Crops

Secale cereale L. - Cereal rye

Taxonomic position

Family: Poaceae Barnhart, genus: Secale L., species: Secale cereale L. - Cherepanov S.K., 1995. Intraspecific classification of rye proposed by Kobylyansky V.D. includes five subspecies: subsp. cereale, subsp. vavilovii (Grossh.) Kobyl., subsp. tetraploidum Kobyl., subsp. derzhavinii (Tzvel.) Kobyl., subsp. tsitsinii Kobyl.

Biology and morphology

2n=14. Rye is an annual herbaceous. It has a fibrous root system consisting of 3 to 4 embryonic (primary) roots which are formed at the moment of seed germination and of nodose (secondary) roots shooting off the underground stem nodes in the area of tillering node. The main primary tillering node is located at the depth of 0.5 to 2 cm, this depth depending on the length of the mesocotyl (the underground internode) which joins the caryopsis with the node. The resistance of different rye varieties to lodging to a great degree depends on the development of its root system and on its cohesion with the soil. Rye stem is a hollow straw consisting of 3 to 7 internodes separated by nodes. Some varieties have been observed to possess a filled upper internode. The cultivated rye plants are 80 to 180 cm high. On the whole rye height may vary with its different varieties from 10 or 15 to 300 cm. The stem of vegetating rye is green with a bluish-gray shade due to a waxy film. There are rye varieties with no waxy film. This waxy film does not protect the stem tissues from penetration of mycosis pathogens. Mature stems are yellow or to different degrees tinged with anthocyan. The stem surface is glabrous. Below the spike is slightly downy. But varieties without down are quite common. The leaf consists of a sheath tightly enveloping the stem, of a linear-lanceolate lamina of the leaf with a ligula and auricles at the base. The rye ligula is horizontally truncated and is located there where the sheath turns into the leaf lamina. It tightly envelops the stem protecting it from the penetration of moisture and insects. There are rye varieties with an oblique ligula or with no ligula at all. It has been determined that the size of the second leaf from the top allows to predict the foliage of the plant as the size of this leaf is equal or close to that of the average leaf. Long and narrow leaves are typical of more drought-resistant varieties while short and wide leaves are typical of low yielders which are relatively late-maturing and are prone to suffer from mildew. Rye inflorescence is a compound spike of imperfect type (without the topmost spikelet). On each nodus of the rhachilla segment there is one biflorous or - more rarely - triflorous spikelet. The two lower flowers are sessile. The third flower has a pedicle. Each productive stem usually forms one spike. Rye rhachilla is not ramose, but there are some rye varieties with hereditarily ramose rhachillae. Cultivated rye varieties have white (straw-colored) spikes. Some old local populations have reddish-brown spikes. Wild growing rye has white, reddish-brown, brown and black spikes. Rye spikes are covered with a waxy film which may be better or worse pronounced depending on specific varieties' features and climatic conditions. A well-pronounced waxy film is typical of cultivars bred in the areas with hot summers as this film protects spikes from overheating reflecting some sunlight. Rye fruit is an oblong or oval caryopsis flattened at the sides. The color of rye grains depends on the combination of the color, thickness and transparency of the seed and fruit coats and of the color of the aleurone layer. They may be white, yellow, light-blue, violet, brown or have different shades of green. 1000 seeds weigh 30 to 45 g.

Ecology

Winter rye is a winter-hardy plant. During winters with little snow it can survive frosts of 30-35°C. It is quite drought-resistant as well. Winter-hardiness is a complex feature which includes cold-resistance and resistance to damping put, which is often related to resistance to snow mold, and to resistance to ice crust and lifting, as well. Therefore it may be increased by land treatment (melioration, high quality of tillage, and timely sowing). Cold resistant rye plants have some typical morphological and biological features. They have narrow and short rosetted leaves with a microcellular structure, spreading bushes, a thicker outer epidermis wall, a short mesocotyl and, therefore, a deeper tillering node. Frost-resistant plants grow more slowly in autumn have a relatively higher concentration of dry matter in their cell sap. They expend this dry matter in their growth processes and respiration in a more economical way. Their vegetation period lasts for 120 to 150 days (their autumnal vegetation period lasting for 45 to 50 days while their spring and summer vegetation period lasting for 75 to 100 days). Rye grows on different kinds of soil except waterlogged soils. It thrives on the black earth. Rye is an allogamous (cross-pollinating) anemophilous plant. Under favorable conditions it begins blossoming on day 7 to 10 after ear formation. With cultivated rye cultivars the anthers usually burst after 1 to 2 minutes upon their emergence from the flower. Rye pollen is carried away by the wind. As all the other anemophilous plants, rye produces lots of pollen (each flower producing up to 60 thousand pollen grains). In rare cases anthers burst prior to their emergence from the flower and self pollination occurs. Each flower remains open for 12 to 30 minutes but the pollen only takes 2 to 4 minutes to spill out from it. The spike begins to blossom in its middle part and blossoming gradually spreads upward and downward lasting for 4 to 5 days. The upper flowers cease to blossom earlier than the lowermost ones. Each plant blossoms for 7 to 8 days. The first to blossom is the spike of the main stem. In the field with optimal air temperature (12 to 15°C) blossoming begins at 5 or 6 o'clock in the morning in southern and central areas of the Russian Federation while in northeast and northwest blossoming begins at 7 or 10 o'clock in the morning. Blossoming has two or three peaks during the day but it is exceptionally intensive early in the morning. When rye fields blossom in dry and warm weather, there is a cloud of pollen floating over them. In direct sunlight rye pollen is viable for 15 minutes, in the shade - for 4 to 8 hours. In artificial environment with lower temperatures and higher moisture it is viable for 1 to 3 days. In rainy and cloudy weather rye pollen is poorly transported by the wind and does not reach flowers greatly increasing incomplete setting of grains, which may spread to 30 to 40 % of flowers. Incomplete setting of grains may also be accounted for by genetic factors. Self-fertility with rye is low, covering on average 0 to 6 %. About 30 minutes go by from the moment when rye pollen falls onto the pistil's stigma till the moment when the pollen tube penetrates into the cavities of the embryo sac while the whole fertilization process lasts for 6 to 8 hours. Ovaries which have not been fertilized remain fertilizable for a relatively long time - up to 14 days. It has been determined that the critical factors for high winter rye yields are the number of its productive stems per square meter and the weight of grains in one ear. The total number of stems and the number of productive stems per unit of area are the adaptability features which characterize biological resistibility of rye cultivars which depends on their hardiness, drought-resistance, resistance to disease and pests, etc. Rye's and other cereal crops' ability to resist lodging is related to plants' height and their stems' strength, the size of their root system and the weight of their ears. 4 kinds of short rye stems have been distinguished. Rye's ability to germinate in the ear and the alpha-amylase activity related to it are typical features of specific cultivars. Fodder rye cultivars used for green fodder and hay in sprung and summer grow fast, have thick bushes and foliage. They are able to re-grow after being mown and their herbage is very nourishing. Their straw is thin and does not coarsen. They resist lodging and react well to application of retardants, which increases their resistance to lodging when they are farmed for their seeds.

