Layering contrasting photoselective filters improves the simulation of foliar shade

Abstract

Background Neutral density shade cloth is commonly used for simulating foliar shade, in which it reduces light intensity without altering spectral quality. However, foliar shade also alters spectral quality, reducing the ratio of red to far-red (R:FR) light, altering the ratio of blue to green (B:G) light, and reducing ultraviolet light. Unlike shade cloth, photoselective filters can alter spectral quality, but the filters used in previous literature have not simulated foliar shade well. We examined the spectral quality of sunlight under color temperature blue (CTB), plus green (PG), and neutral density (ND) filters from LEE Filters, Rosco e-colour + and Cinegel brands either alone or layered, hypothesizing that the contrasting filter qualities would improve simulations. As a proof-of-concept, we collected spectral data under foliar shade to compare to data collected under photoselective filters. Results Under foliar shade reductions in the R:FR ratio ranged from 0.11 to 0.54 (~ 1.18 in full sun), while reductions in the B:G ratio were as low as 0.53 in deep shade, or were as high as 1.11 in moderate shade (~ 0.87 in full sun). Neutral density filters led to near-neutral reductions in photosynthetically active radiation and reduced the R:FR ratio similar to foliar shade. Color temperature blue filters simulated the increased B:G ratio observed under moderate foliar shade, but did not reduce the R:FR ratio low enough. On their own, PG filters did not simulate any type of foliar shade. Different brands of the same filter type also had disparate effects on spectral quality. Layered CTB and ND filters improved the accuracy of moderate foliar shade simulations, and layering CTB, PG, and ND filters led to accurate simulations of deep foliar shade. Conclusions Layering photoselective filters with contrasting effects on the spectral quality of sunlight results in more accurate simulations of foliar shade compared to when these filters are used separately. Layered filters can re-create the spectral motifs of moderate and deep foliar shade; they could be used to simulate shade scenarios found in different cropping systems. Photoselective filters offer numerous advantages over neutral density shade cloth and could be a direct replacement for researchers currently using neutral density shade cloth.

Spring wheat canopy effects on light dynamics and yield of intercropped fine fescues

“…Across Minnesota, monthly averaged DLIs of ≤15 mol m −2 day −1 occur from October to February, and monthly average DLIs of ≤5 mol m −2 day −1 do not occur anytime during the year in Minnesota (Faust & Logan, 2018). While the period where light intensity was reduced under the wheat canopy was relatively short, this light reduction was similar to those observed under dense tree canopy (Petrella et al., 2022).…”

“…These observations are interesting because fine fescues are traditionally considered shade tolerant, whereas PR has been thought to not do well in these conditions (Fry & Huang, 2004). Shade is a very generic term, but reduction of light quantity and spectral quality can result in different molecular and physiological response of the plants; Petrella et al (2022) grew 40 fine fescue entries under a 30% light reduction, and a R/FR ratio of 0.66/0.67 at solar noon and found CH entries were more tolerant to shade than ST entries, and HD entries were mostly shade intolerant (Petrella & Watkins, 2020). More importantly, that study pinpointed that cultivar tolerance to shade varied greatly within species.…”

Association of hard fescue (Festuca brevipila) stress tolerances with genome mapped markers

“…Seedlings of each plant were vegetatively propagated and used for phenotyping of growth under foliar shade and resistance to gray snow mold, and for DNA extraction and genome-wide association analyses. To initiate shade simulation, the plants were again thinned to three tillers and moved into a simulated foliar shade tent within the same greenhouse with photoselective filters layered as described (Petrella et al, 2022). Briefly, the reduction in the red to far-red (R:FR) ratio and the reduction in photosynthetic photon flux (PPF) was achieved with a layer of a one-fourth-strength Cinegal 3208 color temperature blue filter and a 0.30-neutral density E-colour+ 209 filter (Rosco Laboratories Inc.).…”

Effects of light on growth and biomass of Dendrobium officinale (Kimura et Migo) grown in ThaiNguyen province, Vietnam

“…The light intensities are one of the important environmentfactors affectting to the growth and polysaccharide, and alkaloid content in plant (12,18,19,20,21,22). Photosynthetic activity of plants was depressed due to photoinhibition under too low or too hight shade (18).…”