Water penetration into rice grains during soaking observed by gradient echo magnetic resonance imaging

The water penetration into a rice grain during soaking was monitored by three-dimensional gradient echo magnetic resonance imaging, which has the advantage of a short measurement time and a sufficient sensitivity for low-moisture samples. The water penetration route was compared between the milled and brown rice grains of two japonica cultivars. In normal milled rice grains of Koshihikari, water first penetrated the ventral side surface and the embryo attachment site of the endosperm, then migrated along the central line and transverse cracks, and finally diffused to all parts of the endosperm. In milled rice grains of Yamadanishiki with a white core, water quickly infiltrated into the cracks or chalky parts on the dorsiventral line and then diffused to the lateral side. In brown rice grains of both cultivars water penetrated extremely slowly and did not infiltrate directly into transverse cracks or the white core due to inhibition by the pericarp and seed coat. The central part of every grain allowed more water to penetrate. The route, pattern and speed of water penetration were determined by the morphological structure, crack formation and hardness distribution associated with the packing of the starch granules in the grain.     

Variation in rice quality of different cultivars and grain positions as affected by water management

A field experiment was conducted to study the effect of cultivar and grain position on rice quality under different water management treatments. Water treatments significantly affected all quality traits in the study, except alkali digestibility (AD). There were significant interactions of water treatment by grain position and genotype for brown rice rate (BRR), chalky grain rate (CGR) and amylose content (AC), and interactions of grain position by water treatment and cultivar for head milled rice rate (HMRR). The interaction of water treatment by genotype for protein content (PC) was also significant. Of all variance components, water treatment ranked the highest for PC. Similarly grain position was ranked the highest for AC, BRR, CGR and HMRR. In comparison with wet cultivation, plastic-film mulched cultivation had significantly lower BRR, HMRR, CGR and higher PC. There were marked differences in milled quality, appearance and AD among differently positioned grains within a spike. For appearance and PC, the difference between plastic-film mulched cultivation and wet cultivation was greater for upland rice than paddy rice. For milled and cooking–eating quality, the difference between plastic-film mulched cultivation and wet cultivation was greater for the good quality paddy rice than the upland rice and the poor quality paddy rice. In plastic-film mulched cultivation, top grains showed lower milled quality and PC. While in wet cultivation, the opposite result was seen. With the decrease in soil water content, BRR and appearance showed increased and decreased differences among grains within a spike, respectively. The results indicate the possibility of improving rice quality by use of better water management and suitable cultivars.     

直立与弯曲穗型水稻穗上不同部位籽粒碾磨品质的比较

以直立穗型和弯曲穗型水稻材料为对象,研究了穗上不同部位和不同粒位籽粒在碾米品质上的差异。弯曲穗型材料整穗籽粒的糙米率、精米率及整精米率以及粒重均高于直立穗型材料,其中整精米率差异达到显著水平。总体而言,在稻穗的同一部位,两穗型材料一次枝梗籽粒的糙米率、精米率、整精米率和粒重均高于二次枝梗的籽粒;一次枝梗上以第2 或第3粒位籽粒的糙米率、精米率和整精米率较高,第1 粒位籽粒的较低;穗上同一部位二次枝梗籽粒的碾米品质在两穗型材料间的差异大于一次枝梗,而穗型与其排序并无直接关系;两穗型材料籽粒粒重在穗上的分布与排序基本一致。因此,可以通过育种选择来改良直立穗型材料的碾磨品质。     

Soaking time of rice in semidry flour milling was shortened by increasing the grains cracks

To shorten the soaking time of rice grains in the process of semidry-milling, the changes in moisture absorption, damaged starch, and magnetic resonance images during soaking, as well as effect of increasing grains cracks on moisture absorption were investigated. As the results, the soaking time to reach the maximum moisture of Glutinous and Indica rice grains was 40 min and 20 min, respectively, but was 3 h and 30 min to reach the minimum damaged starch contents in rice flour. The moisture penetrated quickly from the embryo attachment site, ventral side, and cracks into the inside, and then diffused through the cracks. The result showed that homogeneous distribution of moisture in the rice grains was necessary to reduce damaged starch. Moreover, owing to the increase of grains cracks, the soaking time of Glutinous and Indica rice grains was shortened from 3 h to 1 h, and from 30 min to 10 min, respectively, by increasing drying temperature to 60 °C.     

