Leung, Hoi Ching. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 114-128). / Abstracts in English and Chinese. / THESIS/ASSESSMENT COMMITTEE --- p.i / STATEMENT FROM AUTHOR --- p.ii / ACKNOWLEDGEMENTS --- p.iii / ABSTRACT --- p.v / TABLE OF CONTENTS --- p.xi / LIST OF FIGURES --- p.xvi / LIST OF TABLES --- p.xviii / LIST OF ABBREVIATIONS --- p.xix / Chapter CHAPTER 1. --- GENERAL INTRODUCTION --- p.1 / Chapter CHAPTER 2. --- LITERATURE REVIEW --- p.4 / Chapter 2.1 --- Nutritional quality of rice --- p.4 / Chapter 2.1.1 --- Classification of seed proteins --- p.4 / Chapter 2.1.2 --- Amino acid composition of rice proteins --- p.5 / Chapter 2.1.3 --- Other nutritional components of rice --- p.6 / Chapter 2.2 --- Rice seed storage proteins --- p.7 / Chapter 2.2.1 --- Properties and classification of seed storage proteins --- p.7 / Chapter 2.2.2 --- Composition and stucture --- p.9 / Chapter 2.2.2.1 --- Glutelin --- p.9 / Chapter 2.2.2.2 --- Prolamin --- p.10 / Chapter 2.2.2.3 --- Albumin and globulin --- p.12 / Chapter 2.2.3 --- "Synthsis, assembly and deposition of rice seed storage proteins" --- p.13 / Chapter 2.2.3.1 --- Storage protein folding and assembly in the ER --- p.14 / Chapter 2.2.3.2 --- Storage protein transport and protein body formation --- p.16 / Chapter 2.2.3.3 --- Protein bodies and their distribution in endosperm --- p.18 / Chapter 2.3 --- Transgenic approaches to improve the nutritional quality of rice seed proteins --- p.19 / Chapter 2.3.1 --- General introduction --- p.19 / Chapter 2.3.2 --- Attempts to improve the nutritional quality of seed proteins --- p.20 / Chapter 2.3.3 --- Rice grain quality improvement by genetic engineering --- p.22 / Chapter 2.3.3.1 --- Increase in the lysine content of rice endosperm --- p.22 / Chapter 2.2.3.2 --- Other examples of rice nutritional quality improvement --- p.25 / Chapter 2.3.4 --- Expression of recombinant protein in transgenic plants --- p.26 / Chapter 2.3.5 --- Effects of recombinant proteins on the high-lysine rice --- p.27 / Chapter 2.4 --- Proteomics --- p.28 / Chapter 2.4.1 --- General overview --- p.28 / Chapter 2.4.1.1 --- Two-dimensional polyacrylamide gel electrophoresis for proteome analysis --- p.29 / Chapter 2.4.1.2 --- Protein visualization --- p.32 / Chapter 2.4.1.3 --- Computer-aided image analysis --- p.34 / Chapter 2.4.1.4 --- Mass spectrometry-based methods for protein identification --- p.35 / Chapter 2.4.1.5 --- Database search --- p.36 / Chapter 2.4.1.6 --- Protein sequence database --- p.37 / Chapter 2.4.2 --- Plant proteomics --- p.40 / Chapter 2.4.2.1 --- Rice proteomics --- p.41 / Chapter 2.4.2.2 --- Comparative proteomics --- p.43 / Chapter 2.5 --- Hypothesis and objectives --- p.45 / Chapter CHAPTER 3. --- MATERIALS AND METHODS --- p.47 / Chapter 3.1 --- Materials --- p.47 / Chapter 3.1.1 --- Chemicals and commercial kits --- p.47 / Chapter 3.1.2 --- Instruments --- p.47 / Chapter 3.1.3 --- Softwares --- p.48 / Chapter 3.1.4 --- Plant materials --- p.48 / Chapter 3.2 --- Methods --- p.49 / Chapter 3.2.1 --- Collection of developing rice seeds --- p.49 / Chapter 3.2.2 --- Extraction of rice seed proteins --- p.51 / Chapter 3.2.2.1 --- Extraction of total protein --- p.51 / Chapter 3.2.3.2 --- Extraction of four fractions of rice seed proteins --- p.51 / Chapter 3.2.3 --- 2D gel electrophoresis --- p.53 / Chapter 3.2.3.1 --- Protein