Abstract:Effects of boron-magnesium on boron forms of rape (Brassica napus) cultvars with different boron efficiency were studied at seedling stage with solution culture. The results showed that under condition of sufficient boron the proportion of free boron and semi-bound boron in boron efficient cultivar(QY10) were higher than that in boron inefficient cultivar(95105), which means that more boron could be retranslocated in boron efficient cultivar. The concentration of the bound boron (located in cell wall) in boron inefficiency cultivar was higher than that in boron efficiency cultivar, but the concentration of the free bound and the semi-bound boron is lower, the coefficient of transportation and utilization was low. At the condition of low boron, in root, bound boron were decreased, and free boron and semi-bound boron were (increased), reversely in leaf, the three boron forms in boron efficiency cultivar could be distributed and utilized excellently to adapt the boron deficient stress, and these were reversed in boron inefficiency cultivar. Transit between boron forms in plant was influenced to some extent by magnesium level, which improved the form of transportable boron form, and (increased) the boron‘s pool capacity. Under low boron condition, the boron pool capacity of the boron inefficiency cultivar was decreased by magnesium, and aggrandizing the boron deficiency in shoot.