JP3813958B2 - Tuber production method - Google Patents

Description

  The present invention relates to a method for growing potato by plant growth and tuber formation using plant tissue culture technology.

  Currently, potato production in the world is carried out mainly using the vegetative reproduction of potato. That is, it is a method of planting tubers that are vegetative propagation organs, so-called pods, and using the tubers formed at the base of the stalks of plant bodies growing from here as next-generation seed pods or for food and processing. In this case, usually about 1 to 10 tubers are reproduced.

  When such vegetative propagation is used for propagation and production, various viral diseases are not limited to potato, and various viral diseases are a major problem. In vegetative reproduction crops, virus-free seeds or mother stocks are not supplied. It is extremely important to improve or maintain productivity.

  In the case of potato, the propagation of virus-free seed pods is carried out by repeating the cultivation and harvesting of individuals that have been made virus-free mainly by growth point culture, first in the greenhouse and then in the field. In this case, i. Low growth rate of potato, ii. Risk of re-infection with virus due to repeated cultivation in the field, iii. For this reason, there are many problems such as isolation from general fields, thorough control, and advanced quarantine systems, and a simpler and safer method is required.

  As an alternative method for supplying virus-free seed pods, the use of tubers (microtubers) prepared under aseptic conditions by tissue culture has been studied in various fields.

As a tuber production method by such tissue culture,
Tovar et al. 1985, CIP Circular 13 (4): 1-5
Rosell et al. 1987, Potato Research 30: 111-116
・ Hussey G. and NJ Stacey, 1984, Ann. Bot. 53: 565-578
・ Japanese Patent Application No. 63-500104 (International Publication Number W088 / 04136)
・ Akita, Takayama, Gakuen Abstract, Spring 63, P.228-229 etc. have been reported.

  These tissue culture methods have initially had problems such as inefficiency and high cost, and have hindered their practical application. However, in recent years, improvements in efficiency, scale-up, etc. have been investigated, It has been improved. However, since these methods contain a carbon source such as sucrose in the medium, there is a risk of contamination with bacteria. The danger of this scale-up is that this risk increases with the size of the container.

  There have been reports on the growth of potatoes under culture conditions that do not contain a carbon source for the purpose of reducing the cost and risk of contamination with bacteria (Kozo et al., Spring 63). However, these are limited only to the growth of the plant body, and there are no examples in which a number of strons are elongated and tubers are formed as in the present invention.

In addition, as an example of hydroponically growing potatoes,
・ KH Fong and A. Ulrich, 1969, American Potato Journal 13: 269-272
・ W. Newton, 1923, Journal of the American Society of Agronomy 15: 392-399
・ H. Griess, 1979, Agrartechnik 29: 225-226
・ I. Simko, 1991, Biologia 46: 89-92
Etc. However, H. Griess's paper relates to a facility for the production of potato tubers by hydroponics and there is no description of how and how many tubers were formed. KH Fong and A. Ulrich and W. Newton papers used hydroponics to test nutrient requirements, and I. Simko papers related to tuber formation by hydroponics. However, none of them describes mass production of tubers.

  The tuber production method of the present invention induces a large number of branched strons and further converts each stron into a tuber, but although the stron branching is observed under natural conditions, the extent is comparable to this method. It is low, and it is hardly observed that the number of tubers per plant body exceeds 20 including small ones.

  An object of the present invention is to provide an efficient and low-cost method for producing a new tuber taking into account the disadvantages of the culture method.

  The present inventor has intensively studied to achieve the above object. That is, a series of experiments were conducted to reduce costs and the risk of contamination with various bacteria, and a large number of strons were successfully derived from plants by hydroponics, but stron tuberification was not achieved. Thereafter, by further studying the day length and temperature, a method for obtaining a large number of tubers that could not be considered under natural conditions per plant was developed, and the present invention was achieved.

  That is, the tuber production method of the present invention is a tuber production method of a Solanum plant, wherein the plant body is subjected to a day length condition of 15 hours or less during the above-ground growth period, and the nighttime minimum temperature is less than 25 ° C. and daytime. Growing strons in a liquid or gas phase by cultivating them at a temperature difference of 3 ° C. or more with the temperature of the water, and forming tubers on the strons.

  According to the present invention, a large number of tubers can be produced very efficiently as compared with the conventional method.

Hereafter, the main matter regarding this invention is demonstrated in detail.
[Plant tissue]
Plants that are the subject of the present invention include all species of the genus Solanum that have the ability to form tubers. Specific examples thereof include potato cultivar (Solanum tuberosum, S. phureja and the like), S. demissum, S.acaule, a S. Stoloniferum like. Of these, potato cultivars are typical.