precipitation and quantification --- p.53 / Chapter 3.2.3.2 --- Isoelectric focusing (IEF) --- p.54 / Chapter 3.2.3.3 --- IPG strips equilibration --- p.54 / Chapter 3.2.3.4 --- Second-dimension SDS-PAGE --- p.55 / Chapter 3.2.3.5 --- Silver staining of 2D gel --- p.55 / Chapter 3.2.3.6 --- Image and data analysis --- p.56 / Chapter 3.2.4 --- MALDI-ToF mass spectrometry (Matrix Assisted Laser Desorption Ionization-Time of Flight) --- p.56 / Chapter 3.2.4.1 --- Sample destaining --- p.56 / Chapter 3.2.4.2 --- In-gel digestion with trypsin --- p.57 / Chapter 3.2.4.3 --- Desalination of the digested sample with Zip Tip --- p.58 / Chapter 3.2.4.4 --- Protein identification by mass spectrometry and database searching --- p.58 / Chapter 3.2.5 --- Detection of LRP fusion protein in 2D PAGE --- p.59 / Chapter 3.2.5.1 --- 2D gel electrophoresis --- p.59 / Chapter 3.2.5.2 --- Western blotting using anti-LRP antibody --- p.60 / Chapter 3.2.6 --- Antiserum production --- p.61 / Chapter 3.2.6.1 --- Purification of glutelin and prolamin proteins --- p.61 / Chapter 3.2.6.2 --- Immunization of rabbits and mice --- p.62 / Chapter 3.2.6.3 --- Testing of antibody specificity --- p.62 / Chapter 3.2.7 --- Transmission electron microscopy (TEM) --- p.63 / Chapter 3.2.7.1 --- Sample fixation and section preparation --- p.63 / Chapter 3.2.7.2 --- TEM observation --- p.64 / Chapter 3.2.7.3 --- Immunocytochemical observation --- p.64 / Chapter CHAPTER 4. --- RESULTS --- p.66 / Chapter 4.1 --- Proteomic analysis of high-lysine rice --- p.66 / Chapter 4.1.1 --- Extraction of proteins --- p.66 / Chapter 4.1.2 --- The proteomic profiles of different storage proteins in developing high-lysine rice seeds --- p.67 / Chapter 4.1.3 --- Quantitative analysis of protein spots --- p.76 / Chapter 4.1.4 --- Proteomic analysis of salt-soluble proteins --- p.79 / Chapter 4.1.5 --- Proteomic analysis of alcohol-soluble proteins --- p.81 / Chapter 4.1.6 --- Proteomic analysis of salt-soluble proteins --- p.82 / Chapter 4.1.7 --- Proteomic analysis of water-soluble proteins --- p.89 / Chapter 4.1.8 --- Comparison of changes in expression patterns of specific proteins in the high lysine rice --- p.89 / Chapter 4.2 --- Antibody production --- p.92 / Chapter 4.2.1 --- The production of anti-prolamin and anti-glutelin antibodies --- p.92 / Chapter 4.2.2 --- The specificity of anti-prolamin and anti-glutelin antibodies --- p.93 / Chapter 4.3 --- Transmission electron microscopy observation of rice protein bodies --- p.95 / Chapter 4.3.1 --- Morphology of protein bodies in high-lysine rice --- p.95 / Chapter 4.3.2 --- Subcellular localization of storage proteins and LRP --- p.98 / Chapter CHAPTER 5. --- DISCUSSION --- p.100 / Chapter 5.1 --- Protein profiling of LRP fusion protein and its effects on the expression of other proteins --- p.100 / Chapter 5.2 --- Over-expression of glutelin and its effects on the expression of other proteins --- p.102 / Chapter 5.3 --- Formation of malformed protein bodies and deposition of storage proteins --- p.103 / Chapter 5.4 --- Relationship between changes in protein expression and the Unfolded Protein Response --- p.105 / Chapter 5.5 --- Effects of transgenes on rice grain quality --- p.108 / Chapter 5.6 --- Allergenic effects of transgenic rice --- p.109 / Chapter 5.7 --- Future perspectives --- p.110 / Chapter CHAPTER 6. --- CONCLUSIONS --- p.112 / REFERENCES --- p.114

