Physiological Coupling Responses To Drought And Salinity Stress In Bluestem, Reed Canarygrass And Switchgrass

Many researches are mostly focus on physiological responses to drough or salinity stressin bluestem (Andropogon virginicus), reed canarygrass(Phalaris arundinacea) andswitchgrass (Panicum virgatum) due to their environmental friendly and wide range ofadaptability while quite little refers to coupling effects to the stresses. Therefore,physiological coupling respones to drought and salinity were studied at their vegetativegrowth stage in the3grasses. The experiments were conducted using orthogonal matrixdesign at3factors (plant, soil water content and saline concentration), each of the factor with3levels in pot in greenhouse. The measurement indexes of its physiological response includesproline, the activity of POD and CAT, soluble sugar and the content of Na+and K+.The results of experiments are as follows:1. The content of proline and soluble sugar increased or decreased first and thenincreased along with the reduce of the soil water content, the content of proline and solublesugar in leaves increased or firstly decreased and then increased along with the increment ofsaline concentration, whereas in bluestem was increased first and then decreased, reachedmaximum at2‰salt concentration. Conclusion is that bluestem, reed canarygrass andswitchgrass have the adaptive capacity under drought stress, but bluestem is more sensitive tosalt stress than reed canarygrass and switchgrass.2. The results showed that the activity of POD and CAT in leaves increased or decreased firstand then increased along with the reduce of the soil water content, but the CAT activity ofswitchgrass firstly increased and then decreased, reached maximum at7%waterconcentration. The POD activity in leaves increased or firstly decreased and then increasedalong with the increment of saline concentration, whereas in bluestem was increased first andthen decreased, reached maximum at2‰salt concentration. The CAT activities in bluestem,reed canarygrass and switchgrass firstly increased and then decreased, and reached maximumat saline concentrations of2‰,4‰and6‰, respectively. By comparison, the preliminaryconclusion is that bluestem and reed canarygrass have the adaptive capacity under drought stress, but are sensitive to salt stress, switchgrass has strong adaptability under drought andsalinity stress.3. The content of Na+increased along with the reduce of the soil water content andincrement of saline concentration, but the content of K+increased first and then decreased,and were lower than the control. The content of Na+in reed canarygrass shoot reachedmaximum at7%water concentration and2‰salt concentration, the content of Na+inbluestem root reached maximum at23%water concentration and2‰salt concentration, thecontent of K+in root reached maximum at15%water concentration and1‰saltconcentration, the preliminary conclusion is that the regulatory capacity of bluestem to ion isweaker than reed canarygrass and switchgrass, and more sensitive to water and salt stress thanreed canarygrass and switchgrass.4. The ratio of K+/Na+presents downtrend basically. the Sk,Na, Na+of the three grasseswere increased first and then decreased along with the reduce of the soil water content, in reedcanarygrass and switchgrass were firstly increased and the decreased, but in bluestem wascontinues to decreased. It shows that the ability to selective absorption K+in root and thentransmit to shoot of three grasses were increased under lower stress, but were weaker alongwith the reduce of the soil water content and increment of saline concentration.5. By overall comparison, the conclusion is that bluestem and reed canarygrass have thestrong adaptive capacity under drought stress, but are sensitive to salt stress, switchgrass hasstrong adaptability both under drought and salinity stress.