TEM-SLC and TEM-SEC switchgrass (Panicum virgatum L.) germplasms (Reg. no. GP-77, PI 607837, and Reg. no. GP-78, PI 607838, respectively) were developed at the Grassland, Soil, and Water Research Laboratory, Temple, TX, and were released by the USDA-ARS and the Texas Agricultural Experiment Station on 24 Feb. 2000. These germplasms resulted from three cycles of recurrent phenotypic selection for reduced and enhanced seedling crown node elevation when grown under dim, continuous light. TEM-SLC and TEM-SEC were derived from `Alamo' switchgrass.
Cell division at the base of the crown node normally stops when the coleoptile tip intercepts an adequate amount of red light (van Overbeek, 1936). When the amount of light is inadequate, continued elongation of the subcoleoptile internode (below the crown node) can push the crown node above the soil surface. Because adventitious roots are required for successful seedling establishment, seedlings with elevated crown (EC) nodes would need to initiate these roots above the soil surface. This seldom happens, and these seedlings often perish.
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