Yu, Chun Wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 115-124). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.iii / ABSTRACT --- p.iv / LIST OF CONTENTS --- p.ix / LIST OF FIGURES --- p.xvi / LIST OF TABLES --- p.xx / LIST OF ABBREVIATIONS --- p.xxi / Chapter CHAPTER 1. --- GENERAL INTRODUCTION --- p.20 / Chapter CHAPTER 2. --- LITERATURE REVIEW --- p.22 / Chapter 2.1 --- Major storage proteins in rice --- p.22 / Chapter 2.1.1 --- Structure and composition of glutelin --- p.22 / Chapter 2.1.2 --- Structure and composition of prolamin --- p.22 / Chapter 2.2 --- Biosynthesis pathway --- p.23 / Chapter 2.2.1 --- "The Biosynthesis, processing & compartmentalization of glutelin" --- p.23 / Chapter 2.2.1.1 --- Endoplasmic reticulum as the site of protein folding and compartmentalization --- p.23 / Chapter 2.2.1.2 --- COP-coated vesicles for protien trafficking between ER and Golgi --- p.25 / Chapter 2.2.1.3 --- Glutelin trafficking beyond ER --- p.26 / Chapter 2.2.1.3.1 --- Golgi as the site of post-translational modification of glutelin / Chapter 2.2.1.3.1.1 --- """Sorting for entry"" and ""sorting by retention"" models: mechanism of dense vesicle formation" --- p.26 / Chapter 2.2.1.3.1.2 --- "“Classical ligand-receptor"" and ""aggregation-mediated"" as the model describing protein sorting in Golgi" --- p.27 / Chapter 2.2.1.3.2 --- Pathway bypassing Golgi apparatus --- p.30 / Chapter 2.2.1.4 --- Prevacuolar compartment and protein body --- p.30 / Chapter 2.2.2 --- "The Biosynthesis, processing and compartmentalization of prolamin" --- p.31 / Chapter 2.3 --- Protein processing enzymes --- p.31 / Chapter 2.3.1 --- Luminal chaperone binding protein (BiP) --- p.31 / Chapter 2.3.2 --- Protein disulfide isomerase (PDI) --- p.33 / Chapter 2.4 --- ER quality control： unfolded protein response --- p.34 / Chapter 2.4.1 --- The importance of quality control in ER --- p.34 / Chapter 2.4.2 --- The target of ER quality control: misfolded protein --- p.35 / Chapter 2.4.3 --- Unfolded protein response --- p.36 / Chapter 2.4.3.1 --- IRE1 --- p.37 / Chapter 2.4.3.2 --- PERK --- p.37 / Chapter 2.4.3.3 --- ATF6 --- p.38 / Chapter 2.4.3.4 --- BiP as the master regulator of three transducers --- p.38 / Chapter 2.5 --- The cause of chalkiness --- p.41 / Chapter 2.5.1 --- "The relationship between ER stress, unfolded protein response and chalkiness" --- p.42 / Chapter 2.6 --- Organelle separation： sucrose density gradient centrifugation --- p.43 / Chapter 2.6.1 --- General introduction --- p.43 / Chapter 2.6.2 --- Plant organelle separation --- p.43 / Chapter 2.6.3 --- Organelle marker enzyme as a mean to elucidate the homogeneity of isolated organelle fraction --- p.44 / Chapter 2.7 --- Rice grain quality improvement by genetic engineering --- p.45 / Chapter 2.7.1 --- Increase in lysine content of rice endosperm --- p.45 / Chapter 2.7.2 --- Physiological and phenotypic changes in GT and LRP-fusion lines --- p.46 / Chapter 2.8 --- Hypotheses and objectives --- p.48 / Chapter CHAPTER 3. --- MATERIALS AND METHODS --- p.49 / Chapter 3.1 --- Materials --- p.49 / Chapter 3.1.1 --- Chemicals and commercial kits --- p.49 / Chapter 3.1.2 --- Instruments --- p.49 / Chapter 3.1.3 --- Plant materials --- p.49 / Chapter 3.1.3.1 --- Glutelin-enriched line (GT) --- p.50 / Chapter 3.1.3.2 --- Gtl-LRP-fusion line (LRP fusion) --- p.50 / Chapter 3.2 --- RNA extraction and northern-blot analysis --- p.50 / Chapter 3.2.1 --- Seed harvesting and RNA extraction --- p.50 / Chapter 3.2.2 --- Northern-blot analysis --- p.51 / Chapter 3.3 --- SDS-PAGE and western-blot analysis --- p.52 / Chapter 3.3.1 --- Seed harvesting and protein extraction --- p.52 / Chapter 3.3.2 --- SDS-PAGE and western-blot analysis s --- p.52 / Chapter 3.4 --- Purification of cellular organelles by SDG centrifugation --- p.53 / Chapter 3.4.1 --- Purification of ER by SDG centrifugation --- p.53 / Chapter 3.4.2 --- Purification of protein body by SDG centrifugation --- p.54 / Chapter 3.4.3 --- Protein body isolation by pepsin treatment --- p.54 / Chapter 3.5 --- Electron-microscopic observation --- p.55 / Chapter 3.5.1 --- Sample preparation for immuno-localization analysis --- p.55 / Chapter 3.5.1.1 --- Sample preparation --- p.55 / Chapter 3.5.1.2 --- Immunocytochemical observation --- p.55 / Chapter 3.5.2 --- Sample preparation for structural analysis --- p.56 / Chapter 3.6 --- Antibodies --- p.56 / Chapter 3.6.1 --- KLH conjugation of synthetic peptide --- p.57 / Chapter 3.6.2 --- Immunization of rabbits --- p.57 / Chapter 3.6.3 --- Antibody purification by affinity column --- p.57 / Chapter 3.6.3.1 --- Preparation of column for coupling --- p.57 / Chapter 3.6.3.2 --- Affinity purification of antibody by prepared column --- p.58 / Chapter 3.6.4 --- Testing of antibody specificity --- p.58 / Chapter CHAPTER 4. --- RESULTS --- p.60 / Chapter 4.1 --- Pro-glutelin accumulation in GT and LRP fusion transgenic lines --- p.60 / Chapter 4.2 --- General morphology and glutelin localization in rice seed --- p.61 / Chapter 4.3 --- "Studies on glutelin, BiP and pdi expression profiles of GT, LRP fusion lines and wild type rice" --- p.63 / Chapter 4.3.1 --- Comparison of the protein and RNA profiles of BiP between wild type and FH transgenic rice lines --- p.64 / Chapter 4.3.2 --- Comparison of the protein and RNA profiles of PDI between wild type and FH transgenic rice lines --- p.66 / Chapter 4.3.3 --- "Comparison of the RNA and protein profiles of BiP between wild type, GH and GL transgenic rice lines" --- p.68 / Chapter 4.3.4 --- "Comparison of the RNA and protein expression profiles of PDI between wild type, GH and GL transgenic lines" --- p.70 / Chapter 4.3.5 --- Summary of RNA and protein level comparison of different transgenic lines with wild type --- p.72 / Chapter 4.4 --- Electron microscopic studies of morphological changes in GLUTELIN OVER-EXPRESSED AND GT1-LRP-FUSION TRANSGENIC LINES AND WILD type rice --- p.73 / Chapter 4.5 --- Isolation of ER-enriched fractions by sucrose density gradient centrifugation --- p.76 / Chapter 4.5.1 --- Cross-contamination assessment by organelle specific marker proteins --- p.77 / Chapter 4.5.2 --- Identification of ER enriched fractions of different transgenic lines --- p.78 / Chapter 4.5.3 --- Studies on ER enriched fraction --- p.85 / Chapter 4.6 --- Isolation and studies on PB enriched fractions of different transgenic lines --- p.91 / Chapter 4.7 --- TEM studies on immuno-localization of ER chaperones (BlP and pdI) in immature rice seeds of different transgenic lines --- p.94 / Chapter CHAPTER 5. --- DISCUSSIONS --- p.101 / Chapter 5.1 --- Distortion of glutelin processing and translocation pathway --- p.101 / Chapter 5.1.1 --- The relationship between proglutelin