Physiology and growth response of roughstalk bluegrass and creeping bentgrass to high temperature stress.

摘要

Roughstalk bluegrass (Poa trivialis L.) (RBG) is a problematic weed in creeping bentgrass fairways (Agrostis stolonifera L.) (CBG) due to its susceptibility to high temperature stress. Our objective was to describe morphological and physiological characteristics of RBG and CBG under high temperature stress to ultimately improve management and control strategies of RBG. Laser (heat-tolerant) and Pulsar (heatsensitive) RBG performed statistically equivalent in the growth chamber study, thus only differences between species were analyzed using Pulsar to represent RBG. Creeping bentgrass maintained better turf quality and produced 15 mg of clipping dry wt. d -1 compared to only 0.5 for RBG 35 d after introduction to high temperatures at 33°C. Root viability of RBG was higher than CBG at 23 and 28oC however, the reverse was true at 33°C. Additionally, fructan concentrations in RBG roots increased as temperatures increased whereas CBG did not follow this trend. Shoot amino acid concentration of RBG increased 223% at 33°C compared to only a 64% increase in CBG at 33°C. Fructan and amino acid concentrations of RBG were most affected by high temperatures in the growth chamber study indicating fructan and amino acid synthesis, degradation, and possibly translocation are critical components of heat tolerance.;Turf quality and percent cover throughout the study was highest for L93 supporting previous observations of poor summer tolerance of RBG. However, mild summer temperatures in 2008 and 2009 resulted in minimal separation between RBG cultivars. Stolon production began in May for RBG and CBG after planting in August of the previous year. Specific stolon dry weights (mg cm -1) of RBG doubled compared to L93 during peak summer. Total nonstructural carbohydrate (TNC) concentration of Pulsar shoots decreased 26%, while TNC in stolons remained unchanged. Unlike in CBG, however, protein and amino acid concentrations increased in stolons and decreased in shoots of RBG during summer stress. Conserving protein and carbohydrates in stolons at the expense of shoots until high temperature stress subsides later in the growing season may be a stress avoidance mechanism of RBG.