Method for increasing content of beta-cryptoxanthin in citrus reticulata blanco through artificial light supplement

Abstract

The invention belongs to the technical field of citrus planting, and particularly relates to a method for increasing the content of beta-cryptoxanthin in broad-peel citrus through artificial light supplement. According to the method, under the condition that the natural sunshine time is shortened from the last ten-day period of September (the solar term of autumn equinox) to the harvesting period every year, facility full-ripening cultivation broad-peel citrus trees including satsuma oranges are subjected to light supplementing treatment of a specific wavelength type, and the content of beta-cryptoxanthin in the broad-peel citrus can be effectively increased; the cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of citrus planting, and particularly relates to a method for increasing the content of beta-cryptoxanthin in broad-skinned citrus through artificial light supplementation. Background Art

[0002] β-cryptoxanthin is a type of carotenoid and is also the most abundant carotenoid in citrus fruits. Carotenoids are a type of natural pigment that plays an important role in human health. They are not only the precursors of vitamin A, but also can scavenge free radicals, improve immunity, prevent cardiovascular diseases, and fight cancer. Vitamin A is an essential micronutrient for the human body. It can promote growth, maintain bones, epithelial tissues, vision, and normal secretion of mucosal epithelium, and other physiological functions. At present, α-carotene, β-carotene, and β-cryptoxanthin are considered to be the most important vitamin A progenitors in animals. At the same time, existing studies have shown that the main carotenoids with anti-cancer activity are α-carotene, β-carotene, β-cryptoxanthin, etc. However, medical research also shows that the anti-cancer ability of β-cryptoxanthin is about 5 times that of β-carotene, and it has a significant anti-cancer effect. At the same time, some other existing studies have shown that increasing the intake of β-cryptoxanthin during pregnancy can reduce the risk of anxiety in pregnant women and enhance the baby's future cognitive and receptive language abilities. Therefore, increasing the intake of β-cryptoxanthin is of great benefit to human health.

[0003] Citrus is one of the fruits with the richest carotenoid content and is an important source of carotenoids. The main carotenoid accumulated in the pulp of wide-peeled citrus is β-cryptoxanthin, and its content is significantly higher than that of other citrus species such as sweet orange, sour orange, grapefruit, lemon and kumquat. Wenzhou mandarin is the most cultivated wide-peeled citrus variety in the world, and it is also one of the wide-peeled citrus varieties with the largest cultivation area in my country. Its pulp is rich in carotenoids, mainly including β-cryptoxanthin, zeaxanthin, violaxanthin, antheraxanthin, lutein and β-carotene, especially β-cryptoxanthin, which can account for more than 43% of the total carotenoid content. Therefore, Wenzhou mandarin is a very good source of β-cryptoxanthin. Due to the large consumption of Wenzhou mandarin, if the natural β-cryptoxanthin content in the pulp can be further increased through cultivation technology, it will not only benefit people's health, but also bring higher economic benefits to agricultural production.

[0004] In order to further improve the quality of Wenzhou mandarin oranges, enhance the nutritional value of the fruit and increase economic benefits, production has begun to use facility-ripening cultivation technology to delay the fruit harvest period and produce high-quality Wenzhou mandarin oranges. However, there are currently few methods in production to increase the β-cryptoxanthin content of citrus through cultivation technology. Summary of the invention

[0005] The object of the present invention is to provide a method for increasing the β-cryptoxanthin content in citrus fruits by artificial lighting, wherein the method can significantly increase the β-cryptoxanthin content in the pulp of citrus fruits grown in facilities including Wenzhou mandarin oranges.

[0006] The present invention provides a method for increasing the content of β-cryptoxanthin in facility-cultivated mature citrus fruits by artificial supplementary lighting, comprising the following steps: from late September to the harvest period each year, artificial supplementary lighting is performed on citrus fruits trees by using supplementary lighting lamps, wherein the supplementary lighting lamps include combined supplementary lighting lamps or white light supplementary lighting lamps:

[0007] The combined fill light includes red light and / or blue light, the wavelength of the red light is 605-700nm, the wavelength of the blue light is 435-480nm, and the photon flux density ratio of the red light and the blue light is (0-4): (0-4);

[0008] The photon flux density of the supplementary light at a distance of 50 cm from the light is 130-510 μmol·m -2 ·s -1 .

[0009] Preferably, the artificial lighting treatment time is 4 to 6 hours per day.

[0010] Preferably, from late September to early November each year, the artificial lighting treatment time is 4 hours / day, and from early November to the harvest period each year, the artificial lighting treatment time is 6 hours / day.