  In order to carry out tuber production according to the present invention, potato seedlings of 1 cm or more, preferably 5 cm or more are required. These seedlings are preferably seedlings maintained in vitro by tissue culture, but in the case of tuber production by this method in an open system, they may not be in vitro. These seedlings have a thick stem, dark green color, and roots that grow faster.

[Day length conditions]
The day length of the above-ground growth period may be 15 hours or less, but if the day length is too short, the plant body is likely to grow due to lack of light, and thus a day length of 10 to 14 hours is preferable. The day length here refers to the time of the light period when the light period and dark period can be clearly separated as in an artificial weather room, and the length of the day (from sunrise to sunset) under natural conditions. Time)) plus the usual twilight time. In the case of an artificial weather room, the light intensity is preferably 10,000 lux or more in order to promote photosynthesis. Moreover, the above-ground part growing season here means a state in which nutrients are absorbed from the roots and the above-ground part is growing. For example, when the nutrient content of the medium is deficient, or when the medium is replaced with a medium that does not contain nutrients, the above-ground growing season is substantially over, the above-ground portion begins to yellow, and eventually dies. In some cases, the growth of the above-ground part is stopped by a chemical or the like, and in this case, the period before the chemical treatment corresponds to the above-ground part growing period.

  In the above-ground growing season, strons are induced and proliferated by day length, temperature conditions, and the like. Tubers are also formed. After the above-ground growing season, enter the tuber filling stage. At this time, along with the yellowing of the above-ground part, the nutrients commutate to the tubers, and when the above-ground part dies, the tuber harvesting period begins.

[Temperature conditions]
Stron induction, growth, and tuber formation, including the above-ground growing season, requires relatively low temperatures at night. Specifically, the lowest night temperature is less than 25 ° C, preferably 5 ° C to 17 ° C. The higher the temperature at night, the smaller the number of large tubers that tend to form. In addition, vigorous generation of strons is not observed at night at 25 ° C (daytime 30 ° C). The daytime air temperature needs to be a temperature suitable for the growth of foliage, and is 10 to 40 ° C, preferably 15 to 35 ° C, more preferably 15 to 25 ° C. At this time, in order to make the daytime temperature higher than that at night, the day-night difference needs to be 3 ° C. or higher, preferably 5 ° C. or higher. When there is no day / night difference at 20 ° C., almost no stron formation is observed even under a short day condition of 12 hours long.

[Cultivation method]
In this method, a solution containing nutrients is used for cultivation. This solution may be a basic medium usually used for plant tissue culture or a commercially available hydroponic liquid (for example, from Otsuka House). Usually, a carbon source may be omitted. However, when light is weak and vigorous growth of the plant body cannot be expected, a carbon source such as sucrose is added. If a carbon source is added, it must be cultivated under aseptic conditions to prevent contamination with germs. In general, a mixture of equal amounts of Otsuka House Fertilizer No. 1 and No. 2 is often used at an electrical conductivity of 0.5 to 3.0 (milimo / centimeter). In the case of such a culture solution, for example, in an Otsuka House hydroponic solution No. 1 and No. 2 mixed in equal amounts (electric conductivity 1.0), the electric conductivity is approximately 0.0 in about 2 months after the start of the culture. Become. Therefore, if necessary, nutrients may be appropriately replenished.

  Any support method may be used as long as the seedling foliage is in the gas phase and the roots are in contact with the culture solution. If it floats only in the culture solution, it does not grow because gas exchange from the pores of the leaves is not sufficiently performed. Examples of support methods include a method in which the base of a stem is sandwiched in urethane used for hydroponics, and the roots are immersed in a culture solution, or Oasis Brown (Smithers-Oasis (USA)) is used on the surface of the culture solution. A method of laying a support and placing a seedling on the support is provided. When the support is a foamed resin or the like, the support must be soft enough to allow the stron to sink freely.

As for the container which puts a culture solution, it is desirable that the liquid level below the culture solution is shielded from light. In addition, although aeration into the culture solution is not essential, it is better to carry out aeration in order to promote root growth.
Moreover, not only in the water tank which stored the culture solution, if the said requirements regarding plant support are satisfy | filled, you may spray a hydroponic solution from the side or lower part of a root.

