THE INFLUENCE OF FACTORS OVER WHICH THE GROWER HAS CONTROL ON FINAL YIELD AND QUALITY OF SUGAR BEET

Vliv pěstitelem ovlivnitelných faktorů na výnos a jakost cukrovky

Ing. Lucie Jozefyová

Doc. Ing. Josef Pulkrábek, CSc.

Department of Crop Production, Czech University of Agriculture in Prague.

Summary

In 1998 and 1999 we observed production of two sugar beet varieties, fertilised by splitting doses of nitrogen in LAV and NP+B fertiliser and cropsprayed with fungicide and growing regulator. Higher doses of nitrogen increased the yield of roots and beet tops and decreased sugar concentration. The highest yield of sugar was in 50 kgN.ha-1 fertilised variant. The variety Epos reacted on NP+B fertiliser better than variety Elan. 200 kgN.ha-1 in NP+B fertilisation did not have positive effect on sugar yield. Fungicide application contributed to increasing of sugar yield, especially because of higher root yield. Variety Elan positively reacted on fungicide application in both variants of nitrogen fertilising. Variety Epos had the same reaction only in higher nitrogen dose. Application of growing regulator did not have influence on final yield. The variety Epos had better yield and technological values than variety Elan in all variants. Nitrogen nutrition had positive influence on chlorophylls content. The highest values of chlorophyll were measured in sugar beets leaves of 150 kgN.ha-1 fertilised variant. Content of chlorophyll in sugar beets leaves was increased by fungicide application in both experimental years. Growing regulators application did not change chlorophylls content.

sugar beet, nitrogen, fertilising, chlorophyll, sugar yield.

Souhrn

V letech 1998 a 1999 jsme sledovali produkci dvou odrůd cukrovky hnojených stupňovanými dávkami dusíku hnojivem LAV a NP+B a ošetřených fungicidem a regulátorem růstu. Vyšší dávky dusíku zvýšily výnos bulev a řepného chrástu a snížily cukernatost. Nejvyšší výnos bílého cukru byl u varianty hnojené 50 kg N.ha-1. Na hnojivo NP+B reagovala lépe odrůda Epos než odrůda Elan. Hnojení 200 kg N.ha-1 v NP+B nemělo pozitivní efekt na výnos cukru. Ošetření fungicidem přispělo k zvýšení výnosu cukru, zejména díky vyššímu výnosu bulev. Odrůda Elan reagovala na ošetření fungicidem zvýšením výnosu v obou variantách dusíkatého hnojení, odrůda Epos pouze při vyšší dávce dusíku. Ošetření regulátorem růstu nemělo vliv na konečný výnos. Odrůda Epos měla ve všech variantách lepší výnosové a technologické ukazatele než odrůda Elan. Výživa dusíkem měla pozitivní vliv na obsah chlorofylu. Nejvyšší hodnoty chlorofylu byly naměřeny u varianty hnojené 150 kg N.ha-1. Obsah chlorofylu v listech cukrovky se při ošetření fungicidem v obou pokusných letech zvýšil, avšak aplikace regulátoru neměla na obsah chlorofylu žádný vliv.

cukrovka, dusík, hnojení, chlorofyl, výnos cukru.

Sugar beet is one of the most productive crops in our geographical conditions (Rybáček, 1985). Sugar beets growing potential is used from only 55% in Czech Republic nowadays, in west Europa countries is it from 60-70% (Chochola, 1997). It is necessary to recognise how is production ability of sugar beet influenced. Final yield of sugar beet and sugar is significantly influenced by factors over which has grower some control: variety, fertilising, application of plant growth regulators, pesticide application, harvesting date etc.

The results mentioned below are averages of two experimental years 1998 and 1999. The experiment was carried out at the experimental station of Agronomical faculty in Červený Újezd. Growing technology corresponds to agronomical praxis (autumn tillage, PK nutrition, pre-sowing soil management). Optimal plant density was achieved by singling and hoeing. There was used two type different varieties (Elan - sugar type and Epos - normal type) in the experiment. Both varieties had ten variants of nitrogen nutrition (LAV and NP+B fertiliser) combined with growing regulators and fungicides application. The variants were six times repeated. Harvest area of each variant was 10m2.

