2-Role_and_deficiency_symptoms_of_Nitrogen_in_Rice

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Transcript 2-Role_and_deficiency_symptoms_of_Nitrogen_in_Rice

Role and deficiency symptoms of Nitrogen in Rice
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Role and deficiency symptoms of Nitrogen in Rice
Introduction
N deficiency is common in all rice-growing
soils where modern varieties are grown
without sufficient mineral N fertilizer.
Significant yield responses to N applied in mineral
and/or organic forms are obtained in nearly all
lowland rice soils where irrigation and other
nutrients and pests are not limiting.
Sufficient N supply during ripening is necessary
to
delay
leaf
senescence,
maintain
photosynthesis during grain filling, and increase
protein content in the grain.
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Role and deficiency symptoms of Nitrogen in Rice
Role of Nitrogen in rice
Essential constituent of amino acids, nucleic
acids, nucleotides, and chlorophyll, etc.
It promotes faster growth, especially increased
plant height and tiller number.
Nitrogen Increases leaf size of rice.
It enhances spikelet number per panicle,
percentage of filled spikelets in each panicle.
N increases protein content in rice grain.
Nitrogen drives the demand for other macronutrients
such as phosphorus and potassium.
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Role and deficiency symptoms of Nitrogen in Rice
It is important to note that:
The demand for nitrogen is between the
early to mid-tillering and panicle initiation
stages is relatively higher.
Adequate N supply during ripening is must be
maintained to delay leaf senescence (maturity),
maintain photosynthesis during grain filling, and
increase protein content in the grain.
Being a mobile nutrient in plant, N moves within the plant
and, because N is translocated from old senescent leaves
to younger leaves, deficiency symptoms tend to occur
initially in older leaves.
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Role and deficiency symptoms of Nitrogen in Rice
N deficiency symptoms
Reduced growth and plants become
yellowish in colour.
In the beginning the deficiency symptoms first
appear on lower (older) leaves and afterwards
the whole plant becomes yellowish green.
Death of leaves may occur under
severe N deficiency.
Affected leaves are narrow, short,
erect, and lemon-yellowish green.
In some cases the entire field may
appear yellowish.
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Role and deficiency symptoms of Nitrogen in Rice
N deficiency symptoms
N deficiency is more prominent at
critical growth stages such as
tillering and panicle initiation when
the demand for N is high.
N deficiency causes reduction in
tillering, leaf size, plant height and
filled grains number in rice.
Sometimes, the visual symptoms of N deficiency
can be confused with those of S deficiency, but
S deficiency tends to first appear on younger
leaves or all leaves on the plant.
Also, mild N deficiency can be
confused with Fe deficiency, but
the iron deficiency first appear on
the emerging leaves.
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Role and deficiency symptoms of Nitrogen in Rice
Nitrogen deficiency in rice nursery
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Role and deficiency symptoms of Nitrogen in Rice
N deficiency in rice
N deficiency
The following link is also useful to know more about deficiency
symptoms of different nutrients:
http://www.laagcon.org/presentations/2008/RBSaichuk.pdf.
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Role and deficiency symptoms of Nitrogen in Rice
Excess of Nitrogen
Dark green foliage.
Increased susceptibility to lodging and
drought
Increased disease incidence and
insect invasion.
In severe excess the crop may fail
to yield grains.
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Role and deficiency symptoms of Nitrogen in Rice
Causes of N deficiency
Soils are inherently low in organic matter (and
hence, nitrogen), and have less N-supplying
power. Simultaneously, inadequate use of mineral
of N fertilizer or organic manures.
Low use efficiency of nitrogenous
fertilizers,
especially
due
to
volatilization, denitrification, leaching,
and runoff, etc.
Permanently submerged conditions
that reduce indigenous soil N
supply.
Heavy rainfall may result in
increased N loss by surface runoff,
leaching and seepage.
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Role and deficiency symptoms of Nitrogen in Rice
Occurrence of N deficiency
N deficiency may be common under the
following soils:
Soils having very low soil organic matter
content (e.g., <0.5% organic C, coarsetextured acid soils).
Soils which have constraints to supply indigenous nitrogen
(e.g., acid sulphate soils, saline soils, P-deficient soils,
poorly drained wetland soils where the amount of N
mineralization or biological N2 fixation is small).
Alkaline and calcareous soils
having very low soil organic matter
content and a high potential for
ammonia volatilization losses.
Intensive cropping without using
adequate doses
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Role and deficiency symptoms of Nitrogen in Rice
Corrective measures (N)
Add organic manure/ green manures
before transplanting / sowing of rice.
Use biofertilizers like Azotobacter
and Azospirillum ,etc.
Apply N fertilizers on the appearance of
deficiency symptoms.
Follow strictly the fertilization schedule
recommended for rice, particularly
suitable for the region.
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Role and deficiency symptoms of Nitrogen in Rice
Corrective measures (N)
If legume crops are greenmanured before rice transplanting,
the rice crop would need 60 kg/ha
less nitrogen through fertilizers or
other manures
Dhaincha
Sannhemp
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Mungbean
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Role and deficiency symptoms of Nitrogen in Rice
Corrective measures (N)
Apply the appropriate
dose of nitrogenous
fertilizers
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Role and deficiency symptoms of Nitrogen in Rice
Let us Sum up
N is a part of the chlorophyll (the green
pigment in leaves) and is an essential
constituent of all proteins.
N deficiency in plants results in a marked reduction
in growth rate. N-deficient plants have a short and
spindly appearance, poor tillering and reduced leaf.
N The effects of N toxicity are less
evident than those of its deficiency.
Excess nitrogen results in prolonged growing (vegetative)
period and delayed crop maturity. Intensive cropping systems
with less input of nitrogen causes N deficiency in crops.
N can be supplied through different
organic sources, chemical fertilizers and
biofertilizers.
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