结实期相对高温对稻米淀粉粘滞性谱及镁、钾含量的影响

选用武育粳3号(粳稻)和扬稻6号(籼稻)两个水稻品种,利用人工气候室在水稻灌浆结实期进行控温试验,设置全结实期相对高温、结实前期相对高温、结实后期相对高温、全结实期适温(对照,日均温23 ℃)对照4个处理,探讨结实期不同时段相对高温(日均温度-30 ℃)对稻米淀粉粘滞性谱和Mg、K等元素含量的影响.结果表明：结实期相对高温使武育粳3号和扬稻6号淀粉粘滞性谱特征值发生改变,其中糊化开始温度、冷胶粘度、回复值和消减值升高,最高粘度、热浆粘度和崩解值下降;结实期相对高温促进了米粉中Mg、K、N含量的提高,特别是K含量的大幅提高,使稻米中Mg/K和Mg/(N·AC·K)明显降低;而2个水稻品种的直链淀粉含量（AC）对相对高温的反应截然相反,武育粳3号的AC降低、扬稻6号的AC升高.全结实期相对高温对稻米淀粉粘滞性谱和Mg、K等元素含量的影响最大,结实前期其次,结实后期的影响较小,开花后20 d内是稻米淀粉粘滞性谱和Mg、K等元素含量受温度影响的关键时期.Mg/K和Mg/(N·AC·K)与淀粉粘滞性谱特征值显著相关,可以作为稻米食味品质评价的参考指标.     

高温对早籼稻花后剑叶氮代谢关键酶活性及籽粒蛋白质含量的影响

为探讨高温对不同类型早籼稻开花后剑叶中氮代谢关键酶活性及籽粒蛋白质含量的影响,利用人工气候室在籽粒灌浆成熟期进行高温(日均温31.5 ℃)和适温(日均温23.5 ℃)处理,对2个早籼稻品种(湘早籼24和株两优611)灌浆成熟期籽粒中蛋白质含量及剑叶中GS和GOGAT活性的动态变化进行了分析.结果表明:供试2个品种在高温...     

灌浆结实期温度对水稻产量和品质形成的影响

灌浆结实期是水稻产量和品质形成的关键时期,该时期温度对水稻籽粒灌浆具有显著的影响.随着全球气候趋暖以及极端天气频发,温度胁迫下籽粒灌浆和稻米品质的响应特征及其生理生化机制是目前稻作研究的热点之一.本文以灌浆结实期温度为切入点,对水稻产量和品质形成的适宜温度与温度影响时段以及温度胁迫下水稻生理生化特征等方面进行了梳理.灌浆初期(齐穗后20 d)是温度影响水稻产量和品质形成的关键时期,适温(21 ～ 26℃)有利于水稻灌浆和淀粉的充实与沉积,过高或过低温度均不利于提高水稻产量和品质.温度胁迫下,水稻生理生化活性下降,光合功能降低,抗逆性减弱,干物质积累和运转受抑,从而造成产量下降及品质变劣.这些可能为水稻优质高产栽培和灌浆结实期温度研究提供一定的参考.     

不同生长调节物质对水稻生长及镉积累的影响

比较脱落酸(ABA)、乙烯利(ETH)、水杨酸(SA)和茉莉酸甲酯(MeJ A)4种植物生长调节物质(PGR)对水稻生长及籽粒镉(Cd)积累的影响差异。试验采用重金属污染土种植水稻,于分蘖期、灌浆期各进行1次PGR叶面喷施处理,分析灌浆期叶片光合指标,丙二醛(MDA)含量以及收获期各部位生物量和Cd含量。结果表明:(1)低浓度ABA(5mg/L)可维持水稻正常产量;高浓度ABA(15mg/L)则导致产量下降。ETH对水稻地上部生长和单株产量有显著抑制作用,SA和MeJ A(0.56mg/L)均可保证地上部正常生长,维持正常产量。(2)外施4种PGR均抑制灌浆期叶片气孔开放,降低蒸腾速率和光合速率,抑制效果最明显的是高浓度MeJ A(0.56mg/L)。(3)在供试浓度范围内SA、低浓度ABA(5mg/L)以及高浓度MeJ A均可降低灌浆期叶片MDA含量,减少质膜过氧化水平。(4)4种PGR均可降低水稻籽粒Cd含量,其中低浓度ABA(5mg/L)抑制籽粒Cd积累的效应最佳。相关性分析结果表明,PGR抑制籽粒积累Cd的效应与地上部向籽粒转运Cd的调控机制有关,与蒸腾速率无显著相关关系。(5)综上所述,低浓度ABA(5mg/L)处理对水稻产量无影响,且籽粒Cd含量降低程度最大。适当浓度的PGR可降低水稻籽粒Cd含量,在中低度重金属污染农田生态修复实践中具有一定的应用前景,但必须精确控制PGR的处理时间和处理浓度,避免出现抑制生长和降低产量的负效应。     

