【作者】 杨泽敏；

【导师】 王维金；

【作者基本信息】 华中农业大学 ， 作物栽培与耕作学， 2003， 博士

【摘要】 以不同品质的水稻品种为材料，研究了施肥及结实期温度对稻米品质的影响及不同品质的品种灌浆过程中与淀粉合成有关的酶活性的动态。应用扫描电子显微镜观察了稻米糊化前后的微结构，同时还观察了运用化学方法分离的直、支链淀粉和中间成分的结构。结果如下： 1、品种及米质性状对温度的反应有别，垩白和整精米率的变幅最大，为温度反应敏感型性状；粒长和粒形及出糙率、精米率的变幅最小，为温度反应迟钝型性状；其它为温度反应中间型性状。因垩白基数的大小不同，导致米质优的品种播期间变异系数大，米质劣的品种的变异系数小。结实期温度的诸因素协同影响米质，含日均温、日均温差、日均最高、最低温的均温因子影响较大；含积温、累计最高、最低温、累计温差的积温因子的影响中等。均温和积温因子对米质影响的方向和大小依品种而有变化，两因子各指标的影响力和效应一致。日均温差指数越高，稻米品质越好；日均温差指数越低，稻米品质越差。外观、加工、营养和蒸煮因子对米质影响较大，贡献率依次为45.54％、19.06％、12.17％、9.16％。品种和播期的影响表现在米质性状的各方面，品质好的稻米整精米率高、垩白少、蒸煮品质良好、蛋白质含量适中。相关分析表明：出糙率与精米率、粒长、直链淀粉含量正相关分别达到极显著和显著水平，与长／宽显著负相关；整精米率与胶稠度、蛋白质含量显著正相关；垩白粒率与垩白度显著正相关，与长／宽、蛋白质含量显著负相关；粒长与长／宽极显著正相关，与蛋白质含量显著负相关；糊化温度与蛋白质含量正相关极显著，与直链淀粉含量负相关极显著；直链淀粉含量与蛋白质含量极显著正相关。11项指标的复相关均极显著。 2、齐穗期喷施叶面肥能改善加工品质，适当提高直链淀粉含量，延长胶稠度，但促进垩白发生。早季种植形成较优米质的最佳氮肥用量大于晚季种植，增氮的同时应选择小垩白品种，以扬其改善加工、蒸煮、营养品质之长，避增垩白之短。重施基肥吻合早季稻生育期短、灌浆快的特点，使其尽早吸收、充分利用氮素，故能形成较优米质，而重施穗肥吻合晚季稻生育期长、灌浆平缓的特点，在生育后期集中向籽粒供氮，利于优良米质的形成。施氮时期及用量调控优质米的形成与适应不同品种类型或不同季节的生长发育特点有关，但伴随加工、蒸煮、营养品质改善的同时，垩白总是增加，因此小垩白品种是运用氮肥调控米质的基础。加工品质与垩白受氮肥调控的影响最大，直链淀粉含量、胶稠度受影响次之，粒长及粒形受影响较小，糊化温度几乎不受影响。施氮越多，施用时期越晚，蛋白质含量越高。 3、灌浆结实期喷施植物生长调节剂，如BR-120，PDJ，ALA等使早季种植的杨泽敏:温度与施肥对稻米品质的影响及其籽粒发育的酶动态与显徽结构研究整精米率下降，使晚季种植的整精米率上升。植物生长调节剂的作用与栽培措施密切联系。采用后期促进水稻生长的栽培方法，在使用植物生长调节剂时使米质下降，故结实期喷施植物生长调节剂应与促进前期生长、重打基础的栽培方法结合使用。 4、籽粒灌浆动态与酶活性变化有密切的联系，灌浆速率最大的时期也是大多数酶活最高的时期，籽粒灌浆平缓，灌浆前、中期时期较长的稻米品质较好。ADPG焦磷酸化酶活性较稳定，不同品种的酶活性高峰一致，而Q酶表现出与其它各酶不一样的动态。 5、利用扫描电镜观察稻米糊化前后的微结构，发现同等条件下不同部位的糊化明显不同。背部糊化最好，细胞完全崩解为絮状或小块状的蓬松态物质;腹部糊化次之，呈较大块状或细胞结构刚刚被破坏，有的细胞轮廓仍然可见;中部糊化最差，多为完整胚乳细胞。不同品种糊化后差异明显，米质好的品种其背、中、腹部的糊化比米质差的品种的相应部位好，米质较差品种的中部明显凹陷，而米质较优品种的断面较平，该现象同样表现在早、晚稻的对比上。品种间，背部糊化的差异小于中、腹部，米质较优的稻米背、腹、中部的差异比米质差的小。米质较好的品种的胚乳横断面可见较多断裂的细胞，而米质较差的品种几乎见不到断裂的细胞，其数目与稻米品质的优劣有一定的正相关。米质优劣与糊化时的吸水率和延长率正相关，吸水率和延长率高则糊化较好。无论至白区还是非坚白区，米质较优的稻米其淀粉体内的淀粉粒均比米质较差的稻米结合紧密，结晶度高。 6、分离稻米粉得到4种成分:非淀粉成分、直、支链淀粉及中间成分，分别为淡黄色致密粉末、白色疏松粉末、玻璃状和薄膜状物质。扫描电镜下观察非淀粉成分为较大的致密团块，直链淀粉为质地疏松的颗粒，支链淀粉由极细的微粒组成、切面有分层产生的窄裂缝，中间成分处于直、支链淀粉的过渡态，但不是二者的简单混合，颗粒较支链淀粉粗糙，切面分层产生的裂缝较大。更多还原

