Mohamed Fahej*, Gopal Kakani

Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK

Abstract

Screening the performance of switchgrass genotypes under water stress will enable to identify traits needed for improving tolerance to water stress. Improved tolerance can be reached by using in vitro culture to enhance somaclonal variation and screen for variation can be beneficial. The objectives of this study are, first to evaluate growth and physiological parameters and identify switchgrass traits that can contribute to increased water use efficiency and second is screening for somaclonal variation to identify cell lines with more water stress tolerance. Under the first objective, thirteen genotypes were screened using physiological parameters including photosynthesis, fluorescence, electron transport rate and stomatal conductance. Total biomass and biomass components of all genotypes were measured at final harvest. Results showed that genotypes responded differently to water stress treatments.  Photosynthesis decreased with increase in water stress and the decrease was steep in 20%WW compared with 60%WW. Genotypes Carthage (lowland) and Forestburg (upland) had the least decrease in photosynthesis at both 60%WW and 20%WW conditions. In general, biomass and its components decreased with increase in water stress. Exceptions for this included upland genotypes Forestburg, Blackwell, Shelter, Sunburst and WI ecotype. These genotypes exhibited either an increase or minimum decrease in biomass under water stress conditions. Under the second objective, Alamo and Forestburg were used in vitro culture procedure to produce callus and induce variation under water stress MS media. Poly Ethylene Glycol (PEG) was used to induce stress (- 0.6 MPa, -1.6 MPa) in addition to control. Callus development was observed in all treatments and cell division was found better performed in all treatments of Forestburg cultivar than Alamo.