|Young B A, - FORMERLY ARS|
Submitted to: Seed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 1994
Publication Date: N/A
Interpretive Summary: Kleingrass is an important grass used to revegetate rangeland in the Southwest. Establishing a suitable stand of this grass is difficult and this is a limitation to its further use. Because kleingrass grows slowly in the seedling stage, many seedlings that germinate then die without producing mature plants. In an attempt to make kleingrass more vigorous in the seedling stage, we grew two populations of kleingrass in a controlled environment and selected out the most vigorous 5% of the seedlings of each population. This selection was performed when the seedlings were two weeks old. These plants were allowed to intermate, and the seed produced was germinated and once again, the most vigorous five percent of the seedlings were saved. This process was repeated yet another time. The seedlings produced from this third cycle of selection were intermated, and the seed produced was compared with those from the starting parents. For both populations, the selected seed was superior to the parents each in terms of seedling mass and other measures of seedling vigor. The differences were more apparent when the respective populations were grown under high light intensity. Also, seed from the populations selected for greater seedling vigor were heavier and contained more starch. This technique successfully produced kleingrass germplasm with greater seedling vigor.
Technical Abstract: Seedling vigor limits the use of kleingrass (Panicum coloratum L.). To improve seedling vigor, we subjected two separate populations of kleingrass to three cycles of recurrent selection for increased shoot mass at 14 days post emergence. These populations were the cultivar 'Selection-75' and the population 'DT' (selected for drought tolerance). The cycle 3 Selection 75 and DT populations were evaluated for seed mass, seed starch content, shoot mass, and seedling root characteristics. Seed mass and seed starch content were significantly higher in Cycle 3 Selection-75 seed compared with the base population. The same trends were noted in the DT populations, but the differences were not significant. Seedling vigor of base and cycle 3 populations were compared in two experiments. In experiment 1, seedlings were grown in a glasshouse with no additional illumination, with seedling harvests being performed at 7, 14, 21, and 28 days after emergence. In experiment 2, seedlings were grown in a glasshouse with solar radiation supplemented with 16 hours of illumination by overhead lights. In both experiments, the cycle 3 populations performed better than the corresponding parental populations. In experiment 1, the Cycle 3 Selection-75 seedlings were most vigorous, while in experiment 2 (under a long duration of high light intensity), seedlings in the Cycle 3 DT population had almost twice the mass of the corresponding Cycle 3 Selection-75 seedlings. Results indicate that selection may have operated on different pools of genetic variation between the two populations.