Seeds and seeding

Good seed is highly essential to successful crop production. Its pu­rity and germinating power should be known before it is planted.

After threshing seeds usually contain foreign materials such as chaff, dirt, weed seeds and seeds of other plants. These can be removed to a large extent¹ but not entirely by cleaning machinery. The presence of weeds in the seed often increases the labour required for the producti-

on of the crop, reduces crop yields and contaminates the product avai­lable as well as the seed and soil in future seasons.

Mature seed is preferable to immature seed. Immature seed having a low reserve of food supply because of its small size usually produces poor plants when conditions are adverse at planting time. In addition², immature seeds, high in moisture, are injured by frost.

Most seeds show dormancy, that is, they do not germinate immedi­ately after having become mature even though³ external conditions favour germination. They must pass through a rest or after-ripening period, the duration of the dormancy varying greatly with different spe­cies. One should know the length of the dormancy period of the seed that will be planted. It ranges from a few days to some months or even years. Dormant seeds can survive conditions which would kill them if they were active.

Good stands can be obtained by seeding high-quality seed. Howe­ver, even the best seed will not produce optimum yields, provided other factors are not proper. A moist, firm and warm seedbed that provides favourable environment for germination is of greatest importance in establishing a vigorous and uniform stand. Unless there is enough mois­ture in the soil, poor germination will take place.

Two critical factors must be controlled during seeding: depth and rate. Planting at a proper and uniform depth favours quick and uniform germination. The depth of seeding is influenced by the type of the soil and the size of the seed. If fine seed were placed too deeply it would have some difficulty in reaching the surface of the soil. Coarse seeds should be planted much deeper than fine seeds.

The establishment of high-quality stand is also favoured by a proper seeding rate, both underseeding and overseeding reducing potential yield. The former does not allow full utilization of the available moisture, nut­rients and light while the latter requires more nutrients than are present in the soil and reduces the yield.

Other agronomic recommentations that should be followed in obtaining a good stand are seeding at optimum time, covering seed properly, using proper weed-control techniques, using proper seeding machines and equipment, and applying proper fertilizers.

Дата добавления: 2015-11-14