Breeding and quality analysis of rapeseed for China

• Oil Crops Research Institute, China

Rapeseed - China's most important oilseed crop - had a total production of 6.73 million tonnes in 1987. However, although high-yielding and disease-resistant, the varieties traditionally grown in China produce oil with high levels of erucic acid and a residual meal high in glucosinolates (double-high varieties). In Australia, and elsewhere, plant improvement in recent years has successfully produced double-low varieties (now known as canola). The reduction of the potentially toxic erucic acid and glucosinolates to acceptable levels for human and animal consumption has greatly expanded the potential uses for rapeseed oil and meal. In addition, plant breeders have utilised a cytoplasmic male sterility (CMS) system to produce hybrid cultivars of rapeseed.

ACIAR Project 8469 made considerable progress in improving the quality of rapeseed in China, chiefly in developing:

. better double-low genetic materials by crossing elite double-low Australian material with double-high materials from China and selection for adaptation to both countries; and

. improved techniques for measuring glucosinolates.

The present project replaces 8469. It will also include both breeding and quality analysis and will continue the effective linkage between the breeders and chemists.

The plant breeders will evaluate and reselect double-low quality rapeseed lines for China, from material already screened for quality characteristics in Australia. Release of adapted material should follow in the early 1990s. Also, a further cycle of crosses is being made, to ensure double-low quality in hybrid cultivars produced using the Polima CMS system. After screening for quality characteristics in Australia, these crosses will be returned to China as F3 lines for evaluation, and the release of material derived from them should continue well into the 1990s.

Quality analysis will proceed in parallel with this work, and the researchers will develop, monitor and support quality analysis of rapeseed in the breeding programs of the collaborating institutions in China. The rapid quantitative method for measurement of glucosinolate content developed in Project 8469 is based on a reflectometer. The present project will implement it in China, and will also assist in the development of an appropriate method for monitoring seed delivered to receival depots. The changeover from high- to low-glucosinolate varieties will make it necessary to separate the seed lots into groups based on their glucosinolate contents.

The test-tape method would be suitable if all seed was either high or low and may be a useful tool for a first evaluation. However, some seed will probably be borderline and will need a quantitative or at least semi-quantitative test. This should be less sophisticated and quicker than the reflectance method and use simpler equipment. Work done in the earlier project should make it easier to develop such an improved test.

At the completion of this project, Chinese scientists should have access to a wide range of double-low germplasm for further selection and evaluation in both hybrid and open pollinated varieties, and further varieties will be released throughout the 1990s. A range of screening methods will also be available for routine use, including reflectometers in the collaborating institutions, with fully trained chemists to operate them.