环境与栽培对稻米品质的影响

本文综述了温度、光照、湿度、种植密度、各种肥料、灌溉、收获时期和方法、干燥方法和温度等因素对稻米品质的影啊。     

栽培模式对稻米品质特性的影响

以超级稻组合88S/1128和常规优质稻品种湘晚籼17号为材料,探讨了不同栽培模式(旱作覆膜、水作覆膜、旱作不覆膜、常规栽培等)对稻米品质的影响。结果表明,2个品种一致表现为旱作覆膜栽培的糙米率、精米率最高,水作覆膜栽培的整精米率最高;同一品种不同栽培模式的粒长和长宽比无显著差异,但覆膜栽培的垩白粒率、垩白大小更高。88S/1128旱作覆膜与常规栽培相比,直链淀粉含量降低、胶稠度变小、糊化温度升高;而湘晚籼17号旱作覆膜与常规栽培相比,直链淀粉含量降低、胶稠度变大、糊化温度降低。2个品种蛋白质含量表现一致,均为旱作不覆膜常规栽培旱作覆膜水作覆膜。稻米品质性状变异度最大的为外观品质,其次为蒸煮食味品质,碾米品质变异度相对较小。     

栽培措施对稻米品质影响的研究进展

随着生活水平的提高,稻米品质愈发受到人们的关注。本文概述了本世纪以来,我国农业科技工作者在栽培措施对稻米品质影响方面的一些研究成果,并从播期、密度、种植方式、肥料运筹、水分管理和种养模式等方面总结了优质稻米生产技术,供生产者参考。     

异季栽培对稻米品质的影响

稻米品质改良是主要育种目标之一。稻米品质的优劣,既受遗传基因的制约,也受环境因素的影响,尤其是灌浆期间的温度条件对稻米品质的作用更大。前人研究认为,灌浆期间温度过高,籽粒的灌浆速率较快,稻米的整精米率下降,透明度变差、垩白度增大,碾磨品质和外观品质变劣;对蒸煮品质来说,高温会使稻米的糊化温度升高、胶稠度变硬,直链淀粉含量也受高温影响,Resurreccion等和赵式英认为这种影响因品种特性而异,Juliano则认为高温会降低直链淀粉含量。从我国目前稻米品质的现状来看,早籼米的品质劣于晚籼米,早籼品种经翻秋栽培后,品质明显变好,但对晚籼品种在早稻生长季节灌浆成熟后,其稻米品质的变化目前尚未见报道。本文通过对同一地点不同季节栽培的稻米进行品质分析,旨在洞悉早籼和晚籼品质差异的原因,以及灌浆期间环境因素对稻米品质影响的程度,以期对水稻品质育种提供依据。     

应用酵素菌肥的有机和传统栽培稻米品质比较研究

随着人们对有机食品需求增加，有机稻米需求也与日俱增。本试验以超级稻中浙优1号为材料，对应用酵素菌肥的有机和传统栽培条件下稻米在碾磨品质、外观品质、蒸煮品质、营养品质上的差异作了研究。结果表明，有机稻米碾磨品质略差于传统稻米，外观品质仅垩白率降低36．05％，直链淀粉含量减少5．80％，蛋白质含量降低1．74％，胶稠度两者相差不大，碱消值提高2．76％，赖氨酸、苏氨酸、蛋氨酸的含量分别比传统稻米高4．32％、6．53％、1．84％，氨基酸总量高于传统稻米2．96％，Mg/K，Mg/K和Mg/N分别比传统稻米提高66．04％和22．22％。虽然有机稻米部分品质参数低于常规稻米，但是重要的品质参数都有不同程度提高。     

玉米种植密度对产量和品质的影响

玉米不同密度下的子粒产量和品质的测定表明：不同种植密度直接影响了子粒产量和品质。密度与产量的关系为：Y=4142.7Ｘ-318.9X²；较大和较小的密度有利于玉米子拉脱水，使收获时含水量降低。在一定密度范围内，玉米子粒蛋白质、脂肪、淀粉的含量在不同成熟阶段及收获时均呈下降趋势，而超出这一范围，这些物质的含量有所提高。玉米子粒中蛋白质、淀粉及脂肪的低含量与高产密度相对应，但这些物质的高含量却不与较低产量的密度相对应。     

