Pear - Pear (English)

Japanese: ナシ - なし（英語表記）pear

A general term for over 30 species belonging to the genus Pyrus in the family Rosaceae (APG classification: Rosaceae). It is distributed mainly in the temperate zone of Eurasia. It is a deciduous tall tree or shrub. The flowers are white. There are basically five sepals and petals. There are many stamens, and 2-5 pistils, which are separated to the base. The ovary is inferior. It consists of 2-5 ventricles, each with two embryos. The fruit is a pseudocarp with a well-developed thalamus, and the seeds are black. The fruit shape is highly variable. The skin is green to brown, and the flesh contains stone cells. The flesh is mainly white to pale yellowish white, but it can also be black-brown, as in the Himalayan pear ( P. pashia D.Don) that grows wild in Yunnan, China, and Nepal. Some varieties can be eaten immediately after harvest, while others require ripening (storing for a few days to soften). Some have an aroma, while others do not.

[Muneo Iizuka January 21, 2020]

Classification

They are broadly divided into those originating from Europe, the Near East, and Western Asia, and those originating from rainy East Asia. Each type has edible species and rootstock species. The main edible species in the former are the European pear P. communis L., and the latter are the Chinese pear and the Japanese pear.

European pear leaves have a glossy surface, are oval to oblong in shape, and have short, pointed tips. The fruit can be in the shape of an inverted cone, sphere, or oval, and has few stone cells. As it ripens it softens, the flesh becomes buttery, fragrant, and tasty. It can be eaten raw or processed. Another known species is the snow pear ( P. nivalis Jacq.), which is distributed from western Switzerland to France and is the raw material for perry wine.

There are more than a dozen species of pear native to China. However, only two groups are widely cultivated: the Ussurian pear ( P. ussuriensis Maxim.), which is widely distributed in the northeastern region; the white pear ( P. bretschneideri Rehd.), which is common in the Yellow River basin and Hebei Province; and the sand pear ( P. pyrifolia Nakai), which is common in the Yangtze River basin. The other species are only cultivated locally. Ussurian pears are tall trees, 10 to 15 meters tall, with many thorns in young trees, densely hairy young branches, and large, broad-egg to oval leaves with sharp sawtooth edges. Most are green pears with green-yellow skin, and the fruit is spherical with the calyx remaining. It requires after-ripening, has many stone cells, and is fragrant. Many can withstand temperatures of around -30°C. The white pear group grows to a height of 8-13 meters, with spreading branches and twigs that are either glabrous or slightly hairy. The leaves are large and oval with sharp sawtooth. The fruits are large and obovate to oblong, with greenish-yellow skin, although some have a pale pink tinge. They have no persistent calyx or only a slight one. The stone cells are small and densely distributed, with little fragrance. They do not require after-ripening and have high storage capacity. Examples of this group include the Yari pear and the Chiupairi pear. The Suna pear is of the same family as the Yamanashi P. pyrifolia (Burm.f.) Nakai ( P. pyrifolia Nakai var. montana Nakai), which is a descendant of the Japanese pear, and is very similar to the Yamanashi in terms of tree shape, flowers, and fruit.

The Japanese pear is based on the Yamanashi, a species native to Japan, and is also partially descended from the Michinoku Yamanashi (Iwate Yamanashi), P. ussuriensis Maxim. var. aromatica Rehd., also native to Japan. The leaves are elliptical to ovate, entire or with serrated edges. The flowers are white, or occasionally pale pink, and have a bad fragrance. The fruits are spherical, oblate, or oblong, weighing 200-500 grams, and have a brown Akanashi skin, green-yellow Aonashi skin, or intermediate colors. The ripe fruit usually does not retain the calyx. It has many stone cells and a hard flesh, but it has been improved in new cultivars. Other species found in Japan include the Blue Pear, P. ussuriensis Maxim. var. hondoensis Rehd., which grows wild occasionally from the Kanto to Chubu regions and has a green-yellow skin; the Mamenashi (also known as Dog Pear), P. calleryana Decne. var. dimorphophylla Koidz., which grows wild in central Honshu and has a brown skin and two ventricles; and the Ainashi , P. × uyematsuana Makino, a natural hybrid between a cultivated species and a Mamenashi, which has three ventricles.

