Effects Of Boron And Cadmium On Growth And Development, Absorption And Distribution Of Cadmium And Physiological Characteristics Of Different Rape Varieties

The effects of boron and cadmium on the growth, cadmium uptake and accumulation, physiological characteristics in two oilseed rape varieties with different boron efficiency were studied under soil and solution culture condition. It also discussed cadmium contamination condition and their mechanism by boron supply in rape. The main results were as follows:1.There were similar responses in growth and development between two oilseed rape varieties with different boron and cadmium. Cadmium in low concentration had no significant effects on the growth and development of rape, but its growth was decreased in high concentration .At seedling stage, the effects of different boron levels on the dry weight of two rape varieties were not obvious under the same cadmium level. At flowering stage, the dry weight of leaves and flowers rised with the increase of boron in the same cadmium level. At maturing stage, the dry weights of seedcase, seeds and whole plant of two oilseed rape varieties were rised with the increase of boron under the same cadmium level.2.The yield and their components of the two oilseed rape varieties were increased with the increase of boron under the same cadmium condition. "Bakow" has no yield and "QY 10" has one point yield under no boron level. The yield and their components of the "Bakow" were decreased with the increase of cadmium when boron concentration is 0.2 mg/kg, but the yeild and their components of the "QY 10" have no significant change There were no significant change in yield and their components of the "Bakow" with increase of cadmium when boron concentration is 1.0 mg/kg, however, the yield and the 1000-seed weight the "QY 10" were increased significantly with the rising of cadmium , the number of effective pods and the number of seeds per pod have no significant change..3.The content and accumulation of cadmium in each part of the two oilseed rape varieties have no significant change with increase of boron under no cadmium treatment at seedling stage ,flowering stage and maturing stage. The content and accumulation of cadmium in roots were more than shoots of the two oilseed rape varieties under the same conditions at seedling stage. The content and accumulation of cadmium of "QY 10"were more than "Bakow".At flowering stage, the cadmium content in each part of two oilseed rape varieties have been significant decreased with increase of boron when cadmium is 1.0 mg/kg ,except the cadmium content in roots and leaves in "Bakow" and the cadmium accumulation in two oilseed rape. The content and accumulation of cadmium in each part of the "QY 10" were increased with the rising of boron, but the content and accumulation of cadmium in each part of the "Bakow" were decreased under Cd 5.0 mg/kg level,except there was a reverse trend in the flower. In the same condition the size order of the content and accumulation of cadmium in each part of whole plant is:leaves>roots>stem>flowers. The content and accumulation of cadmium of "QY 10" were more than "Bakow".At maturing stage, the cadmium content in each part of two oilseed rape varieties have no significant change with increase of boron under Cd 1.0 mg/kg level and it has a decreasing tendency with the increase of boron under Cd 5.0 mg/kg level. The cadmium accumulation in roots and stem of two oilseed rape varieties were decreased with the rising of boron, but the cadmium accumulation in seedcase and seeds have significantly been increased with the increase of boron under applied cadmium.The cadmium content in root ,stem and seedcase of "QY 10" were higher than "Bakow" at different boron levels, but the cadmium content in seeds was lower than "Bakow". The size order of content and accumulation of cadmium in each part of whole plant is:roots>stem>seedcase.4.The boron and cadmium of content of rape cultured in purple sandstone soil was more than yellow brown soil under the same boron and cadmium levels.The cadmium content of rape has increasing tendency with the increase of boron under B 0～1.0 mg/kg conditions, they gradually were decreased while the boron concentration was higher than 1.0 mg/kg under soil culture.The cadmium content of rape has significantly been increased with the increase of boron in B 0～0.25 mg/L and they gradually were decreased while in B 0.25～1.0 mg/L and Cd 0.2 mg/L under hydroponic culture. The cadmium content of rape has increasing tendency with the increase of boron (B 0～1.0 mg/kg) and Cd 0.05 mg/L under hydroponic culture.5.The SOD,POD and CAT activity of leaves in two oilseed rape varieties were increased with the increase of cadmium or have no significant change under the same boron level.The enzyme activity of leaves applied boron was higher than without application boron under the same cadmium level.