Indoor flower bud incubation method capable of improving stigma yield and quality of saffron through rehydration after high-temperature germination acceleration and drought

Abstract

Compared with a traditional two-stage cultivation method, the indoor flower bud incubation method capable of improving stigma yield and quality of the saffron after high-temperature germination acceleration and drought addition has the advantages that a high-temperature accumulated dormancy breaking method is created for the first time in the indoor cultivation and flowering period of the saffron, early flowering of the saffron is promoted, and the stigma yield and quality of the saffron are improved. The flowering number of saffron is increased, the root development time is advanced by two months, the vegetative growth period of corms is remarkably prolonged, and the corm yield is increased. Meanwhile, the method can effectively increase the length and weight of stigma of the saffron, increase the content of crocin in the stigma and enhance the strength of color, fragrance and taste, so that the yield and overall quality of the stigma of the saffron are remarkably improved. In addition, according to the method, through high-temperature treatment and the bacteriostatic action of quick lime, the occurrence of crocus sativus corm rot is remarkably reduced, and the comprehensive economic benefits of crocus sativus production are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of traditional Chinese medicine cultivation, and relates to an indoor flower bud incubation method for improving the yield and quality of saffron stigma by high-temperature germination and rehydration after drought. Background Art

[0002] Saffron, also known as crocus or saffron, is the dried stigma of Crocus sativus L., a plant of the Iridaceae family. It has the effects of promoting blood circulation and removing blood stasis, cooling blood and detoxifying, relieving depression and calming the mind. Since only the stigma on the upper part of the pistil is used as medicine, its resources are scarce and therefore the price is extremely expensive. The economic benefits of saffron mainly depend on the stigma yield and quality. The stigma yield is closely related to the number of flowers and stigma weight of each bulb, and the number of flowers is mainly affected by the weight of the bulb and the environmental conditions during the differentiation of flower buds. The quality of the stigma is judged by the content of the main medicinal ingredients, and the stigma weight and the content of medicinal ingredients are closely related to the environmental conditions during the incubation of flower buds. In addition, the flowering time of the bulb will indirectly affect the weight of the next generation of daughter bulbs, thereby affecting the stigma yield. Therefore, regulating the environmental conditions during the indoor incubation of saffron is of great significance to improving the economic benefits of saffron medicinal materials.

[0003] The origin of saffron generally adopts a continuous planting method for many years. The bulbs are not dug out during the summer dormancy period, and they bloom in the open field in mid-November. The bulb reproduction rate is relatively high. This cultivation mode has low requirements for human resources, but the management is relatively extensive. The yield and quality of saffron stigma are difficult to guarantee. my country successfully introduced it in the 1980s and improved its planting method. The "two-stage" cultivation method is adopted. The bulbs are placed indoors for half a year to cultivate and bloom. After the flowers are picked indoors, they are planted in the field outdoors for half a year to reproduce new bulbs. The quality of saffron stigma is good, but after the flowers are picked indoors, they are planted in the field, which reduces the vegetative growth time of saffron bulbs by about two months. The next generation of daughter bulbs is not easy to grow up and is light in weight. Generally, less than 120 kilograms of daughter bulbs can be harvested from 100 kilograms of bulbs. The reproduction rate is low, which greatly restricts the large-scale cultivation of saffron in my country. If the environmental conditions are adjusted during the indoor incubation to promote early flowering, the vegetative growth time of saffron bulbs can be extended, and larger daughter bulbs can be cultivated, which can not only greatly increase its reproduction rate, but also improve the yield and quality of daughter bulb stigma. Summary of the invention

[0004] The present invention aims to provide a method for incubating flower buds indoors with high temperature germination and rehydration after drought, so as to significantly improve the stigma yield and quality of saffron. The method can promote early flowering of saffron, increase the number of saffron flowering, advance the root system development time by two months, significantly extend the bulb vegetative growth period, and improve the yield of sub-bulbs. At the same time, it can effectively increase the length and weight of saffron stigma, increase the content of stigma crocin, enhance the intensity of its color, fragrance and taste, thereby significantly improving the stigma yield and overall quality of saffron. In addition, the method significantly reduces the occurrence of saffron bulb rot through high temperature treatment and the antibacterial effect of quicklime, and greatly improves the comprehensive economic benefits of saffron production.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for incubating flower buds indoors by high temperature germination and rehydration after drought, which can improve the yield and quality of saffron stigma, comprises:

[0007] 1) No later than May 1, dig the bulbs out of the soil, remove the remaining mother bulbs and withered leaves, spread them on the ground, and spray them with 25% (half the concentration of normal carbendazim) for disinfection to reduce pesticide residues.

