Effect of different boron levels on yield and nutrient content of wheat based on grey relational degree analysis

The objective of this study was to evaluate the effect of boron (B) fertilizer application on the yield and nutritive element content of wheat grain. A field experiment was conducted using wheat at five B treatments consisting of B-0 (no B added), B-0.2, B-0.4, B-0.8 and B-1.6 (B added at 0.2, 0.4, 0.8 or 1.6 mg kg(-1) B, respectively). Boric acid was added to soil to create five B concentrations. Results showed that the there was no significantly difference on yield and thousand seed weight of wheat among different B application treatments. The wheat plant showed a higher B concentration in the root, leaf and shell but lower B concentration in stem and grain. There was an increasing trend for the B concentrations in root, middle stem, leaf and grain with increasing B levels, especially B concentration in grain at B-0.8 treatment. However, the translocation factors (TFs) in grain/shell is low. These results suggested that B is easily absorbed by wheats, but not easily transferred to the grain site. In addition, there was an increased tendency for calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe) and zinc (Zn) concentrations with increased B treatment. Grey correlation model analysis showed that the synthetic characteristics of grain (expressed as grey relation degree) followed the sequence of B-1.6 > B-0.8 > B-0 > B-0.4 > B-0.2. Our results demonstrate that the integrated grain quality is optimal at 1.6 mg kg(-1) B concentration in moderate B level soil.