Drought stress as affecting yield and quality development of different sugarbeet genotypes

Four sugarbeet genotypes with diverse yield and quality and putative different with regard to drought tolerance were tested in field trials under both rainfed and irrigated conditions. Taproot and leaf yield were substantially reduced under drought compared to irrigation, whereas the taproot to leaf ratio was increased. Contents of potassium and sodium in the beet were decreased and contents of sucrose, alpha-amino N and betaine increased. Drought stress gave rise to very high invert sugar contents, whereas nitrate content in the taproot was higher under irrigation. Both irrigation and genotype significantly affected almost all parameters under study, whereas an interaction between these factors occurred only for leaf yield. Therefore climatic conditions of a growing region or the (future) weather conditions do not have to be considered for variety choice. As genetic variability is reduced under water deficit, it seems to be reasonable to conduct variety trials at locations with sufficient water supply. Drought-induced changes in non conventional quality parameters may lead to an erroneous evaluation of technical quality.