JP5164070B2 - How to control seedling growth - Google Patents

Description

  The present invention relates to a method for controlling the elongation of seedlings, which can prevent the growth of hypocotyls and can grow seedlings that are strong and are difficult to fall after transplanting.

In general, hypocotyl elongation of young plants is promoted by red light (Japanese Patent Laid-Open No. 2001-37334), and it is known that plant hormones are also involved.
JP 2001-37334 A

The transplanted seedling is required to have a short hypocotyl and a reduced length. This is because if the hypocotyl is high, it tends to collapse after transplantation.
Conventionally, in order to obtain such seedlings, mainly the soil and fertilizers have been devised to suppress the nutrients and prevent the length of the seedlings, and general techniques have been developed. I can't say that.
Patent Document 1 relates to a method for cultivating soybean sprouts, which adjusts the light to be irradiated, but is intended to extend the hypocotyl, and the hypocotyl of the seedling for transplantation It is not intended to suppress the elongation of

  The present invention has been completed in the light of the above circumstances, and has been completed. A method for controlling the elongation of a seedling that can be suitably used as a seedling for transplantation by suppressing the elongation of the hypocotyl by adjusting the irradiation light. The purpose is to provide.

Control method for elongation of seedlings in the present invention for achieving the above object, after germination, red light, or than the blue light and green light by irradiating light containing a large amount of red light, to promote the elongation of hypocotyls, Thereafter, contains more green light than blue light and red light, at least one of blue light and red light so as to irradiate light including the required amount for the photosynthesis by suppressing the elongation of hypocotyls and uniform height It is characterized by extending the seedling.

It is also characterized by controlling the growth of buckwheat and lettuce seedlings.

  According to the present invention, it is possible to provide a seedling for transplantation that suppresses hypocotyl elongation and has a uniform height and excellent lodging resistance.

Hereinafter, preferred embodiments of the present invention will be described in detail.
Although it demonstrates with a specific Example below, it is not limited to this Example.
≪Plant species and growth conditions≫
Two kinds of plant buckwheat (Shinano No. 1, Kitagawa Seoba) and two kinds of tart soba (Kinoyutaka and Kinotakara) were used. It seed | inoculated to the pot of 4.5 * 4.5 * 5.0 (height) cm filled with the commercially available seedling soil. Twenty-five pots were arranged in a 5 × 5 array, and data was collected in the inner 3 × 3 9 pots. The seedlings were grown in a 50 × 60 × 50 (height) cm growth box coated with an aluminum film. On the 6th day after sowing where the cotyledons were fully extended, one plant per pot was thinned out and irradiated with light at a temperature of 22 ° C. for 24 hours / day continuously. Tap water was supplied every day without fertilization.

≪Light processing and measurement≫
In the present embodiment, the effect of light mixed with various wavelengths on the elongation of the hypocotyl during seedling raising was investigated.
That is, in this embodiment, twelve types of lamps (fluorescent lamps) that include light in the entire wavelength range from 400 to 700 nm from blue to red and have different light intensities by 50 nm range were created.

Table 1 shows the configuration of 12 types of fluorescent lamps.
The spectrum was recorded at the top of the seedlings using a spectroradiometer (HSU-100S, manufactured by Asahi Spectroscopy, Japan) immediately after the light treatment. In the fluorescent lamps 1 to 12 (L1 to L12), the photon flux density is adjusted within a wavelength range of 400 to 500 nm (blue), a wavelength of 500 to 600 nm (green), and a wavelength of 600 to 700 nm (red). However, L1 is white light, L2 is daylight, L7 is monochromatic blue light, and L12 is monochromatic red light.

In order to minimize the influence of light intensity, the state of the low photosynthetic photon flux density was maintained at 10 μmol m ⁻² s ⁻¹ . In each treatment section, five fluorescent lamps were suspended 40 cm above the upper end of the pot in the growth box. The fluorescent lamp system (CCFL light source device) used was provided by Harrison Toshiba Lighting, Japan.

≪Inspection of hypocotyl length and dry weight≫
The hypocotyl length was measured with a laser rangefinder (Leica DISTO (trademark), manufactured by Leica Geosystems AG, Switzerland) every other day after treatment (1st day, 3rd day, 5th day, 7th day). . The hypocotyl was defined as the distance from the soil surface to the node under the cotyledon. The daily hypocotyl elongation rate was determined by applying a logarithmic function (discussed below) for the daily hypocotyl length change. Sampling was performed with the dry weight of the hypocotyl from which the cotyledons on day 7 were removed. All samples were dried at 60 ° C. for 48 hours in a drying oven.

