MULTI-WAY KENTUCKY BLUEGRASS BLENDS AND THEIR EFFECT ON TURFGRASS QUALITY
Kentucky bluegrass (Poa pratensis L.) cultivars are generally sown as blends of two or more cultivars. This study was initiated to examine multi-way bluegrass blends on turfgrass quality (TQ) throughout the year at two US locations. Five improved cultivars ('Award,' 'Liberator,' 'Chicago II,' 'Rambo,' 'NuBlue') with a range of documented TQ performance levels were used to study all possible blend combinations (monostands, 2-, 3-, 4-, and 5-way blends in equal proportions by seed weight). TQ ratings were taken monthly at duplicate trials in Maryland and Idaho over 2 and 3 years, respectively. Stepwise regression showed higher R2 values in Idaho, probably resulting from consistent irrigation; the Maryland site was unirrigated. Regression revealed a complicated cultivar effect, with all five cultivars participating in performance. There were 10 instances of cultivar × cultivar interactions on TQ, a positive slope of which suggests that two cultivars acted synergistically to enhance quality. A categorical ANOVA was used to explore criteria for ejecting a cultivar from a potential blend, and for testing the suitability of a monostand of a high performing cultivar in place of blending. In 76 out of 221 possibilities, 'NuBlue' (a low performing cultivar) decreased TQ of a blend by its presence and increased it in 3 examples, all related to spring greenup. A given blend candidate should be expected to contribute at least an equal number of positive and negative attributes to a blend, and thus 'NuBlue' would be rejected. Out of 403 combinations, the 'Award' monostand outperformed 98 blend combinations and underperformed 9, suggesting that planting a top performing bluegrass monostand might be a valid agronomic practice.
Brede, A.D. 2008. MULTI-WAY KENTUCKY BLUEGRASS BLENDS AND THEIR EFFECT ON TURFGRASS QUALITY. Acta Hort. (ISHS) 783:19-28
grass seed, mixtures, competition, Poa pratensis, smooth-stalked meadowgrass, population dynamics