Propagation method affects Miscanthus × giganteus developmental morphology

• Plant heights and tiller thicknesses were not affected by propagation method.
• Rhizome propagated plants had a larger basal circumference.
• Stem propagated plants had more tillers per plant.
• Morphological differences were consistent despite variable growth conditions.

The Illinois clone of Miscanthus × giganteus has many traits of an ideal biomass crop, including sterility, which significantly limits invasive potential. However, this sterility necessitates vegetative propagation, a time and labor intensive process that currently challenges the crop's adoption. Traditionally propagated by rhizome segments, M. × giganteus can also reproduce by stems like its relative, sugarcane. Previous work indicates, however, that non-traditional propagation of M. × giganteus can affect developmental morphology of resultant plants in the field. We investigated the effect of stem propagation on developmental morphology (part I, this paper), and survival and yield (part II), of field-grown M. × giganteus (Illinois clone) plants at three sites in Iowa, USA during the second and third year of growth. Although stem propagation affected morphology compared to traditional rhizome propagation, the differences were less pronounced than reported for hormone-aided micropropagation. Observed differences (and similarities) between stem and rhizome propagated plants were consistent between different growing environments and years, despite extreme weather. Rhizome propagated plants had larger basal circumferences (146.2 cm vs. 134.7 cm on average, P = 0.0107), but stem propagated plants had more stems per plant (38 vs. 33 on average, P = 0.0492) suggesting that these two propagation techniques result in plants with different growth strategies but may achieve similar yields. Though small, these differences persisted consistently throughout the duration of this experiment, suggesting morphological differences may be maintained over time in mature stands of M. × giganteus.