Abstract
The perennial sunflower Silphium integrifolium Michx. (Asteraceae), also known as silflower, is a prospective dual-purpose forage plus grain crop. Pre-flowering biomass harvest for animal feed and the subsequent delay in plant growth and anthesis has the potential to benefit seed yield and/or offset yield loss from native pests, such as the native North American Eucosma giganteana (Lepidopera: Tortricidae). The aim of this study was to develop a cropping technology for silflower to (A) balance forage and grain production and (B) minimize seed loss. Silflower produced high-quality forage, but biomass harvest in early spring reduced same-season seed production by 45%. Despite significantly delaying flowering, forage harvest alone did not effectively reduce Eucosma colonization, although treating plants with the insecticide permethrin did reduce colonization. Our results do not support the proposal that S. integrifolium could be profitably harvested for both high quality forage and as an oilseed grain within the same season. Nevertheless, our findings suggest the possibility of developing a strategy of alternating between forage or seed production, depending on their differential economic values. The choice between harvesting biomass vs. seed could be made much later in the season for this perennial crop than the choice of planting an annual forage vs. annual grain crop.
Highlights
Domestication, as defined by Stetter et al [1], is the process of adaptation to agro-ecological environments and human preferences by anthropogenic selection
Since we found a significant time x insecticide interaction (F = 10.908, p < 0.001) we analyzed the effect of time on fumigated and non-fumigated plants separately
Forage yields were reduced by 70% for the second harvest
Summary
Domestication, as defined by Stetter et al [1], is the process of adaptation to agro-ecological environments and human preferences by anthropogenic selection. According to this definition the domestication process is a continuum, beginning with the cultivation of wild plants and progressing to the development of staple food crops. The domestication of wild plants involves a dramatic change of habitat and plant form. A major determinant of the success of domesticates was the utility a plant offered to early societies. Annual plants have been very successful as domesticates, because the shortened generation time speeds up response to selection [1]. In the last 50 years, agricultural productivity has increased by Agronomy 2020, 10, 1471; doi:10.3390/agronomy10101471 www.mdpi.com/journal/agronomy
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