Crops

Avena sativa L .- Common oat.

Taxonomic position.

Family: Poaceae Barnhart, genus: Avena L., species Avena sativa L. - Cherepanov S.K., 1995.

Biology and morphology.

2n=42. Oat's stalks are upright or initially prostrate, round, glabrous, and smooth. They are about 3 to 6 mm thick and 30 cm to 2 m high and have 3 to 4 glabrous or downy nodes. Oat's leaves are lanceolate and acuminate, rough, green or bluish-gray often with a waxy coating. They are 20 to 45 cm long and 8 to 30 mm wide, glabrous or ciliate at the edges. The leaf-blade is sometimes downy. The sheaths of the lower leaves are to a different extent downy or glabrous. The ligule is cone-shaped, 3 to 5 mm long, or truncated; more rarely there is no ligule at all. Oat's inflorescence is a panicle. It is spreading, semi-contracted or contracted (one-sided). Oat's spikelets have 2 to 4 flowers, with hull-less varieties they have multiple flowers. The topmost flower usually is underdeveloped. There are two glumes; the upper one somewhat longer than the lower one. As for their consistence and shape, they are membranous, wide lanceolate, and acuminate. They are about 25 to 30 mm long and have 9 to 11 nerves; with paleaceous varieties they are larger than the flowers. With hull-less oat varieties both glumes and lemmae are membranous. The inner lemma is shorter than the outer one. With paleaceous oat varieties the lemmae are white, yellow, gray or brown in color; with hull-less oat varieties they are straw-colored or whitish. The lower lemma is lanceolate or egg-shaped lanceolate. It is about 20 to 25 mm long, downy or glabrous, smooth or rough with 7 to 9 nerves. On top it is biscupid. With aristate oat varieties there is awn on its back. All the flowers of an inflorescence have no articulations and can only be broken off, leaving an almost horizontal fracture. The internodes of the axis tend to break off on top, the pin of the second flower remaining with the lower one. The lodiculae are cross-lanceolate. There are three stamens. The whole surface of the ovary is covered with thick hairs. The pistil has two plumose stigmae. The caryopsis is paleaceous (closely enveloped by lodiculae but not accrete with them) or bare (freely resting between lemmae). Its surface is completely covered with closely adhering hairs. It is 8 to 11 mm long and has a well-pronounced lengthwise groove. It consists of the fruit coat, the seed coat, the aleurone cell layer, the endosperm and the embryo. The seed coat located under the fruit coat has developed from the two ovule's coats. The embryo is strongly compressed at its backside and consists of the plumule, the long seed-lobe with its top separated from the pericarp, and the corymb pushing into the endosperm. The embryo occupies most of the space in the caryopsis, while the endosperm accounts for the bulk of its weight. When seeds germinate, the corymb provides for the embryo the nutritive material from the endosperm. The cells of the aleurone layer contain proteins and fats. The rest of the endosperm is occupied by the cells filled with starch grains, the albumens being distributed in the spaces between these cells.

Ecology.

