Agriculture and Science 2024/5

Light response response of horticultural crops and agricultural technology (2)
　-Theoretical background of light irradiation on flowers and vegetables and control of flower growth.

Former Graduate School of Natural Science and Technology, Okayama University
Masaharu Masuda

1. electric irradiation of horticultural crops

(1) Flowers and plants

　Flowering promotion by daylength control has been demonstrated in many long-day flowering plants, and LEDs are replacing incandescent and fluorescent lamps as the light source. The most common cut flowers are the cassia, stock, lisianthus, and snapdragon. The shuukon kasumisou has long demonstrated its uniqueness as a floral arrangement, or so-called "garnish flower. Its flowering is not promoted by red light, but by far-red light, which is more effective when added to red light, and it can be grown year-round in many prefectures. The effect of far-red light is also observed in stock.¹⁾The demand for stock is considered to be from the end of the year to March. The demand for stock is said to be from the end of the year through March, and Chiba Prefecture is the largest producer in Japan, with a production value of approximately 1 billion yen. The main one-stand iron-type varieties will be illuminated with far-red LEDs from mid-September to provide 16 hours of daylength. Far-red light also promotes flower growth and stem elongation in lisianthus.²⁾The flower buds are not dead. In Kumamoto Prefecture, winter production of flower buds has been reported to suppress flower bud blasting, a phenomenon in which well-developed flower buds die off. Red light has little effect. In Chiba and Saitama prefectures, the use of red LEDs before and after picking (all-night illumination) seems to have been established as a crop type for fall emergence.^3,4)The red LEDs are also responsive to the far-red LEDs. Lepidoptera also respond to far-red LEDs and are generally subjected to daylength extension (16 hours) or a 3-hour interruption of the dark period from the time of plucking.⁵⁾The results of this study show that the use of far-red LED irradiation is a good technique to promote flowering and stabilize cut flower production. In summary, it can be seen that electric illumination with far-red LEDs is a technique that promotes flowering and contributes to stabilization of cut flower production in crops with relatively long days.

2) Vegetables

　Compared to flowers, electric irradiation of vegetables is rare, except for shiso (Perilla frutescens), whose leaves are used to produce products while flower buds are suppressed. It was reported in Miyazaki Prefecture 30 years ago that shiso, a typical short-day plant, is highly effective in suppressing flower buds even with a one-hour interruption of the dark period.⁶⁾Spinach is a long-day plant. Spinach is a long-day plant, but Narimatsu⁷⁾showed that incandescent light with a daylength of about 13 hours in the fall and winter can increase volume without affecting flower growth. Recently, Yamazaki⁸⁾found that two hours of red LED illumination increased leaf area in the cultivar 'Mirage' and that dawn illumination suppressed flower stalk elongation compared to midnight illumination. This report suggests that there is a light technique to promote nutritional growth after the center of the dark period, and that the effect of electric light may be stronger in late-emerging varieties that are insensitive to long daylight hours. The author believes that it may be necessary to enhance the vigor of greenhouse spinach in autumn and winter, especially for the new variety 'Maromi' (released in 2022 by Tohoku Seed Corporation), which is a slow-growing variety with a 70% oxalic acid reduction (Fig. 1).

2. ultraviolet and yellow LED irradiation

1) UV-B irradiation suppresses udder blight and spider mites in strawberries

　It has long been known that ultraviolet light (UV-A: 315-400 nm) accounts for most of the UV light reaching the earth's surface and is necessary for the production of pigments in eggplant and primula malacoides. For example, the eggplant pigment nasunin requires light around 370 nm, which causes poor coloration when grown in glasshouses that block it. UV-B (280-315 nm) also suppresses udder blight and spider mites in roses, and UV irradiation is also highly effective in strawberries, and the Central Agricultural Research Center of the National Agricultural Research Organization (NARO), overseeing many research institutes, published the results of six years of research as a strawberry disease control manual in 2019⁹⁾The UV-B irradiation is particularly important for the introduction of spider mite control. In introducing this method, it is especially important to finish UV-B irradiation at least 3 to 4 hours before sunrise, because UV-B irradiation only takes 3 hours to deter spider mites and the egg hatching rate recovers 50% in 4 hours when the eggs are exposed to sunlight after irradiation. In addition, light-reflecting sheets should be used to enhance the light on the underside of leaves. In addition, the combination use of natural enemy mites and plant-activating agents is also described, and the principal investigator, Dr. Chie Goto, summarizes at the beginning of this report that a pest control system that can reduce pesticide use by 70% or more has been established. As can be seen from this, the results of this research are positioned in the concept of so-called IPM (Integrated Pest Management), or "total pest management," and can be said to be a technology that contributes to improved cost performance.

