Plant breeding: how to create new varieties and improve their characteristics

Plant breeding: how to create new varieties and improve their characteristics

The article focuses on the fascinating topic of hemp plant breeding and its importance for the development of the hemp industry. We will introduce the basic principles of breeding, methods and goals that breeders pursue when creating new varieties. You will learn how breeders are improving the characteristics of cannabis and how breeding affects cannabinoid content, yield and disease resistance.

The genetic basis of cannabis and how to manipulate traits

Cannabis contains genetic material in the form of DNA, which determines various characteristics of the plant, including its cannabinoid content.

Manipulation of the properties of cannabis can be achieved by selecting suitable parental varieties with the desired genetic characteristics.

Modern techniques such as genetic analysis and manipulation allow breeders to better understand the genetic make-up of cannabis and to manipulate its traits in a targeted manner.

Objectives of hemp plant breeding

Increasing cannabinoid content: One of the main objectives of breeding is to increase the cannabinoid content of cannabis plants. This includes increasing the THC content, which may have medical and recreational uses, or increasing the CBD content, which has potential therapeutic effects.

Disease and pest resistance: Another important breeding objective is to create varieties that are resistant to various diseases and pests. This includes developing plants with natural immunity or resistance to fungal, bacterial or viral infections, as well as resistance to pests such as aphids or slugs.

Yield enhancement: Breeders seek to increase the yield of hemp, which is an important agricultural and industrial aspect. This includes higher production of flowers, seeds or biomass for food, industrial and pharmaceutical purposes.

Adaptability to different environments: Another objective of breeding is to create varieties that are able to adapt to different environments, climatic conditions and cultivation systems. These varieties should be able to thrive in different regions and offer stable yields.

Enhancing the eating experience: breeders are also focusing on improving the flavour, aroma and overall eating experience of cannabis. This includes different aromatic profiles, flavour characteristics and aesthetic elements.

Methods and practices of cannabis plant breeding

Cannabis plant breeding involves several methods and practices that allow breeders to develop new varieties with desired characteristics. The following methods are often used in cannabis plant breeding:

Crossbreeding

The crossbreeding method is an essential tool in cannabis plant breeding. Crossbreeding combines the genetic material of two different plants to produce offspring with new combinations of traits. This method allows breeders to develop new varieties of cannabis that exhibit the desired characteristics.

  • Parent plant selection: The first step in crossbreeding is to carefully select the parent plants. Breeders select plants with the desired characteristics such as yield, cannabinoid content, aroma, flowering time, resistance to pests and diseases, etc. A thorough knowledge of the genetic material and characteristics of each plant is essential for successful crossbreeding.

  • Pollination: Pollination is the process by which pollen from the anthers of the male plant is transferred to the stamens of the female plant. The pollen can be transferred directly from one plant to another, or a bagging technique can be used where the flower is covered with a plastic bag or other material to allow it to pollinate itself.

  • Seed development: After pollination, the seed begins to develop. The seeds are harvested when they reach maturity. It is important to record information about the parent plants and the cross itself so that you can monitor and analyse the results in subsequent generations.

  • Generational selection: Once the seeds have been harvested, it is necessary to select and test the offspring in the different generations. The aim is to see how certain traits are inherited and how they may change over time. Breeders select individuals with the desired traits and use them as parents for the next generation.

  • Stabilization and improvement of varieties: the aim is to achieve stable and similar characteristics in new varieties through crossbreeding and selection. Breeders continue the process of crossing and selection until they obtain a variety with the desired characteristics, such as yield, cannabinoid content, taste, aroma and others.

Selective breeding

This method is used repeatedly to select and grow plants with the desired characteristics, allowing the characteristics of the new variety to be gradually improved and stabilised.

  • Parent plant selection: The first step is to carefully select parent plants with the desired characteristics. This may include characteristics such as yield, cannabinoid content, flowering time, resistance to pests and diseases, aroma, taste, etc. It is important to have knowledge of the genetic material and characteristics of the parent plants.

  • Seedlings and testing: Seeds are harvested from the parent plants and sown. After germination, the seedlings are carefully observed and tested for their characteristics. This identifies potential individuals with the desired characteristics for further use in the selection.

  • Generational selection: After the seedlings have developed into full-grown plants, selection is made for those individuals that best suit the desired characteristics. The selected plants are used as parents for the next generation, thus passing on the desired characteristics to the new offspring.

  • Testing and evaluation: The selected individuals are thoroughly tested and evaluated on the basis of predetermined criteria. This may include testing for yield, cannabinoid content, aroma, taste, resistance to pests and diseases and other characteristics. The evaluation provides important information on the performance and stability of the variety.

  • Variety stabilisation: The aim of selective breeding is to achieve stable and stable characteristics in a new variety. Breeders continue repeated selection and breeding, aiming to maintain and improve the desired characteristics. Gradually, the variety is stabilised and developed so that each time it is grown again, it shows the desired characteristics.

Inbreeding

This method is based on the repeated crossing of closely related plants in order to stabilise and maintain certain characteristics of the variety.

