Effect of nitrogen and boron fertilization on the productivity and quality of sugar beet

Abstract

The agricultural policy in Egypt supports sugar beet farmers to increase the cultivated area and thus increase sugar production and reduce the gap between sugar production and consumption. Therefore, the sugar beet crop occupies an important place in the Egyptian crop cycle as a winter crop not only in fertile soils, but also in poor, saline, alkaline and calcareous soils. A field experiment was conducted at Shandaweel Agricultural Research Station, Sohag governorate, Egypt (latitude of 24.54o N and longitude of 32.94o E) during 2019/2020 and 2020/2021 successive winter growing seasons. The objective of this investigation was to find out the optimal levels of nitrogen and boron to get the maximum productivity and quality of sugar beet. Randomized Complete Block Design (RCBD) using a split-plot arrangement with three replications was used in both growing seasons. Three levels of nitrogen (60, 80 and 100 kg N/fed.) were allocated in the main plots and four boron concentrations (0, 80, 160 and 240 ppm/fed.) were sprayed twice on the beet foliage, grown in the sub-plots at 70 and 100 days after sowing. The results revealed that boron and nitrogen levels had a significant effect on vegetative traits, i.e., chlorophyll a and b, root length and diameter, quality characteristics (sucrose%, Na, K, α-amino N, quality index%) and productivity parameters of sugar beet (root and sugar yields/fed) in the two growing seasons. The highest root diameter and root yield, recoverable sugar yield was produced by applying 80 or 100 kg N/fed. with 240 ppm boron, in both growing seasons. Application of 80 kg N /fed. with 240 ppm of boron gave the highest values of sugar lost to molasses %. On the contrary, Na, K and α-amino N were decreased. Supplying sugar beet with 80 kg N/fed. with foliar application of 240 ppm boron is recommended under conditions of the present works in Sohag governorate to obtain the highest recoverable sugar yield, sucrose and quality index of sugar beet.