Submitted to: Grass Breeders Work Planning Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2003
Publication Date: 2/1/2004
Citation: Johnson, R.C., Johnston, W.J., Golob, C.T. 2004. Evaluating genetic resources for sustainable production of poa pratensis. Grass Breeders Work Planning Conference Proceedings.
Interpretive Summary: Air quality issues as they relate to agriculture are becoming increasingly important to public health. In the Pacific Northwest of the United States (Oregon, Idaho, and Washington), where the majority of Kentucky bluegrass (Poa pratensis L.) is produced, field burning has been traditionally carried out after harvest to stimulate seed production the following year. Smoke resulting from combustion of crop residue produces fine particles that can cause respiratory distress, especially for those with respiratory conditions such as asthma. This work reports progress to identify Kentucky bluegrass plants with improved performance under no-burn management. Forty-five diverse Kentucky bluegrass germplasm entries were compared in burned, mechanically removed, and residue retained management systems to assess the potential for improving seed production under no-burn management. As expected, leaving residue on the soil after harvest reduced seed yields sharply. And although yield was generally reduced when residue was mechanically removed, similar to baling, some accessions were found to maintain yield as high as those of the same accessions when burned. Further investigation of these accessions to develop higher yielding Kentucky bluegrass for no-burn management is underway.
Technical Abstract: Field burning to remove post-harvest residue has traditionally been used to stimulate Kentucky bluegrass (Poa pratensis L.) seed production in the Pacific Northwest U.S.A. Air quality issues are, however, making this practice unsustainable. Forty-five diverse Kentucky bluegrass germplasm entries were compared in burned, mechanically removed, and residue retained management systems to assess the genetic potential for improving seed production under non-thermal management. In burned treatments, yield was reduced 27% when residue was mechanically removed from plots, and 63% when residue was retained. Although both seeds panicle-1 and fertile panicles m-2 were positively correlated with yield, lower yield with non-thermal residue management was most closely associated with panicles m-2. For six of the 15 highest yielding entries, the difference between yield in the burned and the residue removed treatments was not significant, showing the dependence of genotype in the yield response under different residue management systems. Turf quality was negatively correlated with yield (r= -0.48**, n=44) and seeds panicle-1 (r= -0.55**, n=44). However, panicles m-2 was not significantly correlated with turf quality, so indirect selection for yield through genotypes with high panicles m-2 in the absence of high seeds panicle-1 would be expected to have minimal impact on turf quality. Sufficient variation for seed production appears available to encourage development of improved germplasm for residue removed management systems.