The improvement of Borage as a commercial source of gamma-linolenic acid

Background: Borage oil naturally contains a high level (around 24%) of Gamma-Linolenic Acid (GLA). This human dietary supplement is experiencing increasing international market demand and borage is favoured as a preferred source of supply. However, commercial yields of seed are low (around 300 kg/ha) both in Canada, New Zealand, and in the UK, where about half of world production occurs, due to a lack of the development of improved commercial varieties and production practices. A project to improve borage production in Australia through the introduction and selection of genotypes is now in progress with industry funding from Willala Agricultural Pty.

This work has found encouraging yields, oil and GLA production in Tasmania, with resulting interest from New Zealand, Canadian and UK companies. In addition, Natural Plant Extracts, a grower group with particular interest and experience in commercial production of herb crops for extraction, is now keen to support improvements to borage agronomy and harvesting through research in order to maximise local advantages in the world marketplace. It is believed that the work already underway to improve plant type, together with improvements in agronomy and harvesting to be derived from research and stakeholder experience in herb and extractive crops, will make local production very market competitive.

Objectives: The project seeks to increase the commercial yield of GLA from borage, through selection for improvements in plant type, such as determinate growth, harvest index, harvestability and yield of oil and GLA among introduced lines, along with exploring improved agronomic methods for borage production.

Work undertaken to date: Replicated trials of 25 seed lines have been conducted at the University/TAFE farm at Burnie, with plots hand harvested then dried and threshed before cleaning and yields taken. Sub-samples from the plots were analyzed for oil/fatty acid and GLA content. Along with this an attempt to compare the ability of the lines to retain seed was conducted. There was significant variation in yields with the more promising lines showing higher yields (up to 500kg/ha than those reported from areas already producing the crop commercially. Significant variation between lines was also found in oil/fatty acid and GLA content.

Preliminary work has been conducted to assess times of planting, with borage being at a number of different times and harvests conducted at industry standard times as well as delayed harvests. Results indicated that there was a significant decrease in yield when planting occurred later in the season, and if harvest was delayed.

To maintain their genetic integrity during multiplication, plants of all lines were grown in greenhouse trays and moved, before flowering too isolated locations. Seed was periodically collected during the season Through this procedure reserves of true to type material have been produced for the coming season, while new seed lines have been sourced from within Tasmania and Australia, and from international sources.