[0008] 2) Place the saffron bulbs in a mild indoor environment until the end of May to promote the aging of the bulb seed coat. Mild indoor conditions refer to: the ambient temperature is controlled at 20-25°C, and the daytime light intensity is controlled at 5umol / m 2 / s, the ambient humidity is controlled within 70%; the CO2 concentration does not exceed 600PPM.

[0009] 3) From June 1st to July 15th, place the bulbs treated in step 2) in a greenhouse, control the temperature to be higher than 30℃ and lower than 35℃ during the day, and maintain it for 8-10 hours a day; control the temperature to be higher than 18℃ and lower than 25℃ at night, and the temperature difference between morning and evening should be no less than 10℃. The light intensity during the day should be controlled at 5umol / m 2 / s, the indoor CO2 concentration does not exceed 600PPM throughout the day, and the ambient humidity is controlled within 60%. As a preferred method, electric heating is used to adjust the temperature, which can effectively avoid O2 consumption and CO2 release caused by chemical combustion heating; ventilation is used to adjust the CO2 concentration; four-layer shading yarn is used to control the light intensity; and a dehumidifier is used to adjust the humidity. Through the treatment of this step, dormancy can be broken one month earlier, the number of flowers can be increased by 20%, and the incidence of rot can be reduced by 20%.

[0010] 4) Starting from July 16, the saffron bulbs treated in step 3) are placed in a drought cultivation device for cultivation. The drought cultivation device is to spread quicklime on the bottom surface, and then spread a vermiculite layer on the quicklime. The vermiculite layer is used to bury the saffron bulbs, and finally a layer of quicklime is covered on the vermiculite layer to form a quicklime-vermiculite-quicklime "sandwich" drought cultivation device. The humidity in the drought cultivation device is controlled within 5%. The environmental conditions during drought cultivation are: the ambient temperature is 18-22° C.; the daytime light intensity is controlled at 1000umol / m 2 / s; ambient humidity is controlled within 50%; indoor CO2 concentration does not exceed 500PPM.

[0011] 5) In early October, observe the color of the pistils of the flowers that develop faster. If the color of the pistils reaches the set color, resume hydroponics;

[0012] 6) Place the saffron bulbs in a hydroponic cultivation device, add distilled water until it just touches the bottom of the bulbs to induce rooting, and change the water every 4 to 5 days until the bulbs bloom. Environmental conditions for hydroponic cultivation: ambient temperature is 14 to 16°C; light intensity is maintained at 15,000umol / m 2 / s or above; ambient humidity 40-60%; indoor CO2 concentration does not exceed 500PPM.

[0013] Preferably, in step 4), the thickness of the quicklime spread on the bottom surface is 2 to 3 cm. Quicklime can not only absorb moisture, but also provide nutrients for the root system to absorb.

[0014] Preferably, in step 4), the thickness of the vermiculite layer is sufficient to cover the saffron bulbs.

[0015] Preferably, in step 4), the thickness of quicklime covering the vermiculite layer is 2 to 3 cm. Quicklime can not only absorb moisture, but also inhibit bacteria, reducing the incidence of rot by 20%.

[0016] Preferably, in step 5), the pistil color is determined by a colorimetric card, and the colorimetric card is arranged in sequence corresponding to the color change of the saffron pistil from the early white stage to the scarlet stage during flowering: white, yellow 1, yellow 2, yellow 3, yellow 4, orange 1, orange 2, orange 3, orange 4, orange 5, red 1, red 2, red 3.

[0017] More preferably, in step 5), 5 bulbs are randomly selected from the dry cultivation device, the longer terminal buds are peeled off, and the pistil colors of the faster developing flowers are observed. If the pistil colors have all reached the red 1 stage in the color chart, hydroponics is resumed.

[0018] Preferably, in step 6), placing the saffron bulbs in a hydroponic cultivation device comprises: placing the saffron bulbs in a hydroponic planting cup, and then placing the planting cup in a disposable plastic cup.

