JP2002153151A - Method for raising paddy rice seedling by hydroponics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for raising paddy rice seedlings by hydroponics, by which mat-like paddy rice seedlings having grass heights suitable for transplantation, suitably shortened root lengths and a grass figure especially suitable for a mechanical transplantation using a rice transplanter can be obtained. SOLUTION: This method for raising the paddy rice seedlings, comprising laying a nonwoven fabric containing sowed paddy rice seeds in a raising seedling bed and flowing a culture liquid to raise the mat-like seedlings for hydroponics, characterized by dividing the raising seedling period into a raising seedling early period, a raising seedling middle period and a raising seedling end period, using the below-described culture solution (1) or water not containing a fertilizer ingredient in the raising seedling early time, using the below-described culture solution (1) in the raising seedling middle period, and using the below-described culture solution (2) in the raising seedling end period. The culture solution (1) is a culture solution which contains ammonia nitrogen and nitrate nitrogen in equivalent amounts (wt.%) or in amounts wherein the amount (wt.%) of the nitrate nitrogen is larger than that of the ammonia nitrogen, as the nitrogen ingredients in the culture solution. The culture solution (2) is a culture liquid containing only the ammonia nitrogen as the nitrogen ingredient in the culture solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of raising matted rice seedlings by a hydroponic method in which a culture solution is passed through a nonwoven cloth laid on a nursery bed, and more particularly, to a method of raising rice seedlings by hydroponics. The present invention relates to a hydroponic seedling method for obtaining a rice plant in the form of a grass that is easy to transplant when a mat-shaped rice seedling is transplanted to a field using a rice transplanter.

[0002]

2. Description of the Related Art In recent years, as a technique aimed at labor-saving rice cultivation, a method of raising rice seedlings by a long mat hydroponic method using a long nonwoven fabric has been developed. By using long mat hydroponic seedlings, the labor for raising and transplanting seedlings can be reduced by reducing the weight of the seedlings, and the efficiency of transplanting operations using a rice transplanter can be improved.

[0003] In the long mat hydroponic method, several long nonwoven fabrics (for example, 6 m long and 28 cm wide) are laid side by side on a nursery bed, and a culture solution in which fertilizer components are dissolved is supplied from one end of the nursery bed and is fed from the other end. Discharge and circulate by pump.
In this state, germinated seeds (germinated rice seeds) are sown on a non-woven fabric, and grown for 12 to 16 days until they reach a predetermined height while controlling the water temperature, pH, and EC (electric conductivity) of the culture solution. A long mat hydroponic seedling in which the roots extending through the front side and the back side of the nonwoven fabric and extending to the backside are entangled to form a mat is obtained.

[0004] Next, the long mat hydroponic seedling is rolled up from one end into a roll, and is set on a seedling table of a rice transplanter. Then, the roll is unwound and transplanted into a field. By using a roll seedling obtained by winding such a long mat hydroponic seedling in a roll shape, the number of times of supplying seedlings to a rice transplanter and the number of handling of seedlings are reduced to one tenth as compared with conventional soil-cultivated seedlings. It becomes possible.

[0005]

When the above-mentioned long mat hydroponic seedlings are transplanted into a field using a rice transplanter, when the seedlings of the long mat are scraped together with the nonwoven fabric by the planting claws, the tangling occurs. In many cases, the combined roots are cut or damaged. Such cut seedlings or damaged seedlings are apparently planted in a field, but do not survive and become absent. Therefore, it is desirable that the roots are made as short as possible so that the roots do not become excessively entangled. On the other hand, if the root length is too short, it will become a floating seedling and fall when planted in a field. Therefore, it is possible to secure a plant height suitable for transplantation and to have a grass shape with a root length kept appropriately short, and it is difficult for roots to be cut off when seedlings are scraped off with planting nails of rice transplanters and do not become floating seedlings Such rice seedlings are desired.

Accordingly, the present invention provides a novel and matt paddy rice seedling having a plant shape that is particularly suitable for mechanical transplantation using a rice transplanter and that can secure a suitable plant height for transplantation and keep the root length appropriately short. An object of the present invention is to provide a method for raising rice seedlings by an improved hydroponic method.

[0007]

Means for Solving the Problems The present inventors have studied the effects of differences in the nitrogen composition in the culture solution and the application time of the culture solution on the growth of seedlings in order to achieve the above-mentioned object. In the early stage of raising seedlings, apply only water or a culture solution in which the proportion of ammonium nitrogen and nitrate nitrogen is equal to% by weight or the weight% of nitrate nitrogen is increased. It has been found that by applying the present invention, it is possible to obtain a mat-like paddy rice seedling in the form of a grass, which secures a suitable plant height for transplantation and has a suitably short root length.