Distribution of proteins and amino acids in milled and brown rice as affected by nitrogen fertilization and genotype

A field experiment involving six japonica rice cultivars with contrasting agronomic traits and seven nitrogen (N) fertilizer treatments was performed to determine the effects of N and genotype on distribution of four kinds of grain proteins and amino acids in milled and brown rice. For brown and milled rice, albumin and globulin were controlled more by genotype than N treatments, whereas prolamin and glutelin were largely determined by N. Substantial genotypic differences in response of milled/brown (M/B) ratios of proteins to N treatments were detected. In comparison with large panicle cultivars, small panicle cultivars such as Wuyujing3 had the lower ratio and exhibited more stability under contrasting N treatments. N had significant influence on amino acid composition of brown and milled rice, with contents of the 17 amino acids measured increasing with elevated N rate. However, cysteine and methionine in brown rice and lysine and methionine in milled rice were not significantly affected by N. In addition, N had little effect on ratios of M/B for most of the amino acids.     

东北三省水稻品质性状比较研究

以2002-2007年辽宁、吉林和黑龙江三省水稻区域试验参试材料为试材,统一取样测定主要品质指标,分析品质性状的省份间差异、变化及其相互关系。结果表明,东北三省水稻碾磨品质普遍较高,其中吉林省参试品种糙米率和精米率最高,辽宁省参试品种整精米率最高;对于垩白粒率和垩白度,辽宁省与吉林省相差不大,但都显著高于黑龙江省;长宽比吉林辽宁黑龙江;蛋白质含量辽宁吉林黑龙江,直链淀粉含量则相反,但辽宁与吉林之间差异没有达到显著水平;胶稠度辽宁黑龙江吉林。近年来黑龙江和吉林水稻整精米率、黑龙江糙米率有所降低。粒长、长宽比与糙米率、精米率呈极显著负相关,垩白粒率、垩白度与精米率、整精米率和长宽比呈极显著负相关。因此,在水稻育种和栽培中,辽宁和吉林应主攻降低垩白粒率和垩白度,黑龙江和吉林应注意防止整精米率降低,黑龙江还要注重提高糙米率。     

Analysis of Storage Protein Distribution in Rice Grain of Seed-Protein Mutant Cultivars by Immunofluorescence Microscopy

Abstract

Localization of storage proteins in rice grains of seed-protein mutant cultivars, low-glutelin cultivars LGC-1, LGCsoft and a 26-kDa-globulin-deficient low-glutelin cultivar LGC-Katsu, was examined by immunofluorescence microscopy using fluorescence-labeled antibodies of 13 kDa prolamin and 23 kDa glutelin. Abundant 13 kDa prolamin and 23 kDa glutelin was observed in the outer regions of rice grains. Image analysis revealed that peaks of fluorescence intensity of both proteins were located at 2–7% of the width or longitudinal length of brown rice distant from the outer surface of brown rice (RDOS) on the dorsal, ventral, and apical sides of brown rice. In these seed-protein mutant cultivars and a normal-type cultivar Nihonmasari, the foot of the distribution peaks of both proteins were located at 20–30% RDOS on the ventral and apical side. In contrast, on the dorsal side of rice grain, varietal differences of RDOS at the foot of the distribution peak of both proteins varied with the cultivar. The RDOS was 20 –40%; and Nihonmasari >LGC-1≒LGCsoft >LGC-Katsu. Although the quantity of 13 kDa prolamin and 23 kDa glutelin greatly varied with the cultivar in the outer region of rice grain, both proteins were distributed uniformly at low levels in the inner region in all cultivars. Furthermore, SDS-PAGE analysis showed that a larger quantity of 13 kDa prolamin localized on the ventral than the dorsal side of rice grains in seed-protein mutant cultivars, especially in LGC-Katsu.     