(2) UV-C irradiation deters greening of yellow chives

　According to Mr. Oka (head of the Vegetable and Flower Research Laboratory, Okayama Prefectural Agriculture, Forestry and Fisheries Research Center), even sun-dried yellow chives gradually turn green when put on the market due to exposure to low light. If these chives are irradiated with UV-C light (200-280 nm) at 5 Klx for 4 hours in advance, they will not green up at all for at least 40 hours.¹⁰⁾(Figure 2). At the time of the discovery of this reaction, this technology had already been patented by another company (Patent Publication No. 2013-48615), but the patent application was withdrawn without any review (November 25, 2014). However, since the peak of the absorption spectrum of nucleic acids is within the UV-C wavelength range, it is thought that light damages nucleic acids in cells and inhibits not only chlorophyll but also all metabolic functions. It is thought that light damages cellular nucleic acids and inhibits not only chlorophyll but also all metabolic functions.

(3) Repellent effect on pests of Aster by irradiation with flashing yellow LEDs

　In my peach orchard in Akaiwa City, where I live, yellow-green mothproof lights are turned on in June to repel moths. Peaches are young fruit, so the influence of light is not a problem at this time. However, it is a problem for crops that are sensitive to daylength. In particular, night lighting is not allowed for Aster, because it affects the development of the flowers. In order to solve the problems of "avoidance of delayed flowering" and "expression of the moth-preventing effect" in kikuyu cultivation at the same time, Ishikura¹¹⁾focused on pulsed light and investigated in detail the effects of pulsed light on bud development in Aster, and demonstrated the usefulness of yellow LED pulsed light. In 2018, they commercialized a flashing LED lamp and verified that it can be applied to tomatoes and spinach in field plots, and concluded that human resource utilization of interpersonal networks through collaboration between researchers and extension workers in the field is necessary to promote this product.¹²⁾The importance of information exchange and mutual discussion among stakeholders, as well as sharing the results of research with local needs, is suggested for the wide dissemination of research results. The study suggests that in order to disseminate research results widely, it is important to exchange information and engage in mutual discussions among the parties concerned, and to share the results with local needs through these discussions.

3. in vivo response of flower bud differentiation induced by day length (electric light)

　The electric irradiation of Aster (Asteraceae), discussed in this paper, is a technique to control flower development by weak light, and phytochrome, a red and far-red photoreceptor, is thought to play a triggering role in this process. It is a water-soluble protein with a molecular weight of about 110,000, and as shown in Fig. 3, exists in Pr type (absorption maximum 660 nm) and Pfr type (absorption maximum 730 nm), and is mutually converted by light irradiation mainly at the indicated wavelengths. Pr-type phytochrome synthesized in the dark is mainly distributed in the cytoplasm, but when converted to the Pfr type, it is transferred to the nucleus, where it interacts with signaling factors to regulate the expression of specific genes. Phytochromes are classified into three groups, A, B, and C. Among them, A is the most photosensitive and is rapidly degraded in the dark after conversion to the Pfr form. The movement of Pr- and Pfr-type phytochromes in leaves during the dark interruption of Aster kantoensis can be explained in light of the phytochrome characteristics shown in Fig. 3.

　The short-day plants, onamomi and morning glory, are, to be precise, long-night plants. The long night induces flower development. The morning glory cultivar 'Purple' forms flower buds after a single 16-hour dark period, and the rate at which the flower formation stimulus produced by the leaves moves to the buds was calculated by a clever experiment to be 51 cm/hour.¹³⁾The phytochrome theory states that during the long 16-hour night, Pfr-type phytochrome is gradually converted to Pr-type phytochrome (dark reversal in the figure). According to the phytochrome theory, Pfr-type phytochrome is gradually converted to Pr-type phytochrome during the long night of 16 hours (dark reversal in the figure), and flowering is induced when the amount of active Pfr is below a certain limit. Therefore, in a short night, such as 8 hours, Pfr does not fall below a certain limit in short-day plants, and thus flower formation is not induced.

　Flowering of Aster, which is familiar to us in our daily life, is thought to be mainly controlled by this reversible reaction, but when red light is used to interrupt the dark period, Pr is converted to Pfr, and Pfr exceeds the limiting amount, thus suppressing flowering. However, in reality, the irradiation time is as long as 3 to 5 hours, and there are many reports that the irradiation effect does not change or is even more effective when far-red is added to red, which may be related to the inactivation of Pfr due to its degradation as described in the figure. In order to maintain the quantitative stability of phytochrome A, it is meaningful to consider that phytochrome A is partially converted to Pr type in the far-red color when irradiation time is long. The reason for this is pointed out by Hakusan (see ref. 3 of the previous report), based on the phytochrome action characteristics, that in Aster, phytochrome A and the high irradiation (higher energy?) by the far-red color may be involved in the reaction. The detailed mechanism of the reaction is still to be elucidated in the future.

　How is the active protein Pfr, which is produced in the leaf, transferred to the subsequent floral development reaction? Recently, genetic studies have revealed that the FT protein produced by the FT gene (Flowering locus T) in Arabidopsis thaliana⁽¹⁴⁾In 2005, this gene was named florigen, a floral growth hormone. Later, it was shown that this FT protein translocated from the leaf to the shoot apex works together with the FD protein present in the shoot apex to turn on the flower bud formation gene (AP1 gene), and the process of making the FT-FD complex was visualized by Abe et al.⁽¹⁵⁾The following is a list of the most common problems with the "C" in the "C" column.

