Fluctuation of photosynthetic photon flux density within a Miscanthus sinensis canopy

1988 ◽  
Vol 3 (3) ◽  
pp. 253-266 ◽  
Author(s):  
Yan-Hong Tang ◽  
Izumi Washitani ◽  
Takayoshi Tsuchiya ◽  
Hideo Iwaki
Keyword(s):  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Miscanthus Sinensis ◽  
Photosynthetic Photon Flux

Do finer gap mosaics provide a wider niche for Quercus gilva in young Japanese cedar plantations than coarser mosaics? Simulation of spatial heterogeneity of light availability and photosynthetic potentialThis article is one of a selection of papers published in the Special Forum IUFRO 1.05 Uneven-Aged Silvicultural Research Group Conference on Natural Disturbance-Based Silviculture: Managing for Complexity.

2007 ◽  
Vol 37 (9) ◽  
pp. 1545-1553 ◽  
Author(s):  
Hiromi Mizunaga
Keyword(s):  
Spatial Heterogeneity ◽  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Reciprocal Relationship ◽  
Growth Potential ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Miscanthus Sinensis ◽  
Photosynthetic Photon Flux ◽  
Gap Mosaic

Both the size and the density of gaps affect seedling growth, but these two parameters have a reciprocal relationship at a given gap ratio. The objective of the present study was to clarify the appropriate gap mosaic coarseness required to facilitate the growth of Quercus gilva Blume seedlings in Cryptomeria japonica D. Don plantations. The spatial heterogeneity of the photosynthetic photon flux density on the forest floor was predicted using mimicked hemispherical diagrams under five levels of gap mosaic coarseness ranging from the finest gap mosaic with a gap size of 25 m2 and a gap density of 100·ha–1 to the coarsest mosaic of 400 m2 and 6.25·ha–1. Photosynthetic potentials (PP) were calculated by combining the predicted photosynthetic photon flux density and photosynthetic relationships of Q. gilva and two nontree major competitors ( Mallotus japonicus (Thunb.) Muell. Arg. and Miscanthus sinensis Anderss.). The coarser gap mosaic formed a more heterogeneous and bimodal PP frequency and resulted in a wider site in which the three species had high growth potential without considering competition among species. However, an intermediate mosaic with a gap width to mean canopy height ratio of 0.7 formed the widest realized niche in which Q. gilva would show good growth with a relative PP > 70%, whereas the competitor species would be suppressed with a relative PP < 70%.

scholarly journals Estimation of Global and Diffuse Photosynthetic Photon Flux Density under Various Sky Conditions Using Ground-Based Whole-Sky Images

2019 ◽  
Vol 11 (8) ◽  
pp. 932
Author(s):  
Megumi Yamashita ◽  
Mitsunori Yoshimura
Keyword(s):  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Diffuse Component ◽  
Photosynthetic Photon Flux ◽  
Physiological Processes ◽  
Sky Conditions ◽  
Mean Square Errors ◽  
Relative Root

A knowledge of photosynthetic photon flux density (PPFD: μmol m−2 s−1) is crucial for understanding plant physiological processes in photosynthesis. The diffuse component of the global PPFD on a short timescale is required for the accurate modeling of photosynthesis. However, because the PPFD is difficult to determine, it is generally estimated from incident solar radiation (SR: W m−2), which is routinely observed worldwide. To estimate the PPFD from the SR, photosynthetically active radiation (PAR: W m−2) is separated from the SR using the PAR fraction (PF; PAR/SR: unitless), and the PAR is then converted into the PPFD using the quanta-to-energy ratio (Q/E: μmol J−1). In this procedure, PF and Q/E are considered constant values; however, it was reported recently that PF and Q/E vary under different sky conditions. Moreover, the diffuse ratio (DR) is needed to distinguish the diffuse component in the global PAR, and it is known that the DR varies depending on sky conditions. Ground-based whole-sky images can be used for sky-condition monitoring, instead of human-eye interpretation. This study developed a methodology for estimating the global and diffuse PPFD using whole-sky images. Sky-condition factors were derived through whole-sky image processing, and the effects of these factors on the PF, the Q/E of global and diffuse PAR, and the DR were examined. We estimated the global and diffuse PPFD with instantaneous values using the sky-condition factors under various sky conditions, based on which the detailed effects of the sky-condition factors on PF, Q/E, and DR were clarified. The results of the PPFD estimations had small bias errors of approximately +0.3% and +3.8% and relative root mean square errors of approximately 27% and 20% for the global and diffuse PPFD, respectively.

