Astir Grow Led Panel Project...

Based upon :
http://www.energyrating.gov.au/wp-content/uploads/2011/02/2009-ref-manual-lighting.pdf

http://www.helios32.com/Measuring Light.pdf

http://ledlight.osram-os.com/wp-content/uploads/2011/01/Radiometry-Photometry.pdf

http://www.opticalres.com/lt/illuminationfund.pdf

http://www.coe.montana.edu/ee/jshaw/classes/EOSystems/F09/ClassResources/EE482_F09_RadiometryOverview_2pp.pdf

http://www.instrumentsystems.com/fileadmin/editors/downloads/Products/LED_Handbook_e.pdf

And finally....
http://www.bfioptilas.com/objects/52_23_2079453411/LED-Measurement-Guide.pdf

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tolakra said:

Nice,
and how far do you believe that a spot of a plant gets fair amount of light for efficient growing-flowering?

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TOTAL IRRADIANCE (Over the range of 280-50,000 nm)

A ratio of total irradiance to PAR of 0.50 or less W m-2 per μmol m-2 s-1 (2.3 W m-2 per W m-2 PAR) is desirable to reduce thermal heating of plants and soil. The solar radiation ratio is less than 0.50 W m-s per μmol m-2 s-1 PAR. A ratio below 0.50 cannot be obtained with most lamps without a barrier and adequate ventilation or a luminaire specifically designed to dissipate infra-red radiation. For example, the ratios for metal halide lamps without a barrier, with an acrylic barrier, and with an acrylic barrier with 5 cm of water was shown to be 0.60, 0.53, and 0.24 W m-2 per μmol m-2 s-1 PAR, respectively. Low temperature sources such as low pressure sodium lamps and light emitting diodes (LEDs) without barriers have been shown to have ratios of 0.41 and 0.28, respectively.

http://biology.mcgill.ca/Phytotron/LightWkshp1994/8.1 Guidelines/Guidelines text.htm

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Since higher plants have developed their present characteristics under sunlight during the long process of evolution, it is quite natural that they adapted themselves to the present state of light environment. Higher plants seem to require all the spectrum bands, except for the band wavelengths 800 nm, of the sunlight coming on the Earth's surface. Blue, UV-A and UV-B light have their respective specific photomorphogenetic actions for higher plants, and are not replaced by light of other wavebands. These wavebands of radiation cooperate (UV-V, RL and BL) or counteract (BL and OL or RL) with light of other wavebands, and their requirements probably depend on the amount of other light. The situations make it difficult to draw a clear formula for lighting. We are required to take a case by case strategy, and gradually to obtain a better combination of individual wavebands. The processes of the development of lighting resembles that of prescription of a culture medium.

For the first step toward lighting formulation, the quantity of PAR should be fixed, because PAR seems to have an absolute quantity requirement. At this step the balance between the RL and BL components in the PAR should be considered. At the next step UV-A should be taken into account. It is less expensive in installment and operation than UV-B, although the functions of UV-A are not clear yet. Finally UV-B comes into consideration. To utilize the beneficial effects of UV-B and minimizing its deleterious effects, caution should be exercised in the selection of its intensity and waveband.

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PSUAGRO. said:

So a couple of these all over and I'm set http://www.homedepot.com/h_d1/N-25ecodZ5yc1v/R-203321688/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=led+flood+lights&storeId=10051#specifications hmm Chronikool was on to something

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There is a question. Is it necessary to prepare optimal light conditions for the photosynthesis of all leaves on the plant or not?
What way is it determined?
The correct decision on spectral composition of light depends very much on certain morphological characteristics of plants.
There is a dependance upon the distribution of fruits(Stardustr flowers) along a stem (Tikhomirov, 1990).

For example, cucumber has equal distribution of fruits along the stem.
There every leaf supplies assimilate to its fruit.(Stardustr flowers)
In this connection cucumber leaves at all layers must be provided with optimal light conditions.
This requires a large portion of green rays in PAR (about 40%).
Red rays in PAR (about 40%) provide high level of photosynthesis of upper leaves.

Green rays penetrate into middle and lower leaves of plants.
Blue rays have regulatory function, but its part in PAR is not very big (about 20%) (Tikhomirov, 1989).


We have another situation, where fruits of a plant concentrate in the upper part of the stem.

Classical example is wheat.

The ear of wheat is supplied with assimilates, primarily from the upper leaves.
With this crop, PAR must have approximately 60-70% red rays (Tikhomirov, 1990).

We've obtained data on specific reactions of plants for the spectral composition of PAR.
It's particularly important during plant development processes.

According to this point of view plants may be divided into two groups (Tikhomirov et al., 1991):

1) The first group is characterized with restricted growth and development processes at definite ontogenetic phases if the PAR spectrum and intensity are not optimized (i.e., cucumber, sunflower);


2) The second group include plants capable of passing through all ontogeneticS phases and producing a harvest irrespective of the PAR spectrum and intensity provided (for example: tomatoes, wheat).

​

Wheat is capable of passing through all phases of ontogenesis regardless of any specific spectral irradiation.
It's correct for PAR range of 100-600 W m[SUP]-2[/SUP] and possibly even higher.

Tomatoes have more restricted PAR range in comparison with wheat. With a PAR of 200 Wm[SUP]-2[/SUP] and higher, tomato productivity is lowered in red rays.

