Space-plant versus sward-plot evaluation of half-sib families to select parents for synthetic cultivars with superior biomass yield in Lowland Switchgrass

Abstract

Switchgrass (Panicum virgatum L.) needs significant biomass yield improvement for its viable use as bioenergy feedstock. Conventional family evaluation under sward plot is very effective in cultivar improvement, but it is time and resource consuming. Family evaluation under space planting using honeycomb design can reduce time and inputs. The objective of this study was to compare conventional sward-plot and modified space-plant evaluation of half-sib families in their biomass yield gain and resource use. Using same initial set of genotypes selected from 'Alamo', two experimental synthetics were developed by the following methods: (i) summer field polycrossing of selected genotypes to produce half-sibs, half-sib family evaluation under sward plot conditions (HSS- ward) at two locations for 2 yr, and polycrossing the five genotypes showing superior half-sibs to produce the experimental and (ii) greenhouse polycrossing genotypes during the winter to produce half-sibs, half-sib family evaluation under space-plant conditions using honeycomb design (HSSpace) for 2 yr at one location, and polycrossing the five best progeny within the five superior half-sibs to produce the experimental. The 2 to 3 yr biomass yield performance of two experimentals across five locations demonstrated that both HSSward and HSSpace led to a significant biomass yield gain over Alamo in three and two of the five locations, respectively. The HSSward produced a superior and more stable synthetic across a wide region than HSSpace. However, the HSSpace produced its synthetic a year sooner and was more resource efficient and, under finite resources, it could be a method of choice for cultivar development especially for a narrow geographic region. © Crop Science Society of America.