　On the other hand, the phenomenon of transition to vegetative growth after induction of non-flowering conditions (even in some leaves), as typified by willow buds in Asteraceae, has been observed in many plants, not only in Asteraceae, suggesting the presence of inhibitors of flower growth in the leaves. Higuchi et al.¹⁶⁾FTL3 is a strong promoter of flowering, but AFT (anti-florigenic FT/TFL1 family protein), which acts antagonistically to FTL3, has been discovered and is called We called it anti-florigen. AFT, which is produced in leaves under non-flowering conditions (long day or dark interruption), moves to the stem apex and suppresses flower development (Fig. 4). AFT levels decrease rapidly after the shift from long-day to short-day, while FTL3 is gradually induced by the repetition of the short-day cycle (Figure 4). Here, phytochrome B, the major photoreceptor for sensing dark interruption, induces the expression of antifloriogen (AFT) while inhibiting the expression of florigen (FTL3). However, phytochrome B has not been shown to be involved in the induction of FTL3 under short-day conditions. Since phytochrome is a red and far-red reversible pigment protein that is always present in leaves, this system should be active even in short-day. At least in the first short-day photoperiod cycle. If the involvement of phytochrome B in the short-day cycle is clarified at the genetic level, I can better understand the flow of research from phytochrome as a light receptor to FT (FTL3) and AFT [energy transfer].

　The history of floristic research is long, and we are now at the stage of genetic analysis at the stem apex. Although a series of genes (proteins) related to qualitative transformation in the apical meristem will be discovered in the future, it is expected that the area around the FTL3-like protein that promotes flower buds, including floral organ formation, will be widely filled in order to utilize these genes for agricultural purposes.

Conclusion

　Figure 5 shows the ratio of the radiation energy of sunlight falling on the earth and the wavelength range effective for plants. It can be seen that far-red light at wavelengths above 700 nm is not effective for photosynthesis, but is extremely important for the morphogenesis described in this paper. Light at this wavelength is dim; at 800 nm it becomes an invisible heat ray. The light response of plants can be broadly classified into high-energy reactions for carbonate fixation and low-energy reactions for morphogenesis.

　The former is the so-called photosynthesis of 6CO₂＋12H₂O^＊＋ (light energy) → C₆indecent₁₂O₆+6O^＊₂＋6H₂O, is a reaction that uses light energy to synthesize sugar from carbon dioxide and water. In potatoes, it is stored as starch in roots and stems, and in fruits, it is accumulated as sucrose and fructose. Some of the sugars are converted to C₆indecent₁₂O₆+6O₂ → 6CO₂＋6H₂O + chemical energy to produce the energy necessary for survival, as indicated by O + chemical energy. This reaction is respiration, and plants use oxygen to release carbon dioxide and water. The website of the Faculty of Science states that this research provides an important basis for the creation of catalysts for "artificial photosynthesis," in which water splitting reactions are artificially carried out using solar energy. The website of the Faculty of Science states that the project provides an important basis for the creation of catalysts for artificial photosynthesis, in which water splitting reactions are artificially performed using solar energy.

　In this paper, we focus on the latter low-energy response, especially irradiation. As mentioned above, irradiation means qualitative conversion to flower bud differentiation in Aster, and quantitative expansion to prevent dwarfing in strawberry. In terms of promoting flower bud formation, short days (long nights) from summer to autumn work in both cases. In the case of Aster, electric light suppresses flower bud formation, but in the case of strawberry, low temperature is the main factor, so flower bud formation continues even with electric light. However, too long irradiation time, i.e., too long a day, can interfere with flower bud differentiation. The irradiation that promotes leaf blade and petiole elongation in strawberries needs to be adjusted according to the growth conditions, and requires more detailed technical methods than irradiation in Aster. Short-day stimulation sensed by the leaves is transmitted to the stem tops. In the case of Aster, AFT is strongly activated and the FT (FTL3) gene is suppressed by irradiation or interruption of the dark period, and flower bud differentiation does not occur. In general, plants are not able to sense day length and initiate flower development until a certain age (phase) has passed. This phase is called the juvenile phase. This is a point of great interest and will be discussed at another time.

　In strawberry, the long-day stimulation at the leaf by electric light must be transported to the stem apex, which at least acts on the quantitative expansion of the leaf. It is possible that leaf-delivered proteins are involved in the synthesis of gibberellins at the stem apex, since gibberellin, a plant hormone, has been shown to be silenced in strawberry. It is certain that the proteins produced in strawberry leaves have functions related to leaf elongation and growth apart from floral development, and we wonder how the AFT gene is involved in the nutritional growth of strawberry under irradiation. Do AFT-like and FT-like genes exist in cultivated octoploid strawberry in the same mechanism as in Aster? However, as shown in Fig. 9 in the previous report, low temperature plays a leading role in flower bud differentiation in strawberry, and the existence of a tentatively named unidentified vernalin (floral growth hormone induced by low temperature) protein, which is different from florigen (floral growth hormone induced by day length), is also expected. We are waiting for the day when this series of research will shed new light on the field of strawberry irradiation, which is of high agricultural value.

