Assessment of drought resistance of Kentucky bluegrass (Poa pratensis) varieties at seedling stage

Abstract

Expansion of turf area together with irrigation have caused concern because of the increased demand for the scarce water resources in arid and semi‐arid regions. Kentucky bluegrass (KBG) (Poa pratensis) has been widely used to establish turf, and selecting varieties with good drought resistance is important in reducing irrigation requirements. Its seedling stage is the key step to successful establishment. Therefore, pot experiments in the greenhouse were carried out to assess drought resistance in 11 KBG varieties. The rate of germination, survival rate, and vertical growth rate of each variety increased as field water capacity (FWC) decreased from 70% (FWC 70) to 50% (FWC 50), and then decreased from 50% to 30% (FWC 30). Tillering rate and shoot‐to‐root ratio decreased as FWC decreased from FWC 70 to FWC 30. Proline content and electrolyte leakage (EL) in leaves of KBG at FWC 50 was lower than those at FWC 30 and FWC 70. Under FWC 30, representing drought stress, rate of germination, survival rate of seedlings, vertical growth rate, and shoot‐to‐root ratio were significantly different among the 11 varieties. Based on the rate of germination. ‘Barlin’ and ‘Baron’ performed best. According to the survival rate of seedlings, ‘Baron’ performed best. For vertical growthrate, ‘Barlin’ and ‘Compact’ were superior to others. ‘Barlin’ was the best variety for lower shoot‐to‐root ratio. ‘Barlin’ and ‘Baron’ had higher proline accumulation and greater cell membrane stability (lower EL) in leaves. Using rate of germination, survival rate, vertical growth rate, shoot‐to‐root ratio, proline content, and EL as analysis factors, cluster analysis indicated that ‘Baron’ and ‘Barlin’ had better resistance to drought than other varieties, and suggested that they are suitable for sowing in arid and semi‐arid regions because of their strong drought resistance at the seedling stage.