That is, in the present invention, when raising a mat-shaped hydroponic seedling by laying a nonwoven fabric seeded with paddy rice seeds on a nursery bed and flowing a culture solution, the seedling raising period is divided into early seedling raising, middle seedling raising and late seedling raising. Initially, the following culture solution (1)
Alternatively, a method of raising rice seedling by hydroponics, comprising using water in which no fertilizer component is dissolved, using the following culture solution (1) as a culture solution in the middle stage of raising seedling, and using the following culture solution (2) in the last stage of raising seedling. Culture solution (1) = Culture solution in which the proportion of ammonium nitrogen and nitrate nitrogen as the nitrogen component in the culture solution is equal to% by weight or weight% of nitrate nitrogen is increased, culture solution (2) = Culture solution A culture solution using only ammonia nitrogen as the nitrogen component in the culture.

According to the above-described method for raising seedlings of the present invention, even if the mat-shaped paddy rice seedlings that have undergone a predetermined seedling raising period after the initial seedling raising stage, the middle seedling raising stage, and the last stage of seedling raising have grown to a plant height suitable for transplantation, the root length is maintained. The grass can be kept moderately short, and the elongated roots are less likely to be excessively entangled. As a result, when transplanting mat-shaped seedlings to a field using a rice transplanter, the roots are less likely to be cut off when the seedlings are scraped off with the planting nails of the rice transplanter, and it is possible to reduce the stock-out rate after transplantation. it can. In addition, it was also confirmed that the growth after transplanting was not different from that of soil-cultured seedlings even in the seedlings in the form of grass with a shorter root length.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an example of a hydroponic seedling raising apparatus using a seedling bed laid with a nonwoven fabric. Rice seeds are sown and seed-raised on a non-woven fabric 2 laid in a nursery bed 1, and a culture solution 3 in which fertilizer components are dissolved is sent from a culture solution tank 4 to one end of a nursery bed by a pump 5 to absorb water. Tube 6
And flows through the nonwoven fabric 2 to the other end of the nursery bed 1, and is circulated by dropping again into the tank 4 via the water distribution pipe 7. When the culture solution decreases due to evaporation or the like in the circulation process, tap water or the culture solution is appropriately replenished, and the pH and EC of the culture solution are appropriately adjusted.

The nonwoven fabric 2 is, for example, 6 m long and 28 cm wide.
Are laid in a nursery bed 1 in parallel with each other, and while the culture solution 3 is circulated, sowing and seedling of paddy rice seeds are performed on the nonwoven fabric 2. The seedling raising period is generally 1 until the seedlings are mat-shaped seedlings suitable for transplanting to the field.
After raising the seedlings for 2 to 16 days, the seedlings 8 on the surface side of the nonwoven fabric 2 are pushed down using a special roller, and then the seedlings 8 are turned inside around the winding core 9 (see FIG. 2). Then, a long mat hydroponic seedling grown on the long nonwoven fabric 2 is wound around the roll to give a roll seedling 10 as shown in FIG. 2, that is, a long mat hydroponic seedling wound in a roll shape.

The roll seedlings 10 thus obtained are set on a rice transplanter, and while the roll seedlings are being rewound, several of them are scraped off together with the nonwoven fabric with a planting claw, and are transplanted to a field as one strain. According to the rice seedling obtained by the present invention,
The root length of the root that penetrates the front side and the non-woven side of the non-woven fabric and extends to the back side is appropriately kept short, so that the roots are not excessively entangled and the roots are hard to be cut when scraping with the planting nail To perform the scraping.

The composition of the culture solution used in the present invention is nitrogen
Ammonia nitrogen (NH _Four-N) and nitrite
Elementary (NO_Three-N) is changed according to the application time.
Except for other large elements (P, K, Ca, Mg),
Trace elements (Mn, B, Fe, Cu, Zn, Mo, etc.)
Conventionally, water by hydroponics using a nonwoven fabric mat
It is possible to adopt a formula commonly used for raising rice seedlings.
it can.

As the water that does not dissolve the fertilizer components used in the early stage of raising seedlings, tap water, well water, or other service water can be used as it is. Some of these waters also contain a small amount of a substance that becomes a fertilizer component, but such water does not prevent application of the water in the early stage of raising seedlings. In the present invention, the term “water without dissolving fertilizer components” means water without artificially dissolving fertilizer components.

When the seedling raising period is divided into three, it is not necessary to strictly divide it into three. For example, if the whole period of the seedling raising period is 15
In the case of days, it is not necessary to strictly divide the days into 5 days, and each period can be appropriately increased or decreased according to the growth of the seedling. As a general guide, the initial stage of seedling raising is from sowing (or the start of seedling raising) to the beginning of the second leaf extraction, the middle stage of seedling raising from the beginning of the second leaf extraction to the beginning of the third leaf extension, and the third leaf extension starting period. The seedling raising is completed with the period from about to the 3.5th leaf stage as the seedling raising end.