There was measured chlorophyll content in sugar beet leaves of all variants during vegetative period. We have used chlorophyllmeter - the apparatus used for determining of chlorophyll relative value in plant leaves. It measures chlorophyll content right on the field, without destroying of measured plants.

Splitting nitrogen fertilising

We have used five different doses of nitrogen fertilisation (0, 50, 100, 150, 200 kg.ha-1). Splitting nitrogen fertilising had an influence on root yield increasing - in average of two varieties from 59.97 t.ha-1 (0 kgN.ha-1 variant) to 65.49 t.ha-1 (200 kgN.ha-1 variant). It had the same influence on tops yield. In average the lowest tops yield was 30.64 t.ha-1 in 0 kgN.ha-1 variant and the highest tops yield was 41.83 t.ha-1 in 200 kgN.ha-1 variant. Sugar concentration gradually decreased in average from 17.85% to 16.84%. Differences between sugar yields were small. Sugar beet without nitrogen fertilising had lowest sugar yield, e.g. 9.44 t.ha-1. The highest yield of sugar was 9.89 t.ha-1 in 50 kgN.ha-1 variant.

Chlorophyll values measured in sugar beet leaves of different variants of fertilising were dissimilar. There were positive influence on chlorophylls content. Sugar beet without nitrogen fertilising had the lowest chlorophyll values during vegetation 1998 and 1999. The highest values of chlorophyll were measured in sugar beets leaves of 150 kgN.ha-1 variant.

NP+B fertiliser

We have tested two 100 kgN.ha-1 variants of NP+B fertiliser. One variant was fertilised before sowing and second later in two splitting doses. Average root yield and sugar concentration were similar in this variants. A bit higher values get the variant fertilised before sowing. 200kg NP+B fertilisation did not have positive effect on sugar yield. Root yield was higher, but sugar concentration decreased.

The variety Epos reacted on NP+B fertiliser better than variety Elan. Variety Epos fertilised with 100 kg.ha-1 in two splitting doses after emergence had high sugar yield (10.20 t.ha-1). The two other variants of NP+B fertiliser (100 kgN.ha-1 before sowing and 200 kgN.ha-1) achieved sugar yield 10.02 t.ha-1.

Growing regulators and fungicides application

Fungicide application contributed to increasing of sugar yield, especially because of higher root yield. More marked difference was by 150 kg.ha-1 nitrogen doses. There were small differences between varieties too. Variety Elan positively reacted on fungicide application in both variants of nitrogen fertilising. Variety Epos had the same reaction only in higher nitrogen dose. Application of growing regulator did not have influence on final yield.

Content of chlorophyll in sugar beets leaves was increased by fungicide application in both experimental years. The differences were small in 1998. Growing regulators application did not changes chlorophylls content.

Variety

We have compared two type different varieties: Elan (sugar type) and Epos (normal type). From results of two years experiment emerge that the variety Epos had better yield and technological values than variety Elan in all variants.

Figure1: The influence of sugar beets variety on final yield.

In 1998 sugar type variety Elan had higher chlorophylls content in all variants of nitrogen fertilising than normal type variety Epos. Next year both varieties had similar chlorophyll values in their leaves.

Table 4: Chlorophylls content in sugar beet leaves measured during vegetation1998.

Table 5: Chlorophylls content in sugar beet leaves measured during vegetation1999.

REFERENCES:

Chochola J.: Výnosový potenciál, jeho rezervy a agrotechnika cukrovky. Zemědělec, Speciální příloha k pěstování cukrovky, 1997, s.5-7.

Rybáček V. a kol.: Cukrovka, SZN Praha, 1985.

Grant vznikl za finančního přispění výzkumného záměru MSM 412100002.

Ing. Lucie Jozefyová

AF ČZU v Praze, Katedra rostlinné výroby; 165 21 Praha Suchdol

tel.: 02/24382537