≪Biological model of hypocotyl growth≫
In each treatment section, the daily hypocotyl elongation rate could be expressed as the following log model.

y = a + bIn (x)

In the above formula, y is the hypocotyl length, x is the number of days elapsed after the treatment, and a is the hypocotyl length (internal value) immediately after appearing from the soil surface. Based on this equation, the daily hypocotyl elongation rate (mm In (day) ⁻¹ ) can be expressed by the slope (b) of the natural logarithmic function.

≪Statistical analysis≫
Statistical analysis of all data was performed using Excel (USA, Microsoft) and Excel Statistics (Esmi, Japan) programs. An average value including standard deviation can be obtained. Correlation analysis was also performed to determine the detailed relationship between light quality and daily hypocotyl elongation rate.

≪Judgment of the daily hypocotyl elongation rate≫
1 to 4 show embryos of ordinary buckwheat (Fig. 1: Shinano No. 1, Fig. 2: Kitagawa Seoba) and Dattan soba (Fig. 3: Kino Yutaka, Fig. 4: Kinotakara) in the treatment of the light source L1 with respect to the number of days elapsed after the treatment. A plot of axial elongation. Significant logarithmic functions could be used to fit daily hypocotyl length changes. In all the processes, the coefficient of determination of the natural logarithmic function was larger than 0.9 as shown in FIGS. The slope (b) of the function is an index of the daily hypocotyl elongation rate.

≪Characteristics of hypocotyl with different light quality≫
Table 2 (ordinary buckwheat) and Table 3 (tart buckwheat) show the hypocotyl length after 7 days, the daily elongation rate, and the dry weight. Since elongation of the hypocotyl peaked out after 7 days, hypocotyl elongation data except after 7 days are not shown. There were significant differences in hypocotyl length, daily elongation rate, and dry weight between varieties and light qualities in both regular buckwheat and tart soba. The variety-light quality interaction was significant for the daily growth rate, but not for the hypocotyl length of both normal and tartary buckwheat. It was significant for the dry weight of hypocotyl of tartary buckwheat, but not for normal buckwheat. The difference between “Shinano 1” and “Kinoyutaka” varieties and hypocotyl parameters was considerably larger than “Kitawase Soba” and “Kinoyutaka”.

≪Relationship between light quality and daily hypocotyl elongation rate≫
To analyze the effect of different light qualities on the hypocotyl elongation rate per day, a correlation analysis was performed. The ratio (%) of the photon flux density in a specific wavelength region (width 50 nm) to the photon flux density in PPFD (400 to 700 nm) was calculated. FIG. 5 shows the correlation coefficient (ordinate axis) of the daily hypocotyl elongation rate of each pot and the rate of photon flux density (abscissa axis) in different wavelength regions of each pot. In “Shinano 1”, a remarkable positive correlation was observed in the region of 600 to 700 nm (red light). In the other three varieties, the same tendency was observed with red light, but not so significant correlation was observed. Thus, in the red light region, elongation of the hypocotyl is promoted.

On the other hand, in “Shinano 1”, a significant negative correlation was observed in the region of 500 to 600 nm (green light). In the other three varieties, a low negative correlation was observed in the region of 500 to 600 nm (green light). Thus, in “Shinano No. 1”, elongation of the hypocotyl is strongly suppressed in the region of 500 to 600 nm (green light), and elongation of the hypocotyl is suppressed in the other three varieties.
In all varieties, a low negative correlation was observed in the region of 400 to 500 nm (blue light).
Thus, the light quality has a great influence on the hypocotyl elongation of normal buckwheat and tart soba (Tables 2 and 3). In addition, regarding the hypocotyl elongation rate per day, a large difference between cultivars and a correlation between cultivar and light quality were observed.

≪Hypocotyl elongation rate per day and red band spectrum≫
As described above, a remarkable positive correlation of “Shinano 1” was observed in the region of 600 to 700 nm (red light) (see FIG. 5). In the other three varieties, the same tendency was observed with red light, but not so significant correlation was observed. However, a low negative correlation was observed in the 400-500 nm (blue light) region for all varieties. These results suggest that red light and blue light not only tend to suppress hypocotyl elongation of buckwheat seedlings, but also promote growth. In addition, the vertical axis | shaft of FIG. 5 is a correlation coefficient with the ratio of the photon flux density of the specific wavelength (width 50nm) with respect to PPFD (400-700nm), and a hypocotyl elongation rate. A correlation coefficient of 0.59 (absolute value) or more is significant at the 5% level.

≪Hypocotyl elongation rate per day and green band spectrum≫
As described above, in “Shinano No. 1”, a significant negative correlation was observed in the region of 500 to 600 nm (green light) (see FIG. 5). This green light suppressed hypocotyl elongation. Suggests to do. In addition, the other three varieties are not remarkable, but hypocotyl elongation tends to be suppressed.
Thus, in the buckwheat seedling, green light shows the inhibitory effect of hypocotyl elongation.