褐飞虱侵害后不同水稻品种根及叶片脱落酸含量的变化

为了解褐飞虱Nilaparvata lugens （Stål）侵害后水稻耐虫性与植物体内源激素关系,应用酶联免疫吸附法（enzyme-linked immunosorbent assay, ELISA）研究褐飞虱若虫侵害分蘖期超级培矮64S/E32和TN1,灌浆期协优963和TN1后根及叶片脱落酸（abscisic acid, ABA）含量变化.结果表明：褐飞虱侵害分蘖期超级培矮64S/E32和TN1后3 d,叶片ABA含量显著上升,ABA含量根冠比（根ABA/叶片ABA）显著下降;侵害后6 d,超级培矮64S/E32叶片ABA含量显著下降,根冠比显著上升;但TN1叶片ABA含量在褐飞虱侵害后3 d和6 d显著上升,根冠比显著下降.褐飞虱侵害灌浆期协优963与分蘖期超级培矮64S/E32变化一致,TN1在褐飞虱侵害后3 d叶片ABA含量显著上升,根冠比显著下降;侵害后6 d,叶片ABA含量、ABA含量根冠比均显著上升.由ABA含量变化百分比可见,分蘖期ABA含量变化幅度较灌浆期大;耐虫品种变化幅度较感虫品种大,持续期较感虫品种短;叶片变化幅度较根部大.褐飞虱侵害后,两种不同生育期两种抗性不同的水稻品种比较,耐虫品种叶片ABA含量先上升（3 d）后下降（6 d）,ABA含量根冠比先下降（3 d）后上升（6 d）;感虫品种叶片ABA含量持续上升（3 d和6 d）,分蘖期ABA含量根冠比持续下降（3 d和6 d）,灌浆期ABA含量根冠比先下降（3 d）后上升（6 d）;耐、感虫水稻品种根部变化规律不明显.这些差别表明不同水稻（耐虫和感虫）品种受褐飞虱侵害后体内ABA含量变化规律不同.本研究结果对深入阐明水稻耐虫品种的机制具有重要参考价值.     

温度对七叶一枝花光合特性及皂苷含量的影响

该研究以珍稀濒危药用植物七叶一枝花(Paris polyphylla)为材料,利用人工气候箱设置3个温度条件,即低温(10℃/16℃)、适温(18℃/24℃)、高温(26℃/32℃),采用盆栽法分析了不同温度条件对七叶一枝花光合特性和主要有效成分皂苷含量的影响。结果表明:(1)适温条件下,七叶一枝花叶绿素含量、最大光合速率、光饱和点、表观量子效率均高于低温和高温处理,而光补偿点、暗呼吸速率则低于两者。(2)适温条件下,七叶一枝花根茎体内皂苷含量最大,达到了4.33%,低温和高温处理下皂苷含量分别只有适温的42.26%和33.49%,氨基酸含量同样表现为适温处理下最大。(3)七叶一枝花有效成分含量与叶片叶绿素含量、光合速率呈显著正相关,而与呼吸速率呈显著负相关,说明温度直接影响植株的光合作用、呼吸作用,进而影响有效成分的积累。温度对七叶一枝花光合特性及有效成分的积累影响显著,22℃左右的平均温度(18℃/24℃)是七叶一枝花栽培的适宜温度,此温度有利于其生长及有效成分的积累,该研究结果为七叶一枝花人工栽培中温度的科学管理提供了依据。     

高温对杂交水稻籽粒灌浆和剑叶某些生理特性的影响

以杂交籼稻特优559为材料,探讨了高温胁迫对水稻灌浆期剑叶中有关生理特性和籽粒灌浆速率的影响.结果表明:高温胁迫加速了剑叶叶绿素的丧失,使SOD活性明显降低,质膜透性和MDA含量明显增加,脯氨酸、AsA、GSH、可溶性蛋白质以及可溶性糖含量明显降低,籽粒灌浆速率和籽粒重下降.高温使灌浆期水稻叶片衰老加速、光合能力下降是其导致灌浆速率、结实率、粒重和籽粒产量降低的主要生理原因.     

