Effect of boron on vitamin level

In the fascinating graph below it shows the effect of boron levels on thiamine (B1), niacin (B3) and vitamin C. I find it very interesting that vitamin C decreases while B1 and B3 increase. This shows how difficult it is to determine exact vitamin levels in produce. Who would think to measure boron levels and then correct the vitamin B levels in plants due to this factor. It shows the impossibility of determining the vitamin levels in the food that we eat. Does the ground which produced my veges have high or low boron levels? 

The good news for us is that I use a trace element mix that always has boron in it. So hopefully we get high vitamin B levels in our green stuff.

Reference: Karl Schutte. 1964 The biology of the trace elements.