Recurrent Selection for Increased Seed Germination in Little Bluestem.

Water is essential for plant growth and under field conditions is often inadequate for satisfactory seed germination.  The objective of this research was to improve the seed germination of little bluestem, Schizachyrium scoparium (Michx.) Nash, lines ‘NU-1’, ‘NU-2’, ‘UC-1’, ‘UC-2’, ‘UO-1’, and ‘UO-3’ at low water potentials.  Selection pressure consisted of germinating pure-seeds of each line in a water potential solution of –0.8 MPa for 7 d.  Recurrent selection was used to create two synthetic populations for each line.  Populations were designated as Syn-0 for the base population, and Syn-1 and Syn-2 for the first and second selected populations. Seeds were harvested from the 18 populations and cleaned to 98 ± 1% pure-seed.  Four 50-spikelet samples for each of the 18 populations were germinated in deionized water having a potential of either 0 or –0.8 MPa for 7 d.  The 7-d seed germination was analyzed separately by water potential with ANOVA.  The data identified interactions among bluestem lines and selection populations at both water potentials (P < 0.01).  At a water potential of –0.8 MPa, lines NU-2 and UO-3 did not have the same magnitude of increase in seed germination compared with other lines after two cycles of selection.  Averaged across bluestem lines, the 7-d seed germination in a water potential of –0.8 MPa increased 600% after two cycles of selection to 21.0 ± 0.9% germination.  At a water potential of 0 MPa, the 7-d seed germination of lines UO-1 and UO-3 diverged from their Syn-0 population’s seed germination producing a line x selection population interaction.  Similarly, averaged across lines, the 7-d seed germination in a water potential of 0 MPa increased 400% after two cycles of selection to 53.0 ± 1.4% germination. Thus, it was possible to select for increased seed germination in little bluestem using recurrent selection.