本文選題：水稻種子干燥 + 黏彈特性��； 參考：《中國農業(yè)大學》2017年博士論文

【摘要】：干燥處理對農作物種子儲藏至關重要,干燥過程能夠降低種子水分含量,減緩微生物造成的腐敗,避免冷凍過程產生的損傷,從而延緩種子老化,提高種子儲藏時間。不適當?shù)母稍锓绞綍䲟p害細胞膜結構,導致細胞內酶失活,蛋白質變性,種皮破裂,從而使種子失去活力。我國對糧食干燥研究較多,對種子干燥研究相對較少。研究種子干燥過程熱動力學特性及其生理生化變化規(guī)律,建立科學合理的干燥技術,對種子干燥行業(yè)的發(fā)展有著重要的指導意義。論文研究水稻種子在不同溫度和水分活度下的平衡含水量,并通過GAB、Halsey、Smith、Oswin、Herderson和修正的Chung-Post模型對水稻種子解吸數(shù)據(jù)進行擬合,發(fā)現(xiàn)GAB模型具有最大相關系數(shù)和最小誤差,其最適合描述水稻種子的解吸過程。通過熱動力學分析,得出最小積分熵來確定水稻種子儲藏的最適含水量,并評估了焓-熵補償理論對水稻種子解吸現(xiàn)象的適用性。研究水稻種子在不同溫度下的薄層干燥曲線,結果發(fā)現(xiàn)Page模型、Two-term模型以及Midilli模型能夠很好描述水稻種子薄層干燥特性,其中Page模型的擬合度最高。將水稻種子視為球體,有限圓柱體和立方體,并在此三個形狀下分析干燥過程的有效擴散系數(shù),研究發(fā)現(xiàn)有效擴散系數(shù)隨著溫度升高而增加,其規(guī)律符合阿倫烏尼斯方程,且在球體形狀下獲得的擴散系數(shù)與實驗值最為接近。通過動態(tài)力學分析儀(DMA)在壓縮模式下研究種子的應力松弛行為和動態(tài)黏彈性變化規(guī)律。研究發(fā)現(xiàn)松弛模量隨著溫度和水分的增加而降低,使用時間-溫度-水分疊加原理可以獲得松弛模量主曲線,廣義的麥克斯韋模型可以很好地擬合松弛模量主曲線的實驗數(shù)據(jù)(R20.997)。水稻種子的動態(tài)黏彈性受溫度、含水量和頻率的影響,溫度和含水量的增加會降低水稻種子的儲能模量和損耗模量,而頻率的升高會增加水稻種子的儲能模量和損耗模量。損耗模量和損耗因子隨溫度變化具有相似的趨勢,即隨溫度的升高而增加,當達到峰值后開始下降。損耗因子的峰值所對應的溫度隨著種子含水量的增加而降低。通過在不同干燥條件下對種子進行干燥處理,研究干燥后水稻種子的生理生化變化特性及細胞超微結構變化規(guī)律。結果表明,在45℃條件下干燥水稻種子,由于打破了種子休眠期,其種子活力指數(shù)最高,隨著干燥溫度的增加,水稻種子的發(fā)芽率降低。水稻外殼顏色不隨溫度的變化而改變,但稻米表面顏色會隨著溫度增加而逐漸變黃。隨著干燥溫度升高,種子導電率逐漸增加。種子淀粉結構和胚細胞結構隨著溫度升高而嚴重受損。水稻種子活力與干燥過程中細胞結構的完整性密切相關。研究不同干燥條件下水稻種子的發(fā)芽率,分析種子起始含水量、干燥溫度和干燥時間對種子發(fā)芽率的影響。通過多個模型對種子發(fā)芽數(shù)據(jù)進行擬合,研究表明改進的Giner1和2模型能夠很好模擬干燥過程水稻種子的發(fā)芽率變化,用于預測水稻種子干燥后的發(fā)芽率。通過干燥-緩蘇工藝對水稻種子進行干燥,探究高溫緩蘇干燥是否能夠保持種子品質的可能性。研究表明:干燥-緩蘇處理可以提高干燥效率,降低干燥時間,同時適當?shù)母稍餃囟�、干燥時間和緩蘇時間可以打破種子休眠期,保持種子品質并提高種子發(fā)芽速率。
[Abstract]:Drying is very important for the storage of crop seeds. The drying process can reduce the water content of the seeds, slow down the corruption caused by the microorganism, avoid the damage caused by the freezing process, delay the aging of the seeds, and improve the storage time of the seeds. There is more research on grain drying in China and less research on seed drying in China. Research on thermal dynamic characteristics and physiological and biochemical changes in the process of seed drying and establishing a scientific and rational drying technology have important guiding significance for the development of seed drying industry. At different temperature and water activity, the equilibrium water content was measured by GAB, Halsey, Smith, Oswin, Herderson and modified Chung-Post model. The maximum correlation coefficient and minimum error of the GAB model were found. It was the most suitable for describing the process of the desorption of rice seeds. The integral entropy was used to determine the optimum water content in rice seed storage, and the applicability of the enthalpy entropy compensation theory to the phenomenon of rice seed desorption was evaluated. The thin drying curves of rice seeds at different temperatures were studied. The results showed that the Page model, the Two-term model and the Midilli model could well describe the thin layer drying characteristics of rice seeds, of which Page The model has the highest fitting degree. The rice seed is regarded as a sphere, a finite cylinder and a cube, and the effective diffusion