外源海藻糖对高温胁迫下穗分化期水稻叶片生理特性及产量的影响

该研究以耐热型水稻品种Nagina22和热敏型水稻品种YR343为供试材料,采用盆栽试验,设置喷施清水+常温处理(NT0)、喷施清水+穗分化期高温胁迫(HT0),以及分别喷施5、10、15、20 mmol·L^-1外源海藻糖+高温胁迫(分别记为HT1、HT2、HT3、HT4)共6个处理,分析外源海藻糖对高温胁迫下穗分化期水稻叶片叶绿素含量、光合气体交换参数、抗氧化酶活性、渗透调节物质含量、活性氧含量等生理特性,以及籽粒产量及其构成因素的影响,为水稻抗热栽培和耐热品种的选育提供理论依据。结果表明:(1)在高温胁迫下水稻穗分化期,2个水稻品种叶片的叶绿素含量、光合气体交换参数及渗透调节物质含量均降低,叶片MDA和H₂O₂含量以及■的产生速率均上升,叶片抗氧化酶活性呈先增后降的趋势,最终显示水稻籽粒产量及其构成因素显著下降。(2)喷施外源海藻糖能显著增加高温胁迫下穗分化期水稻的每穗粒数、千粒重和结实率,从而提高籽粒产量,其中弱势粒千粒重和结实率的增幅高于强势粒,外源海藻糖最适喷施浓度为15 mmol·L^-1...     

高温对水稻黄叶突变体剑叶光合特性和叶绿体超微结构的影响

以水稻黄叶突变体为材料,进行高温胁迫处理(9:30～17:30,40℃;其它时间段与自然温度相同),研究高温胁迫对其剑叶光合特性和叶绿体超微结构的影响。结果表明:高温胁迫使水稻黄叶突变体剑叶净光合速率(Pn)、PSⅡ原初光化学效率(Fv/Fm)、PSⅡ光量子效率(фPSⅡ)和非循环光合电子传递速率(ETR)显著降低,初始荧光(F0)显著增加,同时使剑叶叶绿素、可溶性蛋白质含量显著降低,细胞膜透性显著增加,叶片的叶绿体内基粒和基质片层模糊、疏松,结构紊乱。研究发现,40℃高温胁迫致使水稻黄叶突变体剑叶叶绿体超微结构破坏,引起PSⅡ反应中心的光化学效率降低,最终造成叶片光合能力减弱。     

灌浆期高温对冬小麦籽粒氨基酸含量和组成的影响

以强筋小麦品种郑麦366和中筋小麦品种洛旱2号为材料,采用盆栽和人工气候室模拟的方法,研究了花后不同时段(灌浆前期即花后5 d,灌浆中期即花后15 d)和持续时间(处理2 d和4 d)的高温胁迫对籽粒氨基酸含量和积累量(以单粒中氨基酸含量表示)的影响。结果显示:(1)高温胁迫显著增加了小麦籽粒中必需氨基酸(EAA)、非必需氨基酸(NAA)和总氨基酸(TAA)含量,但降低了其积累量和EAA/TAA,2品种表现一致;(2)灌浆前期高温胁迫对2品种籽粒氨基酸含量的影响大于灌浆中期,而对氨基酸积累量的影响则相反;(3)高温持续时间对籽粒氨基酸含量的影响在2品种间存在差异,洛旱2号籽粒赖氨酸、EAA、NAA和TAA含量均随高温持续时间的延长显著增加,而郑麦366籽粒中上述指标仅在高温胁迫4 d下较对照增加显著;(4)从受高温胁迫的影响看,籽粒EAA/TAA对高温时段更敏感,而氨基酸含量表现为更易受高温持续时间的影响;(5)高温时段与持续时间的互作效应体现在:灌浆前期籽粒氨基酸积累量2品种均以高温胁迫4 d的影响最大,而灌浆中期则均以高温2 d的降幅最大。上述结果表明,小麦籽粒氨基酸及其组分对高温胁迫的响应不仅在品种间存在差异,且受高温时段和持续时间的影响。     

