Data for: Direct and indirect effects of floral defoliation on photochemical and non-photochemical chlorophyll fluorescence dynamics of a semiarid bunchgrass

These data were collected in an experimental field study at the USDA-ARS Northern Great Basin Experimental Range, OR, USA, aimed at assessing the effects of floral defoliation on the ability of crested wheatgrass (Agropyron cristatum) florets to dissipate excess light energy over the 2025 plant reproductive period. Basal florets were clipped by 30-50% ca. 3 cm from the distal end of the seed-head, and the chlorophyll fluorescence responses of clipped basal florets and unclipped florets distal to these were compared to those at the same locations on unclipped control seed heads. Chlorophyll fluorescence measurements were made at night to determine dark-adapted baseline (Fo) and maximum fluorescence yields (Fm) and to calculate maximum photosystem II quantum efficiency (Fv/Fm = (Fm-Fo)/Fm). The same florets were then measured again the following morning when exposed to full incident ambient photosynthetic photon flux densities to determine light-adapted steady state fluorescence (Fs), maximum fluorescence yields (Fm') and light-adapted photosystem II quantum efficiency (PhiPSII = (Fm'-Fs)/Fs). Fs, Fm and Fm’ were used to estimate the quantum yield of non-photochemical energy loss (NPQ) in PS II that is physiologically regulated (PhiNPQ = (Fs/Fm’)-(Fs/Fm)) and unregulated (PhiNO = Fs/Fm). Data was collected over two days within each of three reproductive phenological periods (pre-anthesis, anthesis, and post-anthesis), with concurrent average daily volumetric soil moisture at 10 cm soil depth (Vsm) from six Vsm observations made daily.

                                            [
  "005:18"
]
                                        

                                            {
  "fn": "Hamerlynck, Erik P.",
  "hasEmail": "mailto:erik.hamerlynck@usda.gov"
}
                                        

                                            [
  {
    "@type": "dcat:Distribution",
    "title": "PEI.xlsx",
    "format": "xlsx",
    "mediaType": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    "downloadURL": "https://ndownloader.figshare.com/files/61152661"
  }
]
                                        

                                            [
  "Chlorophyll fluorescence",
  "Crested wheatgrass",
  "Herbivory",
  "Photoprotection",
  "Reproduction",
  "quantum yield parameters"
]
                                        

                                            [
  "005:040"
]
                                        

                                            {
  "name": "Agricultural Research Service",
  "@type": "org:Organization"
}
                                        

                                            "{"type": "Point", "coordinates": [-119.691386, 43.472069]}"