SUGAR BEET RESPONSE TO BALANCED NITROGEN FERTILIZATION WITH PHOSPHORUS AND POTASSIUM. PART III. DYNAMICS OF WHITE SUGAR YIELD DEVELOPMENT

W. Szczepaniak, W. Grzebisz, K. Pepliński, P. Barłóg

Abstract: The main objective of the study was to evaluate the dynamics of white sugar yield (WSY) by beet crop under conditions of imbalanced application of key nutrients, such as P, K with respect to N. The field trial arranged as one-factorial design was consisted of eight treatments: N0P0K0; N0P1K1; N1P0K1; N1P1K0; N1P0.25K0.25; N1P0.5K1; N1P1K1 and N1P1K1+Ca; where 1 is recommended level of NPK fertilization and Ca means that phosphorus applied as partially acidulated phosphoric rock (PAPR). The harvest of sugar beet took place at following days after sowing (DAS): 92, 113, 134, 155 and 175. Yield of white sugar was determined by set of standard methods used in a sugar beet factory. The course of weather was the dominant factor, affecting realization of yielding potential of a crop on the background of supply of P and K. Under favorable growth conditions, yield of sugar increased accordingly with increasing rates of fertilizer P. Yield forming effect of P, as a rule, revealed in the late-season,
resulting in the WSY increase of 30–40% at 175 DAS compared to 155 DAS. The average yield increase in response to optimal application of P was 18.4%, whereas of K only 6.0%. In years with drought, the effect of P was low due to limited development of the storage root to accumulate sucrose. The main reason was a probably insufficient supply of N and K in the mead-season, restricting size of the root. Consequently, the optimum P rate to harvest sufficiently high WSY in years with drought was at the level of 25% of the P recommended rate. On the average, the maximum yield of WSY was harvested in N1P1K1+Ca treatment, indirectly indicating on an importance of Ca as a sugar yield forming nutrient.

Keywords: dynamics of sugar accumulation; imbalanced fertilization; nitrogen; phosphorus; potassium; sugar yield

Date published: 2017-08-28