The potential for tradeoffs between turf quality and seed yield
By Garett Heineck
Figure 1. Roseau MN is the center of the perennial ryegrass turf seed industry. St. Paul MN is the location of the UMN breeding program. Perennial ryegrass profits per acre are in red, soybean is in blue and wheat is in light blue. Numbers are based on 2017 profits. Two experimental locations were used to determine if increased seed yield was negatively associated with turfgrass quality.
Perennial ryegrass (Lolium perenne L.) is an economically important amenity grass grown in many regions of the world for home lawns, sports fields, and golf courses. In fact, most turfgrass seed mixes contain at least 10% perennial ryegrass. To meet consumer demands there is a large seed production industry in northwest Minnesota that produces perennial ryegrass seed; this year approximately 50,000 acres have been planted. Perennial ryegrass is far more profitable than soybean or wheat on a per-acre basis making the production of grass seed an important component to the northwest MN agricultural economy (Figure 1). In support of this industry, the University of Minnesota turfgrass breeding program supplies this industry with elite cultivars of acceptable turfgrass quality and stable seed yields.
Figure 2. Kentucky bluegrass seed yield plotted against turfgrass quality for 45 entries. Three groups of germplasm included were a core collection of 20 representing the USDA collection, 16 plant introduction selection with both good seed yield and quality, and 9 cultivars. As turfgrass quality increases seed yield decreases. Data adapted from Table 3 in Johnson et al. (2003).
Efforts in breeding for turfgrass quality have met with success over the decades; however, breeding to maintain seed yield is important as well. Breeders have long thought that increasing turfgrass quality results in a reduction in seed yield. Although species such as Kentucky bluegrass have research supporting this supposition, there is no such direct correlative evidence for perennial ryegrass (Figure 2). Recent research at the University of Minnesota explored tradeoffs between seed yield and turf performance in perennial ryegrass at two MN locations (Figure 1).
Figure 3. No direction correlation was found between turfgrass quality and seed yield at Roseau (red) and St. Paul (blue). This means that in general, cultivars with good turfgrass quality should be able to have economic seed yields.
Turfgrass quality scores, when averaged across two seasons of data collection, were not correlated with seed yield at either location (Figure 3). This means that the turfgrass quality of a given cultivar was not associated with either high or low yields. However, data from several individual turfgrass quality rating dates were moderately correlated with seed yield at both locations (P < 0.1). Exploring turfgrass component traits, such as turfgrass texture, gave researchers an idea of what might be causing these moderate correlations. Cultivars with more fertile stems (seed-producing organs) were associated with lower turfgrass quality scores (Figure 4). However, more fertile stems were associated with higher seed yields in the same cultivars (Figure 4). This led researchers to conclude that although turfgrass quality and seed yield are not correlated per se, certain components of yield and turf quality are. Future breeding endeavors will focus on the improvement of yield without selecting for increased stem production.
Figure 4. When grown for seed, perennial ryegrass cultivars with many fertile tillers (seed heads) also had increased seed yield at Roseau (red) and St. Paul (blue). When grown for turf, cultivars that produced many stems (seed heads) had poor turfgrass quality. These associations imply a potential tradeoff between yield and turf quality.
Reference
Johnson, R. C., Johnston, W. J., & Golob, C. T. (2003). Residue management, seed production, crop development, and turf quality in diverse Kentucky bluegrass germplasm. Crop Science, 43(3), 1091-1099.