核黄素参与水稻非生物胁迫响应的分析

为探究核黄素在水稻非生物胁迫响应中的作用,以粳稻Kitaake和籼稻T98B为试验材料,考察了核黄素对2种材料的盐、高温、渗透、碱和氧化胁迫响应的影响,重点测定了盐和高温胁迫下水稻体内核黄素合成基因的表达和相关生理指标。结果表明,(1)施加外源核黄素有效提高了2种水稻材料的盐和高温胁迫耐受性,降低了渗透胁迫耐受性,而其氧化和碱胁迫耐受性不受影响。(2)逆境胁迫均不同程度地促进了核黄素在2种水稻材料中的积累,尤其在盐和高温胁迫下促进效果最明显。(3)盐和高温胁迫均诱导了核黄素合成酶基因的表达,促进了核黄素的生物合成,改善了水稻的胁迫耐受性。研究表明,非生物逆境胁迫能促进核黄素在水稻体内的合成和积累,外源核黄素也能明显提高水稻对盐和高温胁迫的耐受性,但却降低了其对渗透胁迫的耐受性。     

抽穗扬花期高温胁迫对水稻主要品质指标的影响

高温热害对水稻生产造成了巨大的损失。利用国际水稻研究所耐热圃材料,在抽穗扬花期进行高温处理,研究了该时期高温胁迫对水稻主要品质评价指标的影响,结果如下：水稻耐热圃材料的耐热性有较大的差别,依然存在高温相对敏感材料;抽穗扬花期高温胁迫对水稻主要品质评价指标影响较大;高温胁迫对水稻籽粒的透明度、长宽比、垩白率、糊化温度和蛋白质含量等品质指标与品种的耐热性相关关系不大;高温胁迫下直链淀粉含量变化与品种耐热系数表现出显著的正相关关系（r=0.659 78）;高温胁迫下胶稠度变化与不同水稻品种的耐热系数呈显著的负相关关系（r=-0.516 70）。     

水稻高温热害的研究现状与进展

全球气候变暖环境下,水稻高温热害频发,孕穗-开花期和灌浆期高温已成为制约水稻产量和品质的主要因素之一。本文综述了水稻高温热害的发生特点(鉴定与分级、区域和时间)和高温对水稻生长发育(生理、产量和品质)的影响,总结了水稻高温热害的数量性状座位定位、转录组和蛋白质组分析等分子生物学研究及监测预警与风险评估,重点阐述了高温热害的防御措施,包括选用耐热品种、改善田间管理和喷施外源物质,并对今后水稻高温热害研究进行了展望,以期为水稻高温热害防御和农业减灾增效提供科学支持。     

Suppression of OsMADS7 in rice endosperm stabilizes amylose content under high temperature stress

High temperature significantly alters the amylose content of rice, resulting in mature grains with poor eating quality. However, only few genes and/or quantitative trait loci involved in this process have been isolated and the molecular mechanisms of this effect remain unclear. Here, we describe a floral organ identity gene, OsMADS7, involved in stabilizing rice amylose content at high temperature. OsMADS7 is greatly induced by high temperature at the early filling stage. Constitutive suppression of OsMADS7 stabilizes amylose content under high temperature stress but results in low spikelet fertility. However, rice plants with both stable amylose content at high temperature and normal spikelet fertility can be obtained by specifically suppressing OsMADS7 in endosperm. GBSSI is the major enzyme responsible for amylose biosynthesis. A low filling rate and high expression of GBSSI were detected in OsMADS7 RNAi plants at high temperature, which may be correlated with stabilized amylose content in these transgenic seeds under high temperature. Thus, specific suppression of OsMADS7 in endosperm could improve the stability of rice amylose content at high temperature, and such transgenic materials may be a valuable genetic resource for breeding rice with elite thermal resilience.     

长江中下游地区水稻孕穗开花期高温发生规律及其对产量的影响

以长江中下游平原7个省(市)的19个地区作为样点,统计分析了各样点近36年(1970—2005年)水稻始穗前15d至始穗后20d内日最高气温≥35℃的时空分布特点;并根据全球气候渐变模型GISS GCM Transient B Runs生成的研究区域2030、2050年的气候渐变情景,分析了该地区未来水稻孕穗开花期≥35℃高温逆境的时空演变趋势。结果表明:近36年来长江中下游的早稻孕穗开花期出现高温日数的上升趋势显著,未来气候情景下水稻逆境指标出现日数最多的是单季稻,其次依次为早稻、后季稻;双季稻种植区,在未来气候变化中,长江中游地区温度逆境出现日数将大于下游地区。研究区域水稻气候产量的增减与该地区水稻逆境指标的关系说明,高温导致的颖花败育是水稻减产的重要原因;未来气候变化的两种(2030、2050)情景下,长江中游地区的减产幅度大于长江下游地区,减产幅度最大的是长江中游地区的后季稻。     