References

1. Tanedani M., Kato M., Shiiki C., Kagawa H. 2016.Flowering promotion technology of iron stock by far-red light irradiation. Chiba Agricultural and Forestry Research Institute Report 8: 41-50.

2. Kudo Y., Yamaguchi S., Sato A., Kuriyama T., Fukai S. 2012. Effect of electric light on flowering, flower bud blasting and stem elongation in lisianthus wintering in Kumamoto Prefecture. Journal of Horticultural Science 11(3): 363-369.

3.Chiba Prefectural Agriculture and Forestry Research Center. 2019.Improvement of quality of lisianthus in autumn by combining red LED and far-red LED light source. Information on dissemination of experimental and research results.

4. Saitama Flower Promotion Council. 2022. high quality cultivation management technology for November shipment in lisianthus.

5. Chiba Prefectural Agriculture and Forestry Research Center. 2019. characteristics of new buttercup varieties and their cultivation methods under electric light and stationary cultivation. Information on dissemination of experimental and research results.

6. Iida, H., Hosoyamada, Y., and Takahashi, H. 1989. Prevention of moss abscission in large-leaved shiso (Perilla frutescens L.) by interruption of the dark period. Kyushu Nutrition Research Institute 51: 204p. 

7. Narimatsu, J. 1996; Studies on the supplementary light cultivation of spinach. Kanagawa Prefectural Agricultural Research Institute Bulletin 137: 17-23.

New Kinki Chu-Shikoku Agricultural Research 2: 46-54. 9. Agricultural Research Center, National Agricultural Research Organization of Japan. 2019. manual for pest control of strawberry based on ultraviolet irradiation ~technical chapter~. 1-51.

Establishment of High-Quality and Stable Production Technology for Yellow Chives. (2) Establishment of greening control technology. Okayama National Agricultural Technology Center, Single-year experimental research results. 127-128.

11. Ishikura, S. 2014; Development of pest control technology using yellow LED pulsed light for cut ginkgo. Hiroshima SOKENDAI Agricultural Technology Center Bulletin 90: 1-88.

12. Nishihama, K., Ishikura, S., Hoshino, S., Okada, M., and Ishida, M. 2018. practicality of flashing LED yellow moth lamps in field cultivation plots and the effect of collaboration between research and extension on the quality of extension agents. Hiroshima Soken Agricultural Technology Center Bulletin 92: 11-22.

Wareing,P.E. and Phillips,L.D.J. 1970. THE CONTROL OF GROWTH & DIFFERENTI-ATION IN PLANTS. Pergamon Press, Oxford. chapter10: The physiology of Chapter10: The physiology of flowering-photoperiodism. 164-195.

Kobayashi, Y., Kaya, H., Goto, K., Iwabuchi, M., Araki, T. 1999. A pair of related genes with antagonistic roles in mediating flowering signals. Science 286 : 1960-1962.

Abe, M., Kobayashi, Y., Yamamoto, S., Daimon, Y., Yamaguchi, A., Ikeda Y., Ichinoki, H., Notaguchi, M., Goto, K., Araki, T. 2005. FD, abZIP protein mediating signals from the floral pathway integrator FT at the shoot apex.

16. Higuchi, Y., Narumi, T., Oda, A., Nakano, Y., Sumitomo, K., Fusaki, S., & Hisamatu, T. 2013. the gated induction system of a systemic floral inhibitor, anti-florigen, determines obligate short-day flowering in chrysanthemums. Proc. Natl. Acad. Sci. USA 110:17137-17142.

Measures to Prevent Crop and Animal Damage in Aichi Prefecture

Agricultural Promotion Division, Agricultural Policy Department, Agriculture and Fisheries Bureau, Aichi Prefecture
Wild Boar Control Room
Osamu Tsujii

Introduction

　Crop damage by birds and animals is a common problem throughout Japan. Aichi Prefecture, with its growing urbanization and strong image as an industrial prefecture, is no exception. This section introduces the basics of measures to prevent damage to agricultural crops by birds and beasts, as well as an overview of efforts in Aichi Prefecture.

Basics of measures to prevent damage to crops by birds and beasts

(1) Basic "Three Pillars"

　The following three efforts are important in crop damage control, or the "three pillars".
(1) Do not attract: Maintain an environment where it is difficult for birds and animals to perch.
(2) Do not let them in: use fences or nets to prevent entry.
(3) Catch: Capture the assailant

　None of this is new, but even today, in the 21st century, there is no other effective way.

(2) Implement in the order of "don't pull in, don't let in, and catch".

　The order in which the "three pillars" are implemented is important. When we talk about measures against birds and beasts, we tend to assume that the first step is capture (extermination), but only capture will not be effective. As a prerequisite for capture, environmental management and intrusion prevention measures by local farmers and residents are indispensable. In the first place, it is impossible to capture all individuals that target crops. Farmers themselves must take basic measures to prevent the invasion of the pests, and then they must take measures to prevent the invasion of the pests.

The sense that the capture is carried out as a finishing touch is desirable.