[Muneo Iizuka January 21, 2020]

Cultivation history and differentiation of varieties

The European pear is one of the oldest fruit trees in Europe. The ancient Greek poet Homer wrote that pears were cultivated as a gift from the gods, and by the time of Theophrastus, varieties had been established and grafting propagation was practiced. Around 50 AD, varieties began to differentiate, and 35 varieties were recorded. Eventually, cultivation spread to central Europe. Economic cultivation began in England around 1200. In the 18th and 19th centuries, breeding progressed rapidly, and today's major cultivated varieties were established. Williams Bon Chretien, which was born in England as a seed-grown variety around 1796, is called Bartlett in America, and is still a major variety in the world today. In Belgium, Winter Nelis and Flemish Beauty were selected. La France and Precose, which were discovered in France, also date from this time.

Pear cultivation in China has been around for a long time, recorded in the Chenfeng chapter of the Book of Songs, and has a history of over 2,500 years. Names such as "Ru Mi Li", "Hong Li", "Bai Li" and other names appear in ancient texts such as the Erya, Records of the Grand Historian, Records of the Three Qins, and Flower Mirror. Grafting propagation, pest control, storage and processing are also recorded in the Qimin Yaoshu. Cold-resistant cultivars such as the Nankuo Li and Jing Bai Li were developed in the northeastern region, while the Kamo Pear, Ci Pear and Qiu Bai Pear have differentiated in the Yellow River basin. In recent years, Japanese cultivars have been introduced to Henan and the Yangtze River basin, and are widely cultivated.

In Japan, the oldest written record is in the "Nihon Shoki" (720), and in the chapter on Empress Jitō (Jitō Tennō), there is a recommendation to cultivate pears and other fruits. The "Sandai Jitsuroku" (908) records pears from Shinano Province, and the "Engishiki" (905-928) records green pears from Kai Province. In 1782 (Tenmei 2), a total of 94 early, mid-season and late-season varieties were recorded, along with records of advanced cultivation methods such as grafting, trellis making and pruning. From this time on, cultivation spread nationwide, and Niigata, Yamagata and Kanagawa prefectures all have a cultivation history of over 250 years. Around 1895 (Meiji 28), the well-known "Chōjūrō" and "Nijisseiki" varieties were discovered. Chojuro was discovered as an accidental seedling in the orchard of Touma Chojuro in Kawasaki City, Kanagawa Prefecture, and is a red pear variety that is disease-resistant and highly productive. Nijisseiki was discovered as an accidental seedling in the residential lot of Matsudo Kakunosuke in Matsudo City, Chiba Prefecture, and is a variety that is weak to black spot disease, but has a good shape, is productive, and has excellent taste. The name Nijisseiki was given to it in 1898 as a variety that would lead the 20th century. Other well-known varieties include the early-ripening Aka Wase and the late-ripening Okusan Kichi. In recent years, breeding has progressed with the goal of developing disease-resistant, high-quality fruit, and varieties such as Kosui, Shinsui, Hosui, Niitaka, Shinko, Akizuki, and Nansui have been developed and spread by the Ministry of Agriculture, Forestry and Fisheries' Fruit Tree Experiment Station. Also attracting attention are the emergence of self-compatible traits due to natural mutations in the twentieth century, and black spot resistance traits due to gamma ray irradiation. European pears were introduced by the Hokkaido Development Commission in the early Meiji period (1872-1873), while Chinese pears, such as the Kamo pear, were introduced by the Industrial Promotion Bureau in 1867 (Keio 3), and the Laiyang Ci pear in 1912 (Taisho 1).

