Сельское хозяйство / 3. Земледелие, грунтоведение и агрохимия

I. Pigorev, N. Dolgopolova

Kursk state agricultural Academy, Russia

FEATURES OF BIOLOGY OF THE SPRING DURUM WHEAT

In our country sow over 100 grades of a spring-sown field. They differ a number of biological, economic features and impose unequal requirements to water, food, temperature, light. Besides and an environment, and also level of the standard of farming in the huge territory of cultivation of spring-sown firm field are very various. Therefore the receptions of an agrotechnology providing big crops, have to be based taking into account biological features of culture, soil and weather conditions. It is counted that about 52% of crops of a spring-sown field are concentrated in regions of droughty, 24% — in areas insufficiently humidified and only about 25% — in the areas provided with moisture. In plant life the root system plays large role. Supply of plants by water and nutrients depends on features of its structure, development power in big degree that, in turn, influences intensity of assimilation, eventually, at a crop size. At wheat distinguish two main types of roots: primary (germinal), and secondary, (nodal). At emergence of shoots primary roots (from 3 to 5) develop. They quickly go deep into the soil: in a kushcheniye phase on 30 — 50 cm. Their quantity and penetration depth depend on a grade and humidity of the soil a little. They generally supply with moisture and nutrients the main stalk of wheat. Secondary roots develop from kushcheniye knot in 15 — 18 days after emergence of shoots. Their quantity and depth of penetration depend first of all on humidity of the soil in a zone of knot of a kushcheniye. In the dry soil they don't develop, and appeared earlier stop growth; at sufficient humidity their quantity increases. Secondary roots get into the soil superficially on 30 — 50 sm therefore they well use mainly the precipitation which is dropping out in the period of vegetation. These roots provide with moisture and food mainly kushcheniye escapes.

Primary roots grow at spring-sown firm field slightly more slowly, and nodal appear for 3 — 6 days later, than at soft, it explains special sensitivity of firm wheat to delay with crops. Weak formation of secondary roots worsens supply of plants by water and food, reduces a crop. Therefore an important problem of an agrotechnology — to provide the most favorable conditions for formation of secondary roots. In our researches it is reached first of all by timely closing of moisture, early crops. Thus in a zone of knot of a kushcheniye more moisture remains, and temperature happens more favorable for growth of roots — about 6-10 °C. At lateness with crops the soil in a zone of knot of a kushcheniye often dries up, and more high temperatures slow down growth of roots. The positive role in rooting is played by ryadkovy application of fertilizers, in our case it is N₄₅P₃₀K₃₀. However the major role belongs to sideralny cultures which introduce additional organic and biological fertilizer. Introduction the ekologizirovannykh of crop rotations with inclusion in them leguminous, annual and long-term herbs, bean and cereals travosmesy, intermediate cultures on green fertilizer well influences both soil fertility, and density of the soil and biological activity of the soil. The root system is very sensitive to density and humidity of the soil, excessively friable, and excessively dense soil worsens its growth. It is known that 70 — 80% of weight of roots are in an arable layer. However power it has essential impact on depth - distributions of roots. Existence of the condensed subarable layer complicates penetration them in the subarable horizons. So, on cespitose and podsolic soils with the condensed, unstructured poor podzoklisty horizon roots seldom get for it limits, and plants often lack for water in the presence of it deeper horizons. Even on chernozem soils at continuous plowing on identical depth at the bottom of a furrow the condensed layer (sole) which too complicates penetration of roots and moisture out of its limits that worsens supply of plants by water and food is created. So, in our experiences on chernozem soils when plowing on depth of 20-22sm in the period of an exit of plants in a tube in a layer of earth of 0 — 20 sm there were 9,68 g of roots in test, in a layer of 20-35 cm — 1,83 g, and when plowing on 35–40 sm – respectively 10,19 and 3,84 g. As showed our researches since 2008-2012, the increase in depth of plowing of a ploughland with 20 to 35 sm raised spring stocks of moisture in a meter layer for 2,3%, including in a layer of 0 - 50 sm for 1,6%, and in a layer of 50-100 sm for 2,9%. Therefore, deep plowing increases weight roots, promotes their penetration into deeper layers and increases spring stocks of moisture that significantly improves water supply of plants and weakens negative influence of droughts, place which takes to be and in our Kursk region. Positive influence of deep plowing remains on chernozem soils 2-4let. Therefore periodic deepening of an arable layer plays very important role in receiving big crops, especially in steppe regions of the European part of Russia. And the spring-sown field positively responds on direct action and on an after-effect of deep plowing. So, in our experiences plowing deepening from 20-22 to 35 sm in the first year raised wheat crop on 1,8 c/hectare, and in the second year — on 1,2 c/hectare (on an exposition of the southern slope). It is necessary to remember that the more favorable develop, water and food modes of the soil, the develop roots more strongly. In these conditions and the smaller quantity them well provides elevated bodies with moisture and food. The following data obtained in experiences of P. K. Ivanov and E. M. Rashkovsky testify to it, experiences - on the typical chernozem at of the elevated weight of 71,2 c with 1 hectare (grains 26,4 and straw of 44,8 c) in a layer of 0 — 40 sm there were 7,0 c of roots, or only 11% of elevated weight; on the ordinary chernozem at a crop of the elevated weight of 43,3 c with 1 hectare (grains 14,0 and straw of 29,3 c) — 12,2 c, or 29,9%; on the southern chernozem at a crop of the elevated weight of 61,4 c with 1 hectare (grains 17,4 and straw 44,0) — 14,2 c, or 30,3%-With increase in a crop of elevated weight the relative weight of roots considerably falls: the plant directs assimilation products mainly on formation of elevated bodies. The similar phenomena are observed in the conditions of an irrigation. Therefore, creation of optimum conditions of water and mineral food (the correct alternation of cultures, deep plowing, snow retention, watering, fertilizer and other receptions) allows a plant to distribute more rationally the organic weight created by it between roots and elevated weight, and in a consequence between straw and grain.