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Switchgrass ( Panicum virgatum L.) has been developed into a major herbaceous bioenergy crop for the production of cellulosic biofuels in North America and many counties in European. As cultivar selection has a major impact on the ultimate biomass productivity, we evaluated the adaptability and yield potential of 12 switchgrass cultivars including both upland and lowland ecotypes from 2010 to 2013 in the Beijing region, Northern China. Plant height was measured after anthesis, but phytomer number and tiller density were investigated at harvest. One single autumn harvest was carried out each year and biomass yields were determined. It was found that the lowland cultivars ‘Alamo’, ‘Kanlow’ and ‘NewYork’ produced the most biomass for their better performances in number of phytomers per tiller and mass per phytomer, though upland cultivars had higher tiller density. ‘Cave-in-rock’ and ‘Trailblazer’ had better biomass production among the upland cultivars and they were also recommended for planting together with lowland ones for their excellent cold tolerance in this region. [ABSTRACT FROM AUTHOR]

So far no successful artificial hybridizations among ornamental grasses in the Pennisetum Rich. (Poaceae) genus that are widely applied in landscape design have been reported because of unclear genetic backgrounds and uncertain evolutionary and genetic relationships among one another, severely restricting the number of ornamental cultivars and their gardening utility. The present study aims to reveal genetic backgrounds and relationships for nine Pennisetum ornamental grasses via karyotype diversity analysis; discuss the morphological classification system proposed in previous studies on morphological, chromosomal and genomic levels; and verify the chromosomal evolution of Pennisetum genus using the combined karyotypic and genomic data. Our results indicated that (1) traditional morphological classification system of Pennisetum genus is reasonable, both from the morphological and cytological points of view; (2) hybridization among Pennisetum alopecuroides , P. alopecuroides ‘Little Bunny’, P. alopecuroides ‘Moudry’ and P. orientale may be easier to obtain a hit; (3) chromosomes with lower basic chromosome number are more asymmetry than those chromosomes with higher basic chromosome number, and taxa with different basic chromosome numbers may have experienced different way of speciation; and (4) chromosomal evolution in Pennisetum genus progressed from a symmetrical to an asymmetrical order in the course of evolution; and the structure of the genome of Pennisetum species involved in the reduction of chromosome number and an increase in their sizes and DNA contents. The present study guides the breeding programs and genome projects of Pennisetum ornamental grasses practically, and provides references for the evolutionary studies on Pennisetum genus theoretically. [ABSTRACT FROM AUTHOR]

Polyploidization is regularly regarded as an important tool for the generation of innovative germplasm resources and plant breeding. In this study, autopolyploid switchgrass lines were produced from calli derived from immature inflorescence of tetraploid switchgrass ( Panicum virgatum L.), both lowland cv. Alamo and Kanlow, and upland cv. Ranlow, through colchicine treatments. Ploidy levels of plantlets regenerated from the calli were screened by flow cytometry. Growth characteristics of the tetraploid and octoploid switchgrass cultivars were further investigated in a field experiment. Compared with the tetraploid plants of the three switchgrass cultivars, the corresponding octoploid plants showed significant reduction in plant height, number of tillers per plant and fresh matter, but an increase in leaf length and width. [ABSTRACT FROM AUTHOR]