[0019] Preferably, in step 6), the room is kept bright, and the doors and windows are not shaded; when the light is insufficient on rainy days, fluorescent lamps are turned on to supplement the light, and the light intensity is maintained at 15000umol / m 2 / s or more.

[0020] The beneficial effects of the present invention are:

[0021] The present invention proposes for the first time a method for indoor incubation of flower buds by high temperature germination and post-drought rehydration, which can improve the yield and quality of saffron stigma: dig out from the soil no later than May 1, place in indoor mild conditions until the end of May after disinfection, place saffron bulbs in a greenhouse from June 1 to July 15 to break dormancy early through high temperature treatment, start drought treatment with a "sandwich" drought cultivation device of quicklime-vermiculite-quicklime on July 16, and resume hydroponics in early October to promote root development. The optimal day and night high and low temperature limits for breaking dormancy, the optimal temperature for incubation during the flower bud differentiation period are screened, the starting point and humidity conditions of drought treatment are optimized, and the optimal time for resuming hydroponics is determined. Compared with the traditional two-stage cultivation method, this method is the first to create a high temperature accumulation dormancy breaking method during the indoor cultivation and flowering period of saffron, which not only promotes early flowering of saffron, but also increases the number of saffron flowers, advances the root development time by two months, significantly prolongs the vegetative growth period of the bulb, and increases the yield of daughter bulbs. At the same time, the method can effectively increase the length and weight of saffron stigma, increase the content of crocin in the stigma, and enhance the intensity of its color, aroma and taste, thereby significantly improving the stigma yield and overall quality of saffron. In addition, the method significantly reduces the occurrence of saffron bulb rot through high temperature treatment and the antibacterial effect of quicklime, greatly improving the comprehensive economic benefits of saffron production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is an overall flow chart of the method of the present invention.

[0023] Figure 2 Schematic diagram of different stages of pistil development in an embodiment of the present invention, A. white, B. yellow, C. orange.

[0024] Figure 3 The figures are the arid cultivation device (left) and the hydroponic cultivation device (right) used in the embodiments of the present invention.

[0025] Figure 4 The effect of different germination temperatures on saffron flowering. A: The difference in the proportion of flowering bulbs to total bulbs at different germination temperatures; B: The difference in the number of flowers per bulb at different germination temperatures.

[0026] Figure 5 The FKPM value of each candidate gene is shown.

[0027] Figure 6 It is the standard colorimetric card of the pistil used in the embodiments of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific implementation methods. The following specific embodiments are helpful for those skilled in the art to further understand the present invention, but do not limit the present invention in any form.

[0029] Example

[0030] 1. Experimental Methods

[0031] like Figure 1 As shown, the present invention provides a method for indoor incubation of flower buds by high temperature germination and rehydration after drought, which can improve the yield and quality of saffron stigma, and mainly comprises the following steps:

[0032] 1. Dig out saffron bulbs from the soil on May 1, sort them out in time, remove the remaining mother bulbs and withered leaves, spread them flat on the ground to avoid stacking and storage to reduce the chance of bulbs getting sick, spray 25% (half the concentration lower than normal) carbendazim for disinfection to reduce pesticide residues.

[0033] 2. After disinfection, place the bulbs in mild indoor conditions until the end of May to provide a suitable environment for the new bulb seed coat to enhance aging and improve the bulbs' ability to withstand high temperatures. Mild indoor conditions refer to: the ambient temperature is controlled at 20-25°C, and the daytime light intensity is controlled at 5umol / m 2 / s, the ambient humidity is controlled within 70%; the CO2 concentration does not exceed 600PPM.

[0034] 3. From June 1st to July 15th, the bulbs were placed in the greenhouse. During the day (i.e. 07:00-17:00), the temperature was controlled to be higher than 30℃ and lower than 35℃, and maintained for 8-10 hours a day; at night (i.e. after 17:00-07:00 the next day), the temperature was controlled to be higher than 18℃ and lower than 25℃, and the temperature difference between morning and evening was not less than 10℃. The light intensity during the day was controlled at 5umol / m 2 / s, the indoor CO2 concentration does not exceed 600PPM throughout the day, and the ambient humidity is controlled within 60%. Electric heating is used to adjust the temperature, which can effectively avoid O2 consumption and CO2 release caused by chemical combustion heating; ventilation is used to adjust the CO2 concentration; four-layer shading yarn is used to control the light intensity; and a dehumidifier is used to adjust the humidity. Through this step of processing, dormancy can be broken one month earlier, the number of flowers can be increased by 20%, and the incidence of rot can be reduced by 20%.

