中国农业科学2017，Vol.50Issue(2)：240-249,10.DOI:10.3864/j.issn.0578-1752.2017.02.004
水稻生长过程中籽粒水分状态和横向弛豫特性分析
Analysis of Moisture State and Transverse Relaxation Characteristics of Grains During the Growth Process of Rice
摘要
Abstract
[Objective] This paper is mainly to observe the changes of moisture state of grains during the growth process of rice after heading by LF-NMR, and investigate the effects of accumulation of starch and protein on the moisture state of kernels, which provides reference for formation regularity of rice qualities.[Method] The spikes of "Yueguang" organic rice were sampled at intervals for 63 days after heading (DAH), The 100-grain weight, hardness, moisture content, starch content and protein content were measured, separately, which were used to compare the changes of whole qualities of grains at different growth periods of rice after heading. The transverse relaxation parameters determined by LF-NMR were adopted to qualitatively and quantitatively analyze the moisture dynamics of grains. What's more, the internal relationships between the formation process of rice qualities and moisture state of grains were discussed.[Result]Both the 100-grain weight and starch content for "Yueguang" organic rice increased most quickly within 7-14 DAH, and they were highly significantly and positively correlated with each other (P<0.01). Hardness was highly significantly and positively correlated with starch content and protein content, respectively (P<0.01), and negatively correlated with moisture content (P<0.01). Within 7-56 DAH, moisture content exponentially declined from 57.16% to 22.39%. With showing an S-shaped growth curve, starch content increased to 50.47 g/100g wet-basis within 42 DAH. Protein content linearly increased to the peak value of 6.56 g/100g wet-basis within 7-49 DAH. On the whole, the whole qualities of rice grains had been formed within 49 DAH. The inversion spectrum of LF-NMR data showed that part of water in the grains moved towards the direction of high mobility within 7 DAH. Within 7-21 DAH, when inversion curves of LF-NMR data gradually moved towards the left, T2b peak representing for "bound water" with least mobility occurred, followed by the differentiation phenomenon of T22 peak representing for capillary water. Four kinds of transverse relaxation times including T2b, T21, T22 and T23, gradually decreased with growth periods, which indicated that whole proton degree of freedom in the kernels dropped obviously. The peak ratio of "bound water" was more than peak ratio summation of capillary water and free water at 21 DAH. The moisture content and transverse relaxation parameters (T2b, T21, T22, T23, A2b, A22 and A23) of grains varied with growth periods highly significantly (P<0.01), which were also highly significantly (P<0.01) related to the accumulation of starch and protein. With endosperm cells filled with starch granules, most of water molecules in the grains were mainly surrounded by starch granules and formed hydrogen bonds with hydrophilic groups of starch, which resulted in the migration of moisture state towards the direction of "bound water". According to principal component analysis of transverse relaxation signals, there were significant differences among the moisture state of rice grains for different growth periods within 42 DAH, followed by keeping steady.[Conclusion] It was found that during the grain-filling process of rice, the moisture state of grains was significantly related to the accumulation of starch and protein. The ratio of "bound water" gradually increased, and the ratios of capillary water and free water significantly decreased in the grains. LF-NMR can be adopted to effectively analyze the whole moisture dynamic changes of grains at different growth periods of rice after heading.关键词
水稻/籽粒淀粉积累/水分状态/核磁共振/横向弛豫特性/主成分分析Key words
rice/starch accumulation of grains/moisture state/nuclear magnetic resonance/transverse relaxation characteristics/principal component analysis引用本文复制引用
邵小龙,汪楠,时小转,沈飞,宋伟,张强..水稻生长过程中籽粒水分状态和横向弛豫特性分析[J].中国农业科学,2017,50(2):240-249,10.基金项目
国家自然科学基金(31201443)、公益性行业(粮食)科研专项(201513002-05)、江苏高校优势学科建设工程资助项目(PAPD) （31201443）
