Field establishment of little bluestem populations selected for improved laboratory seed germination in simulated dry conditions

Authors: Springer, Timothy; CARR, BRANDEN - Natural Resources Conservation Service (NRCS, USDA)

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2022
Publication Date: 1/11/2022
Citation: Springer, T.L., Carr, B. 2022. Field establishment of little bluestem populations selected for improved laboratory seed germination in simulated dry conditions. Crop Science. 62(2):958-963. https://doi.org/10.1002/csc2.20705.
DOI: https://doi.org/10.1002/csc2.20705

Interpretive Summary: Water is essential for plant growth and under field conditions is often inadequate for satisfactory plant development. In previous research, plant populations of little bluestem were selected at low soil moisture conditions for increased seed germination. Little bluestem populations NU1 C1 and C2, NU2 C1 and C2, UC1 C1 and C2, UC2 C1 and C2, UO1 C1 and C2, and UO2 C1 and C2 were developed from populations NU1 C0, NU2 C0, UC1 C0, UC2 C0, UO1 C0, UO2 C0. Our objective was to verify if the improvements in laboratory seed germination of selected populations would result in greater field establishment. Field testing involved planting the 18 populations at three locations over a three-year period and determining the plant frequency at 30, 60, and 90 days after planting (DAP). Plant density was found to vary among bluestem populations, selection generations, and bluestem population by selection generation combinations. Plant density averaged 7.6, 6.6, 6.5, 7.1, 6.6, and 7.1 plants per meter squared for populations NU1, NU2, UC1, UC2, UO1, and UO2, respectively, and density averaged 5.9, 6.6, and 8.2 plants per meter squared for generations C0, C1, and C2, respectively. This research verified that recurrent selection for increased laboratory seed germination in simulated dry conditions resulted in greater field establishment plant densities of little bluestem.

Technical Abstract: Successful field establishment begins with superior plant genetics, quality seeds, land preparation, sowing depth, weed control, and/or moisture. Our research examined the field-establishment plant density of six populations of little bluestem [Schizachyrium scoparium (Michx.) Nash] and three generations of selection at three locations over a 3-yr period. Recurrent selection was used to develop C1 and C2 populations from six improved C0 populations (NU1, NU2, UC1, UC2, UO1, and UO2). In Cycle 1, 3500 open-pollinated seeds of each C0 population were geminated in 35 plastic boxes in water of -0.8 MPa potential for 7-days. For each C0 population, seeds that germinated in 7-days were selected to create six C1 populations. Cycle 2 selection was identical to Cycle 1, except that C1 populations were used to create the six C2 populations. Our objective was to verify if the improvements in laboratory seed germination of selected populations would result in greater field establishment. Plant density (number of plants per meter squared) was determined using a frequency grid method at 30, 60, and 90 d after planting (DAP). The plant density of little bluestem varied with population (P), selection generation (G), P × G interactions, and number of DAP (P < 0.001). Averaged over generations and DAP, plant density averaged 7.6, 6.6, 6.5, 7.1, 6.6, and 7.1 plants m'2 among populations NU1, NU2, UC1, UC2, UO1, and UO2, respectively. Averaged over populations and DAP, plant density averaged 5.9, 6.6, and 8.2 plants per meter squared for generations C0, C1, and C2, respectively. Thus, recurrent selection for increased laboratory seed germination in simulated dry conditions results in greater establishment plant densities of little bluestem.