localization and novel protein body in Gt1-LRP-fusion lines --- p.101 / Chapter 5.1.2 --- The presence of BiP and PDI in novel protein body in Gt1-LR-fusion lines --- p.103 / Chapter 5.1.2.1 --- Glutelin translocation pathway bypassing Golgi --- p.105 / Chapter 5.1.2.2 --- Glutelin translocation pathway through Golgi --- p.105 / Chapter 5.1.2.3 --- Gt1-LRP-fusion protein and proglutelin are trapped in ER --- p.107 / Chapter 5.2 --- "The relationship between novel protein body formation, ER stress, unfolded protein response and chalkiness" --- p.108 / Chapter 5.2.1 --- Relationship between novel protein body formation and unfolded protein response --- p.108 / Chapter 5.2.2 --- Repressing the expression of other storage proteins: consequence of unfold protein response or protein nutrients regulation --- p.109 / Chapter 5.2.3 --- Relationship between novel protein body formation and chalkiness --- p.110 / Chapter 5.3 --- The causes of ER dilation --- p.110 / Chapter 5.4 --- The relationship between different physiological changes in transgenic glutelin lines --- p.111 / Chapter 5.5 --- Future perspectives --- p.112 / Chapter CHAPTER 6. --- CONCLUSIONS --- p.114 / REFERENCES --- p.115 / APPENDIX --- p.125

The effect of drying corn, rice and wheat seed in two stages was studied, using germinability as a measure of quality. For the first stage, fluidised bed dryer (FBD) and spouted bed dryer (SBD) were used to dry seed from 20-25%wb to 18%wb while in-store dryer (ISO) was used in the second stage for drying from 18%wb to below 14%wb. The drying air temperature range of 40-80??C was studied for the first stage while 18-30??C and relative humidity 60-70% were for the second stage. It was found that dryer type, drying temperature, initial moisture content of seeds and drying time had significant effects on the seed germination. From the result, the drying air temperature of 40??C was safe for corn and rice in FBD while 60??C was acceptable for wheat. In SBD, the 40??C was the maximum drying temperature for rice and wheat without quality deterioration. Meanwhile the second stage drying in an ISD under all specified conditions was safe. In this work, the thin-layer drying models were developed. The results showed that the modified Page's model and modified two-compartment model were the best-fitted models with the root mean square (RMS) of the differences between the predicted moisture ratio and the measured values below 0.03. Besides, the existing ISD simulation program provided the RMS of 0.3, 1.1, and 0.9%wb for corn, rice and wheat respectively. The germination models for FBD and SBD were also developed. As a result, the modified Giner's models 1&2 were the best-fitted models for FBD with the RMS of the differences between predicted and measured germination percentages of 7.9, 4.2 and 3.4% for corn, rice and wheat while the modified Giner's models 2&3 were for SBD with the RMS of 5.5 and 6.1% for rice and wheat respectively. The comparison between FBD and SBD revealed that FBD had faster drying rate while SBD consumed less energy. Ultimately, the energy cost analysis showed that single-stage drying in a fixed bed dryer using ambient condition consumed less energy than two-stage drying using a FBD and ISD but lower energy cost must be weighed against the faster drying rate, flexibility, portable design, and product uniformity of FBD.

