A method for promoting flowering and enhancing pollen viability in strawberries

Abstract

The present application relates to the field of plant cultivation, and discloses a method for promoting flowering and improving pollen activity of strawberries to solve the technical problem of how to improve the yield of strawberries.The method for promoting flowering of strawberries comprises the following steps: planting strawberries by using an LED light source as a light source, wherein the percentage of blue light photon flux density in the total photon flux density is 31%-74%, the percentage of green light photon flux density in the total photon flux density is 0%-42%, and the percentage of red light photon flux density in the total photon flux density is 26%-27%.The method for promoting flowering of strawberries can increase the number of present bud plants and the number of production bud plants.The present application also provides a method for improving the pollen activity of strawberries, which can significantly improve the pollen activity of strawberries.The method is beneficial to improving the yield of strawberries in artificial light plant factories, and thus improves the economic benefits.

Description

Technical Field

[0001] This invention relates to a method for promoting strawberry flowering and / or increasing strawberry pollen viability in the field of plant cultivation. Background Technology

[0002] Artificial light plant factories (PFALs), also known as indoor vertical farming systems, enable highly efficient and high-quality food production. With PFALs, high-yield, high-quality agricultural products can be produced year-round worldwide, regardless of climate, weather, or soil fertility. This is primarily due to the environmental traceability, controllability, and repeatability of PFALs. [1] The light source in PFALs is completely controllable. Therefore, lighting is essential. In the past, people have conducted extensive research on the effects of different light qualities on plants. However, plant factories have only been developing for about 20 years, and some technologies are still not mature.

[0003] Artificial lighting is widely used in strawberry production, for example, in Japan where strawberries are cultivated under controlled systems. [2,3] However, according to the research of Zhuang et al. [4] Currently, using PFALs to grow strawberries does not appear to be economically viable. However, research suggests that strawberries are still considered a viable crop for PFALs, and profitability could be achieved with a 20% increase in yield per unit area. [4] Similar to what has happened in lettuce production, breakthroughs in strawberry cultivation techniques could increase yields or reduce production costs, making it a more profitable crop for PFALs (Fragrant Fruit Alcohols). [4] .

[0004] Flower development is a crucial process that determines when a plant begins to flower and eventually bear fruit. By manipulating the timing of this process during transplant production, the fruiting process can be artificially accelerated and the overall yield increased. Strawberry flowering is typically divided into four stages: induction, initiation, differentiation, and development. [5] Development refers to the macroscopic production of flowers, and is evaluated by the yield of flowers grown in greenhouses or growing rooms. [6] However, many studies on strawberry flowering do not differentiate between different stages, which may lead to generalizations or misstatements of the effects of treatments. [6,7] Furthermore, there is a lack of technology for using controlled artificial lighting in strawberry production.

[0005] References

[0006] 1.Kozai T,Niu G,Masabni J.Introduction:why plant factories withartificial lighting are necessary[M] / / Plant Factory Basics,Applications andAdvances.Academic Press,2022:3-10.

[0007] 2.Yoshida H,Hikosaka S,Goto E,Takasuna H,Kudo TJJoS,AgricultureHTi.Effects of continuous lighting and time of initiation of treatments onthe flowering time and growth of everbearing strawberry nursery plants in aclosed plant factory.2013;25(2):77-82.

[0008] 3.Yoshida H,Mizuta D,Fukuda N,Hikosaka S,Goto EJPB.Effects of varyinglight quality from single-peak blue and red light-emitting diodes duringnursery period on flowering,photosynthesis,growth,and fruit yield ofeverbearing strawberry.2016;33(4):267-76.

[0009] 4.Zhuang Y,Lu N,Shimamura S,Maruyama A,Kikuchi M,TakagakiMJFiPS.Economies of scale in constructing plant factories with artificiallighting and the economic viability of crop production.2022;13.

[0010] 5. Durner EF. Flowering Physiology in Fragaria X Ananassa Duch: North Carolina State University; 1985.

[0011] 6. Durner EF, Poling EBJJotASfHS. Comparison of three methods for determining the floral or vegetative status of strawberry plants. 1985; 110(6):808-11.

[0012] 7.Durner EFJSH.Photoperiod affects floral ontogeny in strawberry(Fragaria×ananassa Duch.)plug plants.2015;194:154-9. Summary of the Invention

[0013] The technical problem to be solved by this invention is how to promote strawberry flowering and thus increase strawberry yield.

[0014] To address the aforementioned technical problems, this invention first provides a method for promoting strawberry flowering, comprising the step of using an LED light source with a blue light photon flux density of 31%-74% of the total photon flux density, a green light photon flux density of 0%-42% of the total photon flux density, and a red light photon flux density of 26%-27% of the total photon flux density as the light source for strawberry cultivation.