[0011] Preferably, the wide-skinned citrus trees are supplemented with light for 2 hours before sunrise and after sunset from September 22 to September 24 to November 7 to November 8 every year, and the wide-skinned citrus trees are supplemented with light for 3 hours before sunrise and after sunset from November 7 to November 8 to the harvest period every year.

[0012] Preferably, the light source of the fill light is a light emitting diode.

[0013] Preferably, when artificial supplementary lighting is performed on the citrus tree, the supplementary light is hung 50 cm above the top of the crown of the citrus tree, and a white reflective film is laid on the ground of the citrus tree.

[0014] Preferably, the broad-skinned citrus tree includes a broad-skinned citrus tree having a natural open-heart shape.

[0015] Preferably, the wide-skinned citrus includes Satsuma mandarin.

[0016] Preferably, the step of increasing the β-cryptoxanthin content in Citrus aurantifolia comprises increasing the β-cryptoxanthin content in Citrus aurantifolia fruit.

[0017] Beneficial effects:

[0018] The invention provides a method for increasing the content of β-cryptoxanthin in citrus tangerines by artificial supplementary lighting, comprising the following steps: from late September to the harvest period each year, artificial supplementary lighting treatment is performed on citrus tangerine trees cultivated in facilities with complete maturity by using supplementary lighting lamps, wherein the supplementary lighting lamps comprise combined supplementary lighting lamps or white light supplementary lighting lamps; the combined supplementary lighting lamps comprise red light and / or blue light, the wavelength of the red light is 605-700nm, the wavelength of the blue light is 435-480nm, and the photon flux density ratio of the red light to the blue light is (0-4):(0-4); the photon flux density of the supplementary lighting lamp at a position 50cm below the lamp is 130-510μmol·m -2 ·s -1 The present invention can effectively increase the β-cryptoxanthin content in the wide-skinned citrus by performing a specific wavelength type of supplementary light treatment on fully mature facility-cultivated wide-skinned citrus trees including Wenzhou mandarin oranges when the natural sunlight time becomes shorter from late September (the autumnal equinox) to the harvest period. The method of the present invention is simple, easy to operate, low in cost, and suitable for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0020] Figure 1 The carotenoid content and β-cryptoxanthin content in the Wenzhou mandarin orange fruit in Examples 1 to 7, wherein different letters indicate significant differences compared with the control (P < 0.05). DETAILED DESCRIPTION

[0021] The present invention provides a method for increasing the content of β-cryptoxanthin in citrus tangerines by artificial supplementary lighting, comprising the following steps: from late September to the harvest period each year, artificial supplementary lighting is performed on citrus tangerine trees cultivated in facilities with complete maturity, wherein the supplementary lighting comprises a combined supplementary lighting or a white light supplementary lighting:

[0022] The combined fill light includes red light and / or blue light, the wavelength of the red light is 605-700nm, the wavelength of the blue light is 435-480nm, and the photon flux density ratio of the red light and the blue light is (0-4): (0-4);

[0023] The photon flux density of the supplementary light at a distance of 50 cm from the light is 130-510 μmol·m -2 ·s -1 .

[0024] As an embodiment, the wide-peeled citrus of the present invention includes but is not limited to Wenzhou mandarin oranges. As an embodiment, the increasing the β-cryptoxanthin content in the wide-peeled citrus includes increasing the β-cryptoxanthin content in the wide-peeled citrus fruit; as another embodiment, the increasing the β-cryptoxanthin content in the wide-peeled citrus includes increasing the β-cryptoxanthin content in the wide-peeled citrus pulp.

[0025] As one embodiment, the artificial lighting treatment time of the present invention is 4 to 6 hours per day; as another embodiment, the artificial lighting treatment time is 4 hours per day from late September to early November each year, and the artificial lighting treatment time is 6 hours per day from early November to the harvest period each year; as another embodiment, the present invention supplements light to the wide-skinned citrus trees for 2 hours before sunrise and after sunset from September 22 to September 24 to November 7 to November 8 each year, and supplements light to the wide-skinned citrus trees for 3 hours before sunrise and after sunset from November 7 to November 8 to the harvest period each year; as another embodiment, the present invention supplements light to the wide-skinned citrus trees for 2 hours before sunrise and after sunset from the autumnal equinox to the beginning of winter each year, and supplements light to the wide-skinned citrus trees for 3 hours before sunrise and after sunset from the beginning of winter to the harvest period each year. The reason why the present invention chooses to adjust the duration of the artificial lighting treatment before and after the autumnal equinox and before and after the beginning of winter is that the sunshine time starts to be shorter than 12 hours at the beginning of the autumnal equinox every year, and the sunshine time starts to gradually become shorter than 10 hours before and after the beginning of winter. By adjusting the duration of artificial lighting treatment, sufficient duration and intensity of light can be guaranteed for the citrus fruits, thereby increasing the content of β-cryptoxanthin in the citrus fruits.

