Comparison of quantitative and qualitative yield response of different sugar beet genotypes under drought stress conditions

Drought stress is one of the main reasons for the reduction of quantitative and qualitative yield in sugar beet cultivation, on the other hand, the increasing reduction in available water, especially in arid and semi-arid regions, has made the worse situation. In this situation, the use of drought-resistant cultivars is an effective way to reduce production risk. For this purpose, experiments were conducted in the form of split plots in based of RCBD statistical design with the main factor of irrigation (90 and 180 mm) and sub-genotype factor (16 hybrids and 4 genotype control varieties) in the years 2016 and 2017 at Karaj Sugar Beet Research Institute. The results showed that there is a decreasing trend in the average root yield and white sugar yield in two years under stress conditions of 28.5 and 10.5%, respectively, compared to normal irrigation conditions. However, under stress conditions, sugar content had an increasing trend, and root impurity values (sodium and nitrogen) had a decreasing trend, which was accompanied by the highest values of the sugar extraction coefficient. Also, the reduction of water consumption in stressful conditions led to an increase in the efficiency of irrigation water in stressful conditions compared to normal. In the examination of genotypes, based on two indices of tolerance and resistance to drought stress and yield index, genotypes number 1, 3, 9, 12, and 16 were identified as promising genotypes.