【Abstract】 Using difference varieites with varied quality as materials, effects of fertilization and temperature in ripening period on rice quality and the enzyme dynamic status were studied. The microstructures of endosperms before and after gelatinization and that of the four fractions which have been isolated by chemical methods were observed with scanning electron microscopy. The results were as follows.1 Variations of varieties or quality traits under varied temperature are different. Chalkiness and head rice rate possess the largest C.V., are named sensitive trait for temperature. Grain length, kernel shape, brown rice rate and milled rice rate possess the minor C. V., are named slow-witted trait for temperature. Other traits are named middle trait. Superior variety possess desirable C. V. because of little chalkiness while the inferior variety possess minor C. V. because of big chalkiness. All of the temperature factors during ripening period taken great roles for rice quality. The first part includes daily average temperature, daily average highest temperature, daily average lowest temperature and daily average temperature variation, are called average temperature factor. The second part include accumulate daily average temperature, accumulate daily highest temperature, accumulate daily lowest temperature and accumulate daily average temperature variation, are called accumulate temperature factor. The influence of average and accumulate temperature factor have a little change in view of different varieties. All of the items in each factor have the same influence direction. Higher daily average temperature index cause the better rice quality. The quality of appearance, milling, nutrition and cooking take great roles in rice quality by principal component analysis and correlation analysis. Their contribution ratios are 45.54%, 19.06%, 12.17% and 9.16%. The affection of different varieties and seasons for quality are general for each trait. The better rice possess high head rice rate, little chalkiness, good cooking quality and middle protein content. Correlation analysis show that brown rice rate have notable or very notable directly proportion with milled rice rate, kernel length and amylose content, but it has notable inversely proportion with length/width of grain. Head rice rate have notable directly proportion with gel consistency and protein content. Chalky rice rate has notable directly proportion with chalkiness, have notable inversely proportion with length/width of grain and protein content. Kernel length has notable directly proportion with rate of length/width, have notable inversely proportion withprotein content. Gelatinization temperature has notable directly proportion with protein content, have notable inversely proportion with amylose content. Amylose content has notable directly proportion with protein content. The multiple correlation coefficients of eleven items are all significant at 1% level.2 The grinding quality is polished, amylose content is improved and gel consistency is extended by spraying fertilizer solution during ripening period while the chalkiness is increased. The optimal nitrogen quantity for the best quality planted in early season is more than of the late season. For using the forte of improving grinding, cooking and nutrition quality, avoiding the weakness of increasing chalkiness, little chalkiness variety should be selected when adding the nitrogen quantity. Heavy basis fertilizer is best for the rice quality planted in early season because it coincide with its characters while heavy spike fertilizer is best for the rice planted in late season because of coinciding with its characters. Adjusting the rice quality by applying time and quantity of nitrogen is correlation with whether it could be coincided with the characters of different varieties or seasons. Little chalkiness variety is the key element of adjusting rice quality by nitrogen because it always increasing with the polishing of grinding, cooking and nutrition quality. Variations of grinding quality a更多还原