[0026] As an embodiment, the light source of the fill light is a light emitting diode. The combined fill light of the present invention may be in the form of red light, blue light, or a combination of red light and blue light; as an embodiment, the peak wavelength of the red light may be 660nm; the peak wavelength of the blue light is 450nm; as an embodiment, the photon flux density ratio of the red light and the blue light is (1-4): (1-4); as another embodiment, the photon flux density ratio of the red light and the blue light is 1:4 or 4:1. As an embodiment, when the fill light is a combined fill light, the photon flux density of the fill light at a distance of 50cm from the light is 130μmol·m -2 ·s -1 .

[0027] As an embodiment, when the fill light is white light, the light quantum flux density of the fill light at a distance of 50 cm from the light is 350 to 510 μmol·m -2 ·s -1As an embodiment, the photon flux density of the fill light at a distance of 50 cm from the light is 350 μmol·m -2 ·s -1 .

[0028] As an embodiment, when artificial fill-in lighting is performed on the citrus tree, the fill-in light is hung 50 cm above the top of the crown of the citrus tree, and a white reflective film is laid on the ground of the citrus tree; as another embodiment, the white reflective film is made of high-density polyethylene fiber. As an embodiment, the citrus tree can be, but is not limited to, a citrus tree with a natural open-heart shape. The setting of the natural open-heart shape of the tree in the present invention can ensure that 10%-20% of the light from the fill-in light can be directly irradiated to the bottom of the tree disk, that is, the light spot area directly irradiated to the bottom of the tree disk through the gap between the leaves accounts for 10%-20% of the shadow area of ​​the entire tree body.

[0029] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0030] Example 1

[0031] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0032] This supplementary lighting experiment was conducted in a Wenzhou mandarin orange orchard with fully mature cultivation facilities in Xingan County, Ji'an City, Jiangxi Province. The supplementary lights were hung 50 cm from the top of the tree crown, with one hung on each tree. The ground was covered with white reflective film made of high-density polyethylene fiber to reflect the light that hit the ground. At the same time, the trees were pruned to a natural open heart shape, and 15% of the light from above could directly hit the bottom of the tree tray.

[0033] The fill light is an LED fill light, full red light, with a peak wavelength of 660nm, and a photon flux density of 130μmol·m at a distance of 50cm from the light. -2 ·s -1 .

[0034] The supplementary lighting will start on the Autumnal Equinox on September 23, 2023, with a supplementary lighting time of 2 hours before sunrise and 2 hours after sunset, for a total of 4 hours per day; after the Beginning of Winter on November 8, 2023, the supplementary lighting time will be adjusted to 3 hours before sunrise and 3 hours after sunset, for a total of 6 hours per day, until the fruit is harvested.

[0035] Example 2

[0036] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0037] The fill light method in Example 1 was used to fill light the Wenzhou mandarin oranges. The only difference was that the fill light was set differently: the fill light was an LED fill light, full blue light, with a wavelength peak of 450nm, and a photon flux density of 130μmol·m at a distance of 50cm from the lamp. -2 ·s -1 .

[0038] Example 3

[0039] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0040] The fill light method in Example 1 was used to fill light the Wenzhou mandarin oranges. The only difference was that the fill light was set differently: the fill light was an LED fill light, a combination of red light and blue light, with a red light wavelength peak of 660nm and a blue light wavelength peak of 450nm. The red light photon flux density was 65μmol·m at a distance of 50cm from the lamp. -2 ·s -1 The blue light quantum flux density is also 65 μmol·m -2 ·s -1 .

[0041] Example 4

[0042] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0043] The fill light method in Example 1 was used to fill light the Wenzhou mandarin oranges. The only difference was that the fill light was set differently: the fill light was an LED fill light, a combination of red light and blue light, with a red light wavelength peak of 660nm and a blue light wavelength peak of 450nm. The red light photon flux density at a distance of 50cm from the lamp was 26μmol·m -2 ·s -1 The blue light quantum flux density is also 104 μmol·m -2 ·s -1 .

[0044] Example 5

[0045] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0046] The fill light method in Example 1 was used to fill light the Wenzhou mandarin oranges. The only difference was that the fill light was set differently: the fill light was an LED fill light, a combination of red light and blue light, with a red light wavelength peak of 660nm and a blue light wavelength peak of 450nm. The red light photon flux density at a distance of 50cm from the lamp was 104μmol·m -2 ·s -1 The blue light quantum flux density is also 26 μmol·m -2·s -1 .

