Breaking Tuber Dormancy in Helianthus tuberosus L. and Interspecific Hybrids of Helianthus annuus L. × Helianthus tuberosus

Abstract

<jats:p>Tubers of <jats:italic>Helianthus tuberosus</jats:italic> L. are dormant after production in the late fall until the next spring. In the wild, tuber dormancy is broken after exposure to winter cold, resulting in sprouting and shoot development in the spring when conditions are favorable. The dormancy period typically limits <jats:italic>H. tuberosus</jats:italic> populations to one growth cycle per year. An efficient method for breaking tuber dormancy is needed to have an additional growth cycle per year in a breeding program, which could take place in winter in the nursery or the greenhouse allowing for increased breeding efficiency. The objective of this research was to compare chemical and cold temperature treatments for artificially breaking tuber dormancy in 12 genotypes of <jats:italic>H. tuberosus</jats:italic> and interspecific hybrids of <jats:italic>Helianthus annuus</jats:italic> L. × <jats:italic>H. tuberosus</jats:italic>. Five cold exposures (2, 4, 6, 8, 10 weeks at 2 °C), three plant hormones (ethylene, cytokinin, and gibberellic acid), and one untreated control were examined. Gibberellic acid was the best chemical treatment, initiating plant growth within 6.5 to 11.5 days in the majority of genotypes tested. The best cold treatment was exposure to 2 °C for 8 weeks, where plant growth began 63.6 to 67.5 days after treatment initiation. Although longer cold treatments shortened the time to emergence while in the greenhouse, the penalty of the long cold treatment per se was too long to be useful. The gibberellic acid treatment strategy described here may not need further optimization, because it is short enough to allow for two growth cycles of <jats:italic>H. tuberosus</jats:italic> per year.</jats:p>

Strategies for Evading Blackbird Damage

“…The keys to successful use of WCFP are location close to roosts, protection from predators, and caloric content . Here, we present a case history on the use of WCFP to reduce blackbird damage to sunflower and advocate the continued development of perennial sunflower as a potential cost-effective approach to developing a long-term management scheme to reduce damage to grain crops (Glover et al :2010;Kantar et al 2012Kantar et al , 2014Linz et al 2014;Linz and Hanzel 2015). This approach could attract the support of private conservation groups, state and federal resource agencies, and agriculturalists.…”

“…( , 2010 conducted their study, collaborating scientists at the University of Minnesota and USDA Agricultural Research Service (USDA-ARS) have advanced the development of a perennial sunflower that could reduce planting costs for WCFP and serve as a potential tool to alleviate blackbird damage in commercial (i.e ., annual) sunflower (Linz et at. 2011;Kantar et at. 2012Kantar et at.…”

Potential Use of Perennial Sunflower to Reduce Blackbird Damage to Sunflower

“…The goal of the perennial sunflower breeding program is to develop alternative varieties for commercial production while providing habitat enhancements to landscapes often made barren by intensive agricultural practices (Hulke and Wyse 2008, Glover et al 2010, Kantar et al 2014. Geneticists are currently examining tetraploid interspecific hybrids between the perennial H. tuberosus and annual sunflower (H. annuus) for possible use as a perennial (Hulke and Wyse 2008, Kantar et al 2012, Kantar et al 2014). Characterization of our initial interspecific population showed large variability in phenotypic characteristics but a simple segregation pattern (3:1) for tuber production, which is the habit of perennial sunflower (Kantar et al 2014).…”

“…Perennial sunflower would reduce planting costs for WCSP and serve as potential tool to alleviate blackbird damage in commercial (i.e., annual) sunflower (Kantar et al 2012, Linz et al 2011, Kantar et al 2014). Additionally, perennial sunflower would provide a pesticide-free food source for beneficial insects such as honey bees (Apis mellifera), help stabilize highly erodible lands near wetlands, and offer year-round habitat for wildlife.…”

Interacting duplications, fluctuating selection, and convergence: the complex dynamics of flowering time evolution during sunflower domestication

“…Although these shifts are relatively ancient, crosses between H. annuus and perennials are achievable (e.g. Kantar et al, 2012). Consequently, mapping and expression studies of candidate genes, such as the FT/TFL1 family (Hsu et al, 2011;Wang et al, 2011), may reveal the evolutionary mechanisms leading to these convergent transitions.…”