Grassland Research最新文献

This article represents the perspective of one retired, academic forage breeder and cultivar developer after 50 years of working experience. Developing cultivars that help farmers within pastoral agriculture is the main goal, a system where livestock is the consumer. International Grassland Congress proceedings, as well as the general literature, are historical guides for the state of forage breeding. Efficiency was achieved through technologies; better equipment for planting and harvesting; and advances in computer computation and communication. Biotechnology achievements were fitful and continue to evolve. Cultivar performance mean-reversion, cost to the program, and what the farmer seed buyer was willing to pay are important considerations for applying any technology, especially biotechnologies. Biotech promises were too optimistic. This was due, in part, to a lack of understanding that traditional phenotypic/genotypic field selection programs operate in a complex way with multiple species and several traits screened simultaneously at a modest cost. The majority of current forage cultivars are from field-based selection. Industry participation at scientific conferences declined over time, with less sharing of information the result. Cultivar developers will continue using basic field selection methods but should explore applying any technology; just be clever on when, how, and with whom to use them. Practical advice and experiences are also presented and discussed.

Bekken, M. A. H., & Soldat, D. J. (2022). Quantifying golf course nitrogen use efficiency. Grassland Research, 1(3), 174–186. https://doi.org/10.1002/glr2.12024

There was an error in the variance term used in the growth potential (GP) model in this study. Variances of 10 and 12 were used for C₃ and C₄ turfgrasses, respectively. These variances are for Fahrenheit temperatures; however, this study used Celsius temperatures. When using Celsius in the equation, it is best to adjust these variance terms to 5.5 for C₃ grasses and 7 for C₄ grasses. With the updated variances, the definition of a turfgrass growth day also needed to be adjusted. Following the recommendation of Gelernter et al. (2016), we adjusted the definition of a turfgrass growth day to a day in which the growth potential was greater than 20%.

The updated parameters caused small changes to the number of turfgrass growth days calculated at each golf course in the study. This, in turn, changed the N rate normalized by turfgrass growth days, the Nitrogen Efficiency Scores (NES), the N_max normalized NES, and the correlations between the N rate normalized by turfgrass growth days and the economic factors. Figures 3-9 have been updated and Tables 3–9 have been updated. None of the paper's main conclusions have changed, but a description of the updated results from the original manuscript is included below.

With the updated parameters, the ratio of the golf course-wide N application rate to the GP N requirement prediction (termed the NES) was 0.47, indicating that golf courses used 53% less N than predicted by the model.

With the updated parameters, four (US-East Texas, US-Florida, US-Northwest, Norway) of the eight regions had similar N rates on fairways; median fairway N rates normalized by growth days were between 0.61 and 0.65 kg ha⁻¹ day⁻¹ in these regions. The remaining four regions (Denmark, US-Midwest, US-Northeast, UK) were below this range, with the median fairway N rate normalized by turfgrass growth days between 0.34 and 0.19 kg ha⁻¹ day⁻¹.

With the old parameters, tees in Norway were the only golf course components across all regions for which the median NES was greater than 1. With the updated parameters, US-East Texas, US-Florida, US-Northwest, and Norway had median NES values that were greater than 1 on greens. On tees in Norway, the median NES score remained above 1. In the US-Northwest, the median NES score on tees rose above 1. The median NES score in all other regions across all components stayed below 1.

The updated parameters slightly changed the rankings of NES in Table 9. The ranking of the N rate normalized by turfgrass growth days and the NES of the US-Midwest changed from 6th to 5th and the ranking of the US-Northeast changed from 5th to 6th.