Effect Of Cu,Zn And Combined On Physiological And Biochemical And Spectral Characteristics Of Wheat

In this paper,Jimai No.22 was used as the test material,and the effects of heavy metal Cu,Zn and Zn+Cu on wheat were studied systematically at tillering stage,jointing and heading stage by the field test method.The distribution of heavy metals in wheat leaf cells,and the effects of different types and concentrations of heavy metals on the physiological and biochemical characteristics of wheat at different growth stages were explored.On the basis of the above work,the effect of heavy metals on the spectral reflectance at different periods of wheat was studied.The correlation between the concentration of heavy metals in the wheat leaves and the characteristic parameters of the reflectance spectra was established.The detailed results of this study are as following:1.Under CuL1 and CuL2 stress,Cu in wheat leaves mainly enriched in cell fluid fractions at tillering stage,but under CuL3 stress,Cu enriched in cell wall and cell fluid.At jointing and heading stage,cell wall was the mainly binding construchture.Cu was not found in the organelles at three growth stage above,The total Cu concentration in the leaves increased with the increase of stress Cu concentration.The tiller of wheat could be inhibited by CuL4.It was found that synthesis of soluble total protein and POD activity could be promoted at CuL1 and CuL2 in wheat leaves.While the effects of CuL3 and CuL4 on soluble protein and POD activity were depended on wheat growth stage.The effect of CuL1,CuL2 and CuL3 on the content of MDA was different based on the wheat growth period,but the MDA content was significantly increased under CuL4 stress.The spectral reflectance of wheat varied with different growth stages.Based on the correlation model of spectral characteristic parameters and Cu content of wheat leave cells,it was found that NDVI₇₀₅,Dr and Db could be used to estimate the Cu content in the leave cells of wheat at the tillering stage,jointing stage and heading stage,respectively.The correlation coefficients were 0.7238,0.7593,0.4714 and reached a significant level,respectively.2.The content of Zn in the wheat leave cells was cell wall>cell fluid>organelle under the stress of different Zn concentrations at tillering,jointing and heading stage.The total Zn content in wheat leave cells increased with the increase of stress concentration.At different growth stages,ZnL1 and ZnL2 stress could improved the total soluble protein content and POD activity,but the stress effects of ZnL3 and ZnL4on total soluble protein content and POD activity were depended on growth stages.The levels of MDA in leave cells of wheat were also different depending on different growth periods.The MDA content in the tillering period increased and it was almost unchanged at the jointing period under the stress of ZnL1,ZnL2 and ZnL3,and it was higher than CK only under the stress of ZnL4 at heading stage.It is found that the stress degree of wheat could not be judged only by spectral reflectance.The correlation analysis and verification of the spectral characteristic parameters and the content of Zn were analysized.There could be established an ideal prediction model between the Zn concentration and Dr（at tillering stage）,Rg,MCARI（at jointing stage）,Db（at heading stage）.The correlation coefficients were 0.6007,0.9376,0.8037 and 0.7480,respectively.3.Cell wall and cell fluid were the main enrichment sites of Zn and Cu under different Zn+Cu stresses at different growth stage,and no Cu was found in the organelles.The accumulation of Zn and Cu in leave cells was different due to different growth stage.In tillering stage and heading stage,the Zn content in leave cells increased with the increase of Zn dosage in soil,while Cu content decreased at first and then increased.At jointing stage,the Zn content in leaves increased first and then decreased with the increase of Zn dosage in soil,but it was always higher than that in control group.Cu content increased continuously under all stress of Cu+Zn.According to the changes of physiological and biochemical parameters and spectral reflectance,it is found that there was no significant regulation in physiological and biochemical parameters and spectral reflectance.By analyzing the spectral characteristics at jointing and heading stage and the content of heavy metals in leave cells,it was found that at jointing stage,Rg,Rr,NDVI₇₀₅,MCARI,Dr and SDb were sensitive to Zn content,and WI was sensitive to Cu content.At heading stage,WI was sensitive to Zn content,while Rg,Rr,NDVI₇₀₅05 and MCARI were sensitive to Cu content.Therefore,the spectral sensitivity parameters above could be used to predict the content of Cu and Zn in leave cells of wheat.