factor Y subunit B 11 mutant, hd1dth8 is a double mutant of Hd1 and DTH8, and the percentages in the figure are temperature sensitivity.

[0026] Figure 5 :Evaluation of the effect of daily temperature on the flowering time of Nip and se5. Lowercase letters in the figure indicate significant differences a Planting pattern Figure b Nip and se5 flowering time phenotypes under short-day daily temperature treatment b Nip and se5 flowering time phenotypes under long-day daily temperature treatment Time phenotype. Nip is Nipponbare, wild type, se5 (gene number Os06g0603000): Photoperiod-sensitivity5, the percentage in the figure is temperature sensitivity.

[0027] Figure 6 : Evaluation of the effect of night temperature on rice flowering time. Lowercase letters in the figures indicate significant differences. The percentages in the figures indicate temperature sensitivity. a Planting pattern diagram. b Flowering time phenotypes of DJ, hd1, dth8 and hd1dth8 treated with long-day night temperature. c Flowering time phenotypes of Nip and se5 treated with long-day night temperature. The percentages in the figures indicate temperature sensitivity.

[0028] Figure 7 :Evaluation of the effect of temperature on agronomic traits of rice. Lowercase letters in the figure indicate significant differences. Agronomic traits of Nip and se5 under short-day night temperature treatments. DETAILED DESCRIPTION

[0029] The seeds were placed directly in a plant culture dish filled with ultrapure water and placed in a 30°C constant temperature box for germination in the dark for three days. The white seeds were divided into 4 parts, transplanted to the seedling tray, and placed in a greenhouse with long-day or short-day constant temperature conditions for 7 days. Each material was transplanted to several hydroponic boxes and placed in greenhouses with different light control and temperature control modes for 28 days. Under each condition, 8 seedlings with consistent growth were selected and transferred to the hydroponic strips, and placed in the greenhouses with their own light control and temperature control modes for cultivation until harvest. During the growth period, 1L of culture solution was added to each hydroponic strip every week, and the rest was supplemented with water.

[0030] The lighting mode includes a short-day lighting time of 10 hours and a long-day lighting time of 14 hours in a 24-hour day and night cycle.

[0031] The temperature control mode includes a 24h day and night cycle, and the day temperature processing mode is that during the light time, the temperature is set to 25℃, 28℃, 31℃ and 34℃ respectively, and the night temperature is uniformly set to 25℃. The night temperature processing mode is that the night temperature is set to 17℃, 20℃, 25℃ and 28℃ respectively, and the day temperature is uniformly set to 31℃.

[0032] Example 1

[0033] Seeds of rice mutants with different photoperiod genes (Nip, se5, DJ, hd1, dth8 and hd1dth8) were placed in culture dishes, sterile water was added and placed in a 30°C constant temperature box for light-proof germination. After germination, they were transferred to seedling trays and grown for 7 days. Seedlings with consistent growth status were selected and transplanted into hydroponic boxes and divided into two groups, with 8 samples in each treatment group. The first group was placed under short-day light conditions (photoperiod 24h, 10h light + 14h dark treatment) and the temperature mode was day. The second group was placed in a long-day light condition (photoperiod of 24 h, 14 h light + 10 h dark treatment), and the temperature mode was a night temperature mode (day temperature 31 °C and night temperature 17 °C, day temperature 31 °C and night temperature 20 °C, short-day day temperature 31 °C and night temperature 25 °C, short-day day temperature 31 °C and night temperature 28 °C, short-day day temperature 31 °C and night temperature 25 °C), and the sunlight intensity was 300 μmol m -2 s -1 )( Figure 1-Figure 3 ).

[0034] During the experiment, hydroponic solution ( Figure 2 ). During the flowering period, the flowering date of rice was counted before turning off the lights every day to calculate the flowering time of rice. After the seeds matured, the number of grains per panicle, tillers, primary branches, secondary branches and fruiting rate of the main panicle were counted.