[Muneo Iizuka January 21, 2020]

Cultivation

Japanese pears are propagated by grafting onto a common rootstock, while European pears are propagated by grafting onto a Japanese pear rootstock or a quince rootstock, which is similar to European pears but belongs to a different genus, Quince. Planting should be done as early as possible in winter, with 19-33 plants per 10 ares. Pears are self-incompatible, so other economic varieties that are compatible and have the same flowering period are planted together for pollination. They are trained on trellises to avoid typhoons and make work easier. One flower cluster is allowed per fruit, and the fruit is bagged to protect against diseases and pests and to keep the skin beautiful. When green pears reach a diameter of 2-3 cm, they are transferred to large bags. To prevent powdery mildew, black spot, black spot, red spot, aphids, fruit moths, red mites, etc., pesticides such as "Polyoxin", "Dithen", "Sumithion", and "Kelthane" are sprayed several to a dozen times a year. Red star disease uses the juniper tree, which is a member of the cypress family, as an intermediate host, so this tree should not be planted nearby.

In 1984 (Showa 59), the area of Japanese pear trees bearing fruit was 18,700 hectares, with a total yield of 474,000 tons, of which Nijisseiki accounted for 33.9% in area and 35.4% in yield, Chojuro 17.1% and 19.3%, and Kosui 19.8% and 18.9%. After that, Chojuro fell out of favor due to its hard flesh and poor shelf life, and was no longer cultivated. In 2015 (Heisei 27), the area of Japanese pear trees bearing fruit was 12,400 hectares, with a total yield of 247,300 tons, with Kosui having the highest yield at 32.1%, followed by Hosui at 21.2%, and Nijisseiki at 4.7%. In terms of area by prefecture in 2015, Chiba had 12.7%, Ibaraki 9.0%, followed by Fukushima, Tottori, Tochigi, and Nagano. Yields per 10 ares are 1,670 kilograms for Kosui, 2,270 kilograms for Hosui, and 2,000 kilograms for Nijisseiki. The main variety of European pear is La France, followed by Le Lectier and Bartlett, with 1,510 hectares and 29,200 tons produced nationwide, with most of the production in Yamagata, Aomori, and Nagano prefectures. Looking at the world, a total of 26.76 million tons were produced in 2015, with China producing the most, mainly Chinese pear, at 18.69 million tons, followed by Argentina producing European pear at 870,000 tons, followed by Italy, the United States, and Türkiye.

[Muneo Iizuka January 21, 2020]

Cultural history

In China, the beauty of flowers has been praised since ancient times, such as "A branch of pear blossoms, bringing spring rains" in Bai Juyi's Song of Everlasting Regret. On the other hand, in Japan, there are four poems about pear blossoms in the Manyoshu, but three of them talk about yellow leaves, and the remaining one does not talk about flowers at all. In "The Pillow Book," "Tree Flowers," it is said that pear flowers are so terrible that they cannot be approached, and unlike plums and peaches, it does not directly adopt the aesthetic sense of continental literature. According to "Rites and Music" in the Book of Tang, Emperor Xuanzong of the Tang Dynasty loved music and drama, and built a training school in the Forbidden Garden in Chang'an, where pears were planted, and personally taught 300 children of actors. From this came the term "Pear Garden." In Japan, it also refers to the society of actors and kabuki actors. In the Heian period, Shoyosha in the Imperial Palace was called Nashitsubo (Pear Pot) because a pear tree was planted in front of it. The Five Immortal Poets of the Pear Pot are Akazomeemon, Izumi Shikibu, Murasaki Shikibu, Umanonai, and Ise no Tayu. The Five Immortal Poets of the Pear Pot are Onakatomi Yoshinobu, the compiler of the Gosenshu, Kiyohara Motosuke, Minamoto no Shitagou, Ki no Tokibumi, and Sakanoue no Mochiki.