Common oat is the most demanding cultivated variety of this crop as regards daylight duration. Northern cultivars need for their development longer daylight than southern ones. With 14 hours of daylight they do not head. The analysis of the harvest structure with oat cultivars grown at different photoperiods revealed longer stalks and panicles, a greater number of seeds and a higher overall weight with plants grown at shorter daylight. However, since under such conditions oat panicles emerge much later than otherwise, the seeds have no time to mature properly and are hollow. With 12 hours of daylight different cultivars produce on the average 2 to 3 times less seeds than otherwise. With a very big number of oat's cultivars and varieties, the duration of their vegetation periods varies greatly. The vegetation period of Russian cultivars lasts for 75 to 120 days. Oat's ability to mature early is very important since it allows to cultivate it as far up North as trans-polar regions, while in drought-affected steppes early maturing oat varieties mature before the season of droughts and hot winds. Farther down South such varieties can be used as stubby crops. The oat varieties that mature earlier than the others are grown in Eastern Siberia (Irkutsk Region), in Buryatiya, in Komi, and in the north-west of Russia. In the former republics of the Soviet Union they are found in Armenia, Georgia, and the Ukraine. Oat varieties growing in Palestine and India mature extremely early. In Mexico, Peru, Ecuador, the USA, Sweden, Norway, Mongolia, China, etc. there are many early maturing oat varieties as well. Later than the others mature wintering common oat varieties from Western Europe (Yugoslavia, South of France, England, Spain), which are sown in the fall in the countries of their origin. They easily survive mild winters because they are alternate. Farther up North the first half of oat's vegetation period (from sprouting to emergence of panicles) becomes shorter. It is caused by the longer daylight and the intensity of heat energy. The second half of the vegetation period (from the emergence of panicles to full maturity) becomes longer in direct proportion to the amount of atmospheric precipitation and air humidity and in inverse proportion to the total of temperatures. Oat thrives in the temperate climate. The total of active temperatures during its vegetation period is 1300° C for early maturing varieties and 1550° C for late maturing varieties. Oat seeds begin to germinate at soil temperatures of 1 to 2° C, and if it reaches 3 to 4° C, the germination period is greatly reduced.
When oat bushes out and its secondary shoots and roots are formed, the development of young plants is greatly favored by moderate temperatures. Oat plants begin forming their generative parts, blossoming and bearing fruit at the temperatures of 10 to 12° C. These processes are most active at 16 to 22° C. Oat supports high temperatures worse than wheat and barley, and is rarely cultivated in the southern and south-eastern steppes. In the South high temperatures ruin oat plants when they form leaf-tubes, and their kernels ripen and mature. Such temperatures hinder the processes of generative development as they greatly reduce the number of kernels per panicle and plants' reproducibility. If there is a drought when oat plants blossom, their panicles may become sterile. At the temperatures of 38 to 40° C oat plants suffer greatly from blasting and hot-windburn. After 4 to 5 hours their stomae become paralyzed. This does not regard Byzantine oat varieties which require high temperatures when forming fruit and are more heat-resistant than the others. Oat plants easily survive low temperatures providing they do not last long. In the fall oat sprouts survive night and morning frosts of 3 to 4° C. With further development and growth the ability of oat plants to survive low temperatures decreases. When in blossom, they are ruined by night and morning frosts of 2° C. Oat plants are hygrophilous. When germinating and growing, they require much more moisture than the other crop plants. The yield of oat plants greatly decreases with deficient soil moisture 10 to 15 days prior to the emergence of panicles, when the generative parts begin to develop. With heavy rainfall in the North, the vegetation period of oat plants in the fall drags out too long, and their kernels often do not mature in time for the first frosts.
Oat plants survive high soil acidity, thrive on loamy sands, loamy, clay and peat soils. They are responsive to fertilizers. At their milky ripeness oat kernels accumulate much nitrogen, at their wax ripeness - much potassium and magnesium, and at their full ripeness - much phosphorus and potassium. Nitrogen is the most important nutritive element for oat plants. They are lacking in nitrogen most of all early in spring when nitrates are washed down to the deeper soil layers, and the microbiological processes which produce nitrates are slow because of low temperatures. Application of nitrogen fertilizers helps very much to increase the yield of oat plants, improves the quality of their kernels and favors protein accumulation by them. Application of phosphorous fertilizers helps to increase the yield of oat plants in all areas of the Russian Federation. High quality oat kernels cannot be obtained unless sufficient amount of phosphorus and potassium is supplied to oat plants. In most cases potassium fertilizers help only upon simultaneous application of nitrogen and phosphorous fertilizers. Oat plants are self-pollinating but many of their varieties tend to cross-pollinate. Apomixis with oat pants is rare. Their flowering is usually cleistogamous. It begins when two or three thirds of the total length of the panicles issue from the leaf sheath. The anthers mature at the same time with the stigma and burst. Then the lodiculae open up the flower, the anther filaments stretch out, and the anthers expel the rest of the pollen. With enough warmth, sunshine and brief rains the anthers may emerge prior to opening up. In this case they hang down lower than the stigma, which favors cross-pollination. Oat plants usually begin blossoming at about midday and keep blossoming till 5 o'clock in the afternoon. Most of them blossom between 2 and 3 o'clock in the afternoon. Flowering is favored by wet weather and the temperatures of 20 to 23° C. The flowering of each panicle is irregular. First are to blossom the spikelets on its top, then - those on the tips of the longest branches of the first and second tiers. On each brunch flowers form from its tip to its base. Each panicle blossoms downwards from top to bottom and inwards from outside to the center. The spikelet blossoms upwards. The lower flower is the first to blossom. The kernels develop, ripen and mature in the same order.

Distribution.

