Effect of boron on the nitrate reductase activity in oilseed rape plants

Abstract

Both a solution culture and pot experiment were conducted in the greenhouse to study the effect of variation in boron concentration and in level and form of nitrogen on nitrate reductase activity in rape (Brassica napus L.). The results indicated that nitrate reductase activity in the leaves of rape plants (Ningyou No. 7 and Ningyou No. 8) grown on nutrient solutions increased markedly with increasing boron concentration (from 0.025 μg B/mL to 0.1 μg B/mL). The activity also increased with increasing nitrogen level in soil, and the enhancement caused by nitrogen was more with boron than without boron added. Both with and without boron added, nitrate reductase activity was obviously higher with Ca(NO₃)₂ than with (NH₄)₂SO₄. With boron added, nitrate reductase activity in leaves increased from the basal to the top parts of the plant.