含水量变化对米粒裂纹形成的影响与调控

稻米水分含量变化是引起籽粒裂纹发生、影响整米率的主要因素。潮湿米粒的快速干燥，干燥籽粒的浸水或回潮均会带来严重的裂纹。干燥后润谷可以减少裂纹的发生。生产、加工、贮藏过程中可通过合理处理稻米水分含量减少裂纹发生，提高碾米品质。     

含水量变化对米粒裂纹形成的影响与调控

稻米水分含量变化是引起籽粒裂纹发生、影响整米率的主要因素。潮湿米粒的快速干燥,干燥籽粒的浸水或回潮均会带来严重的裂纹。干燥后润谷可以减少裂纹的发生。生产、加工、贮藏过程中可通过合理处理稻米水分含量减少裂纹发生,提高碾米品质。     

评价田间玉米果穗水分散失率的样本大小

评价田间玉米果穗水分散失率的样本大小Ｒ．Ｍａｇａｒｉ等籽粒干燥速率快的玉米杂交种可减少人工干燥费用。７０年代初，由于燃料价格的上涨和未来可能的能源短缺，对快速干燥的杂交种的需求增加。提高籽粒干燥速率的问题之一就是无法在田间评价籽粒的干燥速率。Ｋａｎｇ...     

水稻裂纹米的成因及防治对策

水稻裂纹米的发生 ,降低了稻谷等级 ,也影响加工大米的品质 ,碎米多 ,整米率低 ,降低了水稻经济效益。水稻裂纹米 ,也称惊纹米 ,机米工艺上称“爆腰” ,是稻米加工过程中产生碎米的主要原因。裂纹米是因糙米表面和中心部的水分差而产生的 ,由于急激的干燥或吸湿所引起的。水稻灌浆优劣、收获期和稻谷入库前机械作用等与裂纹米发生有关 ,其次与水稻品种、成热期温度 ,水分等气候因子也有一定相关性。1　裂纹米发生的主要原因1 1　秆青籽黄的稻穗 ,裂纹米少、水稻早衰秆枯叶黄裂纹米显著增多。蜡熟期倒伏 ,水稻青枯贪青对裂纹米形成有一定影响…     

水稻裂纹米的成因与防止对策研究

水稻裂纹米（Crackedrice－grain，也称稻谷的“热裂”，机米工艺上称“爆腰”）是稻米工过程中产生碎米的主要原因。据报道，裂纹米率（爆腰率）大于60％，碎米率则超过50％，严重影响稻米的商品性和经济价值。研究水稻裂纹米的形成原因，寻求其防止对策，对提高稻米整米率，增强稻米市场竞争力，具有现实的社会经济意义。（－）裂纹米的形成原因据调查分析，裂纹米的形成与品种、灌浆优劣、收获期和稻谷入库前机械作用有关。进一步研究发现，裂纹米的形成与温度、水分和太阳辐射等气候因子也有一定相关性。1．不同品种的裂纹米表现干水稻…     

玉米籽粒水分动态

玉米籽粒水分动态培育收获时籽粒含水量低的杂交种，从而减少干燥籽粒时的燃料消耗，是玉米育种的重要方向之一。在美国更注重这方面的研究。先锋公司的育种家们已达到了最好的实际效果。如杂交种先锋３４７５具有这一特性，并且高产，抗倒伏，在８０年代初期得到广泛的推...     

玉米籽粒水分含量的遗传研究

对生产上常用的７个玉米杂交种的种子水分含量及相关性状进行了分析，结果认为玉米籽粒分的遗传规律符合加性－显性模型，且加性方差比重较高，并且存在的部分显性作用，籽粒水分含量的遗传变异率较大，广义遗传力值较小，杂交种籽粒水分含量与其母本呈正相关。     

