Abstract: 【Objectives】The purpose of this paper is to probe into the relationships between the resistance of Helianthus tuberosus L. Seedlings to alkaline stress and the accumulations of biomass and soluble osmoticum in different organs.【Method】with sandy culture in greenhouse，two Helianthus tuberosus L. genotypes Nanyu 8(Ht 1, alkaline-tolerant) and Nanyu 1(Ht 2, lower alkaline-tolerant) were exposed to nutrient solution with Na2CO3 added(0,12.5,25.0,37.5mmol mmol•L-1), and the biomass and osmoticum in different organs were determined.【Result】under alkaline stress, there were considerable differences in the biomass accumulations, the contents of Na+, K+, soluble sugar and proline in different organs between two genotypes. compared with each other it can be see that, Ht 1presented higher K+ in leaf and biomass invested in root under lower alkaline stress(12.5mmolL-1), higher soluble sugar in leaf and root and also higher K+ but lower Na+ in root under higher alkaline stress(25,37.5mmolL-1), whereas Ht 2 presented higher Na+ in root, proline in all organs and soluble sugar in stem in all designed concentrations.【Conclusion】The results indicated that considerable variations in the amount of biomass and soluble osmoticum among plant organs were related to Helianthus tuberosus L. genotypes in response to alkaline stress; Ht 1 had higher K+ in leaf and biomass invested in root under lower alkaline stress, higher soluble sugar in leaf and root and also higher K+ but lower Na+ in root under higher alkaline stress, which may ascribe to its higher alkaline tolerance. The accumulation of proline may be a damaged response of Helianthus tuberosus L .to alkaline stress.

Key words: Alkaline stress, Helianthus tuberosus L, Genotypes, Biomass allocation, Soluble osmoticum