| The wheat is widely cultivated in China as an important food crop,the safety in production has been China's farmland Cd?Cadmium,Cd?pollution serious threat.The wheat plants absorb too much Cd,and their growth and development are easily inhibited,resulting in a lower yield.In addition,excessive Cd accumulation in grains is easy to cause serious harm to human health through the food chain.Screening and breeding wheat Cd low accumulation germplasm resources is a feasible and effective way to realize safe production of wheat.In this study,139 wheat materials were used as the research objects.By combining field test and soil culture test,low-cd accumulation materials of wheat were screened and Cd accumulation characteristics were explored.The main research results are as follows:?1?Under the field test conditions from 2014 to 2015 and from 2015 to 2016,the content range and variation coefficient of Cd in the grain of 139 wheat materials were0.002-0.271 mg kg-1DW-1,63.097%and 0.095-0.343 mg kg-11 DW-11 and 24.960%,respectively.There were significant differences in the content of Cd in the grain among wheat materials.Based on the cluster analysis index of Cd content in grain,the wheat materials with the same Cd accumulation type in grain in the two-year experiment were obtained comprehensively.12N551,Jimai 22,Shumai 375,Zhongliang 22,30389,B7094,ML2652,G219-24,77782,NannongOzy23,NannongC90097,Pm99915-1,Nannong02y393,Cxk027-4,02Y23,Liangmai no.2 had the characteristics of low Cd accumulation and good reproducibility or stability between years.Under the condition of soil culture,Cd content and yield of wheat with low Cd accumulation in 16 samples were significantly different.At the level of 1 or 4 mg kg-11 Cd,the grain Cd content and grain yield amplitude were 0.286-0.910 mg kg-1,3.199-7.716 g plant-11 and 0.881-1.381mg kg-1,3.075-8.252 g plant-1,respectively.The variation coefficients of Cd content and yield were 33.706%,24.044%,12.276%and 30.351%,respectively.The dominant materials 12N551,Zhongliang 22,G219-24 and Liangmai no.2 with low Cd content and high yield were obtained by using Cd content and yield as clustering indexes.?2?By soil culture experiment,in order to screening the low Cd accumulation of wheat materials 12N551 as the research material,and material selection of ordinary HW2-2 as a control,further in 1 and 4 mg kg-11 Cd level was discussed under low Cd accumulation of wheat materials in tillering stage,jointing stage,heading stage,mature period of Cd accumulation distribution features,the results showed that the two types of wheat materials in tillering stage,jointing stage,pumping period,mature period of biomass were declined with the increase of the concentration of Cd,along with the advancement of growth period,Wheat Cd low accumulation material had good adaptability at the level of 4 mg kg-1Cd.Cd content and Cd accumulation amount of wheat Cd low accumulation materials in each growth period showed an increasing trend with the increase of Cd concentration.In the mature stage of wheat Cd low accumulation material,Cd content and Cd accumulation in stem,leaf and grain were significantly lower than that of common material,while Cd content and Cd accumulation in root were significantly higher than that of common material,indicating that Cd accumulation in root of wheat Cd low accumulation material was stronger,and more Cd could be distributed in root,thus reducing Cd accumulation in grain.?3?By soil culture experiment,explored the wheat 12N551 low Cd accumulation of wheat materials in each part of the jointing stage Cd subcellular distribution and chemical characteristics,the results showed that in different level of the Cd,two kinds of materials of wheat root and stem leaf Cd subcellular components are given priority to with the cell walls of Cd content,subcellular components accounted for 60.601 81.470%and 68.65470.827%of the total,the second part of the Cd content,soluble organelles,Cd content in subcellular distribution to a certain extent,limits the Cd in Cd to transfer or aboveground stem leaves to other parts of the unloading.Under different levels of Cd,the chemical forms of Cd in the roots and stems and leaves of wheat material 12N551 with low Cd accumulation were dominated by acetic acid extraction,with the percentages of75.243-78.972%and 68.712-78.847%,respectively.12N551 low Cd accumulation of wheat materials roots and stem leaves poor mobility of acetic acid in the extract state Cd content is relatively higher than material HW2-2,mobility strong deionized water to extract the state Cd content and percentage significantly lower than material HW2-2,12N551 low Cd accumulation of wheat materials root or stem leaf position of Cd was of poor mobility,to a certain extent,can move to the other parts of the restrictions on Cd. |
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