以能源植物杂交狼尾草(Pennisetum americanum × P. purpureum)为实验材料, 用沙培盆栽的方法, 分别用0、0.3%、0.5%、0.9%和1.2%的NaCl处理4周后, 测定植株鲜重、干重、含水量、株高、分蘖数和不同部位的离子含量, 以确定其耐盐阈值和耐盐方式。结果表明, 随着NaCl浓度的增加, 杂交狼尾草的鲜重、干重、株高和分蘖数都显著降低, 地上部分鲜重和干重分别在NaCl浓度为0.568%和0.570%时下降了50%, 1.2% NaCl处理的杂交狼尾草几乎全部死掉。表明杂交狼尾草的耐盐阈值为0.57%; 但植株含水量和功能叶的Na⁺含量变化不明显, 老叶Na⁺含量在NaCl浓度为0.9%时明显升高, 是对照的2倍; 随NaCl浓度的升高, 根中的Na⁺含量显著升高, 在NaCl浓度为0.9%时, 根中的Na⁺含量达到对照的3倍以上。Na⁺含量在功能叶, 老叶和根中含量依次升高; 随NaCl浓度的升高, 地上部分和根中的K⁺含量都无明显变化; 随NaCl浓度的升高, 根中的Na⁺/K⁺明显增加, 而地上部分Na⁺/K⁺只有当NaCl浓度为0.9%时明显增加。以上结果表明杂交狼尾草具有一定的耐盐性, 其耐盐方式为拒盐, 耐盐阈值为0.57% (约100 mmol·L^-1)。

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).