Effects of periodic fluctuations of photon flux density on anatomical and photosynthetic characteristics of soybean leaves

1987 ◽  
Vol 13 (1) ◽  
pp. 81-89 ◽  
Author(s):  
J. P. Gaudillere ◽  
J. J. Drevon ◽  
J. P. Bernoud ◽  
F. Jardinet ◽  
M Euvrard
Keyword(s):  
Flux Density ◽  
Photosynthetic Characteristics ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Periodic Fluctuations ◽  
Soybean Leaves

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.

scholarly journals Influencia de los mezquites en la composición y cobertura de la vegetación herbácea de un agostadero semiárido del norte de Guanajuato

2017 ◽  
pp. 21
Author(s):  
Juan Antonio Cruz-Rodríguez ◽  
Edmundo García-Moya ◽  
Juan Tenorio Frías-Hernández ◽  
Genaro Montesinos-Silva ◽  
José Luis Flores-Flores
Keyword(s):  
Flux Density ◽  
Tree Canopy ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Diverse Group ◽  
Herbaceous Vegetation ◽  
The Third ◽  
C4 Species ◽  
Long Time ◽  
Shrub Dominance

It has been said for a long time that mesquite reduces significantly cover and productivity of herbaceous vegetation in the range lands. Likewise there are evidences showing the opposite. This controversy make us think that this interaction is not fully understood. This work evaluated the effect of mesquite on the herbaceous vegetation along a gradient which range from open to a heavy dense stands. It was found that isolated arboreal mesquites reduced up to 50% the photosyntetic photon flux density which are not limiting for C4, species, whereas clustered shrubby mesquites reduces 75 % which can limit the growth of these species. Such conditions creates three plant groupings: the first made up of short and caespitose grasses which grow in the open. The second with a better and more diverse group growing under the tree canopy, dominated by bunchgrasses, cacti and shrubs. The third under the close canopy of the clustered shrubby mesquites with shrub dominance.

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