INTERACTION OF SILICON AND BORON IN OILSEED RAPE PLANTS

Shoot and root dry matter yields of oilseed rape (Brassica napus L.) g rown on the solutions containing 0.025 and 5.0 mu g boron (B)/mL (refe rred to as B1 and B3, respectively) were less than those grown on the solutions containing 0.5 mu g B/mL (referred to as B2). Silicon (Si) a dded increased shoot and root dry matter yields of B1-treated plants, while decreased those of B3-treated plants. Shoot and root dry matter yields of B2-treated plants were slightly affected by Si added. The ef fect of B and Si on leaf area was similar to that on shoot and root dr y matter yields. Excessive B supply (B3) and B deficiency (B1) resulte d in a decrease in net photosynthetic rate. Silicon added increased th e net photosynthetic rate under B deficiency, but had little effect at normal and excessive B levels. Silicon seems to enhance B uptake and accumulation by plants under B deficiency, but depresses B uptake at n ormal and excessive B levels. The Si/B ratios of B1- and B2-treated pl ants were much lower than those of the culture solutions, whereas at t he B3 level were slightly higher than those of the culture solutions. Phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) conten ts in plants decreased with increasing Si added at the B3 level, but r emained relatively constant at B1 and B2 levels.