(3) Capturing activities are community-wide

　In principle, a hunting license is required for trapping, which requires special skills and is also dangerous. Furthermore, in recent years, the shortage of local hunters has become serious. It is becoming increasingly difficult to survive without community-based activities, and the active participation of farmers and local residents is desirable.

3. Aichi Prefecture's Efforts

(1) Damage in Aichi Prefecture¹⁾

　In Aichi Prefecture, annual crop damage is around 450 million yen and has remained almost unchanged (Fig. 2). In Aichi Prefecture, however, the amount of damage caused by mammals is about the same or higher than that by birds (Fig. 2). In Aichi Prefecture, however, bird damage is higher (Fig. 2). In addition, horticultural crops account for about 65% of the total amount of damage, reflecting the characteristics of the prefecture's agriculture, which produces many horticultural crops, such as vegetables and fruit trees.

(2) Measures against wild boars and deer in mountainous areas

　In the mountainous areas of central and eastern Aichi Prefecture, damage caused by wild boars and deer is serious. Not only crop damage, but also damage to farmland and farm roads caused by wild boars digging back, traffic accidents, tick infestation, and anxiety over human casualties are problems that cast a shadow over the entire region.

a. Settlement Environment Inspection and Improvement Activities Settlement Environment Inspection and Improvement Activities

　In order to put the aforementioned "three pillars" into practice, the environment of the village must first be inspected, and food resources and hiding places must be eliminated.²⁾The most basic measures are the following. Although these are the most basic measures, not enough efforts have been made in Aichi Prefecture, and unfortunately, this paper cannot introduce any specific examples. In order to preserve the rural environment in mid-mountainous areas, we should aim to strengthen our activities.

b. Maintenance of anti-encroachment fences

　Since the 2010s, in Aichi Prefecture, the construction of fences to prevent wild boars and deer from entering villages has progressed with the help of government subsidies (comprehensive measures to prevent damage by birds and animals). The following three points have been proposed as the key points to increase the effectiveness of the project.
(1) Specifications should be able to handle the wild animals that are a problem.
(ii) Close all routes of entry for wild animals.
(iii) Ongoing inspections and repairs

　Each of these will be explained.

(1) Specifications should be able to handle the wild animals that are a problem.

　Because of the superior jumping ability of deer, it is necessary to ensure that the fence height is above a certain level. A trail camera installed by the authors captured images of deer jumping over a 120-cm-high wire mesh fence without running (Figure 3). Some have pointed out that 150 cm is sufficient height to prevent deer from jumping over the fence.³⁾According to the specifications of the prefectural government's subsidized project, the height of the fence must be 180 cm or higher to prevent deer from entering the area. 　It is impossible to prevent monkeys and medium-sized animals (civets, raccoons, etc.) from entering with a wire mesh fence alone. For these species, a combination of fine mesh netting and electric fences is necessary. Management of electric fences is important to maintain the voltage, but it is difficult to sustain the effect of joint management in large plots4). Therefore, it is desirable for individual farmers to take countermeasures first.

(ii) Close all routes of entry for wild animals.

　It is important to close all potential wildlife entry routes as much as possible with anti-entry fences. Patterns of wildlife entry routes vary depending on geographical conditions and the surrounding environment. In areas where fences have been appropriately installed according to the patterns of entry routes, stable effects have been obtained.

　In areas with mountains and hills in the background, with farmlands and urban areas at the foot of the mountains, a certain level of effectiveness has been achieved by installing linear anti-encroachment fences along the foot of the mountains. In this case, the fences were set up along the foothills of the mountains and hills. In this case, rivers and waterways flowing out of the mountains and roads leading to forests cannot be closed and become openings. Roads that are used infrequently (e.g., forest roads) can be closed with gates to stabilize the effect. Along rivers, stairs leading down to the riverbed can be a route of entry, so it is advisable to erect wire mesh at the entrance to the riverbed.

　In areas surrounded by mountains and forests, where wild animals enter from many directions, it is desirable to completely enclose the farmland. If the enclosure is incomplete, the wild animals can easily get around and enter the area. In a survey conducted in Chiba Prefecture, it was pointed out that incomplete enclosure is the main factor preventing damage control.⁵⁾The first is to enclose as many plots of land as possible in a group. However, it is desirable to enclose as many plots together as possible, since it is inefficient and costly to enclose each brush stroke individually.

(iii) Ongoing inspections and repairs

　Fences are not the end of their life; it is important to manage them to maintain their functions. The status of maintenance and inspection differs from village to village, and those areas where frequent activities are carried out are highly effective. Yamahata et al. reported that the social capital indices of the community improved as a result of the continued implementation of animal damage control measures (in this report, monkey chasing activities).⁶⁾The same is true of the management of encroachment fences. Similarly, the management of anti-encroachment fences is expected to have the secondary effect of maintaining and strengthening ties among residents.