In all the parts of the world Avena sativa L. has the largest natural habitat of all the known species which encompasses Europe with the exception of the Mediterranean coasts, North and Southeast Asia. It is cultivated in North and South America, Africa, Australia, Tasmania and New Zealand. On all the continents oat tends to be cultivated in the areas where the climate is similar to the temperate climate of Europe and North America. Oat occupies a prominent position among grain and forage crops in Australia. It is very rarely cultivated in Asia, South America and Asia because it is not heat-resistant. (Only about 7 % of all the areas where oat plants are grown in the world are on those three continents.) There are large areas sown with oat plants in North America (the USA and Canada) and in some European countries (Poland, Germany, Sweden, Spain, France, Finland). This crop yields most of all in the countries with efficient agricultural techniques and favorable environmental conditions. It yields over 5 000 kg per hectare in Ireland, the Netherlands and Switzerland where areas sown with oat plants are not very large. High yields (over 4 000 kg per hectare) are typical of Germany, Belgium, Denmark, Great Britain and New Zealand. In Russia oat plants are cultivated from the northern limits of feasible agriculture to the subtropics in the South. However its share in areas with different natural and economic environments is not the same. The bulk of the lands sown with oat plants is located in Non-chernozem areas, in the Urals, in Siberia and in the Far East. In European Russia oat plants are mostly cultivated in Perm, Tver, Smolensk and Kirovsk Regions; also in Orel, Tambov, Penza, Ryazan and Samara Regions as well as in Bashkortostan and Tatarstan. In Siberia oat plants are in the first place cultivated in Altai and Krasnoyarsk Territories, in Novosibirsk, Tyumen, Omsk and Chelyabinsk Regions and in Udmurtiya. In 2001 the areas sown with oat plants on the farms of all categories totaled 4865 thousand hectares. (Thus only wheat and barley are cultivated more often.) The average yield is 1,700 kg per hectare. About 80 cultivars of oat plants have been approved for cultivation in specific areas of the Russian Federation. The commonest cultivars are: Astor, Borets, Dance, Kozyr, Komes, Metis, Skakun, Talisman, Tyumensky, Ulov, etc. The main breeding agencies are: Research Institute for Agriculture of the central areas of the Non-chernozem Belt, Vladimir Research Institute for Agriculture, Altai Research Institute for Agriculture, Kemerovo Research Institute for Agriculture, Buryat Research Institute for Agriculture, Siberian Research Institute for Agriculture, N.I. Vavilov All-Union Research Institute for Plant Cultivation, Lgov Experimental Breeding Station, Tulun State Breeding Station, Krasnoufimsk Breeding Station, Kotlas Agricultural Experimental Station, Narym State Breeding Station, Falen Breeding Station of N.V. Rudnitsky Northeastern Research Institute for Agriculture. As a cultivated crop, oat is more recent than wheat or barley and was found in their plantations as a weed. Being less fastidious about the environment in which it grew, it often suppressed and replaced the principal cultures spreading to new areas. Archaeological evidence demonstrates that oat plants were known to the man at least 4000 years ago. The oldest oat kernels were found in Egypt and date back to the 12th dynasty (2000 to 1788 B.C.). The earliest evidence of cultivated oat plants was found in Germany. It dates back to the 1st, 4th and 6th centuries A.D.

Economic Value.

Oat is a staple grain and forage crop. Each kernel of paleaceous oat contains 8 to 10% cellulose, 40 to 60% starch, 10 to 15% protein, 4 to 6% fat. Oat protein includes all the amino-acids indispensable for the man and animals, especially lysine, arginine and tryptophan. Each oat kernel contains a large number of organic compounds of iron, calcium, phosphorus and B-vitamins. It contains quite a large amount of such microelements as manganese, copper, molybdenum and cobalt but little zinc and boron. Oat kernels are processed to produce groats, flour, and flakes which are of considerable nutritive value, are easily digestible, rich in calories and therefore suitable for baby and invalid food. Oat kernels are much richer in some indispensable amino-acids than barley and rice grains. 100 g of oat flakes contain 0.9 g of lecithin, 4 mg of iron, 0.4 mg of vitamin B₁, 4.2 mg of vitamin E and 420 calories; 139 g of oat flakes can satisfy a man's daily need in iron, 17.7 g of them can satisfy a man's daily need in vitamin B1. Oat groats are much higher in protein, fat, phosphorus and iron than semolina, ground millet and buckwheat. Oat kernels are an indispensable concentrated fodder for horses and other livestock and poultry. As for its nutritive value, 1 kg of oat kernels contains 87 g of digestible protein and is equal to one fodder unit. Oat kernels are included into all kinds of mixed fodder intended for young animals. Oat plants are used as green fodder especially mixed with vetch or peas. They are used to prepare grass flour, granules, silage, hay. Oat straw is a good roughage. The best precursors for oat plants are legumes, tilled and winter crops. The average doses of mineral fertilizers are: 30 to 45 kg of N, 45 to 60 kg of P₂O₅ and K₂O per hectare. Oat plants are sown early in spring using usual drill or closed drill techniques. 180 to 250 kg of seeds are sown per hectare. Planting depth is 3 to 6 cm. Oat plants are gathered in by two-phase or direct harvesting.

References.

Zhukovsky P.M. Cultivated Plants and Their Congeners, Leningrad: 1971. pp. 157-162
Cultured Flora. Vol.2, Part.3. Oat Plant. Ed. Kobylyansky V. D. and Soldatov V. N., Moscow: 1994. p. 367.
Individual Selection of Field Crops. Ed. Konovalov Y.B. Moscow: 1990. pp. 78-99
Cherepanov S. K. Vascular Plants of Russia and Neighboring Countries. Moscow: 1995

© Gashkova I.V.