水稻种植模式对水稻籽粒离子组的影响

摘要

亚细胞、细胞、器官乃至有机体内所有矿质元素的组合称为离子组。离子组是植物化学元素指纹，能够定量、精准地反映环境因子驱动下植物体产生的无机化学响应。为探求不同种植模式对水稻籽粒离子组的影响，采用大田试验，研究比较了长期常规种植、绿色蛙稻和有机蛙稻3种水稻种植模式水稻籽粒中矿质元素含量的差异和元素间的相关关系，并探讨了土壤中可利用态元素向水稻籽粒中的转移效率。21种元素含量通过高通量元素分析电感耦合等离子体质谱仪(ICP-MS)测定，并利用主成分分析和方差分析等统计方法分别对数据进行综合分析和各元素处理间差异分析。结果表明，各元素在水稻籽粒中的浓度顺序为： K>P>Mg>Ca>Mn>Zn>Fe>Cu>Rb>Na>Ba>Mo>B>Ni>Sr>As>Cr>Cd>Se>Co>Cs。主成分分析结果表明，不同水稻种植模式对水稻籽粒离子组有显著影响，第1主成分占总变量的32.7%，区分了有机和绿色种植模式；第2主成分占总变量的27.1%，将常规种植模式和另外两种模式区分开。不同水稻种植模式对水稻籽粒离子组有显著影响。与常规种植相比，绿色蛙稻模式下籽粒第1主族元素K、Na、Cs、Rb含量显著增加21%、31%、59%、72%， Mn、Cd的含量显著增加23%、441%， B和Cr的含量显著降低63%和51%；有机模式下水稻籽粒中Co、Ni和Cd含量分别增加60%、286%和488%，而Ca、B、Mo、Sr和Cr的含量显著降低38%、60%、20%、27%和96%，而同主族元素间的竞争并未发现。因此，从水稻必需元素吸收角度出发，绿色蛙稻种植模式优于有机和常规种植模式；但绿色和有机蛙稻种植模式对一些非必需元素的吸收也为水稻食品安全带来隐患。因此，科学的养分管理和合理种植结构的调整对保证水稻食品的安全有非常重要的意义和价值。%The elemental composition of a subcellular compartment, cell, tissue or organism is termed as ionome, which involves of all mineral elements of life, regardless of chemical forms these occur. Ionome is the inorganic chemical element fingerprint of plant that quantitatively and accurately reflects inorganic response of plants to environment stimuli. A field experiment was conducted to explore the differences and correlations of mineral elements in rice seeds cultivated in conventional cultivation ecosystem, green rice-frog ecosystem and organic rice-frog ecosystem under long-term management. The study also determined the transportability of available elements from soil to rice seeds to explore the correlation of elements between soil and rice seed. The concentrations of 21 mineral elements in the rice samples and soil were determined using high-throughput elemental analysis technology such as inductively coupled plasma optical emission and mass spectrometry (ICP-MS). Statistical method used to profile multi-elemental composition, and principle component analysis (PCA) to discriminate differences among treatments. Then ANOVA analysis was used to compare the differences among treatments for each element. The results showed the ranked order of the concentrations of 21 elements in rice seeds was:potassium (K)>phosphorus (P)>magnesium (Mg)>calcium (Ca)>manganese (Mn)>zinc (Zn)>ion (Fe)>copper (Cu)>rubidium (Rb)>sodium (Na)>barium (Ba)>molybdenum (Mo)>boron (B)>nickel (Ni)>strontium (Sr)>arsenic (As)>chromium (Cr)>cadmium (Cd)>selenium (Se)>cobalt (Co)>cesium (Cs). PCA analysis showed that ionome of rice seeds was significantly affected by different cultivation patterns. The fist component accounted for 32.7% of the total variation, which separated organic rice-frog ecosystem from organic rice-frog ecosystem. The second component accounted for 27.1%of the total variation, which discriminated conventional cultivation system from the other two ecosystems. Compared with conventional cultivation, the concentrations of K, Na, Rb and Cs (which belonged to the first group of the periodic table), Mn and Cd in rice seeds significantly increased by 21%, 31%, 59%, 72%, 23% and 441%, respectively, in green rice-frog ecosystem. On the contrary, B and Cr decreased by 63%and 51%under green rice-frog ecosystem. The concentrations of Co, Ni and Cd in rice seeds increased by 60%, 286%and 488%, but Ca, B, Mo, Sr and Cr decreased by 38%, 60%, 20%, 27%and 96%under organic rice-frog ecosystem. However, no competition was observed among element pairs in this study. Moreover, essential elements such as Zn, Cu and P had higher transportability from soil to rice seeds, while non-essential elements such as Na, Ba and Cs had lower transportability from soil to plant. Based on nutrient element accumulation in rice, the study showed that green rice-frog ecosystem was better than both organic rice-frog ecosystem and the conventional cultivation system. However, the uptake and accumulation of some non-essential elements in rice seeds under green rice-frog ecosystem and organic rice-frog ecosystem also put rice crops and food security at risk. Therefore, it was important to improve existing knowledge on scientific management of nutrients as well as reasonable adjustment of planting structures to ensure food security.