Drought tolerance of sugar beet ? Evaluation of genotypic differences in yield potential and yield stability under varying environmental conditions

Drought stress affects yield formation of sugar beet. Under climatic changes with longer periods of drought, the development of sugar beet varieties with a higher drought stress tolerance is gaining importance. Objectives of the study were to investigate genotypic differences in the response to different environments, especially drought stress, to define conditions in which sugar beet can best be selected for root yield and sugar content, and furthermore, to examine the relation between yield potential and yield stability. In 2018 and 2019, field trials were carried out with 6 genotypes at three drought-stressed sites, where an irrigation treatment allowed the comparison with optimal growth conditions, furthermore, trials with 3 N treatments were conducted. In the absence of diseases, no significantly different regression slopes of genotypes were observed for sugar yield in 17 environments. Hence, the trials provided no indication for a special adaptation of the genotypes to drought stress conditions. One reason might be a sink limitation of sugar beet growth. By contrast, a genotype by environment interaction existed for sugar content and root yield. The greatest genotypic discrimination to classify genotypes with either high root yield or sugar content was under optimal growing conditions. With increasing root yield, the sugar content declined similarly in all genotypes. For sugar yield, differences between the genotypes occurred in yield potential and yield stability. High yield potential was not necessarily associated with high yield stability. As it is important to achieve consistently high yields also with higher variability of climatic conditions, yield stability will increase in importance for future breeding.

Automated summary

The study found that different genotypes of sugar beet responded differently to environmental conditions, especially drought stress, with a genotype by environment interaction existing for sugar content and root yield. High yield potential was not necessarily associated with high yield stability, highlighting the importance of stability in future breeding efforts to ensure consistently high yields under varying climatic conditions.