Genotypic Variation Of Zn Absorption And Mechanisms At Low Zn Stress In Rape (Brassica Napus L.)

Zinc is one of the necessary nutrition microelements for human body.The dwarfism in human beings taste bad in children sense the aged dementia and reduction of immunity function due to Zinclacking.At present,the main method which can resolve lacking zinc in human body is the medicinesupplying,but it is expensive and difficult to persevere for long time,particularly for children.Thelow zinc concentration in the food is the basic reason why human beings lack zinc.Applying zinc tosoils or plant leaves can increase crop zinc concentration and improve zinc condition in humanbeings through the food chain.However,applying zinc fertilizers to soils and plants is hard toenforce to developing countries.Furthermore,improper applying fertilizers result in sever seriousenvironmental problem.Scientists and researchers focused their attention on finding a cheaperpracticable way to increase crop zinc concentration.Since the 1990's,genetically improvement andselection of rich zinc crop have drawn the attention of domestic researchers and abroad in recentyears the international meetings were hold and a succession of plans and researches wereimplemented.Quite a number of important achievements were made in this field.The chief studycentered in the grain crops such as wheat,paddy rice and corn etc.limited information is availableon vegetables.Vegetables are necessary nonstaple foods in our daily life and an important source ofmineral matters.The main objectives of the present studies were to investigate effects of low zincstress on resistance biomarkers,and the absorption of N,P,K,Zn compare with genotypic variationof Zn absorption and mechanisms in different genotypic leaf-used rapes (Brassica napus L.).Themain results are as follows:1.Different cultivars of leaf-used rape showed different response to low Zn stress.In solutionand soil pot experiment,the plant growth of rape was markedly decreased under low Zn stress. Along with increasing Zn level,the height of shoots,the number of leaves,the fresh weight of shoots and roots obviously increased.The fresh shoot and root weights of 18 rape cultivars shown strong correlation with Zn level.At low and normal Zn,the highests of shoot height,root length,leave number,shoot and roots fresh weights were found in RiBengHuaGuan,followed by XiaWang,the worst is TeXuanHeiYe.2. The low Zn stress obvious influenced biomarkers and different cultivars of leaf-used rapeshown significant differences in biomarkers under low Zn stress.The activities of SOD,POD and CAT,concentration of MDA,roots system vigor,concentration of chlorophyll and dissoluble protein of leaves increased with increasing Zn levels in 18 rape cultivars,The highest or the second of SOD,POD and CAT activities,roots system vigor,chlorophyll concentration and dissolubles protein wasobserved in RiBengHuaGuan and XiaWang.In soil pot experiment,the activities of SOD,POD andCAT,concentration of MDA,roots system vigor,concentration of chlorophyll and dissoluble proteinof 4 cultivars of leaf-used rape also increased with increasing Zn level,the maximum of allbiomarkers was recorded at Zn 10mg·kg^-1 in soil.At low and normal Zn,the highests of SOD,POD and CAT activities,roots system vigor,concentration of chlorophyll and dissoluble protein were found in RiBengHuaGuan,followed by XiaWang,the lowests were observed in TeXuanHeiYe,Theresult was consistent with the solution experiment.3. Different cultivars of leaf-used rape showed different trends in nutrient concentrations andZn absorption by plant under low Zn stress.In solution experiment,the concentrations of N,P,K,and Zn in shoot and concentration of Zn in roots of eighteen cultivars increased with increasing Zn levels,At low and normal Zn,the highests of N,P,K,Zn in shoots and concentration of Zn in rootsamong four cultivars also increased with increasing Zn levels,and the second determination resultsof N,P,K,and Zn concentrations in shoots and Zn concentrations in roots was found inRiBengHuaGuan and XiaWang,which had bigger biomass.At 30d in soil pot experiment,Zn concentration and absorption of shoot in RiBengHuaGuan was 77.07 mg·kg^-1 and 141.453ug.pant^-1under low Zn stress.4. Based on the index of resistances,nutrient uptake and yield of solution experiment and soilpot experiment,that suggested that RiBengHuaGuan Rape and XiaWang which has higher yield,resistances,N,P,and K uptake and Zn accumulation in leaves under low Zn stress can be used as cultivars of leaf-used rapes in low Zn soil.