不同种植密度下施肥对强筋春小麦品质形成的调控效应

为给春小麦优质栽培提供依据,以优质春小麦品种龙麦26为材料,分析了不同种植密度下施肥量对强筋春小麦品质形成的调控效应。结果表明,随种植密度的增加,千粒重降低,而籽粒容重增大。种植密度对籽粒蛋白质含量、面筋含量以及面粉品质和面团流变学特性无显著影响。适当增加施肥量可以提高小麦籽粒蛋白质含量和面筋含量,增加沉淀值,改善面粉降落值,提高吸水率,延长面团的形成时间和稳定时间,但对面团的拉伸特性影响不大,并降低了容重和千粒重。     

稻米品质及测试方法研究：Ⅱ.碾磨精度对稻米品质性状的影响

采用４个籼稻品种，对分别按６种不同精度处理得到的样品进行了稻米品质性状的分析。结果表明：稻米品质性状除湖化温度碱消值外，其它各性状都明显受磨精度的影响，且碾磨精度分别与精米率、整精米率、精米长、精米宽、精米厚呈负相关；碾磨精度分别与直链淀粉含量（ｇ／１００ｇ淀粉）、胶稠度米胶长呈正相关。     

温度对稻米品质影响的研究进展

水稻灌浆期的温度条件是影响稻米品质的主要环境因子。从稻米碾米品质、外观品质、蒸煮食味品质和营养品质四个方面,综述了温度对稻米品质影响的研究进展。     

密度和肥料水平对高蛋白大豆德豆17号产量的影响

试验采用二次通用旋转组合设计,研究了不同肥料及密度条件对大豆德豆17产量的影响,建立了以德豆17产量为目标函数的数学模型。结果表明:各栽培因子对德豆17产量的影响为:钾肥>密度>磷肥>氮肥>微肥。经计算,初步确定了德豆17号在当地产量大于175.00kg/667m2的栽培方式为:密度0.81～0.83万株/667m2,氮肥施用量19.46～20.29kg/667m2,磷肥施用量39.09～40.91kg/667m2,钾肥施用量21.97～23.04kg/667m2,微肥施用量0.92～1.08kg/667m2。     

施氮量与栽插密度对粳稻稻米品质的影响

以杂交粳稻辽优5218和常规粳稻辽星1号为试材,研究施氮量和栽插密度对粳稻稻米品质的影响.结果表明,辽优5218的垩白粒率和垩白度显著高于辽星1号,施氮量和栽插密度对两品种的垩白粒率、垩白度和籽粒长宽比无显著影响;增施氮肥或降低密度可提高辽优5218和辽星1号籽粒的蛋白质含量,降低食味值;施氮量与栽插密度对辽优5218和辽星1号直链淀粉含量的影响因品种不同有所差异.适量少肥和适度密植可以改善杂交粳稻和常规粳稻的营养和食味品质,但杂交粳稻的高垩白粒率和高垩白度只能通过育种手段去改良,栽培措施对其影响小.     

水稻粒重及其相关性状的遗传解析

 应用292个 Lemont/ 特青F13重组自交系(RILs)和272个标记的遗传连锁图谱分析粒重及籽粒长、宽、厚、长/宽、体积和容重6个相关性状的遗传。所有性状在RILs中出现超亲分离。粒重与其他籽粒性状均呈显著正相关，而涉及籽粒品质的容重与粒宽、粒厚呈显著负相关。检测到影响粒重及其相关性状的主效QTL 48个和互作位点38对，这些QTL解释了各性状55%以上的表型变异。80%以上的主效QTL呈现一因多效或生理相关。QGl3和 QGl2等通过籽粒体积间接影响粒重， Lemont增效等位基因有利于籽粒品质的改良，而QGw5、QGt1和QGv7的特青增效等位基因增加粒重同时降低籽粒容重及品质。通过标记辅助选择进行不同QTL的重组，有望在增加粒重的同时改善籽粒品质。     

