Using 400W HPS to induce dragon fruit flowering"

[Kay]

I am seriously wanting to play with extended days out of the greenhouse and in the field. 

I am hoping to use 400w HPS to cover a larger area than incandescent to save on electricity as we use way too much having everything processed on site. 


i just read this:  http://stfc.org.au/dragon-fruit-by-graham-reindeers

Lamps simulate “Long-days”  The name of the game here is to shock the (Pr) {inactive} Phytochrome, which regresses during increasing dark periods, back into active (Pfr ) and to drive them back into the cell nucleus, to keep making flowering hormone. We can either light the crop continuously after dark or light the “dark” period for 25% of each hour, usually starting at about 10pm and continuing until approx 2.00am. This fools the plant into thinking it is all one long day. Plants yield better when they sleep a bit at night so they can rearrange their sugar storage efficiently. However, a continuous light from 10pm to 2.00am can be used with no real ill-effects. 100 Watt incandescent bulbs are usually used, spaced about 5 feet apart from each plant, delivering about 10 lumens {foot candles}.  The actual lumen output is not very critical because all it has to do is shock the Phytochrome with a few photons. To save power, the lights can be cycled on and off to give about 25% timed light. There is a technique being used lately where 400 Watt Metal Halide or Sodium (High Intensity Discharge) lamps are mounted high enough above the crop to reach plants 40-50 feet away which are either swivelled on a boom or reflected by a reflector, like a “light house”, causing light to fall on each plant 3 of 4 times an hour between 10pm-2.00am. The HID’s are not very high in 660nm red but they make up for it in Lumen output. Again, provided that each plant feels the equivalent of about 10 lumens of light at each passing, the Phytochrome will be switched back to creating flowering hormone. Taiwan is reported to be creating an additional flowering season, extending from the Fall equinox through to the next spring equinox. This de-facto means that the plant is in continuous production. Cooler off-season crops actually have the capacity to make larger sweeter fruits because the plant can deposit more sugars in the fruit when their metabolism is not racing at full speed in the heat. Pitaya fruit can be grown from between 35 – 50 days with no excessive sweetness increase but up to 25% increase in weight. This may be a good way to get a high yield out of the second crop even if the plants get tired. Provided the plant nutrition can be adequately maintained, and the temperature kept within the plant’s comfort zone, continuous production is possible and feasible.

they mention the use being OK.  10 lumens seems like an easy deal, would also like to look into LED, but later as i already have the HPS. 

so my idea was to use rails.  this article mentions they need light 15 mins every hour between 10pm-2am (im sure the time frame varies).  using rails would move the light in a line back and forth slowly, and could be setup to hit 15/60 mins pretty easy.

Can anyone see a flaw in this?  i see it working, but want to make real sure as it takes some effort to setup outdoor things like this that can withstand typhoons.

[nullzero]

Very cool! I got to research this, I can see myself wheeling in dragon fruits around 6pm to get another 4-6 hours of light in the garage during the winter  .

[CoPlantNut]

My experience so far with dragon fruit and artificial light hasn't been good; neither 1000W MH nor high-power LED lights were sufficient to grow the plants well.  (Dragon fruit are the only plants I've encountered yet that seem to require real sunlight to be happy...)  Luckily you're not trying to grow them with artificial light, just trick them into thinking the nights are shorter.

As the article says, HPS bulbs don't provide a lot of light in the spectrum ideal for tricking plants into thinking they're getting long days; the most efficient would be to get LED lights in just the right spectrum, but I'm unaware of any LED light on the market designed purely for phytochrome triggering.  Any energy used to produce other wavelengths of light is wasted in your application as it won't really be strong enough to help the plants grow.

Keep in mind that HPS and MH bulbs don't like being turned on and off frequently; each re-start of the bulb ages it and it will fail much sooner if it is turned on and off frequently (and indeed they cannot be switched back on until they have cooled down sufficiently, which usually takes about 15 minutes).

I've used a Light Rail to move artificial lights over my plants for 15 years now and am very happy with them.  Besides (as you pointed out) weatherproofing it, you may also have a challenge to get the light to move enough distance back and forth on the rail while still getting power.   My setups have the lights moving at most 10 feet on the rail and I can simply festoon the power cords, but in a larger-scale application it may get tricky.

If you get something set up, I'd love to see pictures!

   Kevin

[bangkok]

I studied many variety's of dragonfruit and learned that some of them grow in the shade. Some in half-shade and some in full sun.

Maybe if you try another variety it will fruit under the lights?

[simon_grow]

Make sure you do more research before investing in the lights, HPS and Metal halide lights require a special ballast and the bulbs can explode if you get the oils from your hand on the bulb. If this is for outdoors, you would want to make sure the outlet you connect your light to can handle the light and is GFCI? They do make special HPSs bulbs that have more light in the wavelengths you want, check out Hortilux.

