4. Flow of Presentation
Introduction.
How potassium function in plant.
Role of potassium in lodging resistance.
Conclusion.
5. WHAT IS LODGING ????
Permanent displacement of stem
from its upright position is
known as lodging.
6. EFFECTS OF LODGING
Severe 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.
7. Cont….
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.
8. Control of Lodging
1. Cultivar selection
The first step to help prevent lodging is to
select a variety that has short, strong straw.
Higher plant density lead to lodging of crop.
. It is therefore recommended that plant
densities should be reduced to optimum, since
these will promote stronger straw and more
tillers.
Management of plant nutrition in optimum
range.
9. 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.
10. 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).
11. • 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
12. .
plate 1: Cross-section of 3rd internode of wheat plant with low (left)
and optimum (right) K+ nutrition.
13. 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.
14.
15. 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.
16. .
They may have greater lodging probably due
to increased mechanical stress on the stalk by
greater ear weight and photosynthate
translocation from stalk structurally weakens
the stalk and premature parenchyma
breakdown (Campbell, 1964; Liebhardt et al.,
1968). Measurements made by Campbell
(1964) indicated that there was an inverse
relationship between ear weight and soluble
solids in stalk juice
17. Potassium deficiency increases respiration and
transpiration rate and decreases photosynthesis,
accumulation of starch and cell wall substances,
such as holocellulose, that influence stem
strength in rice.
A close correlation exists between the K+
content of basal part of the culm and the
breaking strength of the stem, implying that
proper K+ nutrition is closely associated with
lignification of sclerenchyma cells and vascular
bundles and strengthening culms, thereby,
increase lodging resistance (Datta and Mikkelsen,
1985).
18. Melis and Farina (1984) conducted experiment
on lodging susceptible maize cultivar. The
percentage of total lodging reduced with the
incremental dose of K+ from 50 to 200 kg ha-1
(.
Fig. 5).
20. 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.