　In the management of wire mesh anti-encroachment fences, we often suffer from vine weed infestation. In some studies, kudzu, a typical vine weed, has been reported to grow up to 17 m per year in the second year of germination, and it has been reported that the vine can grow up to 20 m per year in the second year of germination.⁷⁾The amount of growth is such that the wire mesh fence is completely engulfed. In an unpublished survey conducted by the authors, it was found that the amount of weed attachment was high in areas with sunny areas and sunny trees (red oak, poison ivy, etc.) and relatively low around agricultural land (Fig. 4). Efficient maintenance and inspection will be possible by taking into consideration the sunlight, vegetation, land use, and other factors.

c. Community-based trapping activities Community-based trapping activities

　In order to capture birds and beasts for the purpose of damage prevention, permission from the mayor of the municipality is required, and in principle, a hunting license is required to apply for such permission. For this reason, members of hunters' associations are the main players throughout Japan, and Aichi Prefecture is no exception. It has been pointed out that in the past, there were people who made a living by hunting in Japan's farming and mountain villages, and they secured hunting rights by making a trade-off with hunting to prevent damage to the agriculture and forestry industries.⁸⁾The following is a list of the most common problems with the "C" in the "C" column.

　In recent years, the number of members of hunting organizations has been decreasing and the aging of the hunting community has led to a serious shortage of hunters. In response to this situation, Aichi Prefecture has been implementing a project to allow local residents without hunting licenses to assist in the hunting of pests, starting with Toyone Village in FY2009 (hereinafter referred to as the "project to allow people without hunting licenses to engage in hunting").⁹⁾The company is working to promote and expand the use of The following advantages may be considered with the introduction of the worker acceptance program.
(1) Workload of trappers will be eased.
The number of traps installed and the management condition of traps will be improved to increase the catch rate.
The participants of the project are expected to train new trappers.

　Only when those involved in the effort to prevent damage can the activity be sustained. Farmers' participation in trapping activities, even if it is only a small assistance, is meaningful. It is thought that it will lead to strengthening the cohesion of the community, and active efforts are encouraged.

(3) Measures against crows and medium-sized animals in horticultural farms

　Aichi Prefecture is a major producer of horticultural crops such as vegetables and fruit trees, and there are many reports of damage caused by birds and beasts. In particular, damage by birds such as crows and medium-sized beasts such as civets is serious. According to an awareness survey conducted by the Aichi Prefectural Agricultural Experiment Station targeting fruit tree farmers in the prefecture, birds, medium-sized animals, and large animals were the most important in terms of countermeasures, in that order, and it was estimated that medium-sized animals posed a greater threat than the ratio of the amount of damage. The results also indicated that they consider infestation prevention measures to be the highest priority.¹⁰⁾The agricultural extension centers in the prefecture have actually received many consultations from fruit tree farmers regarding damage to birds and medium-sized animals. In fact, the prefectural agricultural extension center receives many consultations from fruit tree farmers regarding damage caused by birds and medium-sized animals, and is working on field demonstrations of practical techniques.

a. Tegus and stainless steel wire to prevent crows from entering

　Demonstration results from the National Institute of Agro-Environmental Sciences¹¹⁾We are currently verifying the use of Tegus stainless steel wires in an orchard to prevent infestation (Figure 5). The installation and management of the wire is a future issue to be addressed. Orchards have a varied surrounding environment, and windbreaks, buildings, and other factors often hinder installation work. Future improvements are expected, such as the use of drones for extending tegus, in addition to minor modifications to the work system.

　The verification of the effectiveness of the method in this prefecture has so far been limited to fruit trees with large sales per unit area, such as grapes, pears, and peaches. In the future, it is necessary to study cost-effective methods for fruit trees grown on a larger area, such as oysters and open-air mandarins, and open-air vegetables, such as cabbage and broccoli.

b. Measures to prevent entry of medium-sized beasts

　In the cultivation of grapes and other fruit trees with relatively high unit sales prices, Saitama Prefecture has developed a medium-sized beast intrusion prevention facility called "Rakuchi-kun.¹²⁾Since April 1, 2017, farmers have been allowed to capture civets, raccoons, and other animals with small spearhooks on their own business land, regardless of whether or not they have a hunting license.¹³⁾In addition, the importance of disposal of residues has been pointed out. In addition, since the importance of residue disposal has also been pointed out⁽¹⁴⁾The report calls for appropriate measures to be taken.

(4) Measures to prevent the spread of swine fever in wild boars

　In September 2018, the first outbreak of swine fever at a pig farm in Japan in 26 years was confirmed in Gifu Prefecture, and soon after, wild boars in the vicinity were also found to be infected. In Aichi Prefecture, a wild boar infected with swine fever was found in Inuyama City near the border of Gifu Prefecture in December of the same year. Since then, a total of 193 infected wild boars have been confirmed by the end of FY2023, and there is still no end in sight. Currently, the following measures are being implemented.