[0015] In the above-mentioned method for promoting strawberry flowering, the percentage of photon flux density to total photon flux density is the measured value at the strawberry stunted stem.

[0016] In one embodiment of the present invention, the preferred LED light source may specifically be A1 or A2:

[0017] A1 is an LED light source in which blue light photon flux density accounts for 73.5% of the total photon flux density, green light photon flux density accounts for 0.3% of the total photon flux density, and red light photon flux density accounts for 26.2% of the total photon flux density.

[0018] A2 is an LED light source in which the percentage of blue photon flux density to total photon flux density is 31.5%, green photon flux density to total photon flux density is 41.8%, and red photon flux density to total photon flux density is 26.7%.

[0019] In the above method, the LED light source mentioned in A1 is a red-blue LED lamp and a blue LED lamp that illuminate together with a red light:blue light ratio of 7:3, and the total red-blue light ratio measured by the spectrometer is 0.4.

[0020] In the above-mentioned method for promoting strawberry flowering, the LED light source mentioned in A2 is a combination of red and blue LED lamps with a red light:blue light ratio of 7:3 and green LED lamps, and the instrument measures the total red and blue light ratio to be 0.8.

[0021] In the above-mentioned method for promoting strawberry flowering, the strawberry planting period is 16 hours of light exposure (with light source) and 8 hours of dark exposure (without light source), with a light intensity of 300 μmol / m² at the shortened stem. -2 s -1 .

[0022] In the above method for promoting strawberry flowering, the temperature during the light period is 25℃ and the temperature during the dark period is 20℃.

[0023] In the above-mentioned method for promoting strawberry flowering, the strawberry planting is carried out with a CO2 concentration of 500ppm and a relative humidity of 70%. The plants are irrigated with water and fertilizer using the Yamazaki nutrient solution top irrigation method once a day.

[0024] The present invention also provides a method for improving strawberry pollen viability, comprising the step of using an LED light source with a blue light photon flux density of 30% of the total photon flux density, a green light photon flux density of 0.3%-1% of the total photon flux density, a red light photon flux density of 69%-70% of the total photon flux density, and a far-red light photon flux density of 0.3%-1% of the total photon flux density as the light source for strawberry cultivation.

[0025] In the above method for improving strawberry pollen viability, the LED light source is an LED light source in which the percentage of blue light photon flux density to total photon flux density is 30.4%, the percentage of green light photon flux density to total photon flux density is 0.3%, the percentage of red light photon flux density to total photon flux density is 69.0%, and the percentage of far-infrared light photon flux density to total photon flux density is 0.3%.

[0026] The present invention also provides the application of the above-mentioned method for promoting strawberry flowering or the above-mentioned method for improving strawberry pollen viability in strawberry production.

[0027] The present invention also provides the application of the LED light source described in the above-mentioned method for promoting strawberry flowering or the above-mentioned method for improving strawberry pollen viability in strawberry production.

[0028] This invention explores the effects of different light qualities on strawberry flower development. In the embodiments of this invention, although the RBB and RBG treatments consumed more electricity, they produced more buds and flower buds. The RBR treatment consumed significantly less electricity than the RBG treatment, but produced fewer flower buds. In actual production, the relationship between the electricity cost and economic benefits can be considered. According to the "Notice on Approving the Provincial Power Grid Transmission and Distribution Price for 2020-2022" (NDRC Price

[2020] No. 1508), the optimal light quality for strawberry flowering was determined to be RBB or RBG. Using the selected light source in an artificial light plant factory, strawberries produced more buds and flower buds, which is beneficial to improving economic benefits. Attached Figure Description

[0029] Figure 1 The figures show the spectral composition of different light treatments measured at the shortened stem in Embodiment 1 of the present invention. The maximum value of photon flux in the figure is converted to 1.0. Figure 1 (a) represents the spectral composition of the measured RBB. Figure 1 (b) represents the spectral composition of the measured RBG. Figure 1 (c) represents the spectral composition of the measured RBR. Figure 1 (d) represents the spectral composition of the measured RBFR. Figure 1 (e) represents the spectral composition of W as measured.

[0030] Figure 2 This paper illustrates the effect of five different light treatments on the current number of strawberry plants with buds from the start to the end of the treatment in Example 1 of this invention. The data are expressed as average values ​​(n = 16).

[0031] Figure 3 This study describes the effect of five different light treatments on the number of flower buds per plant in strawberry plants from day 20 of treatment to the end of treatment, as observed during the observation period from the onset of budding to the end of treatment. The data are expressed as averages (n = 16).

