Correlation of seed germination capacities under salt stress with four plant species distribution in the Hangzhou Bay Wetlands

Key words: 
• plant physiology /
• Hangzhou Bay Wetlands /
• salt stress /
• seed germination /
• soil salt content /
• correlation

Abstract: In the Hangzhou Bay Wetlands，plant species occupy different habitats. It is not clear whether the distribution pattern of plant species was related to their ability to germinate under salt stress conditions. Soils from the habitats of four populations of Suaeda glauca，Suaeda australis，Phragmites australis，and Artemisia lavandulifolia were sampled respectively and soil salt content，pH，and water content were analyzed and compared. The percent germination of their seeds when exposed to 0-50 gL-1 NaCl solution was measured by germinating 30 seeds in three Petri dishes respectively in an illumination incubator at 28 ℃. Finally，correlation between germination percent of seeds for the four species exposed to a 20 gL-1 NaCl solution versus soil salt content，pH，and water content was analyzed. Results for the four species showed that the soil salt content of the growth habitats was S. glauca ＞ S. australis ＞ P. australis ＞ A. lavandulifolia；soil pH was P. australis ＞ A. lavandulifolia ＞ S. glauca and S. australis；and soil water content was S. glauca ＞ P. australis ＞ S. australis ＞ A. lavandulifolia. With the NaCl solution （0-50 gL-1），the percent germination decreased significantly （P ＜ 0.001） with increase in NaCl concentration. For the same level of NaCl concentration，the percent germination was S. glauca ＞ S. australis ＞ P. australis ＞ A. lavandulifolia. After replacement of NaCl solution （0-50 gL-1） with distilled water，the seed germination percent remarkably increased （P ＜ 0.01）. But the final germination capacity was in the same order as before the replacement. In addition，only the soil salt content was strongly related to percent germination of the four seed-types exposed to 20 gL-1 NaCl solution （P ＜ 0.05）. These results indicated that soil salt content was an important limiting factor for seed germination, and the distribution pattern of the four plant species was generally related to their habitats soil salt content and the ability of the seeds to germinate at high NaCl concentrations.［ch，2 fig. 2 tab. 17 ref.］