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a genus of annual and perennial plants of the family Leguminosae. It comprises six or seven species. In the USSR there are five or six species, including the perennials P. formosum and P. aucheri, which grow in the Caucasus and Asia Minor (sometimes they are classed in a distinct genus, Vavilovia). The other species are the annuals P. syriacum, grown in Transcaucasia, the eastern Mediterranean region, and Asia Minor; Mediterranean pea (P. elatius), grown in the Caucasus, the Mediterranean region, and the Near East as far as Tibet and India; and garden pea (P. sativum), which is divided into the subspecies garden pea (ssp. sativum), field pea (ssp. arvense, sometimes classified as the independent species P. arvense), Asian pea (ssp. asiaticum), and Transcaucasian pea (ssp. transcaucasicum), which is widely distributed in cultivation. In Ethiopia and Yemen, P. abyssinicum grows in both wild and cultivated states.
Pisum has a taproot that penetrates the earth to depths of at least 1 m. The stem is 15–250 cm tall, and it sometimes branches. The leaves are paripinnate, with one to three pairs of leaflets, and as a rule they end in tendrils. There are axillar flowers, usually one or two and more rarely three to seven on a flower stalk, with a corolla ranging in color from white to purple-violet. The fruits (legumes) are cylindrical or flattened, and straight or curved. The seeds (peas) are smooth or wrinkled and have a colorless or colored seed coat, sometimes with a pattern.
M. E. KIRPICHNIKOV
The garden pea is an annual spring or winter plant. The stem has four sides and is bare and lodging. The leaves are blue-gray (with a waxy tinge) or green and have two large stipules at the base. The flowers are white with greenish veins, pink, or reddish-violet. Inside the pods of shelling peas there is a parchment layer. Each bean contains three to 11 seeds (smooth or wrinkled) of various coloring (light green, yellow, speckled, and so forth); 1,000 seeds weigh from 35 to 400 g. The germination period lasts from 45 to 120 days or more. The flowering period is extended. Pisum is self-pollinating, but during a hot, dry summer cross-pollination is possible. Pisum seeds start to grow at temperatures of 1c-2° C; the shoots tolerate frosts of 5°-10° C. The optimal temperature for the formation of vegetative organs is 12°-16° C, and 16°-20° C during budding and flowering. The transpiration coefficient is 400–450. The best soils for Pisum are loamy soils with sufficient aeration and a weak acidic or neutral reaction.
Peas are raised as high-protein food and fodder plants. The grain (mature seeds) is used as food, either boiled or shaped into groats, flour, or canned goods. The green peas and green pods are used as food, either fresh, boiled, or canned. Fodder varieties (the green bulk, hay, and grain), as well as the pea straw and chaff, are fed to cattle.
Pisum is known to have been cultivated since the fourth century B.C. It is considered to be native to eastern Afghanistan and northwest India. Outside the USSR in 1970 more than 6 million hectares (ha) were sown with peas, including about 300,000 ha of green peas. The largest growing areas of peas are in China. India, the USA, Rumania. Hungary, the German Democratic Republic, and Great Britain. In the USSR in 1970 peas were raised in an area of 3.350 million ha; the gross output of grain was more than 5 million tons, and the average harvest was 16.3 centners from I ha. and 30–40 centners in outstanding farms. The basic regions of pea cultivation in the USSR are the central chernozem and noncher-nozem zones, the Volga region, the Ukraine, the Baltic region, the Urals, and Siberia. The grain varieties grown include Ramonskii 77. Torsdag. Kapital. and Uladovskii 208: the fodder varieties are Vostok 55 and Ukosnyi 1: and the vegetable varieties include Pobeditel’ G-33 and Neisto-shchimyi 198.
The best predecessors for peas are sugar beets, potatoes, fertilized winter crops, maize, cabbage, tomatoes, cucumbers, and root crops. Peas themselves are a good predecessor for other crops, because they leave in the soil a large quantity of nitrogen. Peas are cultivated in occupied fallow lands too. In autumn the field used for peas is cleared of husks (when the peas are sown after the grain crops) and autumn-plowed; in the spring it is harrowed and cultivated, and before seeding it is evened out with floats, harrows, or rollers. Phosphorus and potassium fertilizers accelerate maturation and increase the size and quality of the harvest. Molybdenum is applied to soddy-podzolic soils. Before sowing, the seeds are treated with nitrate. Peas are sown as early as possible in the spring, using the row. narrow-row. or crossover methods. The sowing norm for small-seed varieties is 1.5–2 centners per ha, and for large-seed varieties 2.5–3.5 centners per ha (1–1.2 million seeds to I ha) the seeds are planted 4–8 cm deep. Winter sowing is possible in the south. In moist regions peas lodge, and for this reason they are sown with a mixture of oats, phacelia, mustard, and other crops that mature at the same time. Peas are usually harvested by various means when 70 percent of the beans are ripe; in the south they are harvested by straight combine method.
The most dangerous pests in peas are the pea and bean weevil, the pea beetle, the pea aphid, and the pea moth. The most dangerous diseases are rust, powdery mildew, and one caused by Ascochyta fungus.
REFERENCESFedotov. V. S. Gorokh. Moscow. 1960.
Solov’eva. V. K., and Z. V. Dvornikova. Bobovye ovoshchnye kul’tury. Moscow, 1963.
[Generalov. G. F.] Soria i agrotekhnika gorokha. Moscow, 1964.