Effect of Plant Spacing on Growth and Yield Formation of Sugar Beet Taproot

To clarify the effect of plant spacing on the growth, yield formation, and quality of sugar beet taproot. We designed field experiments in 2021–2022, and sugar beet variety KWS1176 was used as experimental material, and 9 plant spacing treatments from 8 to 32 cm were set up. The morphological indicators, photosynthetic characteristics, and the nutrient contents were determined at the stages of the leafage growing period (V1), sugar increase period of taproot (V2), sugar accumulation period I of taproot (V3), and sugar accumulation period II of taproot (V4), and the root yield and quality parameters were measured at the harvest. The results showed that in the plant spacing treatments of 11 and 14 cm, sugar beet had a suitable canopy structure and space for taproot growing. The canopy photosynthetic activity was higher, which provided sufficient photosynthetic products for root growth, and appropriate root size could balance root growth and sucrose accumulation. The highest root yield and sugar content were also obtained in the treatment of 14 cm plant spacing. With the increase of plant spacing, the yield of sugar beet decreased, and the content of α-amino N, K+, and Na+ in the root increased, which had a disadvantageous influence on the processing quality of the root. It was found that the number of cambial rings and the average distance between cambial rings could be used as qualitative indicators of the sugar content of taproot and the processing quality. Therefore, 11-14 cm was recommended as a reasonable planting spacing to obtain higher taproot and sugar yield with better quality.