籼稻背景下抑制不同ALK等位基因表达对稻米品质的影响

【目的】稻米糊化温度是影响稻米品质的重要指标，该性状受主效基因ALK/SSII-3调控，ALK基因具有多个复等位基因，本研究旨在通过RNAi技术明确籼稻亚种中两个不同ALK等位基因的效应。【方法】以分别含有ALKc和ALKb等位基因的高糊化温度品种珍汕97B和低糊化温度品种龙特甫B为试验材料，使用RNAi技术构建ALK表达下调的转基因株系，通过对其稻米理化品质的测定来明确不同等位基因表达下调对稻米品质的影响。【结果】对不同转基因水稻目的基因的表达分析显示本研究中转基因株系的ALK基因受到了不同程度的干扰。重点分析了不同RNAi株系稻米的糊化温度，结果表明珍汕97B的RNAi转基因稻米的糊化温度极显著降低，而在低糊化温度品种龙特甫B背景中下调表达ALK基因后对糊化温度的影响较小；转基因株系与未转化亲本相比，米粉的起始糊化温度都显著降低，表现为提前糊化；在珍汕97B背景下干扰系的峰值温度与未转化亲本相比极显著降低，而在龙特甫背景下米粉的峰值温度与未转化对照相比显著降低。对不同转基因系的理化品质分析表明，ALK下调表达植株稻米的表观直链淀粉含量显著增加，下调表达ALK后会引起米粉峰值黏度和崩解值的改变。高糊化温度品种珍汕97B干扰系与未转化对照相比胶稠度呈现极显著性差异，而低糊化温度品种龙特甫干扰系的胶稠度与未转化对照相比没有差异。【结论】下调表达ALK等位基因对稻米理化品质产生显著影响，并且干扰不同等位基因的效应存在明显差异，即籼稻中的两个ALK等位基因的效应存在显著差异。     

Grain Quality as Affected by Down-regulation of Expression of Different ALK Alleles in indica Rice (Oryza sativa L.)

【Objective】Gelatinization temperature (GT) is one of the key physicochemical properties in rice quality, which is mainly regulated by ALK (SSII-3) gene. In general, there are two ALK alleles among indica cultivars. To detect their functional differentiation in indica rice,【Method】Zhenshan 97B (a high GT variety carrying ALKc allele) and Longtefu B (a low GT variety carrying ALKb allele), were used as receptors for the generation of transgenic rice with down-regulation of ALK expression by RNA interference (RNAi).【Result】Down-regulation of ALK gene significantly decreased the GT of the transgenic lines. Due to the difference of original GT between the two receptors, the GT of transgenic rice lines derived from Zhenshan 97B (a high GT variety) decreased significantly, but it is slightly decreased in transgenic plants derived from Longtefu B (a low GT variety). The differential scanning calorimetry (DSC) results showed that the initial temperature of RNAi transgenic rice was significantly lower than the corresponding control and the transgenic lines were gelatinized in advance. The peak value of GT(Tp) in RNAi rice grains was significantly lower than that of the control under Zhenshan 97B background. However, Tp of RNAi rice grains under Longtefu B background was significantly lower than the control to a lesser extent. Also, down-regulation of ALK expression had a significant effect on rice physical-chemical characteristics. An increase of apparent amylose content in RNAi transgenic plants was detected due to the decreased expression of ALK gene. Besides, the pasting properties showed that down-regulation of ALK gene had obvious effects on peak viscosity and breakdown value, improving the taste of the transgenic rice. The gel consistency was significantly different among Zhenshan 97B RNAi lines and their parents, but no difference was found in Longtefu-derived transgenic lines.【Conclusion】RNA interference to ALK allele expression had a significant effect on rice quality, especially the gelatinization characters. Down-regulated expression level of ALKc allele would cause larger variation of physical-chemical characteristics between transgenic rice and their parent than that of ALKb allele.     

Effects of Water-Saving Irrigation and Nitrogen Fertilization on Yield and Yield Components of Rice (Oryza sativa L.)

Abstract

The effects of nitrogen (N) application (32, 72 and 112 kg N ha-¹ in 2000, and 32, 92 and 152 kg N ha-¹ in 2001) and water-saving irrigation and their interaction on grain yield and yield components of the rice cultivar Champa-Kamphiroozi, which is a local cultivar in a semi-arid area in the south of Islamic Republic (I.R.) of Iran, were investigated. The plants were cultivated under sprinkler irrigation (1.0 ET_p and 1.5 ET_p), intermittent flooding (1-day and 2-day intervals) and continuous flooding (control). The experiments were conducted on a clay loam-clay soil under a semi-arid environment using four replications in a split plot design with irrigation method as main plots and N levels as subplots. The results indicated that intermittent flooding irrigation at 2-day intervals was as effective as continuous flooding for grain yield, showing high water-use efficiency (WUE). The soil moisture tension in the root zone before each irrigation under this condition was –300 to –400 cm. Sprinkler irrigation and intermittent flooding increased WUE by 20 to 60%, compared with continuous flooding, and the increase in N application rate to 112-152 kg ha-¹ increased grain yield under any irrigation condition. Under sprinkler irrigation, grain yield was low and percentage of unfilled grain was high, although WUE was high. However, by adopting sprinkler irrigation, the amount of nitrogen fertilizer application necessary for cultivation was reduced. Furthermore, when nitrogen application must be limited due to groundwater pollution, the amount of nitrogen fertilizer necessary for cultivation can be reduced.     