[0035] 4. Take the saffron bulbs that have ended their dormancy in step 3 (the top buds have begun to elongate and become pointed, and the flower buds have begun to differentiate under a stereomicroscope, and the pistils are white, such as Figure 2 A) is placed in an arid cultivation device for cultivation. The specific method is as follows: quicklime is spread on the bottom surface with a thickness of about 2 to 3 cm; then a vermiculite layer is spread on the quicklime, and the saffron bulbs are buried in this layer, and the thickness of the vermiculite layer is enough to cover the saffron bulbs; finally, a layer of quicklime is covered on the vermiculite layer with a thickness of 2 to 3 cm to form a quicklime-vermiculite-quicklime "sandwich" arid cultivation device, as shown in FIG. Figure 3 (Left) shows that the humidity in the drought cultivation device is controlled within 5%. Environmental conditions for drought cultivation: ambient temperature is 18-22℃; daytime light intensity is controlled at 1000umol / m 2 / s; environmental humidity is controlled within 50%; indoor CO2 concentration does not exceed 500PPM. This period is the development period of flower organs, which requires appropriate light. Too dark indoors will cause excessive elongation of saffron buds and affect flower development.

[0036] 5. In early October, randomly select 5 bulbs from the dry cultivation device, peel off the longer terminal buds, and observe the pistil color of the faster-developing flowers. If the pistil color has reached the color chart (see Figure 6 ) indicates that hydroponics can be resumed.

[0037] 6. Hydroponic cultivation device such as Figure 3 (Right) As shown: Place the saffron bulb in a hydroponic planting cup, then place the planting cup in a disposable plastic cup, add distilled water until it just touches the bottom of the bulb to induce rooting, and change the water every 4 to 5 days until the bulb blooms. When resuming hydroponic cultivation, the environmental setting conditions are: the temperature is 14 to 16°C; the room is kept bright, and the doors and windows are not shaded; when there is insufficient light on rainy days, turn on the fluorescent lamp to supplement the light, and the light intensity is maintained at 15000umol / m 2 / s or more. CO2 concentration does not exceed 500PPM; environmental humidity is 40-60%. Starting from late October, it enters the flowering period, and sufficient light is needed for saffron to bloom.

[0038] 2. Results and Analysis

[0039] 1. Germination temperature screening

[0040] Temperature has a significant effect on saffron flowering. In order to explore the differences in the number of flowers of domestic saffron varieties during the flower bud differentiation period as the temperature changes, 23-27g bulbs (flowering under normal conditions) were treated at 6℃ for one and a half months from June 1st to July 15th and then restored to normal temperature for cultivation. The results showed that all the bulbs did not flower (no flower primordium differentiation was observed); the proportion of flowering bulbs was about 21% when recovered after being treated at 16℃ for one and a half months; the proportion of flowering bulbs was about 71% when recovered after being treated at 18℃ for one and a half months; the proportion of flowering bulbs was close to 100% when recovered after being treated at 20℃, 25℃, and 33℃ for one and a half months (such as Figure 4 A).

[0041] From June 1 to July 15, saffron was treated at 20℃, 25℃, 33℃, and 35℃ for one and a half months, and then returned to normal temperature. The number of flowers per bulb was counted and it was found that at 20℃, the average number of flowers per bulb was about 2.4; after 25℃ treatment, the average number of flowers per bulb was about 3.1; after 33℃ treatment, the average number of flowers per bulb increased significantly to 3.7; after 35℃ treatment, the average number of flowers per bulb began to decrease again, about 2.0 (such as Figure 4 B).

[0042] Based on the above results, the flower bud incubation temperature of 33℃ can significantly increase the number of flowers, so we determined the germination temperature to be higher than 30℃ and lower than 35℃.

