Growth analysis of Kentucky bluegrass cultivars from six classification groups

Kentucky bluegrass (Poa pratensis L.) cultivars are diverse in their phenotype with a common classification system used to describe their growth habit but it is unclear why their growth differs. Growth analysis measurements have been used to explain growth rate differences among grass species and cultivars. The objective of this experiment was to study the growth of six commercially available Kentucky bluegrass cultivars from different growth habit classifications using classical growth analysis. Kentucky bluegrass seed was germinated and transplanted into cone-tainers and transferred to a growth chamber maintained at 25/15 degrees C (day/night) and a 12-h photoperiod. Thirty plants per cultivar were used with six whole plants of each cultivar harvested 8 weeks after transplanting and once per week for the next 4 weeks for a total of five harvests. Barvette HGT produced the largest plants, and Moonlight SLT produced the smallest plants by the end of the experiment, although the relative growth rate and absolute growth rate did not vary between the cultivars. Results from the growth analysis revealed that Moonlight SLT had the highest leaf area ratio (89.4 cm2 g-1), specific leaf area (200.1 cm2 g-1), and rhizome weight ratio (0.101 g g-1), but the lowest stem weight ratio (0.120 g g-1) and root weight ratio (0.338 g g-1). Final plant weights and leaf area measurements were closely aligned with Kentucky bluegrass classification information. Unfortunately, classical growth analysis provided little insight into why some cultivars possess more aggressive growth characteristics or compact growth habits. Modern Kentucky bluegrass cultivars used for turfgrass had similar relative growth rates.Whole plant mass and leaf area measurements were consistent with Kentucky bluegrass growth habit classifications.Classical growth analysis provided little insight into why some cultivars grow more aggressively than others.