Cornell Hemp Webinar Feb. 8: Propagation with Mark Bridgen

Hemp (Cannabis sativa L.) is a commercially valuable plant that is primarily cultivated for its desirable secondary metabolites. Hemp plants can be propagated by both sexual and asexual means. This seminar will cover the various aspects that are important to propagating hemp by seed, vegetative cuttings, and micropropagation. Cannabis plants are dioecious, meaning that pistillate and staminate (female and male) reproductive organs occur on different plants. This reproductive feature results in genetic recombination at each generation, and greater phenotypic diversity when compared to self-pollinating plant species. Dioecy complicates commercial seed propagation of cannabis because the pistillate plants are desirable for cannabinoid production. Growing hemp directly from seed can be undesirable for production because genetic recombination results in segregation of traits, possibly reducing plant uniformity. When seed propagation is desirable, it is not usually difficult. Clonal propagation, also called vegetative propagation, is necessary for maintaining genetically identical plant material. This type of propagation is important if the objective is to grow only female hemp plants. The process of asexual propagation ensures an all-female, genetically uniform crop. Clones can be vegetatively produced by stem cutting propagation or micropropagation (tissue culture). These types of propagation enable the production of crops that are consistent for all of their valuable traits, including cannabinoid and terpene synthesis. The propagation environment is very important when multiplying hemp plants. This presentation will review the environmental factors that are important to hemp propagation such as growing temperatures, media, humidity effects, rooting hormones, proper sanitation, healthy mother plants, IPM, and more. A big part of the propagation discussion will cover our laboratory’s recent discoveries for the rapid micropropagation of hemp. This technique is a little more complicated than traditional vegetative propagation, but tissue culture allows a large number of pathogen-free clones to be produced in a small area under controlled environmental conditions.