REVIEW OF THE MAIN CROPS AND THEIR VARIETIES
There are no domestic varieties certificated for growing in farms in Latvia . The factories conclude contracts with farmers for sugar beet growing and provide sugar beet seeds. There are quotes for sugar beets. In Latvia there are 2 sugar factories, and sugar beets are grown mostly near those factories (In Zemgale and Kurzeme). The import of sugar in Latvia is strictly inspected.
The vegetation of sugar beets in Latvia goes up to 150 - 160 days. In spring 150 000 seeds of beets per ha should be sown. In autumn the optimal amount of beet plants is about 80 000 - 90 000. When growing the varieties of high yielding beets (type E and EN) high yields can be obtained also from 40 000- 50 000 plants per ha. The growing of sugar beets is 100% mechanized. The growing technology is very intensive and suitable only in best soils. To avoid pests and diseases, very important is the crop rotation. The crop rotation mostly includes soft wheat and oil seed rape. Only some little farms do grow sugar beets by hand.
The widely growing varieties are 'Anna', (originator Sweden), 'Axel', 'Gala', 'Kestrel', 'Pilot', 'Salut', 'Vanessa', 'Kassandra', 'Juvena', 'Lorenza' (originator Germany), 'Manhattan', 'Matador' (originator Denmark), 'Conto', 'Univers' (originator the Netherlands).
CROP PHYSIOLOGY
The seed-coat is thick and a large amount of water is needed for good emergency - 150-170% of the weight of seed. The development of assimilation organs is quick. The cotyledons are sensitive to mechanical and pest damages, and damage of cotyledons may cause the decrease of root yield for 20-25 %. The area of leaves influences the increase of root and sugar accumulation. Tap root growth depends on weather conditions, nutrients, and the total area of the leaf. Maturation starts when the concentration of sugar in roots has achieved >15 %. Late added nitrogen fertilizers prolong maturation. Leaves of plants are yellow. Harvest depends on weather conditions in autumn (cold and rainy weather prolongs growing and decreases yield).
SOIL
Sugar beet is a soil selective crop. Properly cultivated soils with high fertility, good aeration and sufficient water content produce higher outcome. Better suited are loamy, and clay soils. In Latvia the most suitable region for sugar beet growing is Zemgale. If having an optimally working drainage system on soddy carbonat soils and loamy soils, sugar beets yield is higher than that in light mineral soils. The optimal pH is 6,0-7,5.
CLIMATE
The minimum temperature for oil seed rape to start germination is +1 ° C, the optimum over +6+7 ° C. Early sowing is essential for successful growth and further development of sugar beets canopy. The growing period depends on weather conditions during autumn (150-160 days). During emergence sugar beets stand short night frosts -4 to -5 ° C. More sensitive sugar beets are at beginning of emergence, when frost -3 ° C can damage sowing. At Latvian weather conditions the required total active sum of temperatures for sugar beets is - 800-2000 ° C. The sunny and warm days and cool nights in autumn during sugar beets maturation promote higher sugar content in beets' roots
RADIATION
Sugar beets are the short day plants. Sugar beets are southern cultivars. The conditions of radiation in Latvia are not suitable for sugar beets growth - in long day conditions, and in wet, cool weather, sugar beets can blossom out, but genetically improved varieties can be grown in Latvia as well. The optimal plant density for sugar beets is 80 000- 90 000 plants per m2 .
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