Tag Archives: leaf

plantsjacques

Optimizing Your LED Spectrum for Leaf Surface Temperature

By Andrew Myers
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plantsjacques

Every detail counts at an indoor grow facility. Indoor growers have complete control over nearly every aspect of their crop, ranging from light intensity to air circulation. Among the most important factors to regulate is temperature. While ambient air temperature is critical, growers will also want to measure leaf surface temperature (LST).

To illustrate, let’s say you keep your living room at a cozy 76 degrees. Then, if you place a thermometer under your tongue – your body is (hopefully) not at 76 degrees but is likely between a healthy temperature of 97 to 99 degrees.

A similar story can be told for cannabis plants grown indoors. A grow facility’s ambient air is often different than the plants’ LST. Finding an ideal LST for plant growth can be complex, but modern technology, including spectrally tunable LED grow lights, can simplify monitoring and maintaining this critical aspect.

Why Should Growers Care About LST?

Temperature plays a pivotal role in plant health. Many biochemical reactions contributing to growth and survival only occur within an ideal temperature range. If temperatures dip or spike dramatically, growers may witness inhibited growth, plant stress or irreversible damage to their crops.

The leaf is among the most important plant structures as it’s where most metabolic processes happen. Therefore, finding an optimum LST can improve growth rate and the production of metabolites such as pigments, terpenes, resins and vitamins.

Because many plants rely on their leaves for survival, it makes sense that leaves have their own temperature regulation system. Evaporation through pores in the leaf – known as stomata – can cool the plant through a process called transpiration. Up to 90% of water absorbed is used for transpiration, while 10% is used for growth.

The efficacy of transpiration is determined by the vapor pressure deficit (VPD), which refers to the relative humidity in the ambient air compared to the relative humidity in the leaf. If relative humidity is low, the VPD can be too high, which may cause plants to have withered, leathery leaves and stunted growth. On the other hand, a low VPD correlates to high relative humidity, and can quickly result in disease and mineral deficiencies. Higher humidity often results in a higher LST as transpiration may not be as effective.

When it comes to LST, growers should follow these basic guidelines:

  • Most cannabis plants’ LST should fall between 72 and 86 degrees – generally warmer than the ambient air.
  • LST varies depending on individual cultivar. For example, plants that have evolved in colder climates can generally tolerate cooler temperatures. The same can be said for those evolved in equatorial or temperate climates.
  • CO2 availability also plays a role in LST; CO2 generally raises the target temperature for photosynthesis.

How Does Light Spectrum Affect LST?

We know that CO2 concentration, specific genetic markers and ambient temperature all play an important role in moderating LST. But another important factor at an indoor grow is light spectrum – especially for those using spectrally tunable LEDs. Growers will want to optimize their light spectrum to provide their crop with ideal conditions.

A combination of red and blue wavelengths is shown to have the greatest impact on photosynthesis and, thus, LST. Photons found along the green and yellow wavelengths may not be absorbed as efficiently and instead create heat.

solsticegrowop_feb
Indoor cultivator facilities often use high powered lights that can give off heat

Optimized light spectrums – those with an appropriate balance between red and blue light – create more chemical energy instead of heat, thereby resulting in a lower LST. Using fixtures that are not spectrally tuned for plant growth, on the other hand, can waste energy and ultimately contribute to a higher LST and ambient temperature, negatively affecting plant growth. Consequently, measuring LST doesn’t only indicate ideal growing conditions but also indirectly illustrates the efficiency of your grow lights.

LED fixtures already run at a lower temperature than other lighting technologies, so indoor growers may need to raise the ambient temperature at their grow facilities to maintain ideal LST. Switching to spectrally tuned LEDs may help growers cut down on cooling and dehumidifying costs, while simultaneously improving crop health and productivity.

What’s the Best Way to Measure LST?

There are several tools available for growers to measure LST, ranging from advanced probes to specialty cameras. However, many of these tools provide a reading at a specific point, rather than the whole leaf, leading to some inaccuracies. Temperature can dramatically vary across the leaf, depending if parts are fully exposed to the light or in the shadows.

