Response of plant biofuel hybrid Pennisetum to NaCl stress and its salinity threshold
能源植物杂交狼尾草对NaCl胁迫的响应及其耐盐阈值

Aims Our objectives were to examine the response of biofuel plant hybrid Pennisetum (P. americanum × P. purpureum) to NaCl stress and determine its salt tolerance mechanism and salinity threshold. Methods We cultured plants of this hybrid in plastic pots filled with sand containing 0, 0.3%, 0.5%, 0.9%, and 1.2% NaCl. After four weeks, we measured the fresh weight, dry weight, water content, plant height, tillering number and ion contents of different parts of the plants. Important findings NaCl treatment significantly reduced shoot fresh weight and dry weight by 50% at 0.568% and 0.570% NaCl, respectively. With increasing NaCl concentration, Na+ content of functional leaves did not change significantly, whereas Na+ content of old leaves and roots increased significantly. Especially when the concentration of NaCl was 0.9%, Na+ content of old leaves and roots increased two and three fold more than that of the control, meaning that Na+ content in functional leaves, old leaves and roots increased gradually. With increasing NaCl concentration, K+ content in the shoots and roots was not affected, whereas Na+/K+ in the roots increased significantly, and Na+/K+ in the shoot increased significantly only at 0.9% NaCl. These results indicated that the salt-tolerant mechanism of hybrid Pennisetum is salt exclusion, and its salinity threshold is 0.57% (about 100 mmol·L–1).