[0032] Figure 4 This study describes the effects of five different light treatments on the number of anthers and pollen viability of the first flower in a fully opened top-flowered greenhouse on day 28 in Example 1 of this invention. Figure 4 (a) represents the number of anthers per flower (n / n). Figure 4 The right-hand figure shows pollen viability (%, 2% TTC). Data are presented as mean (n=9). Different letters indicate significance of the T-test (P=0.05). Error bars represent standard error (SE).

[0033] Figure 5 The error bars represent the hourly power consumption and daily electricity cost for five different light processing methods in Embodiment 1 of the present invention, with the error bar indicating the standard error (SE). Detailed Implementation

[0034] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0036] The strawberry variety 'Princess Chengde' and its bare-root seedlings used in this experiment were bred by the Forestry and Fruit Tree Research Institute of Beijing Academy of Agriculture and Forestry. This variety is a commercial strawberry variety and is available to the public.

[0037] Example 1

[0038] To determine the effects of different light qualities on the development of strawberry flowers, the inventors conducted this experiment from October 18, 2022 to November 14, 2022 in the artificial climate chamber of the Institute of Forestry and Fruit Trees, Beijing Academy of Agricultural and Forestry Sciences (39.97N, 116.24E, Beijing, China).

[0039] Plant materials and growing conditions

[0040] Bare-root strawberry seedlings of the 'Princess Chengde' (Fragaria × ananassa Duch.) variety, with shortened stems of 14-16 mm, uniform growth, and free from pests and diseases (microscopic examination confirmed a flower bud differentiation rate of over 80%), were transplanted into round flowerpots with a diameter of 14.5 cm and a height of 14 cm. Before transplanting, 10 bare-root strawberry seedlings were randomly selected, and their flower bud differentiation was observed under a microscope (JSZ6S SE2200, Jiangnan Instruments). Roots were secured using coconut coir (a product of Qingdao Ranmei Trading Co., Ltd.). The light period was 16 hours, the dark period was 8 hours, and the light intensity at the shortened stem of the strawberry plant was 300 μmol / m². -2 s -1 Daytime (light period): Nighttime (dark period) temperature maintained at 25℃:20℃. CO2 concentration 500ppm, relative humidity 70%. Yamazaki nutrient solution (EC: 0.8dS m) was used. -1 (pH: 5.2-5.5) Top irrigation method is used to irrigate plants with water and fertilizer once a day.

[0041] Light processing

[0042] The treatment lasted 28 days, from October 18, 2022 to November 14, 2022. The strawberry plants were treated with light immediately after transplanting. Five different light treatments were used, employing LEDs (JIUPO-5054FLED, a product of Jiupu Biotechnology Co., Ltd., Fujian).

[0043] RBB: Red-blue light (R:B = 7:3) + Blue light (B), R / B = 0.4. That is, when irradiated with red-blue LED lights (red light:blue light = 7:3) and blue LED lights, the instrument measures that the total red-blue light ratio (R / B) of this treatment is 0.4.

[0044] RBG: Red-blue light (R:B = 7:3) + green light (G), R / B = 0.8. That is, when irradiated with red-blue LED lights (red light:blue light = 7:3) and green LED lights, the instrument measures that the total red-blue light ratio (R / B) of this treatment is 0.8.

[0045] RBR: Red-blue light (R:B = 7:3) + red light (R), R / B = 2.3. That is, when irradiated with both red-blue LED lights (red light:blue light = 7:3) and red LED lights, the instrument measures that the total red-blue light ratio (R / B) of this treatment is 2.3.

[0046] RBFR: Red-blue light (R:B = 7:3) + far-red light (FR), R / B = 1.1. That is, when irradiated with red-blue LED lights (red light:blue light = 7:3) and far-red LED lights, the instrument measures that the total red-blue light ratio (R / B) of this treatment is 1.1.

[0047] W: White light (W), R / B = 2.1. That is, when illuminated by a white LED light, the instrument measures the total red-to-blue light ratio (R / B) of the treatment to be 2.1.

[0048] Sixteen strawberry plants were treated with each light treatment.

[0049] The spectral components of the five different light treatments were measured at the strawberry stunted stem using a spectrometer (PLA-20, Yuanfang Optoelectronic Information Co., Ltd., Hangzhou). The results are as follows: Figure 1 As shown in Table 1.

[0050] Table 1. Spectral data of LED lights at wavelengths of 400-800 nm

[0051] RBB RBG RBR RBFR W % Blue light (400-499nm) 73.5 31.5 30.4 29.9 25.4 % Green light (500-599nm) 0.3 41.8 0.3 0.1 19.5 % Red light (600-699nm) 26.2 26.7 69.0 32.2 53.3 % Far-red light (700-800nm) 0 0 0.3 37.8 1.8 R / B 0.4 0.8 2.3 1.1 2.1

[0052] Note: In Table 1, '%' represents the percentage of blue, green, red, and far-red photon flux density to the total photon flux density, and the maximum photon flux density is converted to 100%. The R / B ratio represents the ratio of red to blue photon flux density.