Investing in a forward-looking infrared camera (FLIR) gives indoor growers a more accurate picture of LST and light efficiency. That being said, growers should not only measure leaves at the top of the plant, but across the middle and bottom of the plant as well. That way, growers receive a complete snapshot of growing conditions and can make changes as needed.

At an indoor grow facility, it’s not enough to only measure ambient room temperature. Of course, this aspect is important, but it will paint an incomplete picture of plant health. Measuring LST gives growers nuanced insights as to how plants respond to their environment and how they can better encourage resilient, healthy growth.

Using spectrally tunable LEDs makes achieving LST easier and more cost-effective. Lights with optimized spectrums for plant growth ensure no energy is wasted – resulting in superior performance and efficiency.

dry cannabis plants

How to Grow Cannabis Plants for Concentrate Production

By Andrew Myers
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dry cannabis plants

While flower is still the most popular way to consume cannabis, the concentrates market is booming. Some predict concentrates will be nearly as popular as flower by 2022, with an estimated $8.5 billion in retail sales. That’s a lot of concentrates and, chances are, cannabis producers are already feeling the pressure to keep up.

Concentrates refer to products made from processing cannabis – often resulting in much higher THC or CBD percentages. The category includes oils, wax, dabs, shatter, live resin and hash. Consumers are increasingly drawn to these cannabis products for their near-immediate and intense effects. They’re often consumed through vaporization, dabbing or sublingual absorption and are sometimes favored by those who want to avoid smoking. Cannabis growers who have traditionally focused on flower yields may decide to prioritize quality and potency levels in order to tap into these changing consumer tastes.

What Growers Should Focus on to Produce High Quality Concentrates
We’ll let you in on a little secret: making good concentrates starts with good flower. If you’re starting with low-quality flower, it’s impossible to create a high-quality concentrate. Whatever qualities inherent to the flower you’re starting with will be amplified post-processing. So, really, the concentrate-making process starts at the seedling level, requiring the right care and attention to coax out the results you’re looking for.

Tetrahydrocannabinol (THC), just one of hundreds of cannabinoids found in cannabis.

But what makes good flower? While this can be a subjective question, those producing concentrates generally look for flowers with big, abundant trichomes. Trichomes are the small, dewy structures found across the cannabis plant on buds, leaves and even the stem. They’re responsible for producing the plant’s cannabinoids and terpenes – the chemical compounds that give a strain its unique benefits, aroma and taste. Evolutionarily, trichomes attract pollinators, deter hungry herbivores and provide some defense against wind, cold and UV radiation.

Generally, trichomes indicate how potent the flower is. Plus, what we’re most often looking for when making concentrates is higher cannabinoid and terpene profiles, while also ensuring absolute safety.

What measures can growers take to produce crops that are ideal for concentrate production? Start with the following:

Avoiding Contaminants
Just like you would wash your fruits and vegetables before consumption, consumers want to be sure there’s no dangerous residuals in the concentrate they are ingesting. Growers can avoid any post-process residuals by taking a few key steps, including:

  • Photo: Michelle Tribe, Flickr

    Cutting out the pesticides. Any pesticides that are on your flowers before they go through processing will show up in your concentrates, often even more – you guessed it – concentrated. This is a serious health concern for consumers who might be sensitive to certain chemicals or have compromised immune systems. It’s dangerous to healthy consumers, too. Rather than spraying hazardous chemicals, growers could consider integrated pest management techniques, such as releasing predatory insects.

  • Limiting foliar spraying. Some growers will use foliar spraying to address nutrient deficiency or pest-related issues through delivering nutrients straight to the leaves. However, this can also result in contaminated concentrates. If you really need to spray, do it during the vegetative stage or investigate organic options.
  • Taking the time to flush the crop. This is a critical step in reducing potential contaminants in your concentrate, especially if you’re using a non-organic nutrient solution or fertilizer. Flushing simply means only giving your plants water during the final two weeks of flowering before harvest, resulting in a cleaner, non-contaminated flower and therefore a cleaner concentrate.

