New innovative methods to grow tomatoes and asparagus, for which expectations are rising

Apr. 6, 2018

New innovative methods to grow tomatoes and asparagus, for which expectations are rising

Satoru Motoki
Associate Professor, School of Agriculture,
Meiji University
 

Nowadays, a steep rise in vegetable prices makes the news. Basically, the production of vegetables depends on the season and weather; in recent years, however, the impact of abnormal climate conditions and earthquake disasters is increasing. Therefore, research and development of new methods to grow vegetables are being pursued, and our School of Agriculture also plays a part of that.
 

To increase the intake of vegetables

I think everyone knows that vegetables include nutrition necessary for the human body. To maintain our health, vegetables are very important food. Recently, other actions of vegetables such as anti-aging or anti-cancer have also been receiving attention. However, the vegetable intake of Japanese people has been gradually decreasing since the peak around 1985. Although the amount of vegetable intake per day recommended in the “Health Japan 21,” which is a health policy of the Ministry of Health, Labour and Welfare, is 350 g, the average for men is 299 g and for women it is 289 g, with neither of them reaching the recommended amount. There are various reasons for this. Challenges on the side of farm producers include responding to the changing tastes and needs of consumers and achieving a stable supply as much as possible even in abnormal climate and bad weather. To overcome these, development of new plant varieties and cultivation methods is conducted at many different research organizations. Also, at our Laboratory of Vegetable Crop Science, various efforts are being made in collaboration with many farm producers, from which cultivation methods valued as innovative and introduced nationwide are born.

“Sauvage Cultivation” of cherry tomatoes
One of the recent researches that are performing well is a new method to grow cherry tomatoes. From the beginning, tomatoes have been in high demand in Japan and their domestic sales are the highest of all vegetables. Although large tomatoes used to be a main product, consumers’ tastes have expanded further to medium-sized and cherry tomatoes and, now cherry tomatoes account for 10 percent or more of total tomato production. Recently, cherry tomatoes of various colors have been developed, and a range of colorful tomatoes are lined up in stores. In the future, the demand for cherry tomatoes is expected to increase.

Many people have an image that the tomato is a vegetable of summer, but in fact, tomatoes are a very difficult vegetable to grow in open-field cultivation during summer. First, when the temperature is 35 degrees or more, the pollen fertility of a tomato is reduced, and it does not easily bear fruit. In other words, pollen is not produced so much, and the tomato becomes unfruitful. Also, in high temperatures, the red pigment lycopene does not develop. Tomatoes do not turn red and instead become discolored. Furthermore, weather such as too much rain increases the risk of disease. The recent summer weather in Japan with abnormally high temperatures and frequent heavy rain has impacted tomatoes negatively. Therefore, we developed a new cultivation method, “Sauvage Cultivation” of cherry tomatoes, in which production during the high summer season is possible and it is also labor-saving.

The point of this cultivation method is to erect 2 m high inverse U-shaped supporting poles 2 m apart, with an interval of 2 m between each pole, and put a net overall on them in order to attract the stems of tomatoes. Letting the stems and leaves climb the netting is a completely new idea, which is not found in the traditional cultivation method of cherry tomatoes. Before long, a tunnel with developed stems and leaves is formed. A lot of sunlight falls on the leaves outside of the tunnel, activating photosynthesis. However, the inside of the tunnel does not get enough sunlight due to the flourishing leaves, and the temperature is lower compared to the outside, where the fruit is produced.

There are several advantages in this Sauvage Cultivation. First, production in the high summer season is possible, and consumer demand can be met when the arriving volume of cherry tomatoes is small. In addition, as the necessary equipment consists only of the supporting poles, nets, and mulching items, the initial investment cost is only about one-third of that for a greenhouse. In recent years, farming has also been seriously damaged by natural disasters such as earthquakes throughout the country. Sauvage Cultivation could be helpful for farmers to recover from such damage. Furthermore, although the crop yield per unit area from Sauvage Cultivation is only slightly higher than for the traditional cultivation method, when it comes to the crop yield per plant, it is five to six times of that of the traditional cultivation method. For example, it means that instead of planting 500 plants before, only 100 plants are needed. Not only is the cost of purchasing plants reduced, if you can ship cherry tomatoes in the summer when high prices are expected due to shortage of stock, profits will be enhanced. And as the cultivation name “Sauvage” shows, growth is left alone and there is little management of cultivation. Removal of small and unnecessary buds and leaves, which was needed repeatedly through the growing period in the traditional cultivation of tomato, is necessary only during the initial growing period and, cultivation management such as cross-fertilization and watering is almost unnecessary. Additionally, there is no work such as continuous pinching (pruning of main and lateral branches grown to a certain size), lowering of vines, or spray of plant growth regulators (plant hormone agents) to stabilize the bearing of fruits in the summer. These advantages are valued as innovative and Sauvage Cultivation has now started to become popular nationwide, mainly in the Tohoku region.

“Whole Harvest Cultivation Method of One-year-old Plants” in asparagus

The “Whole Harvest Cultivation Method of One-year-old Plants” in asparagus is also a new cultivation method valued as innovative. In a traditional method of growing asparagus, it is planted in May through June when no frost damage is expected, and is nurtured its plant. Harvest is started one or two years later, and at the beginning, the harvest volume is minimized to nurture the plants again. Every year, the harvest volume is increased, and the cultivation is continued for about 15 years. The problem with the traditional cultivation method is the high incidence of diseases because asparagus continues to be grown (continuously cropped) in the same field. In vegetable cultivation, continuous cropping is avoided as much as possible; instead, crops are rotated where after one vegetable is harvested, another vegetable is grown. However, asparagus is unsuitable for rotation cropping because it takes several years for a regular harvest and even after that, nurturing of plants and harvesting are repeated over several years. And it was always necessary to fight against diseases. Therefore, based on research of the physiology and ecology of asparagus, we have developed a new method to grow asparagus.

