Comprehensive identification of saline-alkaline tolerance of 16 Jerusalem artichoke accessions at seedling stage

Soil salinization and alkalinization frequently co-occur in nature. The interactive effects of salt and alkali stress on plants are more complex and serious, greatly limiting crop production. However, the comprehensive effect of salt and alkali stress on crops remains largely unclear. Screening and cultivating salt-tolerant plants are the most efficient way of exploiting saline-alkaline soils. Jerusalem artichoke (Helianthus tuberosus L.) has long been considered as a highly promising biological energy material with a considerable tolerance to saline-alkaline soils. The objective of this study was to explore the response of 16 Jerusalem artichoke accessions to saline-alkaline stress at seedling stage, and to screen salt-tolerant accessions for cultivation of saline-alkaline lands and provide critical guidance for the management of saline-alkaline soils. To that end, two neutral salts (NaCl and Na₂SO₄) and two alkali salts (NaHCO₃ and Na₂CO₃) were mixed with mole ratio of 5︰23︰9︰5 to simulate typical saline-alkaline stress. The 16 Jerusalem artichoke accessions were cultivated in plastic pots in a controlled environment chamber. The half-strength Hoagland solution without exogenous saline-alkaline was used as the control. The half-strength Hoagland solution supplemented with 150 mmol·L 1 saline-alkaline mixture was as the treatment. The shoot fresh and dry weight, root fresh and dry weight, SOD activity, and MDA and proline contents were measured after 7 days treatment. The saline-alkaline resistance of different Jerusalem artichoke accessions was evaluated by the fuzzy mathematics method of membership function, principal component analysis (PCA) and clustering analysis (CA). PCA showed that shoot fresh weight, plant dry weight and proline content were the most significant factors, and recommended as the main indexes for identifying saline-alkaline tolerance of Jerusalem artichoke at seedling stage. The degrees of salt-tolerance of 16 Jerusalem artichoke accessions were different. The 16 Jerusalem artichoke accessions were sorted into four groups based on clustering analysis. Jerusalem artichoke accessions of ZH-2 and ZH-3 were strongly tolerant to saline-alkaline stress. Jerusalem artichoke accessions ZH-4, Taiyangdao and Qingyu001 had medium tolerance. Then the remaining 10 Jerusalem artichoke accessions (e.g., ZH-5, ZH-6 and ZH-10) had lower tolerance. Of all 16 Jerusalem artichoke accessions, ZH-9 was the most sensitive to saline-alkaline stress.