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Borage production for oil and gamma-linolenic acid by Rowland Laurence February 2004
RIRDC Publication No 04/040 RIRDC Project No UT-33A
Borage has been considered previously as a crop for south-eastern Australia, with a RIRDC supported, development project between 1994-96 finding that borage was a more promising alternative than evening primrose. The author has also carried out genotypic improvement work on borage since 1998. With commitment shown to borage development both by a cooperative of Tasmanian growers and a downstream processor, a proposal to the RIRDC to carry out agronomic investigations on borage in 1999- 2000 was successful. This work began in September 2000, with the objective of providing local information on key agronomic practices and recommendations for the production of borage.
This work has investigated the effects of sowing time, sowing rate and harvest timing on borage seed yield through field trials and large area observation of commercial harvesting techniques. While crop rotation, stale seed bed preparation, good crop germination and early vigour were the targeted means of weed control, one observation of herbicide application to post-emergent borage was carried out also.
Three field experiments investigating time of sowing effects were carried out in the consecutive seasons 1999-2002. Over this period, earlier sowing times were employed to counter the large reductions in seed yield, which were found to occur due to delayed sowings. The collective results of the three experiments showed that sowing the crop in early August was most conducive to high seed yield and that no yield benefit was apparent from sowing this line of borage in July. However, yields of dry borage seed were reduced by more than one-third when sowing was delayed by about one month and longer delays induced commensurate reductions.
The borage plant sheds its seed quickly upon maturity and the timing of windrowing, the initial harvest operation, was also found to be critical, this being consistent with other published work. Delaying harvest for a period of one week resulted in seed yield reductions of around fifty per cent and similar yield reductions occurred after a four-day delay. It was concluded that windrowing should be completed within one or two days of the loss from the plant of the first mature seed.
These experiments, therefore, have provided strong evidence of the critical importance of early sowing and exact harvest timing from the point of view of the crop’s profitability.
Observation and experimentation on the effects of sowing rate and row spacing were carried out in the consecutive seasons 2000-03 in large field plots, with the additional objective of making observations on the mechanical handling of the crop and demonstration. In the first and third of these seasons’ field operations, weather conditions resulted in the poor preparation of a stale seedbed for weed control and later than optimal sowing times. Under these conditions, increasing sowing rate improved the ability of the crop to compete with weeds and improved seed yields. In the second of these three seasons, 2001-02, improved seedbed preparation, the application of a pre-emergent desiccant herbicide and mechanical brush weeding allowed the crop to compete well with annual weeds. Results of this replicated experiment showed that field germination was marginally improved by decreasing the distance between the rows (i.e.
increasing the distance between plants in the row) but this did not translate into significantly improved seed yields. Yields improved with increasing sowing rates. This experiment indicated that a sowing rate of 16 kg/ha may be worthwhile if seed germinability is poor. However, if high field germination can be achieved, a sowing rate of 8 kg/ha may be sufficient. Given the prospective cost of seed, sowing more than 16 kg/ha of borage seed is unlikely to be worthwhile. While treatment yields were similar to commercial yields reported elsewhere, significant quantities of mature seed were found on the ground after the windrowing operation, which was considered timely. This suggested, therefore, that the windrower used was too harsh to return maximum seed yields. The use of a ‘softer’ windrowing machine, using a Draper belt mechanism, in reducing seed losses in the following season’s work was encouraging in reducing such losses. Other modifications to windrower cutter bar mechanisms may further limit seed losses by reducing sideways movement of the plant at the cutter bar and thence seed loss from shattering. A bulky windrow also may improve the retention of seed dislodged.
In a field observation of the effects on borage of the application of several post-emergence herbicides, Afalon®, Allicide®, Ramrod® and Stomp330® produced no visual symptoms or reduction in plant growth and these herbicides, therefore, may be worth further investigation in order to provide a chemical weed control option when required in growing borage.
The information and experience
gained with the borage crop through this project have been extremely valuable
in determining important field operational factors, without which successful
borage production locally would have been unlikely. While this report concludes
the current project, other work on aspects of genetic improvement of borage
is still in progress and collaboration between a Sydney-based company and
a grower member of this project’s stakeholder group has resulted in about
eight hectares of borage being sown commercially in the current season,
2003-04. A local oil extraction facility, suitable for use with borage
is also available. This crop, if successful, will provide sufficient borage
seed to test the market potential of the local product. Speaking at a growers’
field day in October 2003 in Tasmania, the principal of the interested
company indicated that, grower contracts could follow within two years.
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