onions, carrot, sweet corn, seeds, farmers, coating / agri-Saaten GmbH


Onions
	Cultivation Botany Preconditions for cultivation Soil Crop rotation Sowing Plant stand and Seed densitiy Sowing methods Sowing depth Preparation of the soil Sowing time Fertilization Liquid fertilizer Irrigation Weed control Pests Maturing and harvest Drying Storage


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Sowing
Seeds
Today farmers dispose of seeds of highest quality as regards germination and vigour. It is essential that perfectly coated seeds are used. The coating mustn´t impede the function of modern precision sowing machines ( for example by abraison or reduced running capacity of the seeds) on the one hand, on the other hand, the grain must be best possible protected against diseases (see agricoat).

	I	longitudinal section of onion seed
	Sa	scale of the seed
	N	nutritive tissue
	II	isolated seedling
	Co	winded cotyledon
	K	bud
	W	root rudiment with root cover

The 1000 seed count weight is in the average aprox. 4 g, which corresponds to aprox. 250.000 seeds/ kg. The grain itself has a diameter of 0,3 - 0,4 mm, is very hard and has three edges. Usually it is shrunken between the edges (s. sketch)

Important phases in the development of sown onions:

grain sowing	seedling	1. true leaf	End of cotyledon
after sowing	"Bow" phase; when the subterranean germination is finished, the bow-shaped cotyledon pushes through the surface.	"Whip" phase; the first true leaf is developed and the tip of the cotyledon begins to die off	After the appearance of the third leaf the cotyledon dies off completely.


4. leaf	End of 1 true leaf	Beginning of bulb formation
"Leek" phase, the shaft begins to swell and when the forth leaf appears, the first leaf begins to die off.	The first leaf has finally died off. When the leaves 5, 6 and 7 appear, the second leaf spreads off of the shaft	While the leaves 8 - 13 are developed, the leaves 2 and 3 die off. At the same time the formation of the bulb begins, and the plant reaches ist maximum height and foliage growth.


Bulb formation	Bending down of foliage	Maturity
The vegetative phase commes to its end. The leaves 4, 5 and 6 die off and the leaf tips begin to dry out. Due to their weight, some leaves bend the size of newly developed leaves is reduced. The bulb can now be distinguished, and the skin colour begins to change.	The vegetative phase is definitely finished. The neck is drawn in and becomes softer. The foliage bends down and begins to die off. The onion has now its definite size.	The foliage is completely dry, the neck drawn in and the skin coloured

Note: It goes without saying that in practice not all plants reach the corresponding phases at the same time. It is assumed that a phase is reached when the majority of the plants have entered it.

Courtesy Ch. Rey et al. 1974 Revue Suisse de viculture, aboculture, horticulture; Vol. V9 No. 3, 101 - 104