Cornell University Breaks Ground on Hemp Research

Departments - Smart Start—Research Roundup

A look at pioneering researchers and their recent findings.

January 21, 2020

George Stack, a first-year doctoral candidate at Cornell, speaks to attendees at the university’s 2019 Hemp Field Day.
© Headshots courtesy of respective subjects

Since the U.S. legalized hemp cultivation in 2018, Cornell University has been working to establish itself as a hub for industrial hemp research. The school is working with the U.S. Department of Agriculture (USDA) to re-establish the nation’s sole industrial hemp seed bank. And as New York state’s land-grant university, the school now has a team researching key areas of hemp cultivation, including determining the best new and existing varieties to grow in the state and cultivation barriers.

Here’s a look at what some of the university’s researchers are currently working on.

Who: Lawrence B. Smart, Ph.D., professor in the School of Integrative Plant Science and Hemp Research Team project lead. (He is also a member of the Hemp Grower Editorial Advisory Board.)

Areas of focus: Leading cultivar trials located on Cornell farm properties, overseeing the hemp seed bank collection and directing hemp breeding and genomics efforts.


Currently working on: Testing how environmental stresses affect cannabinoid levels. His experiment involved testing how three different cultivars in replicated plots reacted to different types of stressors, which were: wounding the plants with a weed whacker;  applying ethylene, a stress hormone; spraying them with a diluted solution of glyphosate, the active ingredient in Roundup herbicides; inoculating them with powdery mildew; and flooding them.

One plot served as a control with no stressors. Smart collected shoot tip samples prior to applying the stressors and then once a week for three weeks thereafter.

Results: Coming early 2020


Who: Jacob Toth, a second-year doctoral candidate of plant breeding in Smart’s lab.

Areas of focus: Molecular genetics and developing new tools that make hemp breeding and production easier.


Currently working on: Developing molecular markers to isolate fragments of DNA and determine which traits they represent in the plant. Toth is now focused on photoperiod-insensitive cannabis plants, which can flower at any time of the year regardless of day length. “We’re kind of in a strange space where some of the best knowledge is on marijuana blogs, and according to the marijuana blogs, a photoperiod insensitivity is a recessive trait, so some plants might carry the gene but not express the trait,” Toth says. “If we could know what plants are carrying the gene by looking at the genetics as opposed to [just looking at] the plant, it could very effectively assist breeding.”

Results: Developed tools to differentiate males from females and has discovered that many existing hemp cultivars, whether for cannabidiol (CBD) production or otherwise, contain genes for high tetrahydrocannabinol (THC) production. “Using this … marker on our grain and fiber trial cultivars, we see some cultivars have a surprisingly high level of these genes as well, so this would lead to these particular cultivars testing hot, above the 0.3% THC level,” Toth says.



Who: Craig Carlson, Ph.D., a postdoctoral scientist researching in Smart’s lab.

Areas of focus: Deploying new or existing breeding and genomics strategies to improve: yield; pest and disease resistance; cannabinoid content; and quality traits for grain, fiber and CBD hemp populations.

Currently working on: Carlson has several experiments in the works, including:

  • sex determination and sex ratio modification of hemp populations to increase yields.
  • genotyping and sequencing of hemp cultivars for use in breeding and phylogenomics.
  • production of inbred lines to understand combining abilities for hybrid cultivar development.
  • developing a new genotyping system for hemp that would be available to the public.

Results: Developed over 100 unique crosses between cultivars for breeding, selection and genetic mapping


Who: George Stack, a first-year doctoral candidate of plant breeding in Smart’s lab.

Area of focus: Studying how hemp interacts with biotic factors in the environment, including pathogens, insect pests and other microbes.

Currently working on: Researching which cultivars grow best at five different sites in New York. Stack’s five months of data collection, which concluded in early October 2019, consisted of taking regular samples of 30 different cultivars used for CBD production, along with 37 others for grain and fiber production. The experiment resulted in over 2,000 samples. “Now we can look at how the cannabinoids accumulate in each of the varieties and if the ratios [of CBD to THC] change over time,” Stack says. “Once we get the whole data set together, then we can compare these varieties both to each other and across sites and make recommendations for farmers on what is well-adapted to grow in New York conditions. It will also inform our breeding program on what varieties are good to move forward with to try and develop better varieties.”

Results: Coming early 2020


Conclusions: “Based on all of these guys’ work, we’ve come to what I think is a pretty firm conclusion about the ratio of CBD to THC,” Smart says. “We’ve analyzed cannabinoids from a lot of different samples, and that average ratio falls around 22:1, which is critical now, considering the USDA guidelines pretty strictly limit production to 0.3% total potential THC. In order to stick to that threshold, growers will not be able to produce much more than 6% to 7% CBD.”

Coming soon: Cornell has more research in the works, including mapping genes that determine resistance to different pathogens; testing if any cultivars are optimized for cannabigerol (CBG) production; and collecting and characterizing feral hemp nationwide for the seed bank.

Theresa Bennett is associate editor of Hemp Grower and sister magazine Cannabis Business Times.