水稻籽粒不同部位植酸含量及其与稻米品质的相关性

 选用13个不同类型的水稻品种,对其籽粒不同部位植酸含量品种间差异及与稻米主要品质性状间的相关性进行了分析。结果表明,供试13个水稻品种米糠、糙米、颖壳、精米的植酸含量平均值分别为48.51、9.77、1.40和0.91 mg/g,而且不同水稻品种间籽粒不同部位的植酸含量存在极显著差异。在籽粒中,米糠中植酸积累最多,其次是精米,颖壳最少。米糠中植酸含量与糙米和颖壳中植酸含量呈极显著正相关。糙米和米糠中植酸含量与稻米蛋白质含量均呈显著的负相关,与千粒重均呈显著正相关。     

Moisture distribution in rice grains used for sake brewing analyzed by magnetic resonance imaging

Water absorption in individual white-core and non-white-core grains of rice varieties used in sake brewing was observed during soaking by magnetic resonance imaging (MRI). Water was absorbed faster in white-core grains than in non-white-core grains and was pooled in the core. Moisture distributions were compared using the line profiles of nuclear magnetic resonance signal intensities (SI profiles) generated from magnetic resonance images of grains soaked for 2 h. SI profiles of white-core and non-white-core grains overlapped despite slight differences in the central and intermediate regions of the grains. A white-core-like structure with loosely packed starch granules was found to exist in the endosperm of non-white-core grains. SI profiles of grains polished to 70% of the yield weight of brown rice were similar in shape to those of grains polished to 90% of the yield, but their overall moisture content was higher after the removal of the hydrophobic grain periphery. A varietal difference in the thickness of the intermediate region, which may affect fissuring resistance in the polishing process, was detected in SI profiles. Differences in water absorbability between parents and their offspring were also apparent from their SI profiles. MRI enabled the detection of variety-specific water-absorption properties in grains.     

Milling and cooking of hybrid sorghum grain

Fourteen commercial hybrid cultivars of sorghum grain were examined for physical characteristics before and after being milled by abrasion. Milling to 10% total loss in weight resulted in the pigments in the pericarp being effectively removed but colour spots on the hilar and germ remained on most cultivars and the testa was exposed on some cultivars. Milling showed that the cultivars were of varying degrees of hardness but all gave >80% yield of unbroken kernels with the germ attached. The milled grains were boiled like rice but the cooking time was high for all cultivars (range 57–64 min) although the water uptake and swelling of the cooked grain was satisfactory and the solids lost during cooking was low.     

冷水胁迫对云南粳稻品质性状的影响

 以11个云南粳稻品种为试验材料,研究冷水胁迫对稻米品质性状的影响以及水稻耐冷性与品质性状冷水反应的相关关系。结果表明,品质性状的冷水反应不仅与品种有关,也与具体的品质性状有关。冷水胁迫使粒宽、千粒重、垩白粒率、精米白度、糙米率、味度值、最高黏度、最低黏度、崩解值、最终黏度显著或极显著降低,使长宽比、整精米率、碱消值、蛋白质含量和消减值极显著增加,而粒长、精米率、直链淀粉含量、到达最高黏度时间（峰值时间）和起浆温度不因冷水胁迫发生明显变化。相关分析表明,成熟期综合耐冷性与稻米的味度值、蛋白质含量、最高黏度和崩解值的冷水反应指数具有显著或极显著相关性。因此,提高育成品种的耐冷性对稳定和改善稻米食味品质具有重要作用。     

Prediction of grain weight,brown rice weight and amylose content in single rice grains using near-infrared reflectance spectroscopy

The potential of near-infrared reflectance spectroscopy (NIRS) for simultaneous analysis of grain weight (mg), brown rice weight (mg) and milled rice amylose content (AC, %) in single rice grains was studied. Calibration equations were developed using 474 single grain samples, scanned as both rice grain and brown rice. An independent set containing 90 F₂ generation grains was used to validate the equations. In general, equations developed using the first derivative resulted in superior calibration and validation statistics compared with the second derivative and those developed using brown rice were superior to those developed from the rice grain. Fitting equations were developed and monitored with an external validation set. The standard error of prediction (corrected for bias) SEP(C) for AC, brown rice weight and rice grain weight for equations developed using brown rice were 2.82, 1.09 and 1.30, with corresponding coefficient of determinations (r²) of 0.85, 0.71 and 0.67, and SEP(C)/S.D. of 0.39, 0.57 and 0.59, respectively. It was demonstrated that NIRS provides a convenient way to screen single intact grains. This will be advantageous in early generation selection in rice breeding programs.     

