要世瑾,牟红梅,杜光源,冯 浩,白江平,何建强.小麦种子吸胀萌发过程的核磁共振检测研究[J].农业机械学报,2015,46(11):266-274.
Yao Shijin,Mou Hongmei,Du Guangyuan,Feng Hao,Bai Jiangping,He Jianqiang.Water Imbibition and Germination of Wheat Seed with Nuclear Magnetic Resonance[J].Transactions of the Chinese Society for Agricultural Machinery,2015,46(11):266-274.
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小麦种子吸胀萌发过程的核磁共振检测研究   [下载全文]
Water Imbibition and Germination of Wheat Seed with Nuclear Magnetic Resonance   [Download Pdf][in English]
投稿时间:2015-07-16  
DOI:10.6041/j.issn.1000-1298.2015.11.036
中文关键词:  小麦 种子 萌发 吸水率 核磁共振成像 T2弛豫谱
基金项目:国家高技术研究发展计划(863 计划)资助项目(2013AA102904)、国家自然科学基金资助项目(51209176、31201122)和高等学校学科创新引智计划(111计划)资助项目(B12007)
作者单位
要世瑾 西北农林科技大学 
牟红梅 西北农林科技大学 
杜光源 西北农林科技大学 
冯 浩 西北农林科技大学
中国科学院水利部水土保持研究所 
白江平 甘肃农业大学 
何建强 西北农林科技大学 
中文摘要:将核磁共振成像和T2弛豫检测相结合,对处于萌发过程的小麦种子进行了连续72h检测。小麦种子核磁成像显示,吸胀阶段(0~6h)种子皮层、胚和珠心突起的水分含量明显增加;萌动阶段(6~22h)珠心突起的水分向胚乳扩散;萌发阶段(22~72h),胚根和胚芽鞘陆续长出,吸水率增大,胚乳含水量升高并逐渐活化。T2弛豫检测显示,小麦种子吸水率存在快速吸水、平稳吸水及振荡吸水3个阶段,与成像显示的萌发3阶段相对应,体现了种子萌发对水分需求的动态过程。核磁共振技术能够直观且连续地反映小麦种子内部水分的变化和分布,为科学揭示小麦种子萌发过程、合理调控萌发过程土壤水分状况提供了新的试验方法和理论依据。
Yao Shijin  Mou Hongmei  Du Guangyuan  Feng Hao  Bai Jiangping  He Jianqiang
Northwest A&F University,Northwest A&F University,Northwest A&F University,Northwest A&F University;Institute of Water and Soil Conservation, Chinese Academy of Sciences and Ministry of Water Resources,Gansu Agricultural University and Northwest A&F University
Key Words:Wheat Seed Germination Imbibition Magnetic resonance imaging T2 relaxation spectrum
Abstract:Water absorption influences the germination and metamorphosis of seed. A continuous long term investigation of germination process and water distribution can help to reveal the water absorption mode of winter wheat (Triticum aestivum L.) seed and lay a theoretic foundation for rational water management during seed germination. The nuclear magnetic resonance (NMR) technique can be used on probe water distribution of seed in a noninvasive and nondestructive way and has been broadly used in the studies on seed and water relationship. The techniques of magnetic resonance imaging (MRI) and T2 relaxation spectrum of NMR were used to continuously investigate the water distribution and variation in a germinating seed of winter wheat for 72h. Images of longitudinal and transverse sections of wheat seed were obtained every hour after the starting of imbibition and used to observe water distributions in different seed tissues. When the seed soaked, its volume increased rapidly at the beginning of seed imbibition (0~6h). Some localized hydrations were already evident in the embryo, coat, and nucellar projection. During the germination prepare phase (6~22h), water content of the coat was higher than that of the endosperm and there was a clear boundary between the bran and the endosperm in the images. Although water accumulated in the coat surrounding the endosperm, there was no evident movement of water directly across the coat and into the underlying starchy endosperm. The water content of nucellar projection was also higher than that of endosperm. Only the water from the nucellar projection gradually diffused into the endosperm. This proved that it was through the nucellar projection rather than the coat and embryo, the water entered into wheat seed. This finding is different from the description in some current textbooks. In this process, the water content of embryo increased and the volume of embryo was increasing at the same time. It showed that embryonic cells began to divide and elongate, and the volume of root sheath became remarkably larger than before. In the stage of germination, the root sheath emerged from a breaking hole in seed coat at 22h and the radicle grew smoothly out at 24h. Thereafter, the volume of shoot sheath started to increase and the seed sprouted at 27h. From then on, seed imbibed water through the radicle and hole in the coat. Water content of endosperm increased and endosperm was activated from bottom to top. Nutrients stored in the aleurone cells near the embryo began decomposing and moved to the central area gradually. The above processes of water transfer and distribution could not be visually detected from the outside with traditional methods. The results of T2 relaxation spectrum analysis showed that there were three distinct phases of water uptake during the germination of a mature dry seed of winter wheat. During the first phase, water-uptake was rapid initially and then became stable. In the second phase, water absorption rate increased slowly, which was different from the traditionally observed period of stagnation. This phenomenon was probably due to the temperature change effect and magnetic biological effect on plant growth during the NMR detection. In the third phase, water absorption rate oscillated remarkably. This kind of oscillation was probably caused by the periodic water absorption by plant roots. When roots grew over time, their ability to absorb water was enhanced. Thus, the amount of water involved in metabolic activity became larger. When the seed needed a large amount of water for metabolism, the root had to absorb enough water to meet the metabolic demand. After that, the water absorption rate of roots reduced appropriately until the seed required plenty of water for metabolism again. Hence, the water absorption rate of wheat seed oscillated sharply, but with an overall increase in the third phase. In general, the techniques of NMR can help to reveal the water dynamics and distribution in germinating seed more continuously and precisely. The study also realized the direct inside measurement of water content variation in wheat seed, which could not be detected directly with traditional methods. The results will help lay a theoretic foundation for the study and management of germination and water consumption of winter wheat.

Transactions of the Chinese Society for Agriculture Machinery (CSAM), in charged of China Association for Science and Technology (CAST), sponsored by CSAM and Chinese Academy of Agricultural Mechanization Science(CAAMS), started publication in 1957. It is the earliest interdisciplinary journal in Chinese which combines agricultural and engineering. It always closely grasps the development direction of agriculture engineering disciplines and the published papers represent the highest academic level of agriculture engineering in China. Currently, nearly 8,000 papers have been already published. There are around 3,000 papers contributed to the journal each year, but only around 600 of them will be accepted. Transactions of CSAM focuses on a wide range of agricultural machinery, irrigation, electronics, robotics, agro-products engineering, biological energy, agricultural structures and environment and more. Subjects in Transactions of the CSAM have been embodied by many internationally well-known index systems, such as: EI Compendex, CA, CSA, etc.

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