MEDICINAL AND AROMATIC CROPS (2+1)

Harvesting, processing and yield

Harvesting and processing

• The plants flower within one year of transplanting.
  
• The crop gives a poor yield in the first year and the optimum yields are obtained only during the 2nd and 3rd year.
  
• In Kenya and the Nilgiris in India, three harvests of flowers are obtained as the flowering in these areas continues for 9 months.
  
• In temperate areas like Kashmir, the first harvest is obtained t the end of June or in the 1st week of July.
  
• The flowers should be picked when ⅔rd of the disc-florets are pen and the ray-florets are horizontal.
• The harvesting of immature or over-mature flowers decreases their pyrethrin content.
  
• The flowers are picked at fortnightly intervals in India.
  
• There is a gradual fall in the pyrethrin content of harvested flowers after the third year of planting.
  
• The yields tend to become uneconomical after 3-4 years and replanting is necessary.
  
• Light pruning at the beginning of the dry season, after picking the flowers, is required to keep the plant sturdy.


Drying

• The harvested flower-heads are usually dried immediately in the sun.
  
• They are thinly spread on straw mats and turned over frequently in order to avoid fermentation. At night they are kept under cover.
  
• Dehydration is complete in 5-7 days. The ideal method of drying is to use hot-air driers, in which the temperature should not exceed 800C.
  
• The loss in weight will be about 65-75%. It is safer to dry it in the sun when the acreage is small and there is no chance of rain during the harvesting season.
  
• However, in larger farms, the use of air-driers is essential in order to dry the harvested flowers in time. Mechanical driers have been designed for drying pyrethrum flowers.


Yield and pyrethrin content

• The average annual yield in Kashmir is about 250 kg/ha, against 700 kg/ha in Kenya and 500 kg/ha in Nilgiris.
  
• The yield in the first year, as reported from Kodaikanal, is about 450 kg/ha.
  
• The total pyrethrin content is reported to be 1.0-1.5% in India, while the average content in Kenya is 1.4% and the highest is 2.1%.