不同水分管理方式对旱直播水稻产量和稻米品质的影响

【目的】研究旱直播模式下不同水分管理方式对水稻产量、光合生理特性和稻米品质的影响,以期为干旱气候条件下的节水栽培提供理论依据。【方法】采用大田小区试验,以杂交稻旱优73和常规稻黄华占为试验材料,通过设置全生育期内旱管和水管两种水分管理模式,综合考查旱直播模式下不同水分管理方式对水稻叶片光合特性、地上部干物质积累及分配、产量和稻米品质的影响。【结果】水稻旱直播模式下进行旱作栽培显著提高了水分利用效率和水稻产量,降低了稻米的外观品质和食味品质。与淹水灌溉相比,旱作处理显著提高了叶片SPAD值和齐穗期净光合速率,促进了地上部干物质的积累;增加了茎秆和叶片干物质转运量和对籽粒贡献率,进而提高了水稻有效穗和千粒重。其中,黄华占和旱优73产量分别增加14.0%和11.9%。旱作处理对加工品质没有显著影响,但显著降低了直链淀粉含量,增加了蛋白质含量;同时降低籽粒中重金属砷的含量,增加了重金属镉的含量。【结论】水稻旱直播模式为干旱气候条件下的水稻适应性栽培提供了可能,但稻米品质与产量协同提升因品种而异。因此,旱直播模式下高效优质栽培技术还需进一步研究。     

水稻灌浆期高温对天冬氨酸代谢酶活性及其家族氨基酸含量的影响

 选用粳稻越光和籼稻IR72为材料,研究了灌浆期高温对水稻籽粒中天冬氨酸转氨酶（AAT）、天冬氨酸激酶（AK）活性以及稻米蛋白质组分与天冬氨酸族氨基酸组分含量的影响。结果表明,水稻灌浆期高温下籽粒中AAT和AK活性、天冬氨酸、赖氨酸、苏氨酸、蛋氨酸和异亮氨酸相对含量均显著提高,籽粒中AAT和AK活性与天冬氨酸家族总氨基酸含量分别呈显著和极显著正相关,说明水稻籽粒中AAT和AK对于高温下稻米天冬氨酸家族氨基酸含量的提高具有重要作用。高温有利于稻米中蛋白质组分与天冬氨酸族氨基酸组分相对含量的提高,有利于单粒稻米中谷蛋白与天冬氨酸家族氨基酸组分的积累以及粗蛋白中部分氨基酸比例的改善,但高温降低了每穗稻米中蛋白质组分与部分氨基酸组分的含量。     

降低玉米杂交种籽粒水分的自交系间接选择

降低玉米杂交种籽粒水分的自交系间接选择Ｐ．Ｍ．Ｓｗｅｅｎｅｙ等降低玉米籽粒水分有重要的经济意义，籽粒水分低的玉米可以提早收获，减少田间损失，降低生产成本，并在不利气候和妨碍收获操作的田间条件到来之前收获完毕。籽粒水分提高，出籽率和籽粒品质下降（Ｊｕｈ...     

川南杂交中稻收割期与干燥技术对整精米率的影响

以杂交中稻组合川谷优642和蓉优1015为材料,在冬水田区大面积高产栽培技术条件下,研究了不同收割期、干燥时间与干燥方式对整精米率的影响。结果表明,品种、收割时期、干燥时间与干燥方式4个因子及其互作效应对整精米率有极显著影响。川谷优642的整精米率比蓉优1015高,干燥时间短的处理比干燥时间长的处理整精米率高,坝晒处理比用簸箕晒的处理整精米率高。籽粒水分含量在12.27%~14.67%之间时,整精米率与籽粒含水量呈极显著正相关关系。     

Mapping QTLs for milling yield and grain characteristics in a tropical japonica long grain cross

Percent milling yield is an economically important trait of commercial rice because it largely determines the price that farmers receive for their crop. Analyzing 22 trait variables including milling yield, grain dimensions, chemistry and appearance, we identified 43 quantitative trait loci (QTLs) in a long grain japonica by long grain japonica cross. We report one QTL explaining 20% of the variation in brown rice recovery; two QTLs explaining 14% and 13% of the variation in milled rice recovery; and one QTL explaining 14% of the variation in head rice (HR) recovery. QTLs for the proportion of pre-broken brown rice kernels, seed density, amylose content, and kernel whiteness and chalkiness were found in the same region as the HR QTL. QTLs explaining up to 54% of the variation in grain shape measurements were identified and mapped to areas independent from those identified for milling yield. Analyses of grain appearance traits identified two QTLs for chalk in brown rice and one in head rice, and a QTL explaining up to 33% of the variance in green kernel area. Our results confirm previous findings on the multigenically complex nature of milling yield.     

