You will find the detailed description of one of the most holodostoyky cultures in article, about physiological features and an agrotechnology of a winter rape.
A winter rape – one of the most holodostoyky and least exacting plants to heat
Winter rape – one of the most holodostoyky and least exacting plants to heat. Seeds start to sprout it at temperature slightly above 0oS (0,5-1,5os). However to receive normal amicable shoots in 3-4 days to plants the temperature +14-17os is necessary. Rape shoots easily transfer short-term frosts (to-3 – 5oS). After a potelpeniye of a plant renew vegetation at +2-3os.
In the course of rewintering winter a rape is exposed to influence of negative air temperatures and soils. It is known that ability of plants to transfer temperature below 0oS is defined by their frost resistance. Unlike frost resistance there is a definition – winter hardiness – stability of plants to influence of a complex of adverse conditions in rewintering.
Winter hardiness and frost resistance of a winter rape, as well as other winter crops, in many respects depends on developing weather conditions both before leaving in winter, and in the course of rewintering: existence and size of snow cover, amount of precipitation, temperature mode, its daily allowance and seasonal fluctuations.
There are data of scientific researches, which testify to ability of plants of this culture to transfer quite low negative temperatures when rewintering (-16 … – 20oS), and in the presence of snow cover and to-30.-35os. From them follows that the opinion extended among farmers on allegedly low winter hardiness of a winter rape is obviously exaggerated. It proves to be true also practice of the advanced farms. As an example we will give the following. In 1970-1972 in the North Caucasus winter frosts reached-25.-27os, but thus in the course of rewintering on the considerable areas crops of winter wheat and winter barley while attack of plants of a winter rape didn’t exceed 5 % froze. However cases when also they perished and at light frosts (to – 20oS) are known. Therefore questions of winter hardiness and frost resistance of a winter rape should be considered in a complex: development of plants and weather conditions. This culture when leaving in winter should pass training process. The death of plants from a frost is caused by the changes occurring in a protoplast, its coagulation. Physical and chemical transformations in a protoplast occur owing to water procrastination by the crystals which were formed in intercellular spaces of ice. They subject a protoplast and to mechanical damages by compression. And to increase frost resistance of plants, it is necessary that in cages and intercellular spaces instead of water solution with lower temperature of freezing – soluble carbohydrates which have stabilizing effect on cellular structures collected and protect albuminous connections from coagulation.
Process of training includes two phases: on the first at plants collect sugar and other connections with the lowered temperature of freezing. Ideal conditions for successful passing by plants of the first phase of training – gradual fall of air temperature in the afternoon to 10oS, and at night to 0 – 1oS. On end of the first phase of training there is a complete termination of growth of plants.
The second phase passes at gradual fall of temperature below 0oS. Thus there is a further dehydration of fabrics and concentration of cellular juice that lowers its freezing point raises.
There are two groups of causes of death of plants of a winter rape during the winter period.
The first. Klimato-fiziologichesky. This lack of conditions of training of plants, influence of low temperatures and a wind in the absence of snow cover, a vymokaniye and a vyprevaniye of plants etc.
This group gives in to regulation of its negative influence a little.
The second. Agrotechnical and physiological. Crops terms, density of standing of plants, depth of seal of seeds, fertilizers. This group in many respects depends on applied technology of cultivation. It is necessary to create to a plant all conditions for training passing.
The great value (if not defining) has optimum term of crops. In the presence of moisture in the soil shoots of a winter rape appear for 4-6 day, and 8-10 days later the first pair of real leaves, and in 10-12 days – the sheet socket is formed. The autumn period of vegetation lasts 76-75 days, and then there comes the period of winter rest – 140-145 days. At optimum term of crops before the period of winter rest of a plant form the powerful socket of 6-8 leaves in length 35-45 see.
Worse plants of late terms of sowing winter – they don’t manage to form the powerful socket of leaves which happen shorter 25-30 see. Such plants don’t accumulate enough of the soluble carbohydrates necessary for good training.
It is necessary to note, as early terms of crops don’t promote good rewintering of plants though at early terms there is time enough for accumulation of sugars. However at the outgrown plants in roots and a root neck before leaving in winter always sugars will be less, than at what were poseyany in optimum terms. It occurs because the considerable part of sugars in the form of nutrients is spent for formation of more powerful vegetative weight of leaves.
The great influence on rewintering of a winter rape is rendered by density of standing of plants which is defined by norm of seeding. To Zagushchennye crops even at optimum term of seeding don’t promote creation of conditions for good training of plants. In Germany, Poland and other Western countries the optimum norm of seeding considered 2,5-3 kg/hectares of vskhozhy seeds whereas at us in the Crimea sow from 6-8 to 10,0 and more than a kg/hectare of vskhozhy seeds.
Plants of a rape are capable to self-control of density of standing. Thus the weak perish, but also remained it is impossible to call high-grade developed as a considerable part of the forces spent for fight for a survival. Such plants go to winter weakened, their winter hardiness, and especially frost resistance, much lower, than at plants which developed at optimum density of standing.
In the course of rewintering of this culture it is necessary to give special attention to a diet of plants. Full security with a phosphatic and potassium food during the autumn period promotes winter hardiness increase, and excess of nitrogen reduces winter hardiness since the high content of nitrogen in the soil promotes the strengthened growth of plants that leads to a consumption of the carbohydrates necessary for their good training. There is the same that at early terms of sowing.
It is necessary to note, as the lack of nitrogen during the autumn period also leads to decrease in winter hardiness, especially at late terms of sowing. This phenomenon is observed in the current year in many farms – plants didn’t form the normal socket of leaves, and their length less than 20 cm, and even to 10 see.
According to preliminary data, from 16 thousand hectares sowed by a winter rape in the autumn, 7 thousand hectares were lost. this figures will be specified still.
In the spring on fields where the death of crops of this culture is noted it is possible to sow a summer rape (on an irrigation), and in bogarny conditions pereseyat it is possible summer mustard or flax olive.
Landowners who decided to be engaged in cultivation of a winter rape on maslosemena should imagine model of well developed plant possessing high frost resistance and winter hardiness. It should have before leaving in winter the powerful socket of leaves (6-8 with a length to 35-45 cm). diameter of a root neck should be not less than 8-10 mm, and depth of penetration of a rod root – not less than 100 see. Such crops even at partial their death (on 1 sq.m number of the remained live plants makes 40-50 pieces/sq.m) are capable to provide a high-grade crop maslosemyan thanks to the raised kustistost (a branch of the 1st and 2nd order), and at the expense of it with the increased quantity of pods on one plant and to bigger number of grains in them.
Special attention it is necessary to give to the correct top dressing of plants by nitric fertilizers. By no means it is impossible to feed up them in the winter. Otherwise in possible February "windows" top dressing stimulates growth and by that will weaken their training that can lead to death of plants even at the insignificant frosts subsequent to "windows". Top dressing should be carried out to the period when passes danger of return of colds.
E. SLUCKIJ, candidate of agricultural sciences, assistant professor.