Author
|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/4/2017 Publication Date: 4/24/2017 Citation: Robins, J.G., Jensen, K.B. 2017. Genotype by environment interaction effects of propagation and defoliation on meadow bromegrass. Crop Science. doi: 10.2135/cropsci2017.02.0072. Interpretive Summary: The biomass production and nutritive value of 63 meadow bomegrass families was evaluated for two years at Millville, UT. The families were evaluated under four combination treatments: spaced-plant or seeded plot combined with either grazing or cutting management. The objective was to determine the best management conditions for meadow bromegrass selection and improvement. The results showed little relationship between the different management conditions. They also showed that selection under the spaced-plant conditions was ineffective. Thus, selection is best done under seeded conditions with either grazing or cutting management. Technical Abstract: Sixty-three meadow bromegrass (Bromus riparius Rehm.) half-sib families were evaluated over two years at Millville, UT location for biomass production and nutritive value. Families were evaluated under either space-plant or sward conditions combined with either grazed or cut management. The objective of the study was to determine if selection under standard space-plant and cutting practices resulted in the same selected families as selection under seeded plots and grazing. Due to the presence of genotype-environment interaction, the most appropriate presentation of results was within the individual propagation-defoliation treatments. Spearman correlation estimates were low among the four environments for the same trait. Most correlation estimates did not differ from zero and the highest was p=0.52. Trait differences were less pronounced in the spaced plant conditions. There were no differences among families for biomass in the space/graze treatment; for digestibility in the space/cut treatment; and for protein in the space/cut, space/graze, or seed/graze treatments. There was limited evidence of correlation among the four phenotypes (Table 2). Spearman rank correlation estimates identifed strong association between only digestibility and fiber (p=-0.65 to -0.71, P<0.001) in each environment. Overall, the results suggest that selection for meadow bromegrass improvement under spaced-plant conditions is ineffective. The selection of best harvest management is less clear due to the need for both grazing and hay production. However, the difficulty of grazing for selection will likely lead to the predominance of cutting under more frequent harvest. |