coefficient of the drying process is analyzed under the three shapes. It is found that the effective diffusion coefficient increases with the increase of temperature. The law conforms to the Al enennis equation, and the diffusion coefficient and the experimental value obtained under the shape of the sphere are the most. A dynamic mechanical analyzer (DMA) is used to study the stress relaxation behavior and dynamic viscoelastic changes of the seeds under the compression mode. It is found that the relaxation modulus decreases with the increase of temperature and moisture. The principal curve of the relaxation modulus can be obtained by using the principle of time temperature and moisture superposition. The generalized Maxwell model can be good. The dynamic viscoelasticity of rice seed is affected by temperature, water content and frequency, and the increase of temperature and water content will reduce the storage modulus and loss modulus of rice seed, while the increase of frequency will increase the storage modulus and loss modulus of rice seeds, loss modulus and loss factor, R20.997. There is a similar trend with the temperature change, that is, it increases with the increase of temperature, and begins to decrease when it reaches the peak. The temperature corresponding to the peak value of the loss factor decreases with the increase of the water content of the seed. By drying the seeds under different drying conditions, the physiological and biochemical characteristics of the rice seeds after drying and the cells are studied. The results showed that the seed vigor index of dry rice seeds was highest at 45 degrees centigrade. With the increase of drying temperature, the germination rate of rice seeds decreased. The color of rice hull did not change with the temperature, but the color of rice surface would gradually become yellow with the increase of temperature. With the increase of drying temperature, the conductivity of seed gradually increased. The structure of seed starch and the structure of embryo cell were seriously damaged with the increase of temperature. The vigor of the rice seed was closely related to the integrity of the cell structure during the drying process. The germination rate of rice seeds under different drying conditions was studied, the initial water content, drying temperature and drying of the seeds were analyzed. The effect of time on seed germination rate was fitted by multiple models. The study showed that the improved Giner1 and 2 model could well simulate the change of germination rate of rice seeds in the drying process. It was used to predict the germination rate of rice seeds after drying. The study shows that dry and slow sustaining treatment can improve the drying efficiency and reduce the drying time. At the same time, the appropriate drying temperature, drying time and time can break the dormancy period of the seed, keep the seed quality and increase the germination rate of the seeds.
【學位授予單位】：中國農業(yè)大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S511

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本文編號：2090802