Effect of High Temperature at Ripening Stage on the Reserve Accumulation in Seed in Some Rice Cultivars

Abstract

The resistance to high-temperature stress and the structural appearance of the imperfect grains caused by a high temperature at the ripening stage were studied using 13 selected cultivars of rice. High temperature treatment (daily maximum temperature range, 32-40°C) given from the 4th day after heading caused the decrease in panicle weight in all of the cultivars examined. The number of empty grains in the upper and lower parts of a panicle was increased by the high temperature in 10 cultivars. Cultivars KRN, Citanduy, Belle patna and BPB were tolerant to the high-temperature treatment at the ripening stage, and cvs. Koshihikari, Sanlicun, Tainung 67, Yamada-nishiki and Lady Wright were sensitive. Light microscopic observation showed that, the whole endosperm was covered with a nucellar epidermis (NE) under both high and natural temperature (26-31°C) conditions at the first week after heading (WAH). Under high-temperature conditions the NE degenerated earlier than under natural temperature conditions. Scanning electron microscopic observation showed that, the endosperm cells of the seeds with a specific gravity (s.g.) of higher than 1.06 had large amyloplasts filled with starch granules. However, the endosperm cells of seeds with a s.g. of 1.00-1.06 had many small amyloplasts containing small single starch granules and had numerous spaces among the amyloplasts. In the endosperm cells at the dorsal side of imperfect grain, layered structures showing progressive decomposition of starch granules were observed.     

Grain quality of rices grown in irrigated and upland cultures

Upland culture of nine varieties at Ivory Coast resulted in decreases in grain weight, brown and milled rice translucency, Chroma meter L^* of rough rice, Chroma meter L^* and b^* of milled rice, milled rice protein, and Amylograph peak viscosity, and in increases in total phenolics of hull and brown rice, and Chroma meter a^* of rough, brown, and milled rice of 5 to 8 of the varieties as compared with irrigated culture. Upland culture had no consistent effect on grain resistance to Angoumois grain moth (Sitotraga cerealella).     

Analysis of the milling reduction of bread wheat farina: Physical and biochemical characterisation

The reduction of coarse farina during milling from five representative hard and soft French bread wheat cultivars was followed step by step. Particle size distribution of the milled products and energy required to dissociate wheat farina revealed large differences between cultivars. A grinding index (required energy to produce 1 kg of flour), K′, corresponding to the energy necessary to obtain a given amount of flour, was found to be related with both grain hardness and vitreousness. Analysis of particle size distribution suggested a major influence of hardness in the production of fine particles <50 μm during the reduction process. On the other hand, vitreousness appeared to impact on the extent of coarse particle size reduction. Differences in farina reduction behaviour of the wheats analysed were related to their endosperm mechanical properties as determined by compression tests and structural characteristics as measured by Hg intrusion porosity. Vitreousness appeared to affect the endosperm extensibility and degree of porosity. The profile of the different lipid and protein classes in the reduction products of two cultivars showing opposite behaviour as well as different PINA/PINB ratio were determined. The results suggest that the most resistant parts of the grain are enriched in glycolipids, whereas phospholipids appear associated with the most friable parts, at least in the soft wheat grains tested.     

The influence of milling on the nutritive value of flour from cereal grains. 4. Rice

Brown and milled rices were prepared from rough rice, and the nutritive value of the rices was studied by chemical analyses and in balance experiments with growing rats. The concentration of essential nutrients decreased with the degree of milling, but the energy density of brown and milled rices was similar. In the highly refined white rice the protein content was reduced to 86% and the mineral content to 23% of corresponding levels in brown rice. The zinc concentration was halved. The amino acid composition was rather unaffected by the degree of milling, but the lysine concentration was slightly lower in white rice than in brown rice. Milling was accompanied by an increase in true protein digestibility and a corresponding decrease in biological value. Thus net protein utilization of the different rices was remarkably uniform. A total of 33% of the utilizable protein and 22% of the digestible energy in brown rice was removed during milling. Rats fed rough, brown and lightly milled rices were unable to maintain their femur zinc concentration; deposition of calcium and phosphorus also appeared to be affected. Factors present in the outer part of the rice kernel interfere strongly with zinc utilization. Phytate and/or fibre are not solely responsible for this effect. Unless rice was milled into highly refined white rice, zinc status of rats was adversely affected. The results suggest that zinc might be a limiting factor in rice-based diets.     