With asparagus, spears emerge in a 40- to 50-day cycle, and stems and leaves thrive. In Japan, grown stems and leaves turn yellow in the autumn and, nutrient translocation from the stems and leaves to rhizomes occurs. In the winter, stems and leaves wither (dormancy) and are clipped. And the following year, the plants of the asparagus start to grow again from the size they were before the stems and leaves withered. In other words, if the stems and leaves grow large by autumn in the previous year, we can expect that many spears will be harvested in the following year. Therefore, we came up with an idea to advance the timing for planting to February through March, not in May. The growing cycle of spears is advanced by more than one cycle (40 to 50 days). However, there is frost damage in February through March. Thus, we developed a new instrument for settled planting called Holer (patent pending), by which we can plant asparagus at a depth of about 15 cm, instead of planting it near the surface of the ground. As a result, it has been proven that even if it is very cold, the rhizomes of asparagus can be protected. Asparagus planted by this Holer in February through March grew to a size such that thick asparagus could be harvested in the next year, and for the only three months of the next spring, more than twice the number of spears compared to the annual average crop yield per unit area in the country was harvested. Furthermore, if all stems are harvested with that period, we do not need to nurture more plants. The risk of disease is reduced, and after all spears harvested, the field is vacant, where other vegetables can be grown (rotational cropping). With asparagus, April is called the changeover period of spring harvest (when green-house grown crops end and before open field-grown crops begin) and the shipping volume decreases nationwide; however, if this cultivation method of harvesting all the plants nurtured for one year, called Whole Harvest Cultivation Method of One-year-old Plants, is introduced during the period, spears of asparagus can be shipped in large volume. These points are valued as innovative, and since we publicly announced this cultivation method in 2016 at a seminar inviting farm producers and agricultural instructors, distributors, and others, it has been expanded into joint researches with many different municipalities and research institutes, starting with partnerships with administrative agencies such as Kawasaki City, Tama City in Tokyo, and Yokote City in Akita Prefecture. In the near future, the branded asparagus by Whole Harvest Cultivation Method of One-year-old Plants may make its market debut.

An idea for a breakthrough comes from various experiences
The idea for Whole Harvest Cultivation Method of One-year-old Plants in asparagus came from a cultivation method of planting the seedlings of tomatoes for juice (for processing use) deep in the ground (improved mulching method), which I experienced while I was working in Nagano Prefecture. If we experience different methods of growing vegetables in many regions, we become able to think up many kinds of ideas which are free from a tradition-bound method to grow each crop. In the case of Sauvage Cultivation of cherry tomatoes also, it was important to select a plant variety suited to the cultivation method. Plant varieties whose stems climb well enough to cover the supporting poles of an inverse U shape and make a tunnel (excellent internode elongation) are few in number. We repeated tests to find from among them a plant variety with good internode elongation, easy fruit bearing even in hot weather and less chance of fruit cracking. After all, a plant variety with very good internode elongation is suited to Sauvage Cultivation. In a traditional cultivation method, such variety was avoided, I think because we have to lower the vines many times, which involves additional work. However, when growing tomatoes for juice without supporting poles, I experienced a cultivation method that lets vines trail on the ground without pinching them. This inspired the idea to develop the new cultivation method.

Presently, we repeat a series of tasks where we ask farm producers from all over the country to experience Sauvage Cultivation of cherry tomatoes and Whole Harvest Cultivation Method of One-year-old Plants in asparagus (experimental production); reflect the opinions, improvements and inventions collected there in our laboratory; and feed the results back to the farm producers. Our laboratory holds several seminars every year for people involved such as farm producers and agricultural instructors, distributors, and others. Every time, 200 to 350 participants gather, and by exchanging information with each other, they endeavor to improve their own cultivation techniques and obtain new information. A diversified collaborative research system which is directly connected to the production sites, where our research is reflected in the municipalities and among farm producers without staying in the laboratory, and our research advances further based on that—this is what we aim for, and we believe this to be one of the values offered by the laboratory of a university.


* The information contained herein is current as of March 2018.
* The contents of articles on Meiji.net are based on the personal ideas and opinions of the author and do not indicate the official opinion of Meiji University.


Profile

Satoru Motoki
Associate Professor, School of Agriculture, Meiji University

Research fields:
Vegetable Crop Science

Research themes:

Clarification of physiological and ecological characteristics of different vegetables and development of their stable production techniques and cropping types
Establishment of a system for light labor and labor-saving vegetable crop techniques

Main books and papers:
◆“Asuparagasu no Sagyo Benri-cho” (Useful Notes for Asparagus) (Rural Culture Association Japan: Sole author)
◆“Asuparagasu no Kouhinshitsu Tashuu Gijyutsu” (Techniques for Good-Quality and High-Yield of Asparagus) (Rural Culture Association Japan: Joint author)
◆“Sekai to Nihon no Asuparagasu—Kokusaika-jidai no Nihon no Asuparagasu Saibai—” (Asparagus in Japan and the World—Asparagus Cultivation in Japan in the Age of Globalization—) (Yokendo Co., Ltd.: Author and editor)
◆Effects of various asparagus production methods on rutin and protodioscin contents in spears and cladophylls. Biosci., Biotechnol., Biochem. 76(5):1047-1050
 

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