Understanding Perennial Grain Thinopyrum Intermedium (Kernza®) Response to Vernalization and Photoperiod.

Kate Ivancic and Valentin Picasso University of Wisconsin-Madison Understanding perennial grain Thinopyrum intermedium (Kernza¨) response to vernalization and photoperiod. Perennial grain, Intermediate Wheatgrass (Thinopyrum intermedium) is currently bred for increased seed size and is newly available under its commercial name, Kernza¨. Potential for its expansion to other regions of the globe are limited to the speciesÕ vernalization and photoperiod requirements for reproduction. The primary induction requirement for most wheatgrass species is a combination of vernalization and short daylength, followed by long daylength for secondary induction. In order to assess plant flowering response we compared four treatments in temperature and light controlled growth chambers: 1) low temperature (4¡C) during 10 hour days; 2) low temperature (5¡C) during 11 hour days; 3) medium temperature (10¡C) during 10 hour days; and 4) high temperature (26¡C) during 15 hour days, in a randomized complete block design with 2 replications. We tested plants from three different seed origins of Kernza cycle 4 (Minnesota, Wisconsin large seed and Wisconsin regular seed). 18 plants were grown to the four-leaf stage and transferred to treatments for 7-week incubations. Following incubation, plants were returned to the greenhouse and exposed to 15 hour days to complete induction. Plants flowered across all treatments and there was no treatment by seed origin interaction. Low temperature treatments had higher percentage of flowering (80%) than medium (45%) or high (18%) temperature treatments (p<0.05). There were more spikes per plant in the low temperature treatment. Aboveground biomass and tiller height was also significantly greater in low temperature treatment (p<0.05). These findings are mapped for global Kernza¨ production potential and suggest future development of select, reduced induction requirements for the global expansion of this perennial grain crop.