In China, pears were not written as pears before the Common Era. They appear in the "Gantang" section of the "Book of Songs" as 甘棠, and in the "Chenfeng" section as じゅすい. Gantang is said to be a descendant of the southern Shatang and Sari, and the tree is said to be a descendant of the northern Bai pear and Qiuzhi pear. Sari pears measuring 3-4 cm in diameter were excavated from the Mawangdui No. 1 Western Han Tomb in Changsha. Documents from the 10th century BC to the 3rd century AD show a change from wild pears to cultivated pears in the order of 蟤, 柤, 杜, gantang, and 沙棠 (Biological History, 1979, published by the Chinese Academy of Sciences). Among the ancient varieties of pears in China, there were many unusual ones, such as the Han Dynasty's Ganxiang pear, which was about 5 sho in size. To date, there are said to be as many as 3,500 varieties ("Biological History"). The widespread popularity of pears throughout Japan is largely due to the contributions of Chojuro and Nijisseiki, who appeared during the Meiji period. Oku Tokuhei of Oyodo Town, Nara Prefecture, improved a pear introduced from China and sold it as "Gaika," but this was deemed to be the same variety as Nijisseiki, which led to a lawsuit. Oku lost the lawsuit, but stuck to his guns for the rest of his life. The Nijisseiki is the local flower (prefectural flower) of Tottori Prefecture.

[Hiroshi Yuasa January 21, 2020]

Food

The fruit contains 10-14% sugar, 140-170 mg of potassium and 3-6 mg of vitamin C per 100 grams of flesh, and has 40-55 kilocalories. In addition to being eaten raw, it is mainly processed into canned products, juice, nectar, etc. For canning, after ripening, the pear is peeled, halved, and cored, and then soaked in salt water or a 0.2% hydrochloric acid solution to prevent oxidative browning caused by polyphenolic substances. After processing, 33-36% sugar solution is added to the processed fruit at 60-65% by weight. The acidity of the finished product is adjusted to 0.25-0.3% with citric acid. The product is then degassed, sealed, and sterilized (95°C for 20-25 minutes) to complete the process. The juice is squeezed, filtered, degassed, sealed, and sterilized, either raw or after heating. Adding vitamin C during juicing prevents browning. Nectar is made by heating and softening the flesh of the fruit, creating a drink that tastes as fresh as if the fruit had been crushed. Bartlett pears are often used as the raw material.

[Muneo Iizuka January 21, 2020]

Japanese Pear (Chojuro)
©Shogakukan ">

Japanese Pear (Chojuro)

Japanese pear (Kosui)
©Shogakukan ">

Japanese pear (Kosui)

Japanese pear (Shinsui)
©Shogakukan ">

Japanese pear (Shinsui)

Japanese pear (Hosui)
©Shogakukan ">

Japanese pear (Hosui)

Japanese pear (20th century)
©Shogakukan ">

Japanese pear (20th century)

Japanese pear (Bansankichi)
©Shogakukan ">

Japanese pear (Bansankichi)

Japanese pear flower
In April, white five-petaled flowers bloom in corymbs in the leaf axils. ©Shogakukan Photo by Hideyuki Asakura ">

Japanese pear flower

Japanese pear fruit
The skin is green to brown, and the shape of the fruit varies widely. They ripen from summer to autumn. There are many varieties of Japanese pears, including Chojuro, Nijisseiki, Kosui, and Hosui .

