Variability of nuclear DNA content and agromorphological characteristics of switchgrass (Panicum virgatum L.) germplasm in Lithuania

While searching for novel energy plants, researchers have become interested in switchgrass (Panicum virgalum L.), which is a C4 perennial grass. The objective of this study was to assess switchgrass populations by estimating the variability of nuclear DNA content and agromorphological characteristics. Plant ploidy level was determined using a flow cytometry technique. The switchgrass collection comprised 31 populations differing in ploidy level. Seventeen populations were tetraploid with an average genomic DNA content of 2.5 picograms (pg). The individuals of 4 populations were found to have an average DNA content of 5.4 pg, which is specific to octoploids. The remaining 10 populations were estimated to be of a mixed ploidy level with DNA content ranging from 2.1 to 7.0 pg. The plants of tetraploid and mixed ploidy populations were characterised by significantly taller culms and more abundant fresh biomass production compared with octoploid populations. An analysis of dry matter revealed a similar trend. Earlier heading date was observed for tetraploid populations. All switchgrass populations tested exhibited a similar overwinter survival rate (93.7-96.7%). The most stable characteristics were found to be plant height, bunch diameter, leaf width and length (coefficient of variation 4.0-9.7%). Among all plant characteristics, the greatest variability was established for dry biomass yield (coefficient of variation 5.0-35.8%).