The effect of drying corn, rice and wheat seed in two stages was studied, using germinability as a measure of quality. For the first stage, fluidised bed dryer (FBD) and spouted bed dryer (SBD) were used to dry seed from 20-25%wb to 18%wb while in-store dryer (ISO) was used in the second stage for drying from 18%wb to below 14%wb. The drying air temperature range of 40-80??C was studied for the first stage while 18-30??C and relative humidity 60-70% were for the second stage. It was found that dryer type, drying temperature, initial moisture content of seeds and drying time had significant effects on the seed germination. From the result, the drying air temperature of 40??C was safe for corn and rice in FBD while 60??C was acceptable for wheat. In SBD, the 40??C was the maximum drying temperature for rice and wheat without quality deterioration. Meanwhile the second stage drying in an ISD under all specified conditions was safe. In this work, the thin-layer drying models were developed. The results showed that the modified Page's model and modified two-compartment model were the best-fitted models with the root mean square (RMS) of the differences between the predicted moisture ratio and the measured values below 0.03. Besides, the existing ISD simulation program provided the RMS of 0.3, 1.1, and 0.9%wb for corn, rice and wheat respectively. The germination models for FBD and SBD were also developed. As a result, the modified Giner's models 1&2 were the best-fitted models for FBD with the RMS of the differences between predicted and measured germination percentages of 7.9, 4.2 and 3.4% for corn, rice and wheat while the modified Giner's models 2&3 were for SBD with the RMS of 5.5 and 6.1% for rice and wheat respectively. The comparison between FBD and SBD revealed that FBD had faster drying rate while SBD consumed less energy. Ultimately, the energy cost analysis showed that single-stage drying in a fixed bed dryer using ambient condition consumed less energy than two-stage drying using a FBD and ISD but lower energy cost must be weighed against the faster drying rate, flexibility, portable design, and product uniformity of FBD.

Made available in DSpace on 2014-08-20T13:44:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-10 / This work aimed to maintain the physiological quality of rice seeds through the reduction of the drying time at high dry air temperatures. The rice seeds cultivar El Paso L-144 were dried in an intermittent industrial drying system, with capacity for 11.000 kg, under four drying conditions : 1) at constant temperature of 40°C ; 2) constant temperature of 60°C ; 3) at gradual increasing temperature (since 60°C) during the first two hours and constant temperature of 60°C until the end of the drying cycle; 4) at gradual increasing temperature (since 60°C) in the first two hours and gradual decreasing temperature until the end of drying cycle. The seeds were kept in bags made of trussed plastic yarns in the city of Alegrete, Rio Grande do Sul, Brazil at room temperature and local environment conditions, for the period of 180 days. The storage system was conventional. Hydrotermic dry behavior, milling yields, humidity, and vigour (through accelerated aging, field emergency test, cold test and electrical conductivity) test were analyzed. In conclusion, the drying process at a constant temperature of 40°C is the one which best preserves the physiological seed quality; on the other hand, the drying process at a constant temperature of 60°C is don t preserves the seed quality; finally, the gradual increased temperature not only accelerates the drying speed but also preserves the physiological seed quality. / O trabalho visou à minimização das perdas na qualidade fisiológica das sementes de arroz através da diminuição do tempo de exposição a altas temperaturas de condicionamento do ar durante a secagem. Sementes de arroz, cultivar EL Paso L-144, foram secadas em secador industrial intermitente, marca Pampeiro, fluxo misto, com capacidade estática de 11000 kg, em quatro manejos do ar de secagem: 1) secagem à temperatura do ar constante a 40°C; 2) secagem com temperatura de condicionamento do ar constante a 60°C; 3) secagem com temperaturas de condicionamento do ar crescentes (até 60°C) nas primeiras duas horas e a partir da segunda hora constante a 60°C; 4) secagem com temperaturas de condicionamento do ar crescentes (até 60°C) nas primeiras duas e decrescentes até o término da secagem. Após as sementes foram armazenadas, nas condições ambientais de Alegrete, Rio Grande do Sul, Brasil, por 180 dias. Foram monitorados os parâmetros hidrotérmicos para cada manejo de secagem e durante o período de armazenamento, foram analisados desempenho industrial, grau de umidade, germinação e vigor (pela primeira contagem da germinação, teste de frio sem solo, envelhecimento acelerado, emergência a campo e condutividade elétrica). Concluiu-se que em escala industrial, para secadores intermitentes de bandejas, nas condições em que o experimento foi executado: (1) a secagem intermitente de semente de arroz com temperatura constante do ar a 60°C afeta a qualidade fisiológica; (2) a secagem intermitente com temperaturas crescentes do ar propicia uma constante remoção de água nas sementes de arroz; (3) na secagem intermitente as sementes de arroz resistem a temperaturas do ar constantes a 40°C; (4) o uso de temperaturas crescentes na secagem intermitente de sementes de arroz proporciona a manutenção da qualidade fisiológica.