Japanese pear fruit

European pear (La France)
©Shogakukan ">

European pear (La France)

European pear (Bartlett)
©Shogakukan ">

European pear (Bartlett)

Pear (Le Lectier)
©Shogakukan ">

Pear (Le Lectier)

Pear (pre-cooked)
©Shogakukan ">

Pear (pre-cooked)

Chinese pear (red pear)
©Shogakukan ">

Chinese pear (red pear)

Chinese pear fruit
A variety of Chinese pear, Kamo-nashi. It is large, obovate to oblong, with a greenish-yellow skin. ©Shogakukan ">

Chinese pear fruit

Pear orchards as seen in "Edo Meisho Zue"
The cultivation of Japanese pears can already be seen in the "Nihon Shoki" and "Sandai Jitsuroku." By the latter half of the Edo period, there were over 150 varieties, and many new varieties have been created since the Meiji period. The picture shows commercial pear cultivation in the Edo period. The trellis training is a cultivation method unique to Japan. "Edo Meisho Zue," Volume 7, National Diet Library .

Pear orchards as seen in "Edo Meisho Zue"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

バラ科（APG分類：バラ科）ナシ属Pyrusに属する30余種の総称。ユーラシアの主として温帯に分布する。落葉高木ないし低木。花は白色。萼片(がくへん)、花弁ともに5枚を基本とする。雄しべは多数、雌しべは2～5本で基部まで分離する。子房は下位。2～5心室からなり、各室に2胚座(はいざ)をもつ。果実は花托(かたく)が発達した偽果(ぎか)で、種子は黒い。果形は変異に富む。果皮は緑色から褐色で、果肉内に石細胞(せきさいぼう)がある。果肉は白色から淡黄白色を主とするが、中国の雲南省、ネパールに自生するヒマラヤナシ（パッシア種）P. pashia D.Donのように黒褐色もある。収穫直後に食べられる種類と後熟（数日間貯蔵して軟化させること）を要するものとがある。芳香はあるものとないものがある。

［飯塚宗夫　2020年1月21日］

分類

ヨーロッパ、近東、西アジア起源の種類と多雨の東アジア起源の種類に大別される。いずれも食用種と台木用種とがある。食用種では主として前者にはセイヨウナシP. communis L.が、後者にはチュウゴクナシとニホンナシがある。

　セイヨウナシは、葉は表面に光沢があり、卵形から長楕円(ちょうだえん)形で葉先は短く、とがる。果実は倒円錐(とうえんすい)、球、卵形などあり、石細胞は少ない。後熟すると軟化し、肉質はバター様となり、芳香に富み、味はよい。生食、加工用とする。このほかにスイス西部からフランスに分布し、ペリー酒perryの原料となるユキナシ（ペリーナシ）P. nivalis Jacq.が知られる。

　中国を原生地とするナシ属には十数種がある。しかし東北地方に広く分布するウスリーナシ（秋子梨(チウズリー)）P. ussuriensis Maxim.群と黄河流域、河北省に多い白梨(パイリー)（チュウゴクナシ）P. bretschneideri Rehd.群の2群および揚子江(ようすこう)流域に多い砂梨(シャーリー)P. pyrifolia Nakai群が大栽培され、他の種は地方的に栽培されるにすぎない。ウスリーナシは高木で10～15メートル、幼樹は刺(とげ)が多く、若枝は毛を密生し、葉は大きく、広卵から卵円形で鋭い鋸歯(きょし)がある。果皮が緑黄色の青ナシが多く、果実は球形で萼を残す。後熟を要し、石細胞は多く、芳香がある。多くは零下30℃前後に耐える。白梨群は樹高8～13メートル、枝は開張性で小枝は無毛かわずかに柔毛がある。葉は卵円形で鋭い鋸歯があり、大きい。果実は倒卵球から長球形で大きく、果皮は緑黄色であるが、淡紅色を帯びるものもある。宿存萼はないか、あっても軽度である。石細胞は小さく、密に分布し、香りは少ない。後熟は不要で貯蔵性が高い。鴨梨(ヤーリー)、秋白梨(チウパイリー)などがこれに属す。砂梨はニホンナシの系統であるヤマナシP. pyrifolia (Burm.f.) Nakai（P. pyrifolia Nakai var. montana Nakai）と同類で、樹形、花、果実などヤマナシによく似ている。

