Arabinoxylan (AX) content in barley grains is an important quality determinant when barley is used as raw material of malt or beer production. The cultivar and environmental variations of total arabinoxylan (TAX), water extractable arabinoxylan (WEAX) and endoxylanase activity (EA) were investigated using eight barley cultivars growing at seven locations with diverse environmental conditions. The results showed that both barley cultivar and location significantly affected the TAX, WEAX and EA levels, but the variations of TAX content and EA were mainly attributed to cultivar, while the impact of location on WEAX content was greater than that of cultivar. Correlation analysis indicated that TAX was significantly correlated to WUAX.

The alleviatory effect of silicon (Si) on chromium (Cr) toxicity to rice plants was investigated using a hydroponic experimentwith two Cr levels (0 and 100 μmol L-1), three Si levels (0, 1.25, and 2.5 mmol L-1) and two rice genotypes, differing in grainCr accumulation (Dan K5, high accumulation and Xiushui 113, low accumulation). The results showed that 100 μmol L-1 Crtreatment caused a marked reduction of seedling height, dry biomass, soluble protein content, and root antioxidantenzyme activity, whereas significantly increased Cr concentration and TBARS (thiobarbituric acid reactive substances)content. However, the reductions of seedling height, dry biomass, and soluble content were greatly alleviated due to Siaddition to the culture solution. Compared with the plants treated with Cr alone, Si addition markedly reduced Cr uptakeand translocation in rice plants. No significant differences were observed between the two Si treatments (1.25 and 2.5 mmolL-1) in shoot Cr concentration and Cr translocation factor. Under the treatment of 100 μmol L-1 Cr+2.5 mmol L-1 Si, higherroot Cr concentration but lower shoot Cr concentration and Cr translocation factor were observed in Dan K5 than thosein Xiushui 113, indicating that the beneficial effect of Si on inhibiting Cr translocation was more pronounced in Dan K5than in Xiushui 113. Si addition also alleviated the reduction of antioxidative enzymes (superoxide dismutase (SOD) andascorbate peroxidase (APX) in leaves; catalase (CAT) and APX in roots) and the increase of TBARS content in the Crstressedplants. Furthermore, the beneficial effects of Si on activities of antioxidative enzymes under Cr stress weregenotype-dependent. The highest activities of SOD, POD (guaiacol peroxidase), CAT, and APX in leaves occurred in thetreatment of 100 μmol L-1 Cr+2.5 mmol L-1 Si for Xiushui 113 and in the treatment of 100 μmol L-1 Cr+1.25 mmol L-1 Si for DanK5. The beneficial effect of Si on alleviating oxidative stress was much more pronounced in Dan K5 than in Xiushui 113.It may be concluded that Si alleviates Cr toxicity mainly through inhibiting the uptake and translocation of Cr andenhancing the capacity of defense against oxidative stress induced by Cr toxicity.