The aim of this study was to determine the effect of plant spacing, fertilization and genotype on photosynthetic productivity and leaf macroelements (N, P, K, Na, Mg, Na) status during the sugar beet growth, and root yield and quality at the harvest. The field trial was conducted at two sites in eastern Croatia in 2014 and 2015 with four sugar beet cultivars: Colonia, Serenade, Fred and Danton. Sowing was done at inter-row spacing of 50 cm and four different intra-row spacings: 13 cm (R1), 15 cm (R2), 17 cm (R3) and 19 cm (R4). Nitrogen fertilization was conducted in spring (G0-control, G1-presowing 45 kg ha-1 N and G2-presowing 45 kg ha-1 N + topdressing 40.5 to 55 kg ha-1 N). From May to September plant samples were taken for determination of photosynthetic productivity and the macroelements status in leaf dry matter. At harvest, root yield and quality were determinated. In 2014, the largest leaf dry weight was on August 30 (68.7 g plant-1), leaf area and LAI on July 30 (6019.1 cm2 and 7.6 m2m-2, respectively). In 2015, the largest leaf dry weight was on July 30 (48.6 g plant-1), leaf area on June 30 (3013.1 cm2), LAI on June 30 and July 10 (3.8 m2m-2). The N and P content in leaf dry matter decreases with plant aging, while the content of K, Mg and Na were higher in leaf dry matter of intensive canopy development. On average, the highest root yield was achived in R2G2 (86.9 t ha-1), the sugar content in R1G0 and R1G1 (14.5%) and the sugar yield in R2G2 (10.6 t ha-1). Hybrid Serenade achieved the highest average root yield (81.1 t ha-1), while hybrid Colonia had the highest sugar content in the roots (14.5%) and sugar yield (9.7 t ha-1).
Ivana Varga, Josip Juraj Strossmayer University of Osijek, Faculty of Agriculture in Osijek, Vladimira Preloga 1, 31000 Osijek, Croatia, firstname.lastname@example.org