  In a natural light environment, plants respond to the shade by surrounding plants by sensing changes in light quality, and the hypocotyls grow in response to light (1999 Ballare). Under the community, blue light and red light decrease, but green light and far infrared light increase slightly (1982 Smith). Therefore, it is inferred that the decrease in the elongation rate under the green light condition is to adapt to the growth characteristics in the competitive relationship of plants on the ground. On the other hand, the increase in elongation rate under red light conditions is an effective characteristic under conditions of strong competitive relationship and shade. 2006 Mullen et al. Analyzed the adjustment of leaf blade inclination by green light, suggesting the presence of an unidentified green photoreceptor. The results in this embodiment also suggest the presence of green photoreceptors related to the adaptability in the bright environment around the seedlings due to reflections from surrounding plants.

FIG. 6 is a graph showing the relationship between the wavelength of light to be irradiated and the hypocotyl elongation rate observed with a lettuce material (Melbourne). In the case of this embodiment, a total of 14 types of light treatment sections in which the wavelength spectra of blue, green, red, and ultraviolet rays in visible light were adjusted were provided, and hypocotyl elongation was measured in the same manner as the above buckwheat varieties. The vertical axis in FIG. 6 is a correlation coefficient between the ratio of the photon flux density of a specific wavelength (width 50 nm) to the entire wavelength range (250 to 1000 nm) and the hypocotyl elongation rate. A correlation coefficient of 0.68 (absolute value) or more is significant at the 1% level.
As shown in FIG. 6, even in lettuce, there is a tendency that hypocotyl elongation is promoted in the red region and hypocotyl elongation is suppressed in the green region.

  As described above, both embodiments show that hypocotyl elongation is affected by different light qualities. In particular, “Shinano 1” (FIG. 2) is more sensitive to light quality than other varieties. "Shinano No. 1" and "Kitawase Soba" are the middle and summer type cultivated ecotypes, respectively. Therefore, the photosensitivity of hypocotyl elongation may be related to the normal buckwheat ecotype. These data provide valuable information for regulating buck hypocotyl elongation by controlling light quality.

  In order to suppress hypocotyl elongation and grow seedlings with low hypocotyl height and excellent lodging resistance, it is necessary to irradiate green light to suppress hypocotyl elongation. Note that photosynthesis is not performed only with green light. Therefore, after germination, light that contains abundant green light and a slight amount (necessary amount) of blue light and red light for photosynthesis is irradiated at a time when suppression is necessary. Moreover, in order to promote the elongation of the hypocotyl, irradiation with red light or light containing abundant red light is performed.

For raising seedlings, it is necessary to grow seedlings of uniform height that prevent hypocotyl growth by suppressing hypocotyl elongation. How much light of how much light is irradiated differs depending on the variety. It is necessary to obtain irradiation conditions in advance.
In the present invention, the above-described light irradiation for suppression is essential. In other words, it is because only red light increases.
Immediately after germination, irradiate red light or light containing a lot of red light to promote growth to some extent, and then irradiate suppression light mainly composed of the green light so that it grows to seedlings with uniform height It is preferable to do this.
Or you may make it irradiate light of these both process areas alternately.
In addition, although various buckwheat and lettuce were described above, this invention is applicable also to a Chinese cabbage and other vegetables.

Table 1

Table 2

Table 3

It is the graph which plotted hypocotyl elongation of Shinano 1 in the process of the light source L1 with respect to the elapsed days after a process. It is the graph which plotted the hypocotyl elongation of Kitagawa sesoba in the process of the light source L1 with respect to the elapsed days after a process. It is the graph which plotted the hypocotyl elongation of the mushroom in the process of the light source L1 with respect to the elapsed days after a process. It is the graph which plotted the hypocotyl elongation of Kinotakara in the process of the light source L1 with respect to the elapsed days after a process. It is the graph which showed the relationship between the wavelength of the light to irradiate and the hypocotyl elongation rate observed using the buckwheat material. It is the graph which showed the relationship between the wavelength of the light to irradiate using the lettuce material (Melbourne), and the hypocotyl elongation rate of lettuce.

Claims (3)

After germination, by applying light red light, or than the blue light and green light containing a large amount of red light, to promote the elongation of hypocotyls, then a greater number of green light than blue light and red light, blue light A method for controlling the growth of seedlings, comprising suppressing the elongation of hypocotyls by irradiating light containing a necessary amount of at least one of red light and red light for photosynthesis, and extending the seedlings to a uniform height.   The method for controlling the growth of seedlings according to claim 1, wherein the growth of buckwheat seedlings is controlled.   2. The method for controlling the growth of seedlings according to claim 1, wherein the growth of the seedlings of lettuce is controlled.