Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 19, 2011
Publication Date: January 6, 2012
Citation: Springer, T.L. 2012. Recurrent selection for increased seed germination in sand bluestem (Andropogon hallii). Plant Breeding. 131:198-202. Interpretive Summary: Water is essential for plant growth and under field conditions is often inadequate for satisfactory plant development. The objective of this research was to improve the seed germination of sand bluestem (Andropogon hallii Hack.) lines ‘AB-medium Syn-0’ and ‘CD-tall Syn-0’ at low water potentials. After two cycles of selection it was possible to select for increased seed germination at low water potentials. The average seven day seed germination of unselected lines of sand bluestem was 34% when germinated at a low water potential. Seed germination increased by 9.1% each selection cycle. After two selection cycles, 50-spikelet weight and seedling root length was also increased. Seedling shoot length, however, was not affected by selection. Given the amount of genetic variation within most cross-pollinated chaffy-seeded grass species, selecting for increased germination at low water potentials would be an effective tool for breeding superior genotypes with increased seed germination and seedling root growth at low water potentials. Rapid seed germination and seedling root growth are important characteristics when it comes to stand establishment under variable environmental conditions. Whether the increased germination reported herein results in greater stand establishment remains to be seen and is a problem worth researching. In addition, variations to this selection technique could be applied by changing the germination time interval or the water potential deficit.
Technical Abstract: Water is essential for plant growth and under field conditions is often inadequate for satisfactory seed germination and seedling growth. The objective of this research was to improve the seed germination of sand bluestem (Andropogon hallii Hack.) lines ‘AB-medium Syn-0’ and ‘CD-tall Syn-0’ at low water potentials. Selection pressure consisted of germinating chaffy pure-seeds of each bluestem line in a water potential solution of –0.8 MPa for 7-d. Recurrent selection was used to create two synthetic populations for each bluestem line. Seeds were harvested from the six populations (AB-Medium Syn-0, Syn-1, and Syn-2 and CD-Tall Syn-0, Syn-1, and Syn-2) and cleaned to 98 ± 1% chaffy pure-seed. Four 50-spikelet samples of each population were weighed and germinated in either 0 or –0.8 MPa water potential solutions. Germination counts were made daily for 7-d. Data were analyzed with a general linear mixed model analysis of variance. No significant difference was found between the seed germination of sand bluestem lines ‘AB-medium’ or ‘CD-tall’ (P > 0.05) and no interaction was found between bluestem lines and generation (i.e., Syn-0, Syn-1, or Syn-2; P > 0.05). Averaged across bluestem lines, germination of seed from generation Syn-1 was 6.7% higher than that of generation Syn-0 and generation Syn-2 was 10.2% higher than that of generation Syn-1 in a water potential of –0.8 MPa. In addition, after two selection cycles, 50-spikelet weight and seedling root length were concomitantly increased. Thus, it was possible to select for increased seed germination of sand bluestem at low water potentials.