Naked barley has recently gained worldwide interest due to health benefits claimed for its bioactive polysaccharides, β–glucan and amylose. It was side-lined by European plant breeders as less desirable for cultivation due to its poor field establishment and low yield compared to hulled barley. This project used Deiniol, a naked barley line bred at Bangor University and selected for cultivation in the UK. The aim was to improve the yield and bioactive properties of Deiniol through agronomy and breeding.
The effect of plant growth regulator (application on stem length, yield, yield components, β–glucan and amylose were studied in Deiniol and Sanette (hulled). We found that early PGR application at ZGS 32 significantly decreased the stem length from 118.2 cm to 75.5m for Deiniol and from 80.2 to 68.2 cm for Sanette (SE) ± 2.1, a 36% and 15% decrease in stem length, respectively. There was an increase in straw dry weight for both varieties; in Deiniol it increased from 180 to 595 g and in Sanette from 373 g to 406 (SE) ± 44.86g. That had consequences for the harvest index of Deiniol which was lower compared to hulled barley. Thousand grain weight increased significantly following early PGR application. The β–glucan content increased significantly in both genotypes at (p=0.01). But no effect was seen for the same treatments on amylose and amylopectin content. In contrast, we found that late PGR application on naked barley at ZGS 37 had no significant effect.
In order to identify a potential alternative naked barley line for the UK to replace long stemmed Deiniol, screening progenies (MA lines) of various crosses were carried out for stem length, β–glucan, amylose and field performance. Their β–glucan content ranged from 3.05 to 8.15 ± 0.22 g/100g. As compared to published values for current hulled barley, the β–glucan content in these lines was in the range of moderate to high while the amylose content was in the range of normal to high. The lines associated with significantly higher grain yield and shorter straw than Deiniol could be potential alternatives to Deiniol for UK cultivation. Line MA 1 had significantly shorter stem length (61.3 ± 1.62 cm), grain yield (486.6 ± 21.8g/m2), β–glucan content (4.08 ± 0.15 g/100g) and amylose (66.5 ± 1.27 %) to Deiniol. A new cross between Deiniol and a low-amylose starch mutant (Riso 13; hulled) was made to study the heritability of these traits. Riso 13 had high β–glucan content (8.12 ± 0.22 g/100g) whereas the F3 line 31_2 had very high β–glucan content (14.79 ± 0.71 g/100 g) indicating that transgressive segregation, and broad sense heritability was high (approaching a value of 1). Deiniol had the highest amylose content (60.50 ± 1.87) and F3 line 10_2 had the lowest amylose content (18.75 ± 1.87), but not quite as low as Riso 13. Another new cross between Deiniol and Propino was made with the aim of improving naked barley for UK agronomy. It was advanced to the F5 in pots, but no significant improvement was found over Deiniol for yield components.
Early PGR application did not improve the yield of Deiniol; therefore, a breeding approach is needed. MA lines with higher yield and β–glucan content than Deiniol were identified in field trials, and new crosses improved β–glucan content further. Together, these results indicate that this novel germplasm is potentially valuable for breeding naked barley for the health food sector in the UK.