Carbon Dioxide Exchange Rate and Chlorophyll Content of Turfgrasses Treated with Flurprimidol or Mefluidide

Abstract

Plant growth regulators (PGRs) are being used increasingly for high maintenance turf production. A greenhouse and growth chamber study was conducted to determine the effect of two PGRs, mefluidide and flurprimidol, on the carbon dioxide exchange rate, chlorophyll content, and specific leaf weight of annual bluegrass and creeping bentgrass. Rate-response and time course studies were conducted. In the rate-response study, increasing flurprimidol rates caused a linear decrease in the carbon dioxide exchange rate (CER). Mefluidide had no effect on the CER in the rate-response experiment but did cause a significant drop in the CER at 4 and 8 days after treatment (DAT) in the time course study. Both PGRs increased chlorophyll content at 16 DAT in the time course study. In the rate-response study, chlorophyll content displayed a quadratic response to an increasing mefluidide rate. The 0.28 kg ha −1 rate of mefluidide increased the chlorophyll content to 46 g cm −2 from 21.5 g cm −2 for control plants. Both PGRs increased specific leaf weight, although for flurprimidol the effect was significant only at the 0.1 level of probability. PGRs decreased the CER and increased the chlorophyll content and specific leaf weight for both species tested. The physiologic effects measured were short lived, and so the physiologic significance of these changes is difficult to determine without further research.

Trinexapac‐ethyl and Paclobutrazol Affect Kentucky Bluegrass Single‐Leaf Carbon Exchange Rates and Plant Growth

“…The results of this study in conjunction with previously conducted experiments examining PGR effects on turf CERs fail to provide a clear cause‐and‐effect relationship between PGR altered CERs and reduced clipping production (Beasley and Branham, 2007; Gaussoin et al, 1997; Spokas and Cooper, 1991). Patterns of CER alteration from PGR applications appear to fluctuate greatly for gibberellin inhibitors.…”

“…Patterns of CER alteration from PGR applications appear to fluctuate greatly for gibberellin inhibitors. The effects of PGRs on CERs are the result of, or a combination of, leaf and tiller production, changes in leaf morphology, increased chlorophyll density, and changes in sink demand for photoassimilates (Beasley and Branham, 2007; Gaussoin et al, 1997; Spokas and Cooper, 1991). Since TE and PAC are metabolized quickly within plant tissues, fluctuations in single‐leaf CERs from TE and PAC applications may be in response to changes in plant photoassimilate demand and growth patterns and not the cause of altered growth.…”

“…toassimilates (Beasley and Branham, 2007;Gaussoin et al, 1997;Spokas and Cooper, 1991). Since TE and PAC are metabolized quickly within plant tissues, fluctuations in single-leaf CERs from TE and PAC applications may be in response to changes in plant photoassimilate demand and growth patterns and not the cause of altered growth.…”

“…Amidochlor increased KBG CERs 32 to 68 POC 7 of 23 wk while mefluidide had no effect on canopy CERs. Gaussoin et al (1997) reported that flurprimidol (α‐(1‐methylethyl)‐α‐(4‐(trifluoromethoxy)phenyl)‐5‐pyrimidinemethanol) reduced CERs on a leaf area basis for creeping bentgrass and annual bluegrass ( Poa annua L.). Increasing flurprimidol rates linearly decreased canopy CERs while mefluidide had no effect on creeping bentgrass or annual bluegrass CERs.…”

Growth and Evapotranspiration Response of Two Turfgrass Species to Nitrogen and Trinexapac-ethyl

“…TE interferes with gibberellin biosynthesis and reduces laminar cell elongation, thereby decreasing the need for frequent mowing (Adams et al, 1992). Also, TE application induces production of shorter, thicker cells (Ervin and Koski, 2001b), increased specific leaf weight (Gaussoin et al, 1997;Heckman et al, 2001), increased tillering (Beasely et al, 2005;Ervin and Koski, 1998;Fagerness and Yelverton, 2000;Goss et al, 2002), and changes in total root length and surface area (Beasely et al, 2005). By decreasing canopy height through suppression of vertical shoot elongation, one consequence may be a decrease in evapotranspiration rates.…”