[0053] Record the budding status of strawberries daily.

[0054] The results are as follows Figure 2 As shown, plants treated with RBG and RBFR showed buds earliest. Plants treated with RBG and RBFR showed buds three days earlier than plants treated with RBB and W, and four days earlier than plants treated with RBR. The three treatments with the highest number of buds in the population were those treated with RBB, RBR, and RBG. The budding rates (budding rate = number of budding plants / total number of plants in each treatment) were 87.5%, 75%, and 68.75%, respectively. Plants treated with W and RBFR had the lowest budding rates, both at 62.5%.

[0055] Compared to the other three treatments, plants treated with RBB and RBG produced more flower buds. Plants treated with RBB and RBG produced 1–1.5 times more flower buds than plants treated with RBR and W, and twice as many as plants treated with FBFR. Furthermore, plants treated with RBFR produced the fewest flower buds, averaging no more than two per plant (see [link to treatment]). Figure 3 ).

[0056] Collect stamens and pollen from the first blooming strawberry flower in the top greenhouse.

[0057] Microscopic observation revealed no significant difference in the number of anthers in strawberry flowers among the five treatments. (See results below.) Figure 4 (a)

[0058] Pollen was prepared according to the method described in the reference "Wang Zhuangwei, Zhao Mizhen, Qian Yaming, Wu Weimin, Yuan Ji, WANG Zhuangwei, et al. Determination of strawberry pollen viability. 2010; 41(3):48-52." After collecting the pollen, pollen grains were spotted onto a glass slide using a pollination stick. A 2% TTC (2,3,5-triphenyltetrazolium chloride) staining solution was then dropped onto the slide. The slide was then placed in a constant temperature incubator (DHP-9052, Yiheng Instrument Co., Ltd., Shanghai) and incubated at 35℃ for 20 minutes. The stained pollen was observed under a microscope (XSJ-2 Chongqing Optoelectronics Co., Ltd., Chongqing) to evaluate the staining. The microscope magnification was 10x.

[0059] See results Figure 4 In contrast, the pollen viability of strawberries treated with RBR was significantly higher than that of the other four treatments (b).

[0060] According to the "Notice on Approving Provincial Power Grid Transmission and Distribution Prices for 2020-2022" (NDRC Price

[2020] No. 1508), the electricity price list for non-residential users in Beijing's urban area shows that for agricultural production, the peak electricity consumption is less than 35 kV, with a price of 0.9292 yuan / kWh. The hourly electricity consumption (kWh) and daily electricity cost (yuan) for the five treatment methods are shown below. Figure 5 .

[0061] according to Figure 3 and Figure 5 While RBB and RBG treatments consume more electricity, they result in a higher number of budding plants and flower buds. RBR treatment consumes significantly less electricity than RBG treatment, but produces fewer flower buds. In actual production, the relationship between electricity costs and economic benefits should be considered. Using 31%-74% blue light, 0%-42% green light, and 26%-27% red light is more suitable for promoting strawberry flowering.

[0062] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.

Claims

1. A method for promoting strawberry flowering, characterized in that, The method includes the step of cultivating strawberries using an LED light source; the LED light source is A1 or A2. A1 is an LED light source in which the percentage of blue photon flux density to total photon flux density is 73.5%, green photon flux density to total photon flux density is 0.3%, and red photon flux density to total photon flux density is 26.2%. The LED light source mentioned in A1 is a combination of red-blue LED lamps and blue LED lamps with a red light:blue light ratio of 7:3, and the instrument measures the total red-blue light ratio to be 0.

4. A2 is an LED light source with a blue photon flux density accounting for 31.5% of the total photon flux density, a green photon flux density accounting for 41.8% of the total photon flux density, and a red photon flux density accounting for 26.7% of the total photon flux density; the LED light source mentioned in A2 is a combination of red-blue LEDs (red light: blue light ratio of 7:3) and green LEDs, with the total red-blue light ratio measured by the instrument being 0.8; The strawberry cultivation period is defined as follows: daily light period of 16 hours and dark period of 8 hours; light intensity at the shortened stem location is 300 μmol / m². -2 s -1 The temperature during the light period is 25°C, and the temperature during the dark period is 20°C; the percentage of photon flux density to total photon flux density is the measured value at the strawberry stunted stem.

2. A method for improving strawberry pollen viability, characterized in that, The method includes the step of growing strawberries using an LED light source; The LED light source has a blue light photon flux density of 30.4% of the total photon flux density, a green light photon flux density of 0.3% of the total photon flux density, a red light photon flux density of 69.0% of the total photon flux density, and a far-infrared light photon flux density of 0.3% of the total photon flux density.

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