Study On Difference Of Boron Absorption And Transportation And Its Mechanisms In Rape Cultivars (Brassica Napus L.) With Different Boron Efficiency

The different response to boron deficiency and their mechanism in rape(Brassica napus L.) cultivars with different boron efficiency was studied under solution culture condition. Main results are as follows:1. The study of tracing investigation by Isotope ¹⁰B indicated that: The ability and rate of boron absorbability in B-efficient rape cultivar is higher than B-inefficient rape cultivar at the condition of serious boron deficiency, so the concentration of B is relatively high. meanwhile, compoared with B-inefficient rape cultivar, the ability of transfer boron from old leaves to regenerated tissue was faster and the recycle efficiency of boron was higher.2. Boron concentration and exudation rate in xylem sap of two rape cultivars were decreased by boron deficiency, but the trendy was more obviously in B-inefficient cultivar. B concentration in xylem sap was 3.75 fold in the efficient cultivar and 4.26 fold in the inefficient cultivar under sufficient boron supply (0.5 mg/L), but at a B supply of 0.005 mg/L, B concentration in xylem sap was up to 241.06 fold in the efficient cultivar and 203.28 fold in the inefficient cultivar.3. The mineral nutrients of Ca,Fe,Mn,Cu,Zn concentration and exudation rate in xylem sap of two rape cultivars were decreased by boron deficiency, but the lowered range was different in two cultivars.4. Observation with transmission electron microscope, there are the phenomenon of plasmolysis,cell membrane goffer or fracture and intima system was damaged in two rape cultivars with different B efficiency under boron deficiency, and the damage on B-inefficient rape cultivar is seriouser than B-efficient rape cultivar.5. When two rape cultivars were suffered from boron deficiency, unsaturated fatty acid content were decreased and saturated fatty acid were increased. The results lead to membrane permeability in their roots,steps and leaves were increased,the ratio of unsaturated to saturated fatty acid were decreased, the function of membrane were damaged. however, the increase or decrease degree of boron efficient cultivar was less than that of inefficient one.