Vikas Singh Sengar

06-06-2022 12:43 PM

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Harvesting and threshing of crops

Govind Kumar, Amit Singh Vikas Singh Sengar
Assistant Professor, SIPS

Harvesting is the process of removal mature plant or economic parts of plant from the field. Harvesting includes, operation related to crop - cutting, picking, plucking or digging or any combination of above operation. It means removing the economic valuable plant part of crops which is useful for humankind. The economic product involved grain, seed, leaf, root or sometimes entire plant are needed.

Harvest Index (H.I): it can be measure by the formula-
H.I. = (Economic yield/Biological yield) × 100
Time of Harvesting: If we want to the crop is to be harvested early, in this case the products or produce content high level of. High moisture leads to pest attack and reduction in germination percentage and impairs the grain quality. Late harvesting results in shattering of grains, germination even before harvesting during rainy season and breakage during processing.
External Symptoms of Physiological Maturity 
The major symptoms of physiological maturity of some field crops are given below: 

• Wheat and Barley–are ready to harvest when complete loss of green colour from the glumes. 
• Maize and Sorghum– are ready to harvest when Black layer in the placental region of grain 
• Pearl millet– are ready to harvest when  Appearance of bleached peduncle 
• Soybean– is ready to harvest when Loss of the green colour from leaves. 
• Red gram– are ready to harvest when Green pods turning brown about 25 days after flowering.

Harvest Maturity Symptoms:
The harvest maturity symptoms of some important crops are given below: 

• Rice– are ready to harvest when Hard and yellow coloured grains. 
• Wheat– is ready to harvest when yellowing of spikelets. 
• Sorghum, Pearl millet, foxtail millet– are ready to harvest when Yellow coloured ears with hard grains. 
• Ragi– are ready to harvest when Brown coloured ears with hard grains 
• Pulses– are ready to harvest when Brown coloured pods with hard seeds inside the pods. 
• Groundnut– is ready to harvest when Inner side of the pods turns dark from light color. 
• Sugarcane– are ready to harvest when Leaves turn yellow.
• Tobacco– is ready to harvest when leaves slightly turn yellow in colour.

Criteria for Harvesting of Crops:
The criteria for harvesting of crops are given as
Crop Criteria for Harvesting of Crops:

• Rice:  32 days after flowering, Green grains not more than 4-9%
• Wheat:  harvested when 15% moisture present in grain, Grain in hard dough stage
• Maize:  25–30 days after tasselling, Seed moisture content is at 34%
• Sorghum:  40 days after flowering
• Red gram:  28–35 days after flowering
• Black/Green gram: Pod turns brown/black
• Rapeseed/mustard:  harvested when 75% of the silique turns yellow, Seed moisture at 30%
• Sunflower:  Back of heads turns to lemon yellow
• Groundnut:  Yellowing of leaves and shedding Development of purple colour of the testa
•  Cotton:  Bolls fully opened
• Jute:  50% pod stage (120–150 days)
• Sugarcane:   Brix 18–20%, Sucrose 15%

Methods of Harvesting:
Harvesting is done either manually or by mechanical means. 
(i) Manual: Sickle is the sharp, curved and serrated tool for efficient. Knife is used for harvesting of plants with thick and woody stems. Now-a-days improved type of sickle is available which reduce the drudgery of harvesting labourers. 
(ii) Mechanical: Harvesting process done with the use of implements or machines.