As long as the condition that the foliage is maintained in the gas phase is satisfied, it may be a completely open system, that is, hydroponics or aseptic conditions. When carried out in a closed system, it is better to ventilate the gas phase. However, when performing in a closed system, the temperature inside the container may increase when exposed to direct sunlight, so care must be taken in temperature management.
Carbon dioxide fertilization may be performed to promote the growth of the plant body.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, the scope of the present invention is not limited to these Examples.
The day length of Examples 2 and 3 is “Light and Plant Growth” (Yokendo, Katsumi Inada, published in 1979), page 25, Table I. 2. Calculated with reference to 1.

[Example 1]
5 liters of Otsuka House Hydroponic Liquid No. 1 and No. 2 mixed in equal amounts in a water tank made of polypropylene with an inner size of 336 x 194 x 156 mm and adjusted to an electrical conductivity of 1.0 mm, and for plant support A test tube stand made of stainless steel was put in the container. An oasis brown having a thickness of about 2 cm was laid on the test tube stand, and two potato seedlings (variety make-in, about 10 cm in length) grown in vitro were placed on the oasis brown and placed on the floor. The liquid level was almost the same as the surface of Oasis Brown. This water tank was placed in a Koitotron (manufactured by Koito Manufacturing Co., Ltd.) controlled at 10 ° C for 10 hours long, 20 ° C during the day, and 10 ° C during the night.
In vitro plants were initially susceptible to drying, so they were covered with a clear flower cap and removed after one week.

  Stron began to extend from the 10th day after placement, and continued to extend through the oasis brown. During this time, the foliage continued to grow, reaching a plant height of about 40 cm. Strons that continued to elongate branched and tuber formation began to be observed from the first month after placement.

  The electrical conductivity decreased with the growth of the plant body, and became almost 0 after about 2 months. Thereafter, the aerial part began to turn yellow, and after about 3 months, the aerial part died, and tubers were formed at the ends of the branched strons. When only tubers with a weight of 0.1 g or more were measured, the total number (0.1 g or more) was 400, the total weight was 294.6 g, and the average weight was 0.73 g. That is, about 200 tubers per one seedling were formed. Tuber weight distribution was as shown in Table 1.

[Example 2]
In Example 1, the installation location of the aquarium was a greenhouse (Shoya-gun, Tochigi Prefecture), the seedlings were fixed with urethane in a test tube stand, and cultivation was carried out from February 26, 1990 (day length of about 12.3 hours) to May I went to the 22nd (day length about 15.3 hours). During this period, the minimum temperature was 5 ° C to 13 ° C, the maximum temperature was 22 ° C to 32 ° C, the maximum daily range was 22 ° C, and the minimum value was 10 ° C. The planted seedlings showed the same growth process as in Example 1. The day length around April 30 when the ground began to turn yellow was about 14.6 hours. The total number of tubers formed (over 0.1 g) was 150, the total weight was 133.6 g, and the average weight was 0.89 g.

[Example 3]
In Example 1, the installation location of the aquarium is a greenhouse (Shoya-gun, Tochigi Prefecture) with a daily minimum temperature of about 20 ° C and a maximum temperature of 30-32 ° C. From January 12, 1990 (about 11.7 hours of day length), 4 Cultivation was carried out until 14th of May (day length of about 14.0 hours). The planted seedlings showed the same growth process as in Example 1. The day length around March 15 when the ground began to turn yellow was about 12.8 hours. The total number of tubers formed (0.1 g or more) was 51, the total weight was 164 g, and the average weight was 3.2 g.

[Comparative Example 1]
In Example 2, one seedling was transplanted into a pot containing soil and cultivated for the same period. The total number of tubers (0.1 g or more) was 7, the total weight was 147.8 g, and the average weight was 27.6 g. .

[Comparative Example 2]
In Example 2, cultivation started on June 1, 1991 (day length of about 15.5 hours), and cultivation was continued until September 1 (day length of about 14.3 hours). During this period, the minimum temperature was 16-23 ° C, the maximum temperature was 27-38 ° C, and the daily range was 11-15 ° C. The planted seedlings showed the same growth process as in Example 1. The day length around August 1 when the ground began to turn yellow was about 15.0 hours. However, the number of tubers obtained per seedling was 0.1 g or more, and the total weight was only 9.5 g.

Claims (1)

In the method for producing potato tubers, the potatoes were grown for a day length of 10 to 14.6 hours during the above-ground growth period, the nighttime minimum temperature was 5 to 20 ° C, and the daily difference between the daytime temperature was 10 ° C or more. A method for producing potato tubers, characterized in that strons are grown in liquid or gas phase by hydroponics, and tubers are formed on the strons.