Perfecting the Indoor Environment
When cultivating cannabis indoors, growers are given ultimate control over their crop. They control how much light the plants receive, the lighting schedule, temperature and humidity levels. Creating the ideal environment for your cannabis crop is the number one way to ensure healthy plants and quality concentrates. There are many factors to consider when maintaining an indoor grow:

  • Temperature regulation. Trichomes are sensitive to temperature changes and start to degrade if they’re too hot or too cold. To maintain the best trichome structure, you’ll want to maintain an ideal temperature – for most strains, this falls between an idyllic 68 and 77 degrees.
  • Adequate light. For plants to perform photosynthesis indoors, they’ll need an appropriate light source – preferably one that is full-spectrum. Full-spectrum LEDs are able to closely replicate the sun and provide ample, uniform light to your crop. Another selling point for LEDs is their low heat output, making it much easier for growers to regulate ambient heat.

    dry cannabis plants
    Rows of cannabis plants drying and curing following harvest
  • CO2. Another necessary ingredient for photosynthesis is CO2. Providing your indoor crops with CO2 can boost plant size and yields and, therefore, provides more surface area for trichomes to develop and thrive.
  • Cold snap prior to harvest. Some growers rely on this age-old tactic for one last push before harvest – lowering their temperature for a few days right at the end of the flower cycle. They believe this puts the plants into a defense mode and will produce more trichomes in order to protect themselves.

Following Best Practices Post-Harvest
You made it to harvest – you’re almost done!

When harvesting and storing your plants, handle them with care to reduce damage to trichomes. If you’re planning on immediately making concentrates, you can move forward to the drying and curing process. If you’re going to wait a few weeks before processing, freeze your plants. This will preserve the cannabinoid and terpene profiles at their peak.

As the cannabis industry continues to expand, more consumers are likely to reach for concentrates at their local dispensaries. It makes sense that businesses want to diversify their offerings to satisfy customers looking for the most effective way to consume cannabis. As with any cannabis-derived product, producers will want to prioritize quality and safety – especially in the concentrate market.

Soapbox

Increase Density in your Canopy

By Carl Silverberg
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One goal all growers seem to agree on is the need to increase density in their houses. How that gets done, well, there are a variety of ways and here’s one way a grower chose to do it:

With 45,000 square feet of greenhouse space, Nathan Fumia, a cannabis grower and consultant for a commercial operation in California, wasn’t pleased with what he was seeing. “If I put my hand inside the canopy and I can see sunlight on it, I’m losing money,” was how he described the situation. Unfortunately, the operators and staff of the greenhouse disagreed. They thought increasing density would rob the leaves of needed light.

He chose to test his theory by increasing the number of plants on one of his benches from 140 to 150 plants. To ensure the validity of the research, Nathan grew the same strain on Bench 1 as Bench 2, and to make sure all the metrics were equal, he even processed the crops separately. After weighing, Bench 2 (his research bench) showed an 8% higher yield than Bench 1.

“The post-harvest data from the weight, yield confirmed my decision to maximize density by increasing the total number of plants per bench,” says Fumia. “Whenever I saw red on the canopy heat map from LUNA, I knew there was room for improvement and I knew that I wasn’t making the money that I should have from those areas.”

His next challenge was where to place the extra ten plants? Did it make a difference or could he just shove 150 plants in a space that was originally planned for 140? Again, his greenhouse system was able to pinpoint the best sub-sections on the benches and Nathan was able to see exactly which plants were growing the fastest. That also gave him the ability to understand why certain quadrants of the bench were doing better than others.

“We were able to determine which quadrant on which bench was already at 100% density, and determine which quadrant wasn’t. Without that data, it would have been pure guesswork.”

He dialed down even further to find out which cultivars grew the best on a particular bench in the greenhouse. “Some cannabis cultivars need more light, some need less, some need warmer climates, and some need cooler climates,” Fumia noted. “Additionally, in order to increase the density of flowering points/buds, we began focusing on better pruning techniques in the vegetative phase, directly increasing branches for flowering.”

With optimization even more important now than it was 12-18 months ago, Nathan summed up the impact on his bottom line. “With a crop cycle averaging just over six a year, at that time we were averaging $600-$800 a pound depending on the strain. Some were even more. Ten extra plants per bench per cycle was a nice bounce for us.”

Obviously, this isn’t the only way to increase density. What’s your suggestion? Share your ideas with the rest of us by posting your comments below.