In the present invention, the combination of the change in the composition of the nitrogen component in the culture solution and the application time of the culture solution includes two types of seedling raising and seedling raising as shown in Table 1 below.

[Table 1] Nursery seedling initial stage seedling middle stage seedling end stage seedling raising form Culture solution (1) Culture solution (1) Culture solution (2) Seedling growth water Culture solution (1) Culture solution (2) As culture solution (1) in Table 1 Is a culture solution in which the proportions of ammonia nitrogen and nitrate nitrogen are equal weight% or nitrate nitrogen is increased as the nitrogen component, preferably, the proportion of ammonia nitrogen and nitrate nitrogen is 50 to 15 wt%: 50 ~
A culture solution containing 85% by weight is used. As the culture solution (2), a culture solution using only ammonia nitrogen as a nitrogen component is used.

In general, rice seedlings obtained in a seedling raising form have longer plant height and root length than rice seedlings obtained in a seedling raising form. However, even if the rice seedlings are in any of the nursery forms, even if they grow to a plant height suitable for transplantation, they become grass-type rice seedlings whose root length is kept short enough that the roots are not excessively entangled.

[0018]

EXAMPLES [Experiment 1] A nursery bed (100 cm in total length and 120 cm in total width) of a hydroponic nursery apparatus as shown in FIG.
Spread four rows of nonwoven fabric with a width of 28 cm and germinate Koshihikari seeds (662 g dry paddy, equivalent to 100 g per conventional seedling raising box)
Was inoculated, fed and circulated from a culture solution tank (capacity: 30 L).

The culture solution is based on the composition of the following Kimura B solution and has a concentration three times the reference concentration (N concentration 69 ppm, pH 5.
Prepared in 5). The culture solution (1) contains 28% by weight of ammonia nitrogen and nitrate nitrogen as nitrogen components at a ratio of 28% by weight.
2% by weight, and the culture solution (2) used only ammonia nitrogen as the nitrogen component.

Composition of Liquid B (per liter of water) N 23.0 mg P ₂ O ₅ 13.0 mg K ₂ O 17.2 mg CaO 20.5 mg MgO 22.1 mg Fe ₂ O ₃ 2-5 mg (iron citrate) As)

The seedling raising period is 15 days, the 0th to 4th day is the initial stage of seedling raising, the 5th to 9th day is the middle stage of seedling raising, and the 10th to 15th day is the final stage of seedling raising. Provided.
The volume of the culture broth was replenished daily with tap water or each culture broth, and all of the culture broth was replaced on the fifth and tenth days. The pH was adjusted to 5.5 daily. After raising the seedlings in 15 days, a sampling survey was conducted.

For comparison, seedlings were box-raised using granular soil (seeding amount: dry paddy 100 g, fertilizing amount: N 1 g, P
₂ O ₅ 2 g, K ₂ O 1 g). In addition, the total nitrogen application rate per individual during the seedling raising period was set to the same amount for the hydroponic seedlings and the box seedlings.

The results are shown in Table 3. The value in Table 3 is 1
This is the average value of two individuals. FIG. 3 shows a typical grass form of a seedling obtained in each test plot.

[0024]

[Table 2] nursery initial seedling raising medium-term nursery final test group 0-4 days 5-9 days 10-15 days A-ku culture (1) culture (1) culture (1) B-ku, tap water culture (1) Culture solution (1) Section C Culture solution (1) Culture solution (1) Culture solution (2) Section D Tap water Culture solution (1) Culture solution (2) Seeding date: September 9, 1998

[0025]

[Table 3]

[Experiment 2] Seeding on April 28, 2000, and raising the seedlings in the same manner as in Sections B, D, and Soil Cultivation in Experiment 1, the same characteristics as those obtained in each test in Experiment 1 Was obtained. These seedlings were hand-planted on a container (capacity: 40 L) filled with soil on May 12, and a sampling survey was performed 10 days and 20 days later to examine growth characteristics after transplantation. Table 4 shows the results.

The abbreviations of the growth traits in Table 4 are as follows. [RGR: relative growth rate] It is a dry matter production efficiency per dry matter weight at a certain point in time, and is represented by the following formula. RGR = (1 / w) × (dw / dt) where: w: dry matter weight at a certain time dw / dt: dry matter increase rate at that time Here, if RGR is set to R and integrated as a constant, The dry weight at the time can be determined. This is considered as follows. w = w ₀ e In the ^RT equation, w ₀ : initial dry weight e: base of natural logarithm That is, R (RGR) = (ln w ₂ −ln w ₁ ) / (t ₂ −t ₁ ) = (2.30 × ( log w ₂ −log w ₁ )) / (t ₂ −t ₁ ) where w ₁ and w _{2 are} the first and second dry weights of the plant t ₁ and t _{2 are} the first and the second. Second survey date.