[0043] 2. Phenotypic comparison

[0044] 2.1 Different cultivation methods were used for comparison, among which the two-stage method was to dig the saffron corms from the soil in April-May, place them indoors until the end of flowering, and then plant them back in the soil, and then dig them out again in April-May of the following year; the drought method was to dig the saffron corms from the soil in April-May, place them in a drought device until the end of flowering, and then plant them back in the soil, and then dig them out again in April-May of the following year; the method of this application was to dig the saffron corms from the soil in April-May, place the corms indoors after disinfection until the end of May, place the corms in a greenhouse from June 1 to July 15, and place them in a drought device starting from July 16. Hydroponics was resumed in early October, and they were planted back in the soil after flowering, and then dug out again in April-May of the following year. In the comparative experiment, the saffron corms dug out of the soil on May 1 were cultivated by different methods, and then planted back in the soil after flowering, and then dug out again on May 1 of the following year. The stigma length and fresh weight of saffron cultivated by different methods were measured, and the crocin content was determined by HPLC-MS / MS method. The statistical analysis was performed and the results are shown in the following table:

[0045] Table 1. Results of determination of pistil length, fresh weight and crocin content of saffron cultivated by different methods

[0046]

[0047] 2.2 The color, aroma and flavor intensity of saffron cultivated by different methods were measured using the ISO 3632 standard (ISO 3632-1, 2011), and statistical analysis was performed. The results are shown in the following table:

[0048] Table 2. Results of color, aroma and flavor intensity determination of saffron cultivated by different cultivation methods

[0049]

[0050] Based on the above results, compared with the traditional two-stage cultivation method or the drought method, the method of the present application can significantly improve the stigma length, fresh weight, crocin content and saffron color, aroma and flavor intensity of saffron, and greatly improve the quality of saffron; at the same time, the method of the present application can advance flowering by about 1 month, thereby extending the vegetative growth period of the bulb, which is beneficial to improving the quality and yield of the stigma in the following year.

[0051] 3. Comparison of expression levels of candidate genes

[0052] The transcriptome sequencing of saffron stigma under different treatment conditions was performed, and the expression of genes in the crocin metabolic pathway was analyzed. The gene expression data was correlated with the crocin content data at each stage. Genes with small p values ​​and high correlation coefficients were preliminarily determined as molecular markers that characterize crocin content. The following candidate genes that can be used as molecular markers were screened (see Table 3). By measuring the expression of candidate genes, the ability to synthesize crocin in different groups and individuals can be predicted, and the ability to synthesize crocin can be improved by artificially intervening in cultivation conditions, laying the foundation for increasing the quality of stigma.

[0053] Table 3. p values ​​and correlation coefficients corresponding to different candidate genes

[0054]

[0055] Combination Figure 5 As shown, the above candidate genes all have a strong positive correlation with the crocin content, indicating that these genes can be selected for expression measurement to predict the crocin content.

[0056] 3. Optimization of rewatering conditions after drought

[0057] 1. Starting point of drought treatment and treatment humidity

[0058] In order to optimize the starting point of drought treatment, pistils of different colors were used as the criteria for discrimination, and a standard color comparison card for pistils was made, such as Figure 6As shown. The color change of saffron pistil from the early white stage to the scarlet stage when flowering is a gradual accumulation and change process, and the color is closely related to the crocin content. Literature reports that the expression of crocin synthesis genes at different color stages is very different, so artificial intervention in cultivation conditions at different stages has a great impact on the quality of saffron stigma. Due to personal sensory differences, each person's judgment of different colors varies greatly, so making a standard colorimetric card is crucial for screening and selecting the appropriate stage for artificial intervention to achieve the best conditions for improving stigma quality.

[0059] Different stages of pistil development (such as Figure 2 The crocin content was compared and the optimal starting time and humidity were screened.

[0060] Table 4. Crocin content in plants at different stages of pistil development, after drought treatment at different humidity levels, and then restored to hydroponics at the Red 1 stage

[0061]

[0062] The results showed that when the white pistil was used as the initial stage and the humidity was 5%, the crocin content was the best and the quality improvement was the most significant.

[0063] 2. Time point for resuming hydroponics

[0064] Taking white pistil as the initial stage, drought treatment was carried out at 5% humidity. Hydroponics was resumed when the pistil color reached yellow 4, orange 3, and red 1 in the color card, and the crocin content in different groups was compared to screen the optimal time node for resuming hydroponics.

