The response of the sugar beet (Beta vulgaris L.ssp. vulgaris var. altissima Döll) genotypes to heat stress in initial growth stage

The continuous trend of global warming and increasing interest toward cultivating sugar beet (Beta vulgaris L. ssp. vulgaris var. altissima Döll) in tropical regions led us to conduct this study to investigate the effect of high temperature on sugar beet at initial growth stages. Thirty one genotypes were incubated at two temperatures (20 °C and 30 °C) in laboratory for germination test. The same genotypes were assessed for physiological parameters at 30 °C in greenhouse, too. Increasing temperature decreased germination indices with a high variability among the genotypes. Seed vigor index and seminal root length were decreased higher than other indices. The genotypes with higher greenness index had higher total dry mass, leaf area and leaf temperature depression (LTD), and those with higher seed vigor index indicated great quantum efficiency of PSII (Fv/Fm) values. ‘S1-92521’ produced high records in both laboratory and greenhouse experiments. Although ‘S1-92521’ showed good tolerance in both laboratory and greenhouse experiments, totally, sugar beet genotypes had different performance at two experiments. According to the results, seed vigor index could be used as a screening tool in laboratory, and LTD and Fv/Fm were considered as good criteria for screening heat-tolerant genotypes in greenhouse.