[NAR: net assimilation rate] This is the rate of increase in dry matter per leaf area, and is expressed by the following equation. NAR = (1 / L) × (dw / dt) where L: leaf area at a certain point in time dw / dt: dry matter increase rate at that point, ie, NAR = ((2.30 × (w ₂ −w ₁ )) × ( log A ₂ −log A ₁ )) /
((T ₂ −t ₁ ) × (A ₂ −A ₁ )) where A ₁ , A ₂ : _first and _second leaf areas t ₁ , t ₂ : _first and _second surveys Day.

[LAR: leaf area ratio] The ratio of the leaf area to the dry weight of the plant (L / w). Relative growth rate (RGR) is the net assimilation rate (N
AR) and leaf area ratio (LAR). RGR = NAR × LAR

[SLA: specific leaf area] The ratio of leaf area to leaf dry weight (L / Lw).

[LWR: leaf weight ratio] The ratio of leaf dry weight to dry weight of plant (Lw / w). Leaf area ratio (LAR) is the specific leaf area
(SLA) and leaf weight ratio (LWR). LAR = SLA × LWR Therefore, the following equation is derived. RGR = NAR x SLA x LWR

[RLGR: Relative leaf growth rate]
Is the leaf area expansion rate per leaf area in the following formula.
Be done. RLGR = (1 / L) × (dL / dt) where L: leaf area at a certain time dL / dt: leaf area expansion rate at that time, ie, R (RGR) = (ln A_Two−ln A₁) / (T_Two−t₁) = (2.30 × (log
A_Two−log A₁)) / (T _Two−t₁) Where A₁, A_Two: 1st, 2nd leaf area t₁, T_Two: First and second survey dates.

[0033]

[Table 4]

As can be seen from Table 3, section C had the same plant height as section A and section B, but the longest root length was significantly shorter than both sections. Also D
The ward was about the same height as the soil cultivation area, but A ward and B
The longest root length was the shortest as compared with the section and the section C. From these results, it can be seen that in the C and D sections, the root length is kept short and the root entanglement is reduced, even though the plant height is elongated to a length suitable for transplantation.

As can be seen from Table 4, B in Experiment 1
The seedlings having different grass shapes were transplanted to the soil in the same manner as those obtained in the ward, the D ward, and the soil cultivation ward. As a result, no remarkable difference was observed in each growth trait after 10 days from the transplantation.

[0036]

As can be seen from the above description, according to the method for raising seedlings of the present invention, even when the rice seedlings have grown to a height suitable for transplantation during a predetermined raising period, the root length of the seedlings can be kept appropriately short. It can be shaped and the elongated roots are not overly entangled. As a result, when transplanting seedlings grown in a mat shape to a field using a rice transplanter, the roots are less likely to be cut off when the seedlings are scraped off by the planting nails of the rice transplanter, reducing the stock-out rate after transplantation Can be done.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an example of a hydroponic seedling raising device used in the present invention.

FIG. 2 is an explanatory view of a roll seedling in a state in which a long mat hydroponic seedling that has been raised by the apparatus of FIG. 1 is wound into a roll.

FIG. 3 is an explanatory diagram showing a representative grass shape of a seedling obtained in each test section in Experiment 1 of an example.

[Explanation of symbols]

 1: Nursery bed 2: Non-woven fabric 3: Culture solution 10: Roll seedling

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2B314 MA02 MA07 MA14 NB05 NB06 NB13 NC07 ND07 ND15 PA15 PA16 PB13 PB17 PB44 PB64 PC08 PC24

Claims (1)

[Claims] Claims: 1. When raising a mat-shaped hydroponic seedling by laying a nonwoven fabric seeded with rice seeds on a nursery bed and flowing a culture solution, the seedling raising period is divided into an initial stage of seedling, a middle stage of seedling, and an end stage of seedling. The following culture solution (1) or water in which the fertilizer components are not dissolved is used.
And a method for raising rice seedlings by hydroponics, wherein each of the following culture solutions (2) is used as a culture solution at the end of raising seedlings:
Culture solution (1) = a culture solution in which the proportion of ammonia nitrogen and nitrate nitrogen as the nitrogen component in the culture solution is equal to or equal to% by weight or the weight% of nitrate nitrogen is increased, and culture solution (2) = nitrogen in the culture solution A culture solution using only ammonia nitrogen as a component.