[0065] Table 5. Crocin content in plants treated with drought at 5% humidity and restored to water culture at different pistil colors with white pistil as the initial stage

[0066]

[0067] The results showed that when the pistil color reached the red 1 stage on the color chart, the crocin content was the best and the quality improvement was most significant when hydroponics was resumed.

[0068] Obviously, the above embodiments of the present invention are merely examples to more clearly illustrate the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for incubating flower buds indoors by high temperature germination and rehydration after drought, which can improve the yield and quality of saffron stigma, comprising: 1) After digging the bulbs out of the soil no later than May 1, remove the remaining mother bulbs and withered leaves, spread them on the ground, and spray them with 25% carbendazim to disinfect and reduce pesticide residues; 2) Place the saffron bulbs in a mild indoor environment until the end of May to promote the aging of the bulb seed coat. Mild indoor conditions refer to: the ambient temperature is controlled at 20-25°C, and the daytime light intensity is controlled at 5umol / m 2 / s, the ambient humidity is controlled within 70%; the CO2 concentration does not exceed 600PPM; 3) From June 1st to July 15th, place the bulbs treated in step 2) in a greenhouse, control the temperature to be higher than 30℃ and lower than 35℃ during the day, and maintain it for 8-10 hours a day; control the temperature to be higher than 18℃ and lower than 25℃ at night, and the temperature difference between morning and evening should be no less than 10℃; control the light intensity during the day at 5umol / m 2 / s, the indoor CO2 concentration does not exceed 600PPM throughout the day, and the ambient humidity is controlled within 60%; 4) Starting from July 16, the saffron bulbs treated in step 3) are placed in a drought cultivation device for cultivation. The drought cultivation device is to spread quicklime on the bottom surface, and then spread a vermiculite layer on the quicklime. The vermiculite layer is used to bury the saffron bulbs. Finally, a layer of quicklime is covered on the vermiculite layer to form a quicklime-vermiculite-quicklime "sandwich" drought cultivation device. The humidity in the drought cultivation device is controlled within 5%. The environmental conditions during drought cultivation are: the ambient temperature is 18-22°C; the daytime light intensity is controlled at 1000umol / m 2 / s; environmental humidity is controlled within 50%; indoor CO2 concentration does not exceed 500PPM; 5) In early October, observe the color of the pistils of the flowers that develop faster. If the color of the pistils reaches the set color, resume hydroponics; 6) Place the saffron bulbs in a hydroponic cultivation device, add distilled water until it just touches the bottom of the bulbs to induce rooting, and change the water every 4 to 5 days until the bulbs bloom; environmental conditions for hydroponic cultivation: ambient temperature is 14 to 16°C; light intensity is maintained at 15,000 umol / m 2 / s or above; ambient humidity 40-60%; indoor CO2 concentration does not exceed 500PPM.

2. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: Step 4) placing the saffron bulbs that have been placed in the greenhouse until the dormancy period ends and whose pistils are white in color in a drought cultivation device for cultivation.

3. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: In step 4), the thickness of the quicklime spread on the bottom surface is 2 to 3 cm.

4. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: In step 4), the thickness of the vermiculite layer is sufficient to cover the saffron bulbs.

5. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: In step 4), the thickness of quicklime covering the vermiculite layer is 2 to 3 cm.

6. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: In step 5), the pistil color is determined by a colorimetric card, and the colorimetric card is sequentially set to: white, yellow 1, yellow 2, yellow 3, yellow 4, orange 1, orange 2, orange 3, orange 4, orange 5, red 1, red 2, and red 3 corresponding to the color change of the saffron pistil from the early white stage to the scarlet stage during flowering.

7. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 6, characterized in that: In step 5), 5 bulbs are randomly selected from the dry cultivation device, the longer terminal buds are peeled off, and the pistil color of the faster developing flowers is observed. If the pistil color has all reached the red 1 stage in the color chart, hydroponics is resumed.

8. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: In step 6), placing the saffron bulbs in the hydroponic cultivation device includes: placing the saffron bulbs in the hydroponic planting cups, and then placing the planting cups in the disposable plastic cups.

9. The method for indoor incubation of flower buds by high temperature germination and rehydration after drought according to claim 1, characterized in that: In step 6), the room is kept bright, and the doors and windows are not shaded; when the light is insufficient on rainy days, turn on the fluorescent lamp to supplement the light, and the light intensity is maintained at 15000umol / m 2 / s or more.

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