[0047] Example 6

[0048] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0049] The fill light method in Example 1 was used to fill light the Wenzhou mandarin oranges. The only difference was the setting of the fill light: the fill light was an LED fill light, full white light, and the red light quantum flux density was 350 μmol·m at a distance of 50 cm from the lamp. -2 ·s -1 .

[0050] Example 7

[0051] A method for increasing the content of β-cryptoxanthin in Wenzhou mandarin orange fruit by supplementing light, the steps are as follows:

[0052] The fill light method in Example 1 was used to fill light the Wenzhou mandarin oranges. The only difference was the setting of the fill light: the fill light was an LED fill light, full white light, and the red light quantum flux density was 510 μmol·m at a distance of 50 cm from the lamp. -2 ·s -1 .

[0053] Test Example 1

[0054] The supplementary lighting in Examples 1 to 7 was implemented until the Wenzhou mandarin orange fruits were harvested and put on the market. After the fruits were harvested, the total carotenoid content and β-cryptoxanthin content in the pulp were analyzed, and Wenzhou mandarin orange fruits that were not treated with supplementary lighting and not covered with a white reflective film made of high-density polyethylene fiber were used as controls. Three branches were selected for sampling, and at least five fruits were selected from each branch as one biological replicate, for a total of three replicates.

[0055] The method for determining the total carotenoid content in pulp is as follows:

[0056] 1) Take about 0.5g of fresh Wenzhou mandarin orange pulp, chop it into pieces and mix well.

[0057] 2) The chopped and mixed sample was placed in a 10 mL centrifuge tube, 8 mL of acetone solution with a volume concentration of 80% was added, and the mixture was extracted at room temperature in the dark for 48 hours to obtain an extract.

[0058] 3) The extract was centrifuged at 1000 rpm for 10 min, the supernatant was then poured out and the volume was made up to 10 mL with 80% acetone solution, and the solution was shaken to obtain a carotenoid extract.

[0059] 4) Add the carotenoid extract into a 1 cm optical path cuvette, use an acetone solution with a volume concentration of 80% as a blank control, and measure the absorbance at wavelengths of 663nm, 646nm and 470nm.

[0060] The carotenoid content in the pulp is calculated as follows:

[0061] C a =12.21A 663 -2.81A 646

[0062] C b =20.13A 646 -5.03A 663

[0063]

[0064] In the above formula: Ca and Cb are the concentrations of chlorophyll a and chlorophyll b in the extract (μg / mL); A 663 , A 646 and A 470 are the absorbance of the extract at wavelengths of 663 nm, 646 nm and 470 nm, respectively, and W is the sample weight (g).

[0065] The method for determining the content of β-cryptoxanthin in pulp is as follows:

[0066] 1) Weigh 5 g of Wenzhou mandarin orange pulp and place it in a 50 mL centrifuge tube. Add 15 mL of carotenoid extract and vortex to mix.

[0067] 2) After vigorous shaking in the sample grinder for 6 minutes, centrifuge at 4000g for 10 minutes, transfer the supernatant to another 50mL centrifuge tube, and extract the precipitate twice with 15mL of carotenoid extract solution until it is colorless (extract three times in total, and transfer the supernatant to the same centrifuge tube).

[0068] 3) Combine the supernatants, wash the supernatants three times with saturated NaCl (10%) aqueous solution in a 50 mL separatory funnel until neutral, and discard the lower layer (aqueous layer).

[0069] 4) The supernatant was transferred to 10 mL centrifuge tubes in batches and vacuum concentrated to dryness. After vacuum concentration, it was dissolved with 2 mL MTBE (containing 0.1‰ BHT), and then 2 mL 10% KOH-methanol solution (containing 0.1‰ BHT) was added, and saponified for 10 h in dark conditions.

[0070] 5) Add 4 mL of saturated NaCl aqueous solution and 2 mL of MTBE (containing 0.1‰ BHT) to achieve better stratification, remove the aqueous layer with a rubber-tipped pipette, and then add 5 mL of saturated NaCl aqueous solution three times to wash until neutral.

[0071] 6) Transfer the remaining pigment supernatant to 2 mL centrifuge tubes in batches, vacuum concentrate to dryness (can be temporarily stored in a -80°C refrigerator and re-dissolved before testing), and then dissolve to volume with 0.15-1 mL (only 0.15 mL can be added for low concentrations, and a membrane can be filtered) MTBE.

[0072] 7) Centrifuge at 15871 g for 30 min, filter through membrane, transfer to a sample injection bottle, and then perform high performance liquid chromatography detection.