Dr. Ed Askew
From The Lab

Quality Plans for Lab Services: Managing Risks as a Grower, Processor or Dispensary, Part 4

By Dr. Edward F. Askew
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Dr. Ed Askew

In the last three articles, I discussed the laboratory’s responses or defenses used to reply to your questions about laboratory results that place stress on the success of your business. The Quality Control (QC) results can cause this stress if they are not run correctly to answer the following questions:

  1. Are the laboratory results really true?
  2. Can the laboratory accurately analyze sample products like my sample?
  3. Can the laboratory reproduce the sample results for my type of sample?

Now let’s discuss the most important QC test that will protect your crop and business. That QC sample is the Matrix Sample. In the last article in this series, you were introduced to many QC samples. The Matrix Sample and Duplicate were some of them. Take a look back at Part 3 to familiarize yourself with the definitions.

The key factors of these QC sample types are:

  1. Your sample is used to determine if the analysis used by the laboratory can extract the analyte that is being reported back to you. This is performed by the following steps:
    1. Your sample is analyzed by the laboratory as received.
    2. Then a sub-sample of your sample is spiked with a known concentration of the analyte you are looking for (e.g. pesticides, bacteria, organic chemicals, etc.).
    3. The difference between the sample with and without a spike indicates whether the laboratory can even find the analyte of concern and whether the percent recovery is acceptable.
    4. Examples of failures are from my experiences:
      1. Laboratory 1 spiked a known amount of a pesticide into a wastewater matrix. (e.g. Silver into final treatment process water). The laboratory failed to recover any of the spiked silver. Therefore the laboratory results for these types of sample were not reporting any silver, but silver may be present. This is where laboratory results would be false negatives and the laboratory method may not work on the matrix (your sample) correctly. .
      2. Laboratory 2 ran an analysis for a toxic compound (e.g. Cyanide in final waste treatment discharge). A known amount of cyanide was spiked into a matrix sample and 4 times the actual concentration of that cyanide spike was recovered. This is where laboratory results would be called false positives and the laboratory method may not work on the matrix (your sample) correctly.
  2. Can the laboratory reproduce the results they reported to you?
    1. The laboratory needs to repeat the matrix spike analysis to provide duplicate results. Then a comparison of the results from the first matrix spike with its duplicate results will show if the laboratory can duplicate their test on your sample.
      1. If the original matrix spike result and the duplicate show good agreement (e.g. 20% relative percent difference or lower). Then you can be relatively sure that the result you obtained from the laboratory is true.
      2. But, if the original matrix spike result and the duplicate do not show good agreement (e.g. greater than 20% relative percent difference). Then you can be sure that the result you obtained from the laboratory is not true and you should question the laboratory’s competence.

Now, the question is why a laboratory would not perform these matrix spike and duplicate QC samples? Well, the following may apply:

  1. These matrix samples take too much time.
  2. These matrix samples add a cost that the laboratory cannot recover.
  3. These matrix samples are too difficult for the laboratory staff to perform.
  4. Most importantly: Matrix samples show the laboratory cannot perform the analyses correctly on the matrix.

So, what types of cannabis matrices are out there? Some examples include bud, leaf, oils, extracts and edibles. Those are some of the matrices and each one has their own testing requirements. So, what should you require from your laboratory?

  1. The laboratory must use your sample for both a matrix spike and a duplicate QC sample.
  2. The percent recovery of both the matrix spike and the duplicate will be between 80% and 120%. If either of the QC samples fail, then you should be notified immediately and the samples reanalyzed.
  3. If the relative percent difference between the matrix spike and the duplicate will be 20% or less. If the QC samples fail, then you should be notified immediately and the samples should be reanalyzed.

The impact of questionable laboratory results on your business with failing or absent matrix spike and the duplicate QC samples can be prevented. It is paramount that you hold the laboratory responsible to produce results that are representative of your sample matrix and that are true.

The next article will focus on how your business will develop a quality plan for your laboratory service provider with a specific focus on the California Code Of Regulations, Title 16, Division 42. Bureau Of Cannabis Control requirements.

