Effect Of Se On Buckwheat Growth Under Lead Stress

Heavy metal lead pollution is a problem that needs to be solvedurgently in agricultural production, selecting a kind of the regulationof chemical substances that can not only reduce the heavy metalslead pollution but also improve the crop growth conditions is oftheoretical and practical significance. Selenium is an importantbeneficial bioelement. It is an important biological pathway to use Seto help relieve the stress of plant lead. A pot experiment wasconducted to study the effects of different concentrations of Se(Se1, control, Se2,1mg/L, Se3,2.5mg/L, Se4,5mg/L, Se5,10mg/L) onphysio-morphological indices and accumulation of lead changes ofbuckwheat under lead stress (Pb1,0mg/kg, Pb2,500mg/kg, Pb3,1000mg/kg). The main results are as follows:(1) Under the same concentrations of Pb, plant height, total rootlength, root surface area, and yield of buckwheat increased firstlyand then decreased with the increasing of concentrations of Se indifferent growth period. Se3(2.5mg/L) reached the maximum, and thevariations in each treatment are different. Under the same seleniumamount, each index gradually decreased with the increase of leadconcentrations. During the whole growth period, the variousindicators are gradually increased with the advancing of growthperiod and reached the maximum in mature stage. (2)Under the same concentrations of Pb, SOD and POD activity,the content of soluble sugar, proline content, content of solubleprotein,MDA content firstly decreased and then increased with theincreasing concentrations of Se. Se3(2.5mg/L) reached the minimum.Under the same selenium amount, SOD and POD activity firstlyincreased and then decreased with the increasing concentrations ofPb, and reaching a maximum at Pb2(500mg/Kg),whereas the contentof soluble sugar, proline content, content of soluble protein, MDAcontent presented a gradually increasing trend.(3)With the increasing of Se concentration，the leaf chlorophyllcontent,fluorescence parameters (Fv/Fo,Fv/Fm) and root activityincreased firstly and then decreased under the same concentrationsof Pb. Se3(2.5mg/L) reached the maximum. Under the same seleniumamount, the leaf chlorophyll content, fluorescence parameters(Fv/Fo,Fv/Fm) and root activity presented a declining trend with theincreasing of the concentrations of lead. In the whole growth period,they all reached the maximum in flowering stage, showing the trendof low-high-low.(4)With the increasing of Se concentration, the lead content inbuckwheatroot, stem, leaf, seed firstly decreased and then increasedunder the same concentrations of Pb. Se3(2.5mg/L) reached theminimum. Under the same selenium amount，its content graduallyincreased.In the whole growth period, lead content in different organsof buckwheat gradually increased with the advancing of the growthperiod, and reached the maximum in mature stage.In conclusion, under the condition of same amount of moistureand nutrients, the spraying suitable amount of Se-fertilizer to leaves can adjust the physiological activities of buckwheat, thus cansignificantly promote its growth. At the concentration of the Pb2andPb3, spraying Se-fertilizer to leaves can relieve the toxicity brought bylead stress and reduce the content of lead in plants especially inseeds. Therefore, in agricultural production, the plant’s absorption ofheavy lead metal can be controlled by spraying suitable amount ofSe-fertilizer to leaves to prevent them from entering the food chainand reduce the harm of lead pollution.