叶面喷施氨基酸对水稻Cd转运特性和稻米氨基酸含量的影响

Effects of foliar application with amino acids on Cd transport and amino acid content of rice

为了探讨氨基酸叶面肥的降Cd潜力,在湖南水稻开花期喷施6种氨基酸,对水稻Cd转运特性及其稻米Ca、Fe、Mn、Zn和氨基酸含量的变化进行了分析。试验结果表明:喷施2次10 mmol·L^(-1)苯丙氨酸(Phe)、甘氨酸(Gly)、异亮氨酸(Ile)、丝氨酸(Ser)、蛋氨酸(Met)和0.02 mmol·L^(-1)的色氨酸(Trp),能使稻米、穗颈、穗下节中的Cd含量显著下降,稻米中的Cd平均含量从0.63 mg·kg^(-1)分别下降至0.27~0.48 mg·kg^(-1)。其中喷施Ser、Trp和Met的降Cd幅度高达51.1%~57.3%,而Phe和Gly的降Cd幅度仅为24.7%~35.1%。与此同时,水稻各器官中Ca和Fe的含量显著上升,Mn的含量显著下降,Zn的含量无显著变化。喷施氨基酸对Cd在水稻器官间的转移系数无显著影响,但显著降低了稻米、穗颈和穗下节中Cd含量与Ca、Fe、Mn含量的比率。喷施Ser和Met使稻米中的必需氨基酸含量分别增加7.5%和10.5%、非必需氨基酸分别增加13.9%和5.5%;喷施6种氨基酸都能显著增加稻米谷氨酸(Glu)、亮氨酸(Leu)和半胱氨酸(Cys)的含量。稻米Cd含量与Cd∶Ca、Cd∶Fe、Cd∶Mn的含量比率呈极显著正相关,与Glu和Ca含量呈极显著负相关。综上所述,喷施Ser、Trp和Met能显著促进Ca、Fe转运和Glu合成,提高Ca、Fe、Mn离子通道对Cd的拦截能力,从而有效降低稻米、穗颈和穗下节中的Cd含量。

To investigate the potential of foliar application with amino acids in inhibiting Cd transport,changes in the Ca,Fe,Mn,Zn,and amino acid content of rice were analyzed after spraying six amino acids during the flowering stage of rice plants in Hunan.Experimental results showed that spraying 10 mmol·L^(-1) phenylalanine(Phe),glycine(Gly),isoleucine(Ile),serine(Ser),methionine(Met),and 0.02 mmol·L^(-1) tryptophan(Trp)twice significantly reduced the content of Cd in rice grains,spike necks,and the uppermost nodes.The average Cd content in rice grains decreased from 0.63 mg·kg^(-1) to 0.27-0.48 mg·kg^(-1),respectively.Spraying Ser,Trp,and Met reduced rice Cd by 51.1%-57.3%;whereas Phe and Gly reduced rice Cd by 24.7%-35.1%,respectively.At the same time,the content of Ca and Fe in rice organs increased significantly,while Mn content decreased significantly and Zn content showed small fluctuations.Spraying amino acids had no significant effect on the transfer coefficient of Cd between rice organs,but significantly reduced the ratios between Cd content and the content of Ca,Fe,or Mn in rice grains,spike necks,and the uppermost nodes.Spraying Ser and Met increased the content of essential amino acids in rice by 7.5%and 10.5%,and non-essential amino acids by 13.9%and 5.5%,respectively.After application of the six amino acids,the content of glutamate,leucine,and cysteine in rice was significantly increased.Cd content in rice was positively correlated with the value of Cd∶Ca,Cd∶Fe,and Cd∶Mn,but negatively correlated with glutamate and Ca content.These results indicate that spraying Ser,Trp,and Met can efficiently reduce the Cd content in rice grains,spike necks,and the uppermost nodes by promoting the transport of Ca and Fe ions and synthesis of glutamate,as well as improving the interception ability of Ca,Fe,and Mn channels to Cd ions.