NITROGEN

u   

Sunflower responds to 30-80 kg N/ha depending upon soil moisture status.

u   

Hybrid sunflower, though a high yielder, does not have a high demand for N.

u   

On sandy loam and slightly alkaline soils, significant yield increases have been obtained upto 80 kg N/ha ,but in fine textured soils, the optimum rates are much lower.

u   

Sunflower respond upto 80-90 kg/ha but only 40-60 kg N/ha was profitable .

u   

Very high rates of N can depress the oil content and impair seed quality.

u   

For rainfed crop the nitrogen schedules are adjusted as per soil moisture status.

u   

Excess nitrogen application reduces the yield and oil content of seed.

PHOSPHORUS

     

Sunflower responds markedly to P, even somewhat more than to N.

     

Under rainfed conditions, optimum rates vary from 0 to 50 kgP2O5/ha ,and responses may even be absent .

     

Spring-planted crop with irrigation can respond upto 70 kg P2O5/ha.

     

Optimum yields can be had through balanced fertiliser use in which the basal dose should be drilled 10-15 cm deep at sowing.

     

Full dose of N and P applied pre-plant as side placement or broadcast was superior but drilling N+P below the seed adversely affected crop emergence and produced the lowest yield .

     

In light textured soils phosphatic fertilizer application preferably in the form of single super phosphate.

     

Sulphur in single super phosphate will improve the quality of oil.

 

POTASSIUM

l     

A significant increase in seed yield due to application of 20 kg K2O/ha in combination with 20 kg N and 30 kg P2O5/ha has been reported.

l     

For the irrigated crop, the requirement is 80 kg N,80-100 kg K2O/ha.

l     

There is a positive relationship between the NPK accumulated at complete head formation and seed yield as well as oil production.

l     

Oil yield and nutrient uptake are increased with balanced NPK application.

l     

Seed yield of hybrid (MSFH-8) increased from 2100kg/ha in control to 3200 kg/ha with the application of NPKS.

l     

Potash can be applied only when the soil test reports showed K-deficiency need based micro nutrient application is taken up.

 

SULPHUR

u   

Yellowing spreads from the base to the apex.

u   

Yield increase is brought about largely by the production of larger heads and heavier seeds.

u   

Plants showing paling/yellowing of leaves.

u   

Growth of plants is reduced.

u   

The size of capitulum is severely restricted.

u   

Inflorescence may remain covered within the bracts.

u   

Maturity of flowers is delayed

 

Control

•        

Sulphur added to S-deficient soils increases seed yield at 13 kg/ha.

•        

Application of 25 kg S/ha increases seed yield by 38%.

•        

An average increase of 3.8% in the oil content of seeds due to S application .

•        

In alkaline , clay soil having 12ppm available S, application of 10 kg S/ha more than doubled seed yield and increased oil yield.

•        

N+S application produces largest heads, heaviest grains and more seeds/head.

•        

80 kgN+25 kg S will give more oil yield .

 

COPPER

Nature and symptoms of deficiency

 
Copper deficiency

•       

Copper deficiency symptoms appear as interveinal chlorosis of the upper half of the old leaves starting from the tip of the leaf.

•       

Chlorosis is generally restricted to the apical half of the lamina.

•       

Chlorotic areas later develop dark brown necrotic scorching, which spreads along the margins towards the base of the leaf

•       

Due to the formation of necrotic lesions in the chlorotic areas, the affected portion of the laminae becomes shrivelled and withered.

•       

As deficiency persists, marginal scorching of the leaves becomes more pronounced and brown necrotic spots develop near the midrib.

•       

Size of the leaves is greatly reduced.

Control

•       

Two to three sprays of 0.2% copper sulphate solution at weekly intervals is recommended.

 

Molybdenum

Molybdenum deficiency

•        

Molybdenum deficiency in sunflower is characterised by pale green foliage, interveinal and marginal chlorosis of old leaves and inward curling of leaf margins of the young leaves giving them a "cupped" appearance.

MANGANESE

 

Nature and Symptoms of deficiency

 
Manganese deficiency

•        

Deficiency symptoms appear in the form of interveinal chlorotic mottling of apical part of the second set of leaves.

•        

When manganese supply is severely limited, the entire laminae become severely mottled and the interveinal chlorotic areas develop light brown irregular necrotic patches.

•        

These patches, which are initially more conspicuous near the leaf apices, later spread to the entire laminae which eventually turn severely necrotic.

•        

Symptoms gradually spread from the middle to the young and old leaves.

Control

•        

Manganese sulphate should be applied to the soil at 50 kg per hectare.

•        

Foliar spray of 0.2 - 0.3% manganese sulphate solution 2-3 times at weekly intervals is also recommended.

BORON

Boron deficiency

•        

When boron supply is severely limiting, at about 3 weeks growth, young and middle leaves of plants develop small chlorotic patches.

•        

Cotyledons of these plants become massive and the shoot apex becomes globose and deformed.

•        

Later, chlorotic patches become more pronounced and develop orange coloured necrotic areas in young leaves.

•        

Shoot apex of plants may turn necrotic and cease to grow.

•        

Young leaves show severe curling and distortion.

•        

This leads to appearance of side branches bearing small leaves.

•        

Eventually all the young leaves turn necrotic.

 

          Borax application

•        

Give directed spray of Borax(0.2% i.e 2 gms/lit.of water) to capitulum at ray floret opening stage for increasing seed filling, yield and oil content.

•        

A spray mixture of 500 lits/ha is required.

•        

Dissolve required quantity of Borax (2gms/lit) in small quantity of hot water and make up the required volume.