Effect of Soaking on Wet-milling of Rice

Soaking is an essential step in wet-milling of rice flour. The effects of soaking duration and temperature (5 and 25 °C) on the properties of rice flour have been investigated. The uptake of water by rice kernels increased with temperature and reached a plateau at about 30–35%. Protein, lipid, and ash leached out during soaking. The moisture content after soaking appeared to be a key factor on loosening the structure of rice kernels, which resulted in the production of small particle flours with little starch damage. The particle size of flours did not alter the gelatinisation temperature (T_oand T_p) in DSC thermograms. Small particle and low lipid content flours appeared to have high peak viscosity measured by RVA. The change in microstructure of rice kernels during soaking was also examined by SEM.     

植酸和氯离子对稻米品质的影响

 以原丰早为材料进行了在不同时期施用植酸与氯离子的试验。在水稻抽穗至成熟期间叶面喷施植酸，能抑制水解酶类的活性，减弱淀粉酶分解淀粉的反应，提高淀粉合成酶的活性，有利于淀粉合成，改善稻米品质。水稻齐穗期叶面喷施50、100 mg/kg 两种浓度的植酸，碎米率的平均值比对照低2. 8～23. 1个百分点，整精米率上升5～7个百分点；垩白等级、垩白率降低，乳白米粒减少，与对照相比差异显著；对碱消值、直链淀粉含量亦有影响。氯离子作为淀粉酶的激活剂，喷施后能抑制淀粉合成酶的活性，对稻米品质呈逆向效应。     

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.     

精度对稻米品质的影响

 以5个中至长粒形的籼稻品种为材料,研究了碾米精度对稻米品质的影响。结果表明,精度对以精米为对象的各项米质指标的影响十分显著,其中精度与精米的白度、胶稠度、糊化温度及直链淀粉含量等米质指标成正相关,而与精米的整米率、长宽比以及蛋白质含量等米质指标成负相关。     

Magnetic resonance imaging and analyses of tempering processes in rice kernels

This research involved a magnetic resonance imaging (MRI) technique that was applied to examine water distribution and migration in single rice kernels during the tempering process. The imaging experiments were performed in a Bruker 9.4T MRI system. Three-dimensional spin-echo (SE) imaging sequences were optimized by adjusting the scanning parameters of echo time (TE) and repetition time (TR) to obtain images with maximum contrast. The MR images showed that the moisture distribution in the rice kernel is non-uniform and compartmental. The embryo region exhibited much higher MR signal intensity than the starchy endosperm portion. The tempering process was analyzed with spatial-temporal signal intensities of the endosperm following the drying process of the rice kernel. The transient change of the signal intensities in the endosperm was well fitted with a double exponential function suggesting that both convection and diffusion contributed to the reduction of the moisture gradient within the rice kernel during tempering. This hypothesis was further supported by the experimental data of the insulated rice kernel whose convective mass transfer was excluded. The experimental results revealed that MR imaging of rice kernels could be used as an efficient tool to examine the mechanisms of moisture migration within cereal grains.     

水稻种子含水量与耐冷性的关系研究

试验选择18份水稻品种的休眠种子作为材料,其中具有耐冷性的水稻品种13份,不具有耐冷性的常规水稻品种5份。测定了每份种子样品中含水量,并将这项指标分别与水稻品种是否具有耐冷性以及耐冷性强弱进行相关性分析。结果表明：①水稻品种是否具有耐冷性与种子中含水量呈极显著负相关关系,即耐冷性品种含水量明显低于常规品种;②具有耐冷性的水稻品种,其耐冷性程度与种子的含水量没有显著的相关性。因此认为水稻休眠种子的含水量可以作为判断水稻耐冷性有无的参考指标,但不能直接用作判定水稻耐冷性强弱的指标。     

不同收获时期对超级稻沈农014主要稻米品质影响

以沈农014为试材,根据不同抽穗天数进行收获,研究水稻不同收获时期对产量和主要稻米品质的影响。结果表明,过早收获,稻谷的含水量较高,千粒重相对较低,严重影响了产量。从加工品质来看,过早收获对糙米率和精米率影响较小,对整精米率影响较大,过晚收获也会使整精米率下降。从稻米外观品质来看,过早收获使垩白粒率和垩白度增加。从营养和食味品质来看,收获期对蛋白质含量的影响不大,但对直链淀粉和脂肪酸影响较大,对食味值的影响则无明显规律。确定沈农014在9月30日至10月10日达到最佳收获期。