A. Wild boar inspection Wild boar inspection

　Blood and other specimens are collected from captured wild boars and tested for viral genes by real-time PCR at a laboratory. Some of the specimens are also tested for antibodies, and the acquisition of immunity against swine fever virus is also investigated. The results are shared with relevant personnel and used as basic data for the oral vaccine and enhanced capture measures described below.

b. Field spraying of oral swine fever vaccine

　To immunize wild boars against swine fever virus, a precedent in European countries.¹⁵⁾The oral vaccine is a preparation consisting of liquid vaccine capsules containing attenuated virus wrapped in food consisting of corn flour and oil or fat. The oral vaccine is a preparation consisting of a capsule of vaccine solution containing attenuated attenuated virus wrapped in food consisting of corn flour and oil, which is buried underground in the habitat of wild boars and fed to the animals (Fig. 6).

c. Enhancement of capture

　Increased subsidies for capture activities have been provided to increase motivation for such activities, and intensive capture activities have been conducted by certified bird and wildlife trappers in wildlife sanctuaries, national forests, etc.

4. Conclusion

　Aichi Prefecture also disseminates information on its website and SNS regarding measures to prevent damage to birds and animals and the spread of swine fever among wild wild boars (Fig. 7).

5. references

(1) Aichi Prefectural Bureau of Agriculture and Fisheries. Status of Crop Damage Caused by Wild Birds and Animals (FY2022). 2023 (2) Ministry of Agriculture, Forestry and Fisheries of Japan. Manual for the Prevention of Damage Caused by Wild Birds and Beasts - Comprehensive Measures -. 2023.
(3) DOYAMA Soichiro. How do Japanese deer invade fences? JATAFF Journal 7.2019
(4) NAGATO Yuji, YOSHINAKA Rei. Actual situation and direction of electric fence management in measures against damage by birds and beasts. Journal of Agricultural Management 49, 2011.
(5) Muramatsu, Hirotaka et al. Reasons Why Extension of Protective Fences Does Not Directly Lead to Reduction of Rice Damage Caused by Wild Boars. Wildlife and Society 7. 2019
(6) Yamahata, Naoto et al. Effects of Continuation of Beast Damage Control on the Social Capital of Villages. Journal of Rural Planning Association 34.2015
(7) Okazaki (Tanaka) Maiko et al. Growth and capsular production of kudzu (Puerarialobata (Willd.) Ohwi) climbing stems. Journal of Japan Green Industry 43.2018
(8) Takahashi, Mitsuhiko. Will the Fundamentals of Avian and Wildlife Law Change...on the Subject of the 2014 Law Amendment. Wildlife Forum Spring/Summer 2014. 2014.
(9) Matsuo, Koji (Ministry of the Environment). Outline of the system for workers without hunting licenses. Presentation material for the workshop on community-based measures against damage caused by birds and beasts. 2013.
(10) Tsujii, O. et al. Sensitive Evaluation of Avian Control of Fruit Trees by Hierarchical Analysis Method. Aichi Agricultural Experiment Station Research Report 53. 2021
(11) National Institute of Agrobiological Sciences, Avian Pest Management Project. (11)National Institute of Agrobiological Science, Project for Bird and Animal Hazard Control. 2013.
(12) Saitama Agricultural Technology Research Center. Manual for Installation of Raku-Raku Light. 2018 (13) Ministry of the Environment. Basic guidelines for implementing projects to protect birds and animals (October 2016 notification version).2016
(14) Kosakai, Chinatsu. Waste Fruit Farms, Feeding Ground for Birds and Animals with High Energy Acquisition Efficiency - Necessary for Prevention of Bird and Animal Hazards. jataff journal 7. 2019.
(15) Sophie Rossi et al. Controlling of CSFV in European wild boar using oral vaccination: a review Frontiers in Microbiology6. 2015

The 31st Annual Soil Festival
　　World Soil in Peril - Part 1
　　　Collapse of ancient civilizations and soil degradation

Former Technical Advisor, Hokkaido Branch, Jcam Agri Co.
Teruo Matsunaka

　From the 25th to the last issue of this series, it has been stated that agriculture can have a negative impact on the environment, depending on how it is conducted. Therefore, it is important to conduct agriculture in an environmentally friendly manner. This is because agriculture cannot be stopped because it produces food for people.

　Soil is what supports crop production in agriculture. However, the phenomenon of soil degradation, in which the soil becomes degraded and unsuitable for crop production, is spreading on a global scale, and one-third of the soil has already been degraded (Silva, 2014). The soil is indeed in danger. We will explore the current situation and causes of soil degradation in this article.

1. indifference to the soil will destroy civilization

　About 10,000 years ago, primitive man acquired the wisdom to secure food through agriculture. Once the foundation for stable food production was established through agriculture, the ability to support the population increased. Ironically, however, it also made it impossible to return to a hunter-gatherer lifestyle. The food supply of the increased population could no longer be supported by hunting and gathering. The agricultural and sedentary lifestyle gradually flourished as people left the natural ecosystem, created artificial ecosystems, and built settlements. This is where the seeds of ancient civilization were planted.

　However, the prosperity of this civilization did not last more than 30 to 70 generations (800 to 2000 years). The root cause, Carter and Dale (1975) point out in their famous book "Soil and Civilization," is the inability to produce food sustainably because of neglect of the natural ecosystem and indifference to maintaining soil fertility.

Let's look at some of their points below.

