Assessment of drought tolerance in seedlings of sugar beet (Beta vulgaris L.) cultivars using inorganic and organic solutes accumulation criteria

Abstract

Drought is a major environmental factor limiting the production of crops. Drought tolerance of sugar beet (Beta vulgaris L.) cultivars in terms of growth and inorganic and organic solute accumulation was analyzed in this study. Four-week-old seedlings of three cultivars, "Gantang7", "SD13829" and "ST21916", differing in drought tolerance, were treated with different degrees of drought stress. Plant shoots and roots were harvested at 5 d after stress and subjected to analysis. Drought significantly reduced shoot fresh weight and water content in the three cultivars, though the least reduction was found in "ST21916". Either decrease or no change in sodium (Na+) and potassium (K+) concentrations was observed in the three cultivars as an effect of drought, whereas a higher root Na+ and a lower root K+ concentration was noted in "Gantang7". Root calcium (Ca2+) concentration significantly increased in "Gantang7" exposed to moderate and severe drought. Severe drought also caused a significant increase in the proline level in "SD13829" but not in "Gantang7" and "ST21916". Under drought stress, soluble sugar concentrations significantly increased in both "Gantang7" and "SD13829" whilst remaining unchanged in "ST21916". It is clear that Na+, K+ and soluble sugars are major contributors to osmotic adjustment (OA), while Ca2+ and proline have minor contributions to OA in all three cultivars. According to our comprehensive assessment of drought tolerance, it is shown that "ST21916" is more tolerant to drought than the other two cultivars. Therefore, our results suggest that "ST21916" may be more suitable for planting in arid and semi-arid regions. © 2014 © 2014 Japanese Society of Soil Science and Plant Nutrition.