　ニホンナシは日本原産のヤマナシを基本種とし、一部では同じく日本原産のミチノクヤマナシ（イワテヤマナシ）P. ussuriensis Maxim. var. aromatica Rehd.の血も受けている。葉は楕円から卵形で、全縁または鋸歯をもつ。花は白色で、まれに淡紅色のものもあり、香りは悪い。果実は球、扁球(へんきゅう)、長球形などで、200～500グラム、果皮は褐色のアカナシ、緑黄色の青ナシおよび中間色がある。熟果は普通は萼を残さない。石細胞は多く肉質は硬いが、新品種では改良されてきた。日本にはそのほか、関東から中部にまれに野生し、果皮が緑黄色のアオナシP. ussuriensis Maxim. var. hondoensis Rehd.、本州中部に自生し、果皮が褐色で2心室のマメナシ（別名イヌナシ）P. calleryana Decne. var. dimorphophylla Koidz.、栽培種とマメナシの自然雑種で3心室のアイナシP. × uyematsuana Makinoなどがある。

［飯塚宗夫　2020年1月21日］

栽培史と品種の分化

セイヨウナシはヨーロッパではきわめて古い果樹の一つである。古代ギリシアの詩人ホメロスは「ナシは神の贈り物」として栽培されていたことを示し、またテオフラストスのころには品種が確立され、接木(つぎき)繁殖が行われていた。紀元50年ころになると品種は分化を始め、35品種が記録された。やがて栽培地はヨーロッパ中部へと広まった。イギリスでは1200年ころから経済栽培が始まった。18～19世紀には品種改良が急速に進み、今日の主要栽培品種が確立した。イギリスで1796年ころに実生(みしょう)品種として生まれたウィリアムス・ボン・クレッシェンWilliams Bon ChretienはアメリカではバートレットBartlettとよばれ、今日も世界の主要品種となっている。ベルギーではウィンターネリスWinter Nelis、フレミッシュビューティFlemish Beautyなどが選ばれた。フランスでみいだされたラ・フランスLa France、プレコースPrecoseなどもこのころのものである。

　中国におけるナシ栽培は古く、『詩経』の晨風篇(しんぷうへん)に記載され、2500年以上の歴史をもつ。『爾雅(じが)』『史記』『三秦記(さんしんき)』『花鏡(かきょう)』などの古籍にも「如蜜梨(ルーミーリー)」「紅梨(ホンリー)」「白梨」その他の名がみられる。『斉民要術(せいみんようじゅつ)』には接木繁殖、害虫防除、貯蔵加工なども記録されている。東北地区では南果梨(ナンクオリー)、京白梨(チンパイリー)など耐寒性品種群が育成され、黄河流域では鴨梨、慈梨(ツーリー)、秋白梨などが分化してきた。近年では河南や揚子江流域などへ日本品種が導入され、栽培も多い。

　日本では『日本書紀』（720）の記載が最古の文献で、持統天皇(じとうてんのう)の章に梨その他栽培の勧めがある。『三代実録』（908）には信濃国(しなののくに)から梨が、『延喜式(えんぎしき)』（905～928）には甲斐国(かいのくに)から青梨子が献じられた記録がある。1782年（天明2）には早生(わせ)、中生(なかて)、晩生(おくて)合計94品種が記録され、接木、棚づくり、剪定(せんてい)法など進んだ栽培法の記録もある。このころから全国的に栽培が広がり、新潟、山形、神奈川県などはいずれも250年以上の栽培歴史をもつ。1895年（明治28）ころ、今日よく知られる「長十郎」と「二十世紀」が発見された。長十郎は神奈川県川崎市の當麻長十郎のナシ園で偶発実生として発見されたもので、病気に強く豊産性の赤ナシ品種である。また、二十世紀は、千葉県松戸市の松戸覚之助の宅地内で偶発実生として発見されたもので、黒斑(こくはん)病には弱いが、形もよく豊産で食味が優れた品種である。二十世紀の名は、1898年、20世紀を担うべき品種としてつけられた名である。このほか、早生の赤(あか)早生、晩生の晩三吉(おくさんきち)などもよく知られる。近年、耐病性で品種のよい果実を目標とした育種が進み、農林水産省果樹試験場によって幸水(こうすい)、新水(しんすい)、豊水(ほうすい)、新高(にいたか)、新興(しんこう)、秋月(あきづき)、南水(なんすい)などの品種が育成され、普及してきた。また、二十世紀の自然突然変異による自家和合形質、γ(ガンマ)線照射による黒斑病抵抗性形質の出現も注目されている。セイヨウナシは明治初期（1872～1873）に開拓使により導入され、チュウゴクナシは鴨梨が1867年（慶応3）勧業寮により、莱陽慈梨(ライヤンツーリー)は1912年（大正1）に導入された。

