Creeping bentgrass responses to drought stress and polyamine application

Abstract

Polyamines (PAs) such as spermidine (Spd), spermine (Spm), and putrescine are involved in various biological functions including abiotic stress response. Whether PAs play an important role in cool-season turfgrass tolerance of drought stress is not well investigated. We have conducted a series of growth chamber (GC) studies including one hydroponic and two soil-based GC studies with creeping bentgrass (Agrostis stolonifera) ‘Penncross’ and ‘Penn-G2’ to determine whether exogenous application of PAs may affect plant growth and stress tolerance. Application of relatively low concentrations of Spd (500 or 750 μM) or Spm (500 μM) promoted tillering rates under optimal growth conditions in hydroponics. The same levels of PA treatments moderated the damages associated with drought stress in the soil-based GC studies. The most notable differences in drought response associated with PA treatment were increased membrane health. This was observed as greater photochemical efficiency, higher quantum yield, less electrolyte leakage, and less lipid peroxidation (malondialdehyde content) in PA-treated plants compared with control plants. The relatively low level of exogenous PAs used in this study did not have a major effect on plant water relations under drought stress. Canopy temperatures and soil moisture content were unaffected by any PA treatment; however, on some days during early drought stress, relative water content was significantly higher in PAtreated plants compared with controls. PA could play a major role in protecting photosynthetic and cellular membranes during drought stress of creeping bentgrass.