Introduction to major field crops (1+1)

Harvesting and Threshing

Harvesting of sunflower crop at its optimum stage of maturity is very important to minimize field losses and to get best quality seed with higher viability. Delay in harvesting causes field losses as sunflower is very prone to bird damage. Rainfall at maturity causes rotting of capitulum which results in fungi attack and discoloration of seed.

Generally, maturity of sunflower is judged by visual observation of colour of capitulum and seed as well. Sunflower is harvested when colour of the capitulum turns to lemon yellow.When seed turns to darker in colour, its coat also becomes hard and seed easily removed from capitulum at this stage, if seed is pressed with fingers, kernel remains intact whereas in case of immature seed, kernel is smashed on pressing. Measurement of moisture content in seed is a scientific way to judging sunflower maturity. At the time of harvesting seed moisture content, should not exceed 15 per cent. Harvesting of sunflower is done mostly by sickles. At the time of harvesting, capitulum is separated from stem and left for sun-drying. Threshing is done by beating the centre of the head with a stick or with thresher. After threshing, cleaning of seeds should be done by separating foreign materials by sieving and winnowing. Further, sun drying of the seed is desirable before storage and the moisture in seed should not exceed 10 per cent.




Fig: Maturing stage.




Fig: Maturity stage.




Fig: Sunflower growth stages.