PAR range for radish appeared to be more narrow.
Even when red and green light is equal at a PAR of 200 Wm[SUP]-2[/SUP],plants of radish perish.
Cucumbers appeared to be the most greatly influenced by the spectrum of PAR.
For example in red wavelengths with less than PAR of 50 Wm[SUP]-2[/SUP], plants die.


We shouldn't ignore these great differences in reaction of plants on spectrum and PAR intensity.
All compromising decisions including introduction of universal spectrum of irradiation lead to partial loss of productivity.



Equal-energetic spectrum ("white" light) or a spectrum similar to curve of the action spectrum of photosynthesis have been proposed for use as a universal spectra for plants growing under lamp lighting.

The first might be chosen because of consideration of phylogenesis of plants,
the second - because of research familiar to you (McCree, 1972; Inada, 1976).

Either of these options could be accepted as a temporary compromise for initial research.


I do not believe that we have to copy illumination of plants in natural conditions for use in controlled environment growing.

For example there's no need to grow some species of plants under alternative light dark periods. Our research showed that productivity of some plants (radish, wheat) can be increased under continuous irradiation (Tikhomirov et al., 1976; Lisovsky et al., 1987). Also, we should not strictly aspire to duplicating morphophysiological characteristics of field grown plants. Thus, for example, we achieved a very large radish productivity when we sharply changed its photomorphogenesis (Tikhomirov et al., 1976). This is true for increasing cucumber productivity too. However, if we accept this concept, we must know where and how we should deviate from natural conditions to increase productivity of plants grown in controlled environments.

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High R:FR Ratios ( R:FR ratio 655-665 nm vs 725-735 nm )

Fluorescent tubes and high pressure sodium vapor lamps are popular PAR sources in CE, and both provide R:FR ratios several times higher than sunlight. Due to the spectral properties of Pr and Pfr, changes in R:FR above ca. 1.5 do not cause a proportional change in the phytochrome photoequilibrium (Smith and Holmes 1977). Therefore, the R:FR-based neighbor detection mechanism is likely to be distorted or disabled when canopies are grown under extremely high R:FR ratios. Some experimental evidence for this idea has been provided by studies with amaranth, in which CuSO[SUB]4[/SUB] filters were used to increase the R:FR ratio of the light received by the canopies and reduce stem elongation. These studies have shown that very high R:FR ratios result in decreased (rather than increased) canopy net productivity. It is not clear whether this decrease is caused by (1) the elimination of an active sink of assimilates (i.e. the growing internodes), a change in the pattern of light penetration through the canopy (see below), or a combination of the two. In any case, these results appear to directly contradict the notion that canopy growth at high densities is limited by the diversion of photosynthate to "shade-avoidance" responses. Of course, the use of artificially high R:FR ratios may be a convenient way to obtain short-statured plants in CE, which may be desirable for many crops grown for horticultural or ornamental purposes (McMahon and Kelly 1990, Rajapakse and Kelly 1992).

Another predictable consequence of the use of extremely high R:FR ratios in CE is the elimination of phototropic responses triggered through phytochrome. Since these responses may play a role in the dynamics of gap-filling by the canopy, it is suggested that the increase in light interception over time (and therefore canopy growth) will be slowed under very high R:FR. Of course, the extent of this retardation would depend upon (1) the quantitative importance of phototropic responses in gap-filling by the shoot population, and (2), the extent to which phytochrome and B-absorbing photoreceptors play redundant roles in controlling phototropic responses in canopies.
Finally, very high R:FR, which disable the phytochrome-mediated mechanism of neighbor etection, will almost certainly result in increased size structuring in dense plant populations. From a plant grower stand-point the establishment of a strong size hierarchy in the population might have two negative consequences: reduced total yield at high densities and reduced yield uniformity.


You know by now,where to find those....

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INTRODUCTION

Attempts to use artificially lit cabinets to grow plants identical to those growing in sunlight have provided compelling evidence of the importance of light quality for plant growth. Changing the balance of red (R) to far-red (FR) radiation, but with a fixed photosynthetic input can shift the phytochrome photoequilibrium in a plant and generate large differences in plant growth. With FR enrichment the plants elongate, and may produce more leaf area and dry matter (see Smith, 1994 these proceedings). Similar morphogenic responses are also obtained when light quality is altered only briefly (15-30 min) at the end-of-the-day (Ballare 1994; these proceedings). Conversely, for plants grown in natural conditions the response of plant form to selective spectral filtering has again shown that red and far-red wavebands are important as found by Kasperbauer and coworkers (Kasperbauer, 1992). Also, where photosynthetic photon flux densities (PPFD) of sunlight have been held constant, the removal of far-red alone alters plant growth (Mortensen and Stromme 1987; McMahon et al., 1991). As shown in Table 1 for chrysanthemum, with FR depletion plants grown in sunlight are small, more branched and darker green. Here we examine the implications for plant growth and flowering when the far-red composition of incident radiation in plant growth chambers is manipulated.

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OVERVIEW

As a broad generalization, far-red rich lamps are beneficial and sometimes essential, for plant growth and flowering in artificially lit chambers. Thus fluorescent and sodium lamps, being FR deficient may cause stunting and poor flowering. Brief end-of-day FR exposure may alleviate some of the stunting of growth but will probably have complex effects on flowering. A more beneficial approach appears to be continued FR enrichment over the whole photoperiod. A further complexity is that the need for FR input may vary cyclically over the day.

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