[0073] 8) Preparation of mobile phase for liquid chromatography detection: Mobile phase A is: acetonitrile: methanol = 3:1 (750 mL: 250 mL, containing 0.01% BHT); Mobile phase B is: 100% MTBE (containing 0.01% BHT).

[0074] 9) After preparation, use a vacuum filter equipped with a 0.22 μm organic filter membrane to filter the mobile phase to remove impurities.

[0075] 10) Place the mobile phase in an ultrasonic device and sonicate for 30 minutes to remove bubbles.

[0076] 11) HPLC analysis procedure:

[0077] Mobile phase: flow rate is 1 mL / min, injection volume is 20 μL.

[0078] Gradient elution was used: 0min: AB (95:5); 0-10min: AB (95:5); 10-19min: AB (86:14); 19-29min: AB (75:25); 29-54min: AB (50:50); 54-66min: AB (26:74); 67-76min: AB (95:5).

[0079] Data analysis: The β-cryptoxanthin peak was determined based on the sample elution time, and the system automatically calculated the β-cryptoxanthin content based on the peak area. The qualitative information of the carotenoid standard is shown in Table 1.

[0080] Table 1 Qualitative information of carotenoid components

[0081]

[0082]

[0083] The total carotenoid content and β-cryptoxanthin content of Wenzhou mandarin orange pulp after supplementary light in Examples 1 to 7 are as follows Figure 1 As shown in Table 2.

[0084] Table 2 Total carotenoid content and β-cryptoxanthin content in pulp of different examples

[0085]

[0086] Depend on Figure 1 From Table 2, it can be concluded that artificial supplementation of red light, blue light, mixed red and blue light, and white light with higher light intensity can significantly increase the β-cryptoxanthin content in Wenzhou mandarin orange fruit, and the effect of blue light is better than that of red light under the same light intensity. As shown in the experimental analysis results, the photon flux density of the red light of the supplementary light is 26μmol·m -2 ·s -1 The blue light quantum flux density is also 104 μmol·m -2 ·s -1 (Example 4) and white light quantum flux density of 350 μmol·m -2 ·s -1 (Example 6) is more suitable for supplementing light in winter for Wenzhou mandarin oranges to increase the content of β-cryptoxanthin in the carotenoids in the fruit.

[0087] It can be concluded from the above examples that the method of the present invention can significantly increase the β-cryptoxanthin content in the pulp of wide-skinned citrus fruits including Satsuma mandarin.

[0088] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for increasing the content of β-cryptoxanthin in citrus fruits by artificial lighting, characterized in that: The method comprises the following steps: from late September to the harvest period each year, artificial lighting is performed on the fully mature citrus trees cultivated in the facility using a fill light, wherein the fill light comprises a combination fill light or a white light fill light: The combined fill light includes red light and / or blue light, the wavelength of the red light is 605-700nm, the wavelength of the blue light is 435-480nm, and the photon flux density ratio of the red light and the blue light is (0-4): (0-4); The photon flux density of the supplementary light at a distance of 50 cm from the light is 130-510 μmol·m -2 ·s -1 .

2. The method according to claim 1, characterized in that The artificial lighting treatment time is 4 to 6 hours per day.

3. The method according to claim 2, characterized in that From late September to early November each year, the artificial lighting treatment time is 4 hours / day, and from early November to the harvest period each year, the artificial lighting treatment time is 6 hours / day.

4. The method according to claim 3, characterized in that From September 22 to September 24 to November 7 to November 8 every year, the wide-skinned citrus trees are supplemented with light for 2 hours before sunrise and after sunset respectively; from November 7 to November 8 every year to the harvest period, the wide-skinned citrus trees are supplemented with light for 3 hours before sunrise and after sunset respectively.

5. The method according to claim 1, characterized in that The light source of the fill light is a light emitting diode.

6. The method according to claim 1, characterized in that When artificial supplementary lighting is performed on the citrus mandarin orange tree, the supplementary light is hung 50 cm above the top of the crown of the citrus mandarin orange tree, and a white reflective film is laid on the ground of the citrus mandarin orange tree.

7. The method according to claim 1, characterized in that The broad-skinned citrus tree includes a broad-skinned citrus tree having a natural open-heart shape.

8. The method according to any one of claims 1 to 7, characterized in that: The wide-skinned citrus includes Wenzhou mandarin oranges.

9. The method according to claim 8, characterized in that The method of increasing the β-cryptoxanthin content in citrus aurantifolia includes increasing the β-cryptoxanthin content in citrus aurantifolia fruit.

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