Robert W. Welch

Kernel (1 → 3) (1 → 4)-β-d-glucan content of oat genotypes*

A method for the estimation of (1 → 3) (1 → 4)-β- d -glucan in oats - involving alkali extraction at 45 °C, precipitation with Calcofluor and the colorimetric estimation of glucose - has been modified and compared with a hydrazinolysis procedure. Close agreement between the methods was found for oat kernels and for oat bran samples. This indicates that the β-glucan of oats was completely soluble under the conditions used. Comparison of the modified Calcofluor method with previous results also showed a reasonable agreement for total β-glucan content. The modified Calcofluor method which is suitable for small samples has been used to analyse kernels from 100 diverse oat genotypes. Significant genotype differences were found and kernel β-glucan levels ranged from 3·2 to 6·3 %. Associations between β-glucan and other kernel and plant characteristics were weak, indicating that it is possible to manipulate the β-glucan content of high-yielding oat varieties by plant breeding. However, the modified Calcofluor method gave a low value for β-glucan content, compared with the hydrazinolysis procedure, with a sample of barley and appears unsuitable for this species.

Variation in the kernel (1→3)(1→4)-β-D-glucan content of oat cultivars and wild Avena species and its relationship to other characteristics

Kernel (1 → 3) (1 → 4)-β-n-glucan, kernel protein and mean kernel size have been estimated in six cultivars of oats ( Avena sativa ) L, and eight wild Avena species grown at two levels of nitrogen fertility in a pot experiment. In the oat cultivars, kernel protein and kernel β-glucan were both increased at the higher nitrogen fertility level. Comparison with the results from field grown material which had still higher kernel protein contents indicated that this association between β-glucan and protein occurred over a wide range of kernel protein levels. However cultivar differences were more distinct at lower fertility levels. Six of the eight Avena species had a mean kernel size that was substantially lower than the cultivars. However the protein contents of the Avena species were in general higher and they showed a wider range of β-glucan contents. Although higher nitrogen fertility increased grain protein in the wild species, β-glucan was only significantly increased in one species. Kernel β-glucan content was independent of both kernel protein and mean kernel size in the wild species. Results show that phenotypic variations in kernel protein are associated with concomitant variations in β-glucan in oat cultivars and furthermore that wild Avena species may be useful additional sources of variation for this characteristic.