KIRIN Develops Technology to Enhance Heat and Drought Tolerance in Hop Seedlings Contributing to a Sustainable Supply of Beer Ingredients Amid Climate Change

Kirin Holdings Company, Limited (Kirin) (TOKYO: 2503) has developed a seedling cultivation technology that enhances heat and drought tolerance in hops through acquired tolerance, helping to address the growing challenges of reduced yield and quality caused by extreme heat and drought. This method enables hops to gain resilience without compromising flavor quality, and is expected to contribute to a more sustainable and stable supply of beer ingredients. This technology was presented at the Scientific-Technical Commission of the International Hop Growers' Convention in June 2025.

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Field trial in Iwate Prefecture. Variety: Saaz. Left: untreated control plants; Right: heat-treated plants.

Background of the Research

• Global warming is known to act as heat stress on plants, inhibiting their growth^*1. Hops, which prefer cool climates, suffer from poor growth under high temperatures and dry conditions, leading to declining yields and quality worldwide. This raises concerns about rising raw material costs and impacts on product quality, necessitating the development of technologies enabling stable cultivation and procurement even under climate change.

^*1 In plants, temperatures higher than their optimal growth range cause heat stress. This can lead to delayed growth and symptoms such as leaf whitening.

Research Overview

• Leveraging Kirin’s long-standing expertise in plant cultivation technologies^*2 , we have developed a seedling production technique to induce heat tolerance and drought tolerance in hop seedlings. This is achieved by growing the seedlings in a liquid medium and applying a six-week heat treatment at 25°C during the mass propagation process. Unlike traditional breeding or genetic modification, this technique allows hops to acquire resilience without altering their original aroma or flavor profile. This research was evaluated using the Czech variety “Saaz” and the German variety “Hersbrucker.”

^*2 Kirin Succeeds in Developing the World’s First Technology to Promote Axillary Bud Formation in Hops—A Breakthrough in Mass Propagation of Hop Plants (Website in Japanese)

Research Findings

Laboratory evaluation of high-temperature and dry environments

• In laboratory tests simulating high-temperature and drought-conditions^*3, heat-treated hop plants exhibited significantly higher plant height and chlorophyll^*4 content compared to untreated control plants, demonstrating improved growth and enhanced tolerance.

*3 Drought condition testing was conducted using the “Saaz” variety only.
*4 Chlorophyll is a natural green pigment essential for photosynthesis. As leaves wither, they turn white or yellow due to reduced chlorophyll levels.

Cultivation evaluation at the test field

• In cultivation evaluations conducted in Esashi City, Iwate Prefecture, heat-treated hop plants showed significantly higher plant height and above-ground weight compared to untreated control plants, and tended to produce higher cone yields.

Future Outlook

• Moving forward, we will advance the refinement of mass seedling production technology, elucidate physiological changes induced by heat treatment, and verify applicability across multiple fields and varieties, while exploring implementation overseas. Our company aims to contribute to the realization of a sustainable beer ingredient supply.

The Kirin Group will continue to tackle complex and interrelated environmental issues (biological resources, water resources, containers and packaging, and climate change) in an integrated manner, and to work together with all those involved in the value chain to link our desire to enjoy and pass on the bounty of the Earth’s abundance to future generations. We will actively promote various initiatives that have a ‘positive impact’ on nature and people.

Reference: Kirin’s Environmental Initiatives

Kirin Group's Environmental Vision 2050 | The Environment | KIRIN - Kirin Holdings Company, Limited
Kirin Group Environmental Report | Sustainability Information | KIRIN - Kirin Holdings Company, Limited

Attachment: "Research Findings"

Background and Objective

• Hops are a dioecious vine plant belonging to the Cannabaceae family. The female flowers, known as strobili, contain diverse secondary metabolites that impart bitterness, aroma, and antimicrobial properties to beer, making them an essential ingredient in brewing. Hops are plants that prefer cool climates and are primarily cultivated in regions between 35° and 55° north and south latitude, such as Europe, North America, and Australia. In response to recent declines in hop yield and quality due to rising temperatures and drought, accelerating Research and Development on climate change adaptation—including breeding improvements and cultivation techniques—to achieve sustainable raw material procurement has become an urgent priority.

Research Methodology

• Methods for conferring stress tolerance to plants include breeding, genetic modification, the use of biostimulants, and environmental condition control. This study selected environmental condition control, as it is expected to have minimal impact on flavor. Specifically, we developed a technique to confer acquired heat and drought tolerance by growing hop seedlings in liquid medium and applying a six-week heat treatment at 25°C during the propagation process. This study evaluated the Czech variety “Saaz” and the German variety “Hersbrucker”.

Research Findings

1. Stress Tolerance Evaluation in Laboratory Conditions

• In tests conducted under both high-temperature and drought-conditions ^*5, heat-treated hop plants showed significantly higher plant height and chlorophyll content compared to untreated control plants, confirming improved growth and enhanced tolerance.

*5 Drought condition testing was conducted using the “Saaz” variety only.

2. Field Evaluation in Japan

• In April 2023, heat-treated plants and untreated control plants were planted in Esashi City and Tono City, both located in Iwate Prefecture, and evaluated over a two-year period.
• In Esashi City, where the average temperature from May to September is approximately 2°C higher than in Tono City, heat-treated plants showed a significant tendency toward larger aboveground weight and higher boll yield compared to untreated control plants. No significant difference was observed in Tono City, where temperatures are lower than in Esashi City.

About Kirin Holdings

Kirin Holdings Company, Limited is an international company that operates in the Food & Beverages domain (Food & Beverages businesses), Pharmaceuticals domain (Pharmaceuticals businesses), and Health Science domain (Health Science business), both in Japan and across the globe.

Kirin Holdings can trace its roots to Japan Brewery which was established in 1885. Japan Brewery became Kirin Brewery in 1907. Since then, the company expanded its business with fermentation and biotechnology as its core technologies, and entered the pharmaceutical business in the 1980s, all of which continue to be global growth centers. In 2007, Kirin Holdings was established as a pure holding company and is currently focusing on boosting its Health Science domain.

Under the Kirin Group Vision 2027 (KV 2027), a long-term management plan launched in 2019, the Kirin Group aims to become “A global leader in CSV*, creating value across our world of Food & Beverages to Pharmaceuticals.” Going forward, the Kirin Group will continue to leverage its strengths to create both social and economic value through its businesses, with the aim of achieving sustainable growth in corporate value.

*: Creating Shared Value. Combined added value for consumers as well as for society at large.

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