［飯塚宗夫　2020年1月21日］

栽培

繁殖はニホンナシでは共台(ともだい)、セイヨウナシではニホンナシ台かセイヨウナシに似ているがナシ属とは別のマルメロ属のマルメロ台を用いた接木(つぎき)による。植え付けは冬季なるべく早く行い、10アール当り19～33本とする。ナシは自家不和合なので、交配親和で開花期が同じ他の経済品種を授粉用に混植する。台風を避け、作業を容易にするため棚仕立てとする。1花房1果とし、袋かけをし、病気、害虫を防ぐとともに、果皮を美しく保つ。青ナシでは果径2～3センチメートルになったとき、大袋にかけかえる。うどんこ病、黒斑病、黒星病、赤星病やアブラムシ、シンクイムシ、アカダニなどを防除するため「ポリオキシン」「ダイセン」「スミチオン」「ケルセン」などの薬剤を年数回から十数回散布する。赤星病はヒノキ科のビャクシンを中間宿主とするので、この木を近くには植えないようにする。

　1984年（昭和59）のニホンナシの結果樹面積は1万8700ヘクタール、総収量は47万4000トンで、そのうち二十世紀が面積で33.9％、収量で35.4％を、長十郎が17.1％と19.3％を、幸水が19.8％と18.9％を占めていた。その後、長十郎は果肉が硬く、日持ちが悪いことが嫌われ、栽培されなくなった。2015年（平成27）のニホンナシの結果樹面積は1万2400ヘクタール、総収量は24万7300トンで、もっとも収穫量の多いのは幸水で32.1％、ついで豊水が21.2％、二十世紀が4.7％となっている。府県別面積順位では2015年では千葉12.7％、茨城9.0％で、以下福島、鳥取、栃木、長野と続く。10アール当り収量は幸水で1670キログラム、豊水2270キログラム、二十世紀2000キログラムである。セイヨウナシはラ・フランスが主で、ル・レクチェ、バートレットが続き、全国で1510ヘクタール、2万9200トンを産し、山形、青森、長野県に多い。世界をみると、2015年では総計2676万トンを産し、国別ではチュウゴクナシを主とする中国が1869万トンともっとも多く、ついでセイヨウナシのアルゼンチンが87万トン、以下イタリア、アメリカ、トルコと続く。

