水稻叶面调理剂的降Cd效果及其对营养元素转运的影响

为了探讨叶面调理剂的降Cd机理,通过水稻开花期叶面喷施苹果酸(MA)和微量元素Mn及Zn,对它们的降Cd效果及对主要营养元素含量的影响进行了比较研究。结果表明:喷施10 mmol·L~(-1)MnCl_2、10 mmol·L~(-1)ZnCl_2、5 mmol·L~(-1)苹果酸均能显著降低Cd在稻米、穗轴、穗颈、旗叶中的积累,稻米中的Cd含量从0.63 mg·kg~(-1)分别下降到0.47、0.28、0.26 mg·kg~(-1),降镉幅度分别为23.84%、55.44%、58.86%。喷施苹果酸显著提高了Mg、Fe从旗叶向穗颈以及K、Mn、Zn从穗轴向籽粒的转移效率,却显著抑制了Cd从旗叶向穗颈的转移,使穗颈和穗轴中的Cd浓度分别下降59.84%和75.77%。喷施Zn显著提高了籽粒中的Ca、Fe含量。喷施Mn显著促进了K从穗轴向籽粒的转移。由此可见,喷施苹果酸和Mn、Zn能有效促进K、Mn、Zn等必需元素向籽粒的转运,致使稻米中的Cd含量显著下降。

Effects of foliar modulators on cadmium accumulation and transport of nutrient elements in rice

To explore the mechanism of foliar regulators in decreasing the uptake of cadmium (Cd), the effects of foliar application with malic acid, manganese, and zinc, at the anthesis stage, on cadmium accumulation in grains and other organs of rice plants were studied. The results showed that Cd concentrations in the grains, rachises, uppermost internodes, and flag leaves of rice plants decreased. The Cd concentration in grains decrensed from 0.63 mg·kg^-1 to 0.47, 0.28, and 0.26 mg·kg^-1 after spraying 10 mmol·L^-1 MnCl₂, 10 mmol·L^-1 ZnCl₂, and 5 mmol·L^-1 malic acid, respectively, and the corresponding percentages of Cd decrease were 23.84%, 55.44%, and 58.86%. Spraying malic acid promoted the transfer of Mg and Fe from flag leaves to the uppermost internodes, and of K, Mn, and Zn from rachises to grains, but significantly inhibited the transfer of Cd from flag leaves to the uppermost internodes. Furthermore, the application of malic acid decreased the concentration of Cd in the uppermost internodes by 59.84%, and in rachises by 75.77%. Spraying Zn significantly increased the content of Ca and Fe in grains. Spraying Mn significantly promoted the transport of K from rachises to grains. These results indicate that spraying malic acid, Mn, and Zn can significantly decrease the Cd content in rice grains by promoting the influx of essential elements (i.e., K, Mn, and Zn)into them.