粳型杂种稻米品质性状的遗传表达

应用莫惠栋等新近提出的P十ｑ＋2Ｐｑ交配设计及其分析方法,分析了模型杂种９个品质性状的遗传表达,试验材料P＝４,ｑ＝７。结果表明：（１）糙米率、精米率、整精米率、粒长、粒宽和垩白率６个性状的遗传受母株基因型控制,它们在Ｆ２米粒间（着生在Ｆ１植株上）没有发生遗传分离,而糊化温度、直链淀粉含量和胶稠度３个性状在民米粒间有显著的遗传分离,因此主要受胚乳基因型控制。（２）除直链淀粉含量外,其余８个性状的遗传变异均以加性方差为主。在直链淀粉含量、糊化温度和胶稠度３个性状中,种子性状分离方差都占有较高比例,进一步证明了Ｆ２种子的这３个性状的遗传主要是由胚乳自身的基因型决定的。（３）正反交测验的结果表明,９个品质性状均存在显著的细胞质效应,但细胞质遗传方差仅占遗传总方差的２．４９％（糊化温度）～２９．３％（精米率）,多数性状集中在２％与５％之间,所以品质性状的细胞质遗传效应在总体上是不大的,但在性状间存在差异。     

硅肥对北方粳稻产量和品质的影响

 以沈农265和丰优2000为材料,在盆栽条件下,研究了硅肥不同施用量对水稻产量和品质的影响。结果表明,施用硅肥能提高水稻产量,其中有效硅240 kg/hm2使沈农265显著增产,有效硅180 kg/hm2对丰优2000增产效果达到显著水平。从产量构成因素上看,施用硅肥能提高每穴穗数、一次枝梗上籽粒千粒重、二次枝梗上籽粒千粒重、每穗粒数。施用硅肥能显著改善稻米品质,主要表现为稻米的糙米率、精米率和整精米率显著提高,稻米的垩白粒率和垩白度显著降低。相关分析表明,两品种的精米率和整精米率与有效硅施用量呈正相关。沈农265的稻米脂肪酸含量与有效硅施用量呈正相关,食味值与有效硅施用量呈负相关。有效硅施量在0~240 kg/hm2内,两品种直链淀粉含量和蛋白质含量与有效硅施用量相关不显著。综合考虑各处理稻米产量和品质,以180~240 kg/hm2的有效硅施用量较好。     

外源Pb含量变化对水稻品种籽粒中Pb含量差异的研究

采用田间小区试验方法,以福建省大面积推广应用的7个水稻品种为试材,在施PbCl2不同处理条件下,研究土壤中外源Pb含量的变化对水稻品种籽粒中Pb含量的差异。结果表明,在不同浓度的Pb处理下,水稻糙米中Pb含量在品种间存在显著差异,而且不同水稻品种的籽粒对土壤中重金属Pb的敏感性不同,以此可找出适合污染地区种植的品种。     

浙江省早籼稻近期区试品种品质性状的综合分析

 根据浙江省1995年早籼稻品种区域试验6个试点13个参试品种11项品质性状的测定结果,研究了各品质性状的品种（基因型）、地点、品种×地点互作效应相对变异。除整精米率性状以外,其余各品质性状均以品种效应为主,而且品种效应以直链淀粉含量、胶稠度、粒型相对较大;整精米率以环境效应相对最大,环境对糊化温度、垩白面积、垩白率、精米率也有一定影响;将品种×地点互作效应分解为各参试品种×地点互作效应发现,某些品种整精米率、垩白率、垩白面积、糊化温度存在基因型×地点互作效应。