If you want low lumens over a wide area compact fluorescents may be the easiest way to go for maximum coverage although I'm not sure about the wavelength of the light. HID lights loose lumens very quickly as you increase the distance from the plant, much of the light will be wasted. The plants closest to the light will get lots of light and plants just several feet away will only get a fraction of the light. I believe it is called the inverse square law?

I have grown the Yellow Dragonfruit under T5 lights and it has grown extremely fast under this kind of lighting. My Yellow DF actually grew faster under T5 lighting than it did under the sun. 
Simon

[Kay]

My experience so far with dragon fruit and artificial light hasn't been good; neither 1000W MH nor high-power LED lights were sufficient to grow the plants well.  (Dragon fruit are the only plants I've encountered yet that seem to require real sunlight to be happy...)  Luckily you're not trying to grow them with artificial light, just trick them into thinking the nights are shorter.

locally lights are used a lot.  last couple years we have had dragon fruit around all year!  they are mostly using incandescent.  LED you can buy a specific wavelengths.  i already sourced diodes years ago, not tricky, but an expensive experiment!

As the article says, HPS bulbs don't provide a lot of light in the spectrum ideal for tricking plants into thinking they're getting long days; the most efficient would be to get LED lights in just the right spectrum, but I'm unaware of any LED light on the market designed purely for phytochrome triggering.  Any energy used to produce other wavelengths of light is wasted in your application as it won't really be strong enough to help the plants grow.

actually i think the article didnt mention HPS, but MH/HID.  HPS are on the red end.  i know lots of wasted wavelengths....but an incandescent puts out say 20 lumens/watt whilw hps puts out 120l/w AND will cover greater range. 

one thing i am wondering is if the other spectrums might initiate a vegetative response and slow flowering?  i think i need to re read and try some more sites.

Keep in mind that HPS and MH bulbs don't like being turned on and off frequently; each re-start of the bulb ages it and it will fail much sooner if it is turned on and off frequently (and indeed they cannot be switched back on until they have cooled down sufficiently, which usually takes about 15 minutes).

very good point, this is why i was thinking a rail, they wouldnt always be switched.  that seem right to you?  i feel i am missing something

I've used a Light Rail to move artificial lights over my plants for 15 years now and am very happy with them.  Besides (as you pointed out) weatherproofing it, you may also have a challenge to get the light to move enough distance back and forth on the rail while still getting power.   My setups have the lights moving at most 10 feet on the rail and I can simply festoon the power cords, but in a larger-scale application it may get tricky.

yes, i know now its going to have to be fabricated myself.  maybe i can search around more here.  Taiwan is a fantastic place to be to find machines and equipment.  the cord will be tricky as outdoor 220 thick wire is stiff.  will likely need a second line above and some sort of drape kind of thing...

Make sure you do more research before investing in the lights, HPS and Metal halide lights require a special ballast and the bulbs can explode if you get the oils from your hand on the bulb. If this is for outdoors, you would want to make sure the outlet you connect your light to can handle the light and is GFCI? They do make special HPSs bulbs that have more light in the wavelengths you want, check out Hortilux.

I have used them for years in greenhouses.  They are also cheap here, about $60 USD for 400w hps.  outdoor, enclosed unit ready to go.  wiring we are  doing ourselves as Taiwanese electrical standards are shocking.  everything will be very safe in that regard.  most places here dont even have a ground...anywhere...

If you want low lumens over a wide area compact fluorescents may be the easiest way to go for maximum coverage although I'm not sure about the wavelength of the light. HID lights loose lumens very quickly as you increase the distance from the plant, much of the light will be wasted. The plants closest to the light will get lots of light and plants just several feet away will only get a fraction of the light. I believe it is called the inverse square law?

CFL wont put out as much as tubes.  T5/8 can have 100l/w, CFL, here at least, max at 72l/w.  problem with fluorescent is the lumens dont travel far, they would need to be right above each plant, and the coverage would be poor i think.  but i will setup a couple dummy poles and measure them at night to see.  but for purchase costs 6 CFL = 1 HPS.  i think moving lights will also hit more branches and maybe provide more even fruitset?

I have grown the Yellow Dragonfruit under T5 lights and it has grown extremely fast under this kind of lighting. My Yellow DF actually grew faster under T5 lighting than it did under the sun. 

i like T5 too.  but i wonder if they were not etiolating.  because cactus stretch very much when in poor light, and given the growth style of vine cacti and the light intensity of fluorescents i cant see it being good on large poles of plants.



currently having trouble figuring out a track support as HPS  is about 5kg.

I wont be actually planting until October as we are currently building the house/ponds/greenhouses etc.