EFFECT OF VARIOUS RATES OF BORON ON YIELD AND QUALITY OF HIGH-GRADE SUGAR BEET VARIETIES

Sugar beet is an extremely demanding culture regarding soil properties, regular and timely applied agro-technical measures, correct selection of hybrids in terms of leaf and root disease, crop protection, as well as proper fertilization based on the results of chemical and microbiological analyzes. In addition to fertilization with macroelements (nitrogen, phosphorus, potassium), it is extremely important to apply boron as a microelement. An insufficient supply of boron results in reduced yields and sugar content in sugar beet production. This is because boron is involved in the process of transport and disposal of sugar in the root. The greatest need for boron is in the phase of intense leave growth, from closing the ranks (end of May, beginning of June) until reaching the maximum leaf surface (mid-July). The introduction of new high-yield hybrids in sugar beet production requires, in most cases (depending on the availability of boron in the soil), a greater amount of boron. The research was conducted on two locations during two vegetation years (2015, 2016). The experiments were set up as a split-block scheme in 12 variants and 4 repetitions on two different soil types. The used treatments were as follows: A - sugar beet varieties (A1 - Jadranka, breeding house KWS, A2 - Antek, breeding house Strube, A3 - Protecta, breeding house Syngenta-Hill, A4 - Boomerang breeding house SESVanderHave); B - boron fertilization (B1 - control; B2 - 1 kg ha(-1) B; B3 - 2 kg ha(-1) B). Fertilization was carried out based on chemical soil analysis results. The fertilization on the two soil types was as follows: 95 kg ha(-1) N, 65 kg ha(-1) P2O5, 220 kg ha(-1) K2O were applied on the soil type eutric brown soil; while on humogley soil type 85 kg ha(-1) N, 50 kg ha(-1) P2O5, 200 kg ha(-1) K2O were applied. Boron was applied foliar in the form of sodium borate (Borax, 37% sodium borate; Ekoprom d.o.o.). Two foliar treatments were performed, before closing rows, and another 14 days later. After harvest, samples were collected to determine the root yield and quality. Compared to the control variant, both boron fertilization variants achieved statistically significant higher yield, sugar content and pure sugar yield on both soil types and among all tested hybrids during the research. On soil type eutric brown soil, the best results of the examined parameters were achieved in variants B3 (2 kg ha(-1) B), while in soil type humogley there were no statistically significant differences between variant B2 (1 kg ha B) and variant B3 (2 kg ha(-1) B), except for the sugar yield parameter.