Applications for Tissue Culture in Cannabis Growing: Part 1

By Aaron G. Biros
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Dr. Hope Jones, chief scientific officer of C4 Laboratories, believes there are a number of opportunities for cannabis growers to scale their cultivation up with micropropagation. In her presentation at the CannaGrow conference recently, Dr. Jones discussed the applications and advantages of tissue culture techniques in cannabis growing.

Dr. Hope Jones, chief scientific officer at C4 Labs

Dr. Jones’ work in large-scale plant production led her to the University of Arizona Controlled Environment Agriculture Center (CEAC) where she worked to propagate a particularly difficult plant to grow- a native orchid species- using tissue culture techniques. With that experience in tissue culture, hydroponics and controlled environments, she took a position at the Kennedy Space Center working for NASA where she developed technologies and protocols to grow crops for space missions. “I started with strawberry TC [tissue culture], because of the shelf life & weight compared with potted plants, plus you can’t really ‘water’ plants in space- at least not in the traditional way,” says Dr. Jones. “Strawberries pack a lot of antioxidants. Foods high in antioxidants, I argued, could boost internal protection of astronauts from high levels of cosmic radiation that they are exposed to in space.” That research led to a focus on cancer biology and a Ph.D. in molecular & cellular biology and plant sciences, culminating in her introduction to the cannabis industry and now with C4 Labs in Arizona.

Working with tissue culture since 2003, Dr. Jones is familiar with this technology that is fairly new to cannabis, but has been around for decades now and is widely used in the horticulture industry today. For example, Phytelligence is an agricultural biotechnology company using genetic analysis and tissue culture to help food crop growers increase speed to harvest, screen for diseases, store genetic material and secure intellectual property. “Big horticulture does this very well,” says Dr. Jones. “There are many companies generating millions of clones per year.” The Department of Plant Sciences Pomology Program at the Davis campus of the University of California uses tissue culture with the Foundation Plant Services (FPS) to eliminate viruses and pathogens, while breeding unique cultivars of strawberries.

A large tissue culture facility run in the Sacramento area that produces millions of nut and fruit trees clones a year.

First, let’s define some terms. Tissue culture is a propagation tool where the cultivator would grow tissue or cells outside of the plant itself, commonly referred to as micropropagation. “Micropropagation produces new plants via the cloning of plant tissue samples on a very small scale, and I mean very small,” says Dr. Jones. “While the tissue used in micropropagation is small, the scale of production can be huge.” Micropropagation allows a cultivator to grow a clone from just a leaf, bud, root segment or even just a few cells collected from a mother plant, according to Dr. Jones.

The science behind growing plants from just a few cells relies on a characteristic of plant cells called totipotency. “Totipotency refers to a cell’s ability to divide and differentiate, eventually regenerating a whole new organism,” says Dr. Jones. “Plant cells are unique in that fully differentiated, specialized cells can be induced to dedifferentiate, reverting back to a ‘stem cell’-like state, capable of developing into any cell type.”

Cannabis growers already utilize the properties of totipotency in cloning, according to Dr. Jones. “When cloning from a mother plant, stem cuttings are taken from the mother, dipped into rooting hormone and two to five days later healthy roots show up,” says Dr. Jones. “That stem tissue dedifferentiates and specializes into new root cells. In this case, we humans helped the process of totipotency and dedifferentiation along using a rooting hormone to ‘steer’ the type of growth needed.” Dr. Jones is helping cannabis growers use tissue culture as a new way to generate clones, instead of or in addition to using mother plants.

With cannabis micropropagation, the same principles still apply, just on a much smaller scale and with greater precision. “In this case, very small tissue samples (called explants) are sterilized and placed into specialized media vessels containing food, nutrients, and hormones,” says Dr. Jones. “Just like with cuttings, the hormones in the TC media induce specific types of growth over time, helping to steer explant growth to form all the organs necessary to regenerate a whole new plant.”

Having existed for decades, but still so new to cannabis, tissue culture is an effective propagation tool for advanced breeders or growers looking to scale up. In the next part of this series, we will discuss some of issues with mother plants and advantages of tissue culture to consider. In Part 2 we will delve into topics like sterility, genetic reboot, viral infection and pathogen protection.