Distribution

The areas occupied by cultivated rye in the world are only exceeded by those occupied by seven other crops: wheat, rice, barley, maize, oats, millet, and sorghum. Rye and especially its winter variety (99.8 %) is cultivated practically in all agricultural climatic zones of the Russian Federation (the Volga Region, The Volga and Vyatka, Central and Uralian economic regions), in Belorus, in the Ukraine, and in Baltic countries. Rye has been cultivated since the 1st or 2nd millennium B.C. in the basins of the Dnieper, Dniestr, Oka and on Swiss, Hungarian and Danish territories. Spring rye is cultivated on the small scale in Eastern Siberia (in Transbaikalia) and in mountainous areas of Central Asia and Transcaucasia. Poland and Germany also are main rye-cultivating countries. Rye is also important for agriculture of Scandinavian countries, Canada and the USA. In 2001 rye was cultivated in the Russian Federation on all categories of farms on 3636 thousand hectares (7.7 % of the whole area sown with cereal crops). By now about 50 cultivars of winter rye and 1 cultivar of spring rye (Onokhoyskaya) have been approved for cultivation in specific areas of the Russian Federation. The main cultivars of winter rye are: Bezenchukskaya 87, Valday, Volkhova, Vyatka 2, Dymka, Kirovskaya 89, Orlovskaya 9, Radon, Saratovskaya 5, Saratovskaya 7, Talovskaya 15, Talovskaya 29, Talovskaya 33, Chulpan, Era. The main breeding agencies are: Northwestern Research Institute for Agriculture of Russian Academy of Agricultural Sciences, Krasnoyarsk Research Institute for Agriculture, N.M. Tulaykov Samara Research Institute for Agriculture, Stavropol Research Institute for Agriculture, N.V. Rudnitsky Zonal Research Institute for Agriculture of Northeast, All-Union Research Institute for leguminous plants and groats crops, Urals Research Institute for Agriculture, Tatarstan Research Institute for Agriculture, Siberian Research Institute for Agriculture, Bashkortostan Research Institute for Agriculture.

Economic value

Rye is the second important bread crop after wheat. Each rye grain contains 12 to 14% protein (with lysine content of about 4%). Technological qualities of rye grains depend on their resistance to the activation of the enzymes of the carbohydrate-amylase complex. Viscosity of the water-and-flour suspension is measured with an amylograph while the Falling Number is measured with the Hagberg-Perten instrument or one of its varieties. Rye cultivars used to improve the quality of the flour should have amylograph readings over 600 units and the Falling Number over 200 s. Rye cultivars whose grains may be used to produce flour suitable to bake bread without other additions should have amylograph readings of 300 to 600 units and 140 to 200 s. Rye grain is used to produce flour, starch, molasses, mixed fodder, etc. Rye herbage, hay and grains are used as fodder for livestock. Rye is cultivated as a part of field crops-rotation. Its best precursors are bare and full fallow, annual and perennial herbs, flax. Fertilizers: 20,000 to 40,000 of manure, 20 to 30 kg of N (during spring additional fertilizing), 60 to 90 kg of P₂O₅ and 40 to 60 kg of K₂O per hectare. Rye is sown in closed drills or in ordinary drills. 4.5 to 6 million of germinable seeds are sown per hectare (200 to 250 kg). Rye seeds are planted at the depth of 4 to 6 cm. Rye is gathered in by two-phase and by direct combined harvesting. Rye yields about 2,000 kg per hectare.

References

State Register Breeding Achievements Approved for Practical Application. Moscow: 2004, pp. 11-12
Zhukovsky, P. M. Cultivated Plants and Their Congeners. Leningrad: 1971
Particular Breeding of Field Crops. Ed. Konovalov, Y.B., Moscow: 1990, pp. 36-59.
Cherepanov, S.K. Vascular Plants of Russia and Neighboring Countries. St. Petersburg: 1995

© Gashkova I.V.

Photo Gashkova I.V.