农业工程学报Issue(15)：279-284,6.DOI:10.11975/j.issn.1002-6819.2015.15.038
利用低场核磁共振分析水稻种子浸泡过程中的水分变化
Analysis of moisture changes during rice seed soaking process using low-field NMR
摘要
Abstract
Low field nuclear magnetic resonance (LF-NMR) has the technique advantages of nondestructive and non-invasive, which can be used to study the variation, distribution and flow of different phase state moisture in rice seed through the detection of proton’s density and distribution in samples. In this paper, Shennong No. 9816 and No. 9903 rice seeds were used in the study. The center frequency and pulse width were determined using the FID pulse sequence in the NMR spectroscopic analysis software. The low field NMR technique and dynamic detection of the CPMG pulse sequence signal were used to determine the spin relaxation time of samples (the transverse relaxation timeT2). The variation and flow of different phase state moisture during seed soaking were analyzed by the change of time signal and the peak position due to the inversion mapping ofT2. The value of the relaxation timeT2 reflected the value of the water degree of freedom in the sample. The change of the relaxation timeT2 can reflect the mobility of the water molecules. The effects of rice varieties and soaking temperature on the moisture absorption ratio has been studied according to the regression equation between theT2 relaxation spectrum total area of peakA and rice seed moisture absorption ratio. The experimental results showed that the regression equation of theT2relaxation spectrum peak area and the moisture absorption ratio of rice seed was correlated well and the equation reached a significant (P < 0.05) level of detection. The moisture absorption ratio of rice seed was reasonably estimated through theT2relaxation spectrum peak area. The moisture in the rice seeds was in two phases, combined moisture and free moisture during soaking process according to the multiple components characteristics ofT2 and moisture characteristics of the seed. The critical value of combined moisture and free moisture was 10 ms. The short relaxation timeT21 (0.1-10 ms) was defined as combined moisture. This water was closely linked to protein, sugar, phospholipids and other through hydrogen bonds. This water can not flow freely and evaporate. The longer relaxation timeT22(10-1000 ms) was defined as free moisture in magnetic field. This water was in the vacuole, the intercellular and cells gap, which can not be absorbed by the colloid or with poor adsorption capacity. This water can flow freely and can be used as solvent since it has the general properties of water. As for Shennong No. 9816, the trends of combined moisture and total moisture content kept increasing, while the variation of free moisture content was irregular during 18℃ and 6 h soaking process. The variation of moisture content can reflect the physical and chemical reactions in rice seed during soaking process. The differences of rice seed moisture absorption in two rice cultivars were not significant (P>0.05), but rice seed moisture absorption was highly sensitive to the soaking temperature. With the increased soaking temperature, the rice seed moisture absorption per unit time significantly (P< 0.05) increased. This experiment proposed a non-destructive rice seed moisture content detection method, which can reveal the moisture variation more directly and accurately during seed soaking, thus the results can be used to determine the best soaking conditions.关键词
水分/核磁共振/种子/横向弛豫时间/反演谱/水稻/浸种Key words
moisture/nuclear magnetic resonance/seed/transverse relaxation time/inversion spectrum/rice/seed soaking分类
农业科技引用本文复制引用
宋平,杨涛,王成,潘大宇,任鹏..利用低场核磁共振分析水稻种子浸泡过程中的水分变化[J].农业工程学报,2015,(15):279-284,6.基金项目
国家高技术研究发展计划（863计划）作物生产智能监控关键技术与系统研究（2012AA10A503）；国家重大科学仪器设备开发专项“便携式植物微观动态离子流检测设备研发与应用”（2011YQ080052）；公益性行业（农业）科研专项“作物育种材料农艺性状信息高通量获取与辅助筛分技术” （）