1) The Fertile Crescent, an example from Mesopotamia

　The "Fertile Crescent" refers to the lowlands in the basin of the Tigris and Euphrates Rivers, from their upper reaches to the Jordan River basin and the Dead Sea. In the past, this area had fertile soil that was even called "a land flowing with milk and honey. This area has low precipitation.

　Therefore, irrigation from the Tigris and Euphrates rivers was essential for crop cultivation. The Armenian plateau, located upstream of both rivers, was richly forested. However, when civilization inspired people to gather there, the forests were cut down for fuel and building materials, and livestock were overgrazed. The soil on the plateau, which had lost its forests, could no longer hold water, and the topsoil eroded, causing sediment to flow into rivers and accumulate in irrigation canals. The function of the irrigation canals was maintained by the removal of sediment by slave labor.

　However, the peoples attacking Mesopotamia were indifferent to the irrigation canals. Eventually, the irrigation canals were blocked by earth and sand, rendering them unusable. The decisive blow came when the nomadic Mongols attacked the region. The nomads did not understand the importance of irrigation and completely destroyed the canals. Even worse, in this region of high evaporation, when irrigation connected the groundwater to the surface, a tremendous amount of salt was introduced and accumulated on the surface, causing the soil to become salinated. This salinization completely destroyed the soil's ability to produce crops.

　Waterways for irrigation water, which is essential for food production, were filled with soil and sand, and the soil was easily salinized.These factors made it difficult for Mesopotamia to sustain a stable supply of food and reduced its ability to support its population. Thus, civilization declined.

(2) Example of the Nile River Basin, Egypt

　Maintaining soil fertility by taking advantage of nature: The situation in the Nile River basin in Egypt is different from that in Mesopotamia, even though they are the cradle of the same ancient civilization. The Nile River rises and falls every year in precise cycles. This is because the main source of water was melted snow from the Ethiopian plateau and the highlands of Central Africa. The floods, which always came once a year in the summer, brought harvests to ancient Egypt.

　First, an enclosure is built along the Nile River basin, similar to the footpath between rice paddies. In this enclosure, muddy water that overflows during the flooding season is stored like rice paddies before planting (called flooded irrigation). After a few weeks of irrigation, the fertile silt (fine sand) contained in the muddy water settles on the ground, and the water permeates the soil sufficiently. The excess water is then drained away, and wheat and other seeds are sown in the fertile muddy soil. People of that time, who thought in harmony with nature, did not try to conquer the enormous water energy of the Nile during the flooding season. Rather, they established a waterlogging irrigation technique that made good use of nature. However, this technology also had its drawbacks. It was a weakness in that it could only be planted once a year during the period of the Nile's rising waters.

　Turning point to year-round irrigation: From the 19th century onward, Egypt planned to export cotton. However, cotton is a summer crop that is sown during the low-flow period of the Nile River (March-April) and harvested in October. Therefore, it is not possible to use the water during the flooding season. Therefore, deep irrigation canals were dug to take advantage of the low water level during the low-flow season. In this way, an environment was created in which water could be used all year round, regardless of the increase or decrease of the Nile's water volume. 　This passion for year-round irrigation led to the completion of the Aswan Dam with British assistance in 1903. The use of this dam ensured stable agricultural production. Thanks to this, the population grew significantly, from 7 million in 1882 to 20 million in 1952, 70 years later. However, as land use for human subsistence increased, forests were cut down and livestock began to be overgrazed in the watershed area. As a result of these changes in land use, more and more sediment was carried into the dams, which gradually filled up with sediment, and the water storage function declined.　The reduced function of the dam caused irrigation to become impossible, leading to a decrease in crop production. Construction of the Aswan High Dam began in 1960 with Soviet (now Russian) assistance and was completed 10 years later. The construction of the Aswan High Dam, with Soviet (now Russian) assistance, began in 1960 and was completed 10 years later, allowing for year-round irrigation of farmland and the planting of crops several times a year, greatly expanding the area under cultivation.

　The merits and demerits of dams and the order of nature: The completion of the Aswan High Dam seemed to have solved the water problem. However, aquatic snails began to proliferate in the irrigation canals, and the parasite Birkhartz's blood-sucking worm began to spread, using the snails as intermediate hosts, and the soil began to become salinated.

　The annual Nile floods wash away the salts that tend to accumulate on the earth's surface. Moreover, they carry nutrient-rich fertile silt from upstream and deposit it on top of the old soil. This naturally overcame the salinization of the soil and maintained its fertility. This was the ancient natural order of things that supported the "fertile lowland soil of the Nile.

　In modern times, however, people have attempted to control the flow of the Nile themselves. The Aswan High Dam, which was supposed to have been built to stabilize agriculture, caused salt damage and parasites. This is a tragedy of irrigated agriculture that failed to take advantage of the natural order of things.

2. how to apply lessons learned

　What the decline of ancient civilizations teaches us is the fact that without preserving the soil, the foundation of food production, there can be no food security and no advanced civilization can be sustained. The collapse of civilization due to resource depletion on the isolated Pacific island of Easter Island also offers valuable lessons for us today (Ponting, 1994). The question for us today is how to apply these lessons.