scholarly journals Different LED Light Wavelengths and Photosynthetic Photon Flux Density Effect on Colletotrichum acutatum Growth

Plants ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 143
Author(s):  
Neringa Rasiukevičiūtė ◽  
Aušra Brazaitytė ◽  
Viktorija Vaštakaitė-Kairienė ◽  
Alma Valiuškaitė
Keyword(s):  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Growth Characteristics ◽  
Colletotrichum Acutatum ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Light Emitting ◽  
Led Light ◽  
Fungus Growth

The study aimed to evaluate the effect of different photon flux density (PFD) and light-emitting diodes (LED) wavelengths on strawberry Colletotrichum acutatum growth characteristics. The C. acutatum growth characteristics under the blue 450 nm (B), green 530 nm (G), red 660 nm (R), far-red 735 nm (FR), and white 5700 K (W) LEDs at PFD 50, 100 and 200 μmol m−2 s−1 were evaluated. The effect on C. acutatum mycelial growth evaluated by daily measuring until five days after inoculation (DAI). The presence of conidia and size (width and length) evaluated after 5 DAI. The results showed that the highest inhibition of fungus growth was achieved after 1 DAI under B and G at 50 μmol m−2 s−1 PFD. Additionally, after 1–4 DAI under B at 200 μmol m−2 s−1 PFD. The lowest conidia width was under FR at 50 μmol m−2 s−1 PFD and length under FR at 100 μmol m−2 s−1 PFD. Various LED light wavelengths influenced differences in C. acutatum colonies color. In conclusion, different photosynthetic photon flux densities and wavelengths influence C. acutatum growth characteristics. The changes in C. acutatum morphological and phenotypical characteristics could be related to its ability to spread and infect plant tissues. This study’s findings could potentially help to manage C. acutatum by LEDs in controlled environment conditions.

Photomorphogenesis of wheat sprouts with LED irradiation of different intensities

2019 ◽  
Vol 52 (5) ◽  
pp. 583-594
Author(s):  
T Han ◽  
T Astafurova ◽  
S Turanov ◽  
A Burenina ◽  
A Butenkova ◽  
...  
Keyword(s):  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Optimum Level ◽  
Photosynthetic Photon Flux ◽  
Plant Cultivation ◽  
Key Factor ◽  
Definition Of ◽  
Led Irradiation

Definition of the growth and development characteristics of plants in varied light conditions is a key factor for the creation of highly efficient light facilities for plant cultivation. Experimental research was conducted using an LED irradiation facility with photosynthetic photon flux densities ranging from 0 to 261 μmol m−2 s−1 and a continuous spectrum with maxima at 445 and 600 nm. Under the maximum photosynthetic photon flux density (261 μmol m− 2 s−1) wheat germs demonstrated diminishing leaf surface with high values of specific leaf area, enhanced pubescence of ground tissues, increases in the number of stomata on the upper epidermis and palisade, and an increase in the thickness of the leaves as well as an increase in carotenoids but a decrease in the chlorophyll a+b/carotenoids relation. It was revealed that the optimum level of photosynthetic photon flux density for the referred spectrum was in the range from 82 to 100 µmol m−2 s−1, which may enable a reduction of irradiance under specific conditions during early development with no harm to the plants while minimizing energy consumption during cultivation.

Sign in / Sign up

Export Citation Format

Share Document