Production Practices and Quality Assessment of Food Crops. Vol. 1

exert a vertical pulling force to the plant. Functional parameters of this system
are then:
– belts and
– working speed,
– belt angle of inclination, and
– the pulling force exerted by the belts due to friction and compression between
the belts and the plants.
At the upper end of the belts, a pair of topping implements (counter-rotating bars
or rotating disks) are placed to remove the tops.
3.1.2. Surface crops
Fruit and Vegetables Harvesting Systems 265
Figure 1. Pulling principle.
Cutting, combing, stripping, vibration and threshing are different functions used
for the detachment of the very wide range of aerial parts found in the diverse commodities
to be harvested.
Cutting action is applied mainly to the so-called leafy products: cabbage, lettuce,
spinach, endive-escarole, Brussels sprouts, celery, broccoli, cauliflower, artichokes,
chard, chicory, mustard, parsley, watercress, and any other so-called greens or similar
plant parts. Each of these products need multiple harvests for maximum yield for
fresh market, except perhaps spinach, which is mostly grown and harvested for
processing. Their common properties are that they have to be cleanly removed
and handled softly for minimum leaf loss. Cutting is the most effective method of
removal, and it is also used in combination with other harvesting systems (like
the cutting of whole plants of tomato; cutting undesired aerial parts of root crops
(see above); cutting of Brussels sprouts stalks for subsequent stripping of the sprouts,