Deprive (vegetable biology)
The deprives (of Latin carere , to miss) indicates in Physiologie the absence or the insufficient contribution of one or several substances necessary for the growth and the balance of an organization Animal or Végétal.
Types of deficiencies
- the primary deficiency: she is explained by the deficiency of one or more nutritive elements of the ground.
- the induced deficiency: the nutritive element in question is present in the ground, but its assimilation by the plant is opposed, either generally by a blocking due to an unfavourable pH, or, more rarely, following an imbalance between biogenic salts or organic. For example, a too strong phosphatic manure can involve a blocking of the Zinc.
The deficiency can also come from a fertilizer excess, which can involve a disturbance of the physiological mechanisms of the plant.
Symptoms of a deficiency disease
- Of the anomalies in the coloring of the Feuille S.
- the Necroses certain fabrics, sheets, bud S, stems, barks, etc
- a deceleration of the growth.
- a fall of the output of the culture (cultivated species).
- the deficiencies in principal elements (Nitrogen, Phosphorus, Potassium, Magnesium) are not very current in moderate zone. In fact disorders of the mineral nutrition can be observed at the time of the strong growths of the spring (“nitrogen hunger” of cereals which presents a characteristic yellowing). An adapted manure makes it possible to cure it. On the other hand, the tropical grounds, often poor, frequently induce deficiencies marked in major elements (except on the young grounds of volcanic origin or the grounds Tourbe ux).
the deficiencies (primary or induced) in Oligo-élément S are more frequent. One cures it in particular by contributions on the ground or pulverizations foliar, once the identified responsible element. In the majority of the cases, the cause is not the deficiency of only one element. The direct observation on the ground provides at least as many answers (and of interrogations) analyzes.
On the ground, the treatment of the induced deficiencies requires sometimes a modification of pH by liming (typical case of the deficiency in Molybdène). One can also treat by contributions of Oligo-élément S in an organic form (natural or of synthesis), less prone than rock salt equivalent to a blocking by the ground. One often appeals, for that, with “chelating” agents, which react (in factory) with trace elements by forming Chélate S (of Fer, Cuivre, Bore, Zinc, etc). These Chélate S is rather stable, on the ground, and their evolution towards an insoluble form (thus, inassimilable by the roots) is more or less slow, according to the chelating starting agent, of pH of the ground, luminosity etc
This technique has its limits and for the Manganèse, for example, there does not exist, at present, of “stable Chélate” in the alkaline grounds (limestones). One can thus have to make the corrections by foliar way.
By foliar way, the corrective contributions can be done by pulverization of solution of salt S soluble (Chlorure S, Sulfate S, Nitrate S), or of Chélate S (DTPA, HEDTA, EDTA, etc) of the elements necessary. The quantities brought will be less than by the ground and several treatment is necessary, in the majority of the cases. The treatments will have to be done at one time when the sheets will remain wet long enough, to improve the penetration. The corrections intervening at the beginning of the demonstrations of deficiencies are more effective, because better comparable, and make it possible, generally, to lead harvests to their maturity.
Other means of fight
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