Made available in DSpace on 2014-08-20T13:44:38Z (GMT). No. of bitstreams: 1 tese_cristine_saravia.pdf: 270583 bytes, checksum: a44b18a5e03ef6d7c57acad44a2919db (MD5) Previous issue date: 2006-07-10 / This work aimed to maintain the physiological quality of rice seeds through the reduction of the drying time at high dry air temperatures. The rice seeds cultivar El Paso L-144 were dried in an intermittent industrial drying system, with capacity for 11.000 kg, under four drying conditions : 1) at constant temperature of 40°C ; 2) constant temperature of 60°C ; 3) at gradual increasing temperature (since 60°C) during the first two hours and constant temperature of 60°C until the end of the drying cycle; 4) at gradual increasing temperature (since 60°C) in the first two hours and gradual decreasing temperature until the end of drying cycle. The seeds were kept in bags made of trussed plastic yarns in the city of Alegrete, Rio Grande do Sul, Brazil at room temperature and local environment conditions, for the period of 180 days. The storage system was conventional. Hydrotermic dry behavior, milling yields, humidity, and vigour (through accelerated aging, field emergency test, cold test and electrical conductivity) test were analyzed. In conclusion, the drying process at a constant temperature of 40°C is the one which best preserves the physiological seed quality; on the other hand, the drying process at a constant temperature of 60°C is don t preserves the seed quality; finally, the gradual increased temperature not only accelerates the drying speed but also preserves the physiological seed quality. / O trabalho visou à minimização das perdas na qualidade fisiológica das sementes de arroz através da diminuição do tempo de exposição a altas temperaturas de condicionamento do ar durante a secagem. Sementes de arroz, cultivar EL Paso L-144, foram secadas em secador industrial intermitente, marca Pampeiro, fluxo misto, com capacidade estática de 11000 kg, em quatro manejos do ar de secagem: 1) secagem à temperatura do ar constante a 40°C; 2) secagem com temperatura de condicionamento do ar constante a 60°C; 3) secagem com temperaturas de condicionamento do ar crescentes (até 60°C) nas primeiras duas horas e a partir da segunda hora constante a 60°C; 4) secagem com temperaturas de condicionamento do ar crescentes (até 60°C) nas primeiras duas e decrescentes até o término da secagem. Após as sementes foram armazenadas, nas condições ambientais de Alegrete, Rio Grande do Sul, Brasil, por 180 dias. Foram monitorados os parâmetros hidrotérmicos para cada manejo de secagem e durante o período de armazenamento, foram analisados desempenho industrial, grau de umidade, germinação e vigor (pela primeira contagem da germinação, teste de frio sem solo, envelhecimento acelerado, emergência a campo e condutividade elétrica). Concluiu-se que em escala industrial, para secadores intermitentes de bandejas, nas condições em que o experimento foi executado: (1) a secagem intermitente de semente de arroz com temperatura constante do ar a 60°C afeta a qualidade fisiológica; (2) a secagem intermitente com temperaturas crescentes do ar propicia uma constante remoção de água nas sementes de arroz; (3) na secagem intermitente as sementes de arroz resistem a temperaturas do ar constantes a 40°C; (4) o uso de temperaturas crescentes na secagem intermitente de sementes de arroz proporciona a manutenção da qualidade fisiológica.