Genotypic Variation of Stomatal Conductance in Relation to Stomatal Density and Length in Rice (Oryza sativa L.)

Abstract

Stomatal conductance (g_s) is an important trait responsible for the genotypic difference in gas diffusion for photosynthesis and transpiration in rice (Oryza sativa L.). We measured g_s, stomatal density and stomatal length (guard-cell length) at two weeks before heading for 64 accessions from a rice diversity research set of germplasm (RDRS) and for three high-yielding cultivars (HYC) under field conditions. Considerable variations in g_s, and stomatal length were observed among varieties in RDRS, and it was considered that RDRS covers the species diversity of the stomatal characteristics in rice. When it was compared among the varieties with similar plant earliness, g_s was higher in HYC than in most varieties of RDRS. Stomatal density did not correlate with g_s, and there was a negative correlation between stomatal density and stomatal length. However, noticeable variance existed in the latter relation, where HYC exhibited a higher stomatal density and slightly shorter stomatal length than RDRS. High g_s in HYC is attributable to their high stomatal density and moderate specific stomatal conductance (g_s / stomatal density) while the high-g_s varieties in RDRS tended to have a lower stomatal density and higher specific stomatal conductance. Stomatal length is related to specific stomatal conductance, but there are remarkable differences between these traits. Specific stomatal conductance in HYC has not reached the upper limit for their stomatal size, which raises a possibility of further improvement of HYC in g_s.     

施氮量与栽插密度对丰两优1号稻米品质的影响

研究了氮肥施用量和栽插密度对丰两优1号稻米主要品质性状的影响。结果表明,随着施氮量的增加,稻米垩白粒率和垩白度增加,胶稠度变短,直链淀粉含量降低;随着栽插密度的减小,垩白粒率和垩白度降低,直链淀粉含量先增加后降低。丰两优1号优质栽培适宜施氮量为180 kg/hm2,栽插密度为19.07万穴/hm2。     

密度对优化定抛水稻产量和群体质量的影响

水稻优化定抛密度试验结果表明：密度主要影响有效穗数进而影响产量，12万穴／hm^2处理的产量显著低于其它处理，密度在18万～36万穴／hm^2内各处理产量差异不显著。群体茎蘖数，LAI、干物质积累量和干物质在穗中的分配比例均以127万穴／hm^2处理最少，24万～36万穴／hm^2处理较大，但30万和36万穴／hm^2处理的群体透光率低，且36万穴／hm^2处理的茎秆抗倒伏能力变差，因此最适密度为24万穴／hm^2左右。     

水稻小粒基因SG101的鉴定和精细定位

【目的】籽粒大小是决定水稻产量的重要农艺性状之一,开展水稻籽粒大小相关基因的克隆和功能研究对于阐述水稻产量形成的遗传调控机制具有重要意义。【方法】利用甲基磺酸乙酯诱变粳稻品种中花11,筛选获得一小粒突变体,命名为sg101(small grain 101)。通过形态学、细胞学手段调查了SG101的突变对籽粒大小、穗部主要性状及颖壳细胞数目和大小的影响,通过测定叶夹角和胚芽鞘长度分析其对外施油菜素内酯的差异响应,结合定量PCR技术分析了油菜素内酯合成途径和信号途径相关基因表达情况,并利用图位克隆的手段精细定位了水稻小粒基因SG101。【结果】与野生型相比,突变体sg101粒长和粒宽均极显著减小,从而导致千粒重极显著降低。此外,sg101还表现出结实率降低、穗长变短、二次枝梗数减少、植株变矮等。细胞学观察发现sg101的颖壳细胞大小没有改变,但细胞数目明显减少。定量PCR检测表明sg101中的细胞周期相关基因表达显著下降。另外,突变体sg101对外施油菜素内酯响应迟钝,其油菜素内酯合成途径和信号途径相关基因表达亦显著降低。【结论】遗传分析表明sg101突变体由隐性单基因控制,通过图位克隆的方法将SG101精细定位于第1染色体上,物理距离为265 kb的区间内。这为该基因的克隆及深入的功能研究奠定了基础。