EFFECT OF BORON ON THE NITRATE REDUCTASE-ACTIVITY IN OILSEED RAPE PLANTS

Both a solution culture and pot experiment were conducted in the green house to study the effect of variation in boron concentration and in l evel and form of nitrogen on nitrate reductase activity in rape (Brass ica napus L.). The results indicated that nitrate reductase activity i n the leaves of rape plants (Ningyou No. 7 and Ningyou No. 8) grown on nutrient solutions increased markedly with increasing boron concentra tion (from 0.025 mug B/mL to 0.1 mug B/mL). The activity also increase d with increasing nitrogen level in soil, and the enhancement caused b y 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 p lant.