[0035] First, during the growth of rice, the flowering time of rice under different conditions was counted. The results showed that the flowering time of rice was delayed as the daily temperature increased ( Figure 4 ), the growth period is extended, promoted as the night temperature rises, and the growth period is shortened ( Figure 5 and Figure 6 ). Secondly, under the night temperature treatment mode, in the late stage of rice growth, the number of grains per ear, tillering, primary branching, secondary branching and seed setting rate of the main ear of rice were counted. The results showed that the increase in night temperature led to a decrease in the number of grains per ear, tillering, primary branching, secondary branching and seed setting rate, reducing the yield ( Figure 7). This result shows that rice temperature sensitivity is a key indicator in rice breeding, and high temperatures will directly lead to reduced yields.

[0036] In summary, the technical solution of the present invention has an intuitive embodiment in the indoor identification of the temperature sensitivity of rice, directly evaluates the strength of the temperature sensitivity of rice, and uses the flowering time prediction model to infer its suitable planting area according to the temperature and day length conditions at different latitudes. In hybrid rice seed production, investigating the temperature sensitivity of parents and mother parents and reasonably arranging the planting time are conducive to the encounter of flowering periods, improving the success rate of seed production, and having outstanding advantages. In extremely hot weather, screening high-temperature resistant rice germplasm is conducive to ensuring food security. The present invention utilizes indoor identification of the temperature sensitivity of rice, which is not restricted by seasons, realizes a single variable, does not require multi-year multi-latitude testing, and is accurate and efficient. Compared with the temperature sensitivity identification in traditional breeding, the identification of the temperature sensitivity of rice by setting different lighting modes and temperature control modes indoors proposed by the present invention can better evaluate the response of rice to night temperature and day temperature respectively, and has good implementation prospects.

[0037] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for identifying the temperature sensitivity of indoor rice, characterized in that: The steps include: Step 1: During the growth period of rice, place the rice to be tested in an indoor environment; Step 2: Using artificial light sources to set different temperature control and light control mode culture conditions, the artificial light sources are lights of different wavelengths and intensities; Step 3, during the flowering period, before turning off the lights every day, the flowering date of the rice is counted to calculate the flowering time of the rice; After the seeds mature, the number of grains per ear, tillers, primary branches, secondary branches and fruiting rate of the main ear are counted; Step 4: According to the result of step 3, the temperature sensitivity of the tested variety is obtained.

2. A method for identifying the temperature sensitivity of indoor rice as claimed in claim 1, characterized in that: In step 1, after germination, the rice seeds were transferred to seedling trays and grown for 7 days. Seedlings with consistent growth status were selected and transplanted into hydroponic boxes, which were then placed in an indoor environment to begin testing.

3. The method for identifying the temperature sensitivity of indoor rice as claimed in claim 1, characterized in that: In step 2, the plants were cultured in a greenhouse with different light and temperature control modes for 28 days with a photoperiod of 24 h. Eight mature seedlings with consistent growth were selected under each condition and transferred to the hydroponic strips for culture until harvest. During the growth period, 1 L of culture solution was added to each hydroponic strip every week, and the rest was supplemented with water.

4. The method for identifying the temperature sensitivity of indoor rice as claimed in claim 1, characterized in that: In step 2, the lighting pattern includes a short-day lighting time of 10 hours and a long-day lighting time of 14 hours in a 24-hour day and night cycle.

5. The method for identifying the temperature sensitivity of indoor rice as claimed in claim 1, characterized in that: The temperature control mode includes a 24h day and night cycle, in which the day temperature processing mode is that during the light time, the temperature is set to 25°C, 28°C, 31°C and 34°C respectively, and the night temperature is uniformly set to 25°C; the night temperature processing mode is that the night temperature is set to 17°C, 20°C, 25°C and 28°C respectively, and the day temperature is uniformly set to 31°C.

6. The method for identifying the temperature sensitivity of indoor rice as claimed in claim 1, characterized in that: In step 4, the temperature sensitivity of rice is determined based on the number of grains per panicle, tillering, fruit setting rate, primary branches and secondary branches of the panicle.

7. Use of the method for identifying the temperature sensitivity of indoor rice as claimed in any one of claims 1 to 6 in rice breeding.

8. The method for identifying the temperature sensitivity of indoor rice as claimed in claim 1 is characterized in that There are two temperature control modes: the first temperature control condition is the day temperature mode, in which different temperatures are set in the light range, and the temperature is set to a constant temperature in the light-off range; the second temperature control condition is the night temperature mode, in which the temperature is set to a constant temperature in the light range, and different temperatures are set in the light-off range.

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