Submitting to,

Dr. Jayadeva sir,

Assoc. Professor

Dept. of Agronomy

Presentation by

Madhu . L .

PALB 4285.

POTASSIUM NUTRITION TO REDUCE LODGING IN CEREALS

.

Flow of Presentation

Introduction.

How potassium function in plant.

Role of potassium in lodging resistance.

Conclusion.

WHAT IS LODGING ????

Permanent displacement of stem from its upright position is known as lodging.

EFFECTS OF LODGINGSevere lodging is very costly due to its effects on grain

formation and associated harvesting problems and losses.

Secondary growth in combination with a flattened crop

makes harvesting difficult and can subsequently lead to poor

grain quality and high yield losses.

Lodging alters plant growth and development.

It affects flowering, reduces photosynthetic capabilities of

the plant, hence affecting carbohydrate assimilation.

Severe lodging interferes with the transport of nutrients and

moisture from the soil, and thus with food storage in the

developing kernels.

Lodging often contributes to uneven maturity, high moisture constant

and loss of grain quality due to sprouting and possible moulding.

When a crop lodges before flowering, the culms (stem) may regain

their upright position if favourable weather conditions prevail.

If a crop lodges sometime after flowering, the heads will not regain

their upright position. At this stage, kernel numbers are not affected,

but the grain weight may be severely reduced.

The extent of weight reduction depends on prevailing weather

conditions after the crop had lodged.

Cont….

Control of Lodging

1. Cultivar selection

The first step to help prevent lodging is toselect a variety that has short, strong straw.

Higher plant density lead to lodging of crop.

. It is therefore recommended that plantdensities should be reduced to optimum, sincethese will promote stronger straw and moretillers.

Management of plant nutrition in optimumrange.

How Potassium Functions in Plants

Helps retard crop diseases.

Builds cellulose needed for stalk and stem strength.

Aids in photosynthesis and food function.

Increases root growth

and improves drought resistance.

Produces grain rich in starch.

Necessary for plant protein formation.

Reduces water loss and

wilting.

Assists many enzyme actions.

ROLE OF POTASSIUM:-

. It may result from the interactive effects by environmental and soil conditions, plant type and nutrient management

In K-deficient plants, the diameter of stem is reduced making the plant susceptible to lodging. Because Sclerenchyma fiber cell and woody parenchyma cells in the stems of K- deficient plants form thin and poorly lignified cell walls resulting reduced stem diameter (Mulder, 1954; Wakhloo, 1975)

Increase in the thickness of sclerenchyma tissue layers by optimum potassium nutrition has been reported for rice (Vaithilingam and Balasubramanian, 1976).

• Cross section of wheat internode(Plate 1) show that plants of better

K+ nutrition has thick stalk wall. Higher stem stability and improved thickness might be associated with a less senescing pith parenchyma and more active general defence mechanism under optimum K supply

.

plate 1: Cross-section of 3rd internode of wheat plant with low (left) and optimum (right) K+ nutrition.

The addition of K+ reduces the per cent of senescent stalks and stalk lodging in corn grown on K-deficient soils (Plate 2)

Plate 2: Effect of K+ supply on maize plant.

Crushing strength and rind thickness increases with K+ application. The influence of K+ on senescent stalks varies with hybrids (Welch and Flannery, 1985). The high yielding corn hybrids have the ability to translocate the photosynthates from leaves and stalk to grains.

. They may have greater lodging probably due

to increased mechanical stress on the stalk bygreater ear weight and photosynthatetranslocation from stalk structurally weakensthe stalk and premature parenchymabreakdown (Campbell, 1964; Liebhardt et al.,1968). Measurements made by Campbell(1964) indicated that there was an inverserelationship between ear weight and solublesolids in stalk juice

Potassium deficiency increases respiration andtranspiration rate and decreases photosynthesis,accumulation of starch and cell wall substances,such as holocellulose, that influence stemstrength in rice.

A close correlation exists between the K+content of basal part of the culm and thebreaking strength of the stem, implying thatproper K+ nutrition is closely associated withlignification of sclerenchyma cells and vascularbundles and strengthening culms, thereby,increase lodging resistance (Datta and Mikkelsen,1985).

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Melis and Farina (1984) conducted experimenton lodging susceptible maize cultivar. Thepercentage of total lodging reduced with theincremental dose of K+ from 50 to 200 kg ha-1(Fig. 5).

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Conclusion.

The whole structure of proteins and protein activity needs optimum concentrations of K+ in the cytosol for optimum plant functions. However, to withstand stresses that causes osmotic stress and unusual physical burden, prior accumulation of K+ is shown to reduce the damage to plants.