［飯塚宗夫　2020年1月21日］

文化史

中国では白楽天の長恨歌に出ている「梨花(りか)一枝春帯雨」をはじめ、古くから実よりも花の美しさがたたえられた。一方、日本では『万葉集』に4首詠まれているが、うち3首は黄葉(もみちば)を詠み、残りの1首も花を取り上げてはいない。『枕草子(まくらのそうし)』「木の花」では、梨(なし)の花世にすさまじきものにして近うもてなさず、と述べ、梅、桃と異なり大陸の文学の美意識をそのまま取り入れてはいない。『唐書(とうじょ)』の「礼楽」によると、唐の玄宗皇帝は音律や戯曲を好み、長安の禁苑(きんえん)の梨が植えられていた園に養成所をつくり、俳優の子弟300人を自ら教えた。これから梨園(りえん)の呼称が生じた。日本でも俳優や歌舞伎(かぶき)役者の社会をいう。平安時代、内裏(だいり)の昭陽舎は、その前に梨を植えたので、梨壺(なしつぼ)とよばれた。梨壺の五歌仙は赤染衛門(あかぞめえもん)、和泉式部(いずみしきぶ)、紫式部、馬内侍(うまのないし)、伊勢大輔(いせのたゆう)の5人をいう。また、梨壺の五人とは、『後撰集(ごせんしゅう)』の撰者の大中臣能宣(おおなかとみのよしのぶ)、清原元輔(きよはらのもとすけ)、源順(みなもとのしたごう)、紀時文(きのときぶみ)、坂上望城(さかのうえのもちき)をさす。

　ナシは中国では紀元前には梨と書かれていなかった。『詩経』の『甘棠(かんとう)』に甘棠、「晨風(しんぷう)」に樹(じゅすい)の名で出る。甘棠は南方の沙棠(さどう)、沙梨(さり)の、樹は北方の白梨や秋子梨の系統とされる。長沙(ちょうさ)にある馬王堆(まおうたい)1号前漢墓からは直径3～4センチメートルの沙梨が出土している。紀元前10世紀から後3世紀にかけての文献には、、(り)、柤(そ)、杜(と)、甘棠、沙棠の順で野生梨から栽培梨への変化がみられるとされる（『生物史』1979・中国科学院出版）。中国の古い梨の品種のなかには、漢代の含消梨(がんしょうり)のような5升大の大きさの梨など変わり物がいろいろあった。現在までに3500もの品種が数えられるという（『生物史』）。日本でナシが全国に普及するのは明治時代に登場した長十郎と二十世紀の功績が大きい。奈良県大淀(おおよど)町の奥徳平(おくとくへい)は中国より導入した梨を改良して「凱歌(がいか)」として売り出したが、それが二十世紀と同一品種とされ、訴訟を引き起こした。奥は裁判では敗れたが、終生、主張を譲らなかった。二十世紀は鳥取県の郷土の花（県花）である。

［湯浅浩史　2020年1月21日］

食品

果実は糖分10～14％で、果肉100グラム中にカリウム140～170ミリグラム、ビタミンC3～6ミリグラムを含み、40～55キロカロリーをもつ。生食のほか主として缶詰、果汁、ネクターなどに加工される。缶詰の場合、セイヨウナシでは追熟ののち、除皮、半切りにして芯(しん)をとり、ポリフェノール物質による酸化褐変を防ぐため食塩水か0.2％の塩酸水溶液に浸(つ)ける。処理後、33～36％の糖液を処理果に対し重量比で60～65％加える。成品の酸度は0.25～0.3％とし、クエン酸で調節する。その後、脱気、密封、殺菌（95℃、20～25分間）により完成する。果汁は、生果のまま、または果実を加熱したのち、搾汁、濾過(ろか)、脱気、密封、殺菌する。搾汁のときビタミンCを加えると褐変が防げる。ネクターは、果肉を加熱軟化して調整し、生果をそのままつぶしたような新鮮な感じの飲料としたもので、原料にはセイヨウナシのバートレットが多く用いられる。

［飯塚宗夫　2020年1月21日］

[参照項目] | 赤星病 | アブラムシ | うどんこ病 | 偽果 | 黒斑病 | 梨壺の五人 | バラ科 | 梨園

ニホンナシ（長十郎）

ニホンナシ（幸水）

ニホンナシ（新水）

ニホンナシ（豊水）

ニホンナシ（二十世紀）

ニホンナシ（晩三吉）

ニホンナシの花

ニホンナシの果実

セイヨウナシ（ラ・フランス）

セイヨウナシ（バートレット）