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Cloning Wars

(An abridged version is found in the February 2011 issue of Maximum Yield.)

Dense Matrix LED technology battles its way into the lucrative world of cloning

There's no question what Dense Matrix LED technology is capable of. With its growing presence in the indoor gardening industry, LEDs boast energy efficiency, long lifetimes, and more importantly, they can produce specific spectrums optimized for plant growth. After years of research, scientists have discovered various wavelength combinations for vegetative growth in addition to ideal wavelength blends for fruiting and flowering. Indoor growers everywhere are benefiting from the ability of LEDs to emit specific spectrums.

The deep light penetration that's only possible with Dense Matrix LED technology allows LED lights to be used as a standalone source and replace traditional, wasteful broadband lights. These LED units are also great as boosters to supplement missing spectrums in existing grow light systems. The flexibility of mixing and matching different spectrums is empowering growers to do more with their indoor gardens, such as plant steering and improving production.

The efficiency of Dense Matrix LEDs also comes from the consistency of its light output, especially in comparison to broadband sources. Fluorescent, metal halide, and high pressure sodium lamps all have variable burn in times, in which there is a period before they reach their optimal light output. In addition, metal halide and high pressure sodium sources need to warm up each time they turn on and also require a 15-minute cool down period before they can be restarted. This is not a problem for LEDs, giving growers assurance that their plants are constantly receiving the light output that is expected.

We've seen the power of LEDs in vegetating, flowering, and fruiting applications, but what about for seeding, rooting, and cloning? With its low heat emission that is ideal for sensitive seedlings or cuttings, LEDs are perfect for these applications. Let's see how Dense Matrix LED technology fares in the sphere of cloning.

Cloning and Light

While the ideal wavelengths for cloning Husky Cherry tomato cuttings is still undergoing vigorous investigation, our current experiments show that Dense Matrix LED technology is a viable, more energy-efficient and consistent alternative to fluorescent lighting. From the experiments, we also saw that LEDs produce healthy foliar vegetation, preparing the tomatoes to move to soil or soil-less media. A compact form factor and long lifetimes give even more incentive to use Dense Matrix LED lights.

Although it seems that intensity and specific wavelength combinations may not be as important for cloning as it is for other phases of growth, the results from Experiment 2 have prompted us to probe deeper into wavelength formulas. With the flexibility to pick and choose spectrums with LEDs, we are continuing our studies on the effect of various wavelengths on different facets of rooting.

As we do more research and technology continues to advance, growers can only benefit from the findings and innovations that arise. With its spectrum specific, penetrating light combined with low heat emission and vast energy-savings, Dense Matrix LED technology will continue to push the boundaries of how light is used for indoor growing.

Experiment #1: Comparison Testing

For our experiments, we departed from a traditional approach to cloning and used cloning units designed to make cloning more accessible to the consumer. We chose to take softwood cuttings from tomatoes to see the propagation of herbaceous plant material more clearly and for their responsiveness to different spectrums of light.

The typical timeline for cloning tomatoes using fluorescents over cloning units lasts about a week and a half to two weeks. Cuttings should begin forming calluses and start to root by the second or third day. From days five to seven, root branching should be evident. By the tenth to fourteenth day, cuttings should be able to be transplanted.

We successfully followed this schedule using Dense Matrix LED technology and at the same time, test the effect of different spectrums. For each of our experiments, a 30-site cloning unit was set up. Using green cuttings of Husky Cherry Red tomatoes, both terminal and middle cuttings, two nodes were left above the media and the rest exposed to the mist for most cases. Based on recommendations from industry experts, trials were run under multiple wavelengths: green, red, and purple at different intensities to evaluate the LED treatment that would best promote rooting. We also set aside a unit to run in the dark for comparison as a control group.

At the end of this experiment, we saw that light was necessary for rooting in propagated green tomato cuttings. In the cuttings subjected to darkness, there was not only a lack of rooting, but also severe foliar degeneration. However, high intensities of light did not appear to be necessary for root production.

The results for the different intensities of purple light were comparable, and in all proceeding tests, one Dense Matrix LED unit was implemented over each cloning unit and found to be sufficient, intensity-wise.

The red LED treatment from the primary trials demonstrated the best rooting. There seems to be little advantage in continuing tests with green LED light due to its lack of root promotion. (Please note: trials were conducted using green as the only source of light. While it is not a good treatment for promoting rooting when used exclusively there remains the possibility that green in conjunction with other wavelengths of light is beneficial for root production.)

Although red outperformed purple as a rooting light treatment, our observations under purple were sufficient for it to be included in the next experiment. Rooting results were also similar to tests run under fluorescent lighting; however, extremely healthy foliage vegetation and a dark green color on leaves denoting dense chlorophyll production is specific to our LED treatment.

Experiment #2: Blue, Red, and Purple Spectrums

For the next set of experiments, we included blue in addition to red and purple, as blue is known to be conducive to vegetative growth in early stages. To provide uniformity of environmental conditions, three cloning units were assembled in the same grow cube but with separate Dense Matrix LED treatments over each unit at uniform heights.

For the next set of experiments, we included blue in addition to red and purple, as blue is known to be conducive to vegetative growth in early stages. To provide uniformity of environmental conditions, three cloning units were assembled in the same grow cube but with separate Dense Matrix LED treatments over each unit at uniform heights.

We ran the test a second time and rearranged the placement of the lights to maintain accuracy of results. Red was placed over the same unit that received the blue treatment in the first trial. In this second run, red provided better results for promoting rooting as well as more root branching. However, when the first blue treatment was compared to the second red treatment, the blue demonstrated greater mass overall in addition to promoting longer root lengths.

We are currently running more tests to eliminate unit bias. Promising results from both the red and especially the blue treatments prove that Dense Matrix LED light works just as well as fluorescents for cloning and suggests that the effectiveness of wavelengths vary on different aspects of rooting (red for branching, blue for length).

Conclusion

While the ideal wavelengths for cloning Husky Cherry tomato cuttings is still undergoing vigorous investigation, our current experiments show that Dense Matrix LED technology is a viable, more energy-efficient and consistent alternative to fluorescent lighting. From the experiments, we also saw that LEDs produce healthy foliar vegetation, preparing the tomatoes to move to soil or soil-less media. A compact form factor and long lifetimes give even more incentive to use Dense Matrix LED lights.

Although it seems that intensity and specific wavelength combinations may not be as important for cloning as it is for other phases of growth, the results from Experiment 2 have prompted us to probe deeper into wavelength formulas. With the flexibility to pick and choose spectrums with LEDs, we are continuing our studies on the effect of various wavelengths on different facets of rooting.

As we do more research and technology continues to advance, growers can only benefit from the findings and innovations that arise. With its spectrum specific, penetrating light combined with low heat emission and vast energy-savings, Dense Matrix LED technology will continue to push the boundaries of how light is used for indoor growing.