|Van Esbroeck, G - TEXAS A&M UNIV|
|Hussey, M - TEXAS A&M UNIV|
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2003
Publication Date: December 20, 2003
Citation: Van Esbroeck, G.A., Hussey, M.A., Sanderson, M.A. 2003. Reversal of dormancy in switchgrass with low-light photoperiod extension. Bioresource Technology. 91:141-144. Interpretive Summary: Switchgrass is used for warm-season forage production and soil conservation and has potential as a biomass source for fuel ethanol and biomass-generated electricity. Little is known about the physiological basis for apparent late-season dormancy in northern switchgrass varieties. We examined the effects of low-light photoperiod extension on the dry matter accumulation of four switchgrass varieties originating from different latitudes. The studies showed that dormancy for some switchgrass varieties could be overcome by an extended photoperiod. The greatest response to photoperiod was observed with the variety Caddo, which is of mid-latitude origin and Cave-in Rock, which is of northern origin. The variety Kanlow showed limited response whereas the variety Alamo, from south Texas, did not show a response. These findings, showing vegetative growth of some cultivars to be inhibited by short days, may explain the lack of growth observed during late-summer and fall for northern switchgrass cultivars when grown for biomass feedstock production in the southern U.S.
Technical Abstract: Some switchgrass (Panicum virgatum L) cultivars originating in the northern USA show limited late-summer and fall growth when grown in more southerly locations despite adequate temperature and moisture. Our objective was to determine the effects of low-light photoperiod extension (7 umol photosynthethic photon flux density) on the vegetative growth of switchgrass cultivars originating from contrasting latitudes. Seedlings of the four cultivars (Cave-in-Rock, Caddo, Kanlow, and Alamo) were grown for 100 d in a greenhouse in winter under ambient (11.2-12.2 h) and extended (18 h) photoperiods. Photoperiod extension was with 7 umol photosynthethic photon flux density. Cultivars responded differently to photoperiod extension (P<0.05). Large increases in dry matter yields (DMY) at extended photoperiods were observed in Cave-in-Rock (+98%) and Caddo (+129%). The DMY of Kanlow was increased by 31% whereas DMY of the southernmost cultivar Alamo was unaffected by photoperiod extension. Yield enhancements in Cave-in-Rock and Caddo were associated with increases in the number and weight of tillers. A reversal of dormancy for some cultivars with a photoperiodic signal verified that dormancy was not simply a result of a low radiant input.