  • Parent plant selection: plants with the desired characteristics such as yield, cannabinoid content, aroma, flavour, flowering time, etc. are selected for inbreeding. It is important to choose parent plants that have the most similar genetic material.

  • Crossing closely related plants: The selected parent plants are repeatedly crossed with each other. This is usually between siblings or between parents and offspring. This ensures that as much common genetic material as possible is passed on.

  • F1 generation: the offspring in the first generation, called F1 (first filial generation), are hybrids and have combined genetic material from both parent plants. At this stage, the traits and characteristics of the offspring are observed and evaluated.

  • Repeated crosses between selected individuals: Selected individuals from the F1 generation are further crossed with each other. The aim is to preserve closely related genetic material while increasing the homogeneity of the varieties.

  • F2 generation and stabilisation of varieties: The offspring of the second filial generation, called F2, are the result of repeated crosses between selected individuals. At this stage, individuals with the desired characteristics are evaluated and selected. Repeated crossing and selection gradually stabilises the variety and ensures that the desired characteristics are maintained in subsequent generations.

Genetic engineering

Genetic engineering, also called gene editing, is an advanced technique that has been used in recent years to breed cannabis plants. This method makes it possible to modify the genetic material of cannabis plants, allowing the rapid development of varieties with precisely tailored characteristics.

  • Identifying the target strain: The first step is to identify the specific strain to be modified. This may be a gene that is responsible for a particular trait, such as cannabinoid content, enzyme production or pest resistance.

  • Design and preparation of gene editing tools: Tools such as CRISPR-Cas9 are often used for gene editing, allowing precise targeting and editing of the genetic sequence. This tool is designed specifically for the gene and is being prepared for use.

  • Delivery of the gene editing tool into the plant: The gene editing tool is delivered into the plant, often through transformation, a process whereby the target gene is edited or new genetic material is inserted into the plant.

  • Editing and genome editing: Once the gene editing tool is delivered to the plant, the actual editing and genome editing is performed. The gene editing tool allows for targeted alteration of the genetic sequence, which may include turning off or activating specific genes, changing or inserting a specific DNA sequence, and other genetic modifications.

  • Analysis and selection of edited plants. Individuals with the desired genome modifications are selected and used for further cultivation and breeding.

Breeding success by different methods

Crossbreeding method

  • Blueberry: Blueberry is a popular cannabis variety bred by crossing Purple Thai and Afghani. It has a characteristic sweet and fruity aroma and distinctive blue-purple flowers. Blueberry is known for its calming effects and high THC content.

  • Northern Lights. This indica-dominant strain is known for its high potency, strong body effects and sweet-spicy aroma.

  • White Widow: White Widow is a hybrid cannabis strain created by crossing Brazilian and South Indian varieties. It has dense and resinous flowers with a high THC content. It is known for its stimulant and euphoric effects and has a delicate aroma and flavour.

  • Skunk #1: Skunk #1 is a classic cannabis strain bred by crossing Afghan, Colombian and Mexican varieties. It has a high yield and a distinctive aroma that combines notes of citrus, spice and skunk. Skunk #1 is known for its strong effects and pleasant taste.

  • Jack Herer: Jack Herer is a hybrid cannabis strain that was bred by crossing Haze, Northern Lights #5 and Shiva Skunk. It has a high THC content and strong sativa effects. It is prized for its uplifting and inspirational effects, citrus aroma and long-lasting flavour.

Selective breeding

  • Girl Scout Cookies: Girl Scout Cookies is a hybrid strain that combines Durban Poison and OG Kush. It has balanced effects, combining euphoria and relaxation, and stands out for its sweet and spicy aroma.

  • Wedding Cake: Wedding Cake is a hybrid variety that was bred by crossing Cherry Pie and Girl Scout Cookies. It is known for its strong and relaxing effect and has a sweet and fruity aroma with a hint of vanilla.

  • Gelato: This hybrid variety combines Sunset Sherbet and Thin Mint Girl Scout Cookies. Gelato is known for its strong and balanced effect and has a sweet and earthy aroma.

  • Sour Diesel: Sour Diesel is a well-known sativa dominant cannabis strain that has been selectively bred. This strain is the result of a combination of Chemdawg, Northern Lights and Skunk. Sour Diesel is prized for its energising and uplifting nature and has an intense, pungent aroma.

  • Blue Dream: This variety combines Blueberry and Haze. Blue Dream is known for its balanced effect that combines relaxing and invigorating effects. It has a sweet and fruity aroma.

Inbreeding

  • OG Kush.

  • Chemdawg: This variety is known for its strong and burning effect and stands out for its unique chemical aroma. Chemdawg has become the basis for many other popular varieties.

  • Afghani: This indica is native to Afghanistan and is known for its high resin production and relaxing effects. Afghani has a strong and spicy aroma.

  • Sensi Star: This strain combines different Afghani var ieties and is known for its high potency and strong body effects. Sensi Star has a distinctive sweet and spicy aroma.

  • Hindu Kush: This indica dominant variety is considered one of the purest and most original cannabis varieties. It has a strong sedative effect and an earthy aroma.

Here we have just presented a few examples of cannabis varieties that have been bred using different methods to produce unique combinations of properties and effects.

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