Effects of ambient temperature and the mud snail <Emphasis Type="Italic">Cipangopaludina chinensis laeta</Emphasis> (Architaenioglossa: Viviparidae) on performance of rice plants

A factorial experiment was conducted in 2015 to assess the effects of ambient temperature and the presence of the mud snail, Cipangopaludina chinensis laeta (Martens) (Architaenioglossa: Viviparidae), on rice plant performance. The presence of mud snails resulted in significantly increased rice plant height and SPAD value (reflecting leaf color), although the number of tillers was not significantly affected. The effects of temperature (high vs. normal) on rice plant performance were examined in experiments inside and outside the greenhouse. The average temperature of the water in experimental containers with rice seedlings showed that the temperature inside the greenhouse tended to be higher than that outside. The results suggest that the effects of temperature differed among plant traits; plants grew taller but had fewer tillers when the rice was grown at a high temperature, whereas SPAD was not significantly affected. A significantly greater number of roots were observed on the soil surface when snails were present. In general, the mud snails produced less excreta at a high temperature than a normal temperature. The results of this study indicate that ambient temperature had both a direct influence on rice plant performance and an indirect influence through the activity of the mud snails.     

Pollen germination and in vivo fertilization in response to high‐temperature during flowering in hybrid and inbred rice

High‐temperature during flowering in rice causes spikelet sterility and is a major threat to rice productivity in tropical and subtropical regions, where hybrid rice development is increasingly contributing to sustain food security. However, the sensitivity of hybrids to increasing temperature and physiological responses in terms of dynamic fertilization processes is unknown. To address these questions, several promising hybrids and inbreds were exposed to control temperature and high day‐time temperature (HDT) in Experiment 1, and hybrids having contrasting heat tolerance were selected for Experiment 2 for further physiological investigation under HDT and high‐night‐time‐temperature treatments. The day‐time temperature played a dominant role in determining spikelet fertility compared with the night‐time temperature. HDT significantly induced spikelet sterility in tested hybrids, and hybrids had higher heat susceptibility than the high‐yielding inbred varieties. Poor pollen germination was strongly associated with sterility under high‐temperature. Our novel observations capturing the series of dynamic fertilization processes demonstrated that pollen tubes not reaching the viable embryo sac was the major cause for spikelet sterility under heat exposure. Our findings highlight the urgent need to improve heat tolerance in hybrids and incorporating early‐morning flowering as a promising trait for mitigating HDT stress impact at flowering.     

Climate Change: Implications for the Yield of Edible Rice

Global warming affects not only rice yield but also grain quality. A better understanding of the effects of climate factors on rice quality provides information for new breeding strategies to develop varieties of rice adapted to a changing world. Chalkiness is a key trait of physical quality, and along with head rice yield, is used to determine the price of rice in all markets. In the present study, we show that for every ∼1% decrease in chalkiness, an increase of ∼1% in head rice yield follows, illustrating the dual impact of chalk on amount of marketable rice and its value. Previous studies in controlled growing conditions report that chalkiness is associated with high temperature. From 1980–2009 at IRRI, Los Baños, the Philippines, annual minimum and mean temperatures, and diurnal variation changed significantly. The objective of this study was to determine how climate impacts chalkiness in field conditions over four wet and dry seasons. We show that low relative humidity and a high vapour pressure deficit in the dry season associate with low chalk and high head rice yield in spite of higher maximum temperature, but in the opposite conditions of the wet season, chalk is high and head rice yield is low. The data therefore suggest that transpirational cooling is a key factor affecting chalkiness and head rice yield, and global warming per se might not be the major factor that decreases the amount and quality of rice, but other climate factors in combination, that enable the crop to maintain a cool canopy.     

地方稻资源D43的开花期耐热特性研究

水稻在抽穗开花期对高温胁迫非常敏感,通过挖掘耐热资源,培育耐热水稻品种是应对高温热害最有效的方式。前期研究发现,地方稻资源D43在花期连续高温条件下能保持较高的结实率。本研究在大田和人工气候室不同高温处理下,分析了D43的开花时间与耐热性之间的相互关系。结果表明,高温能够使水稻的开花时间提前,D43表现出稳定的早花时特性,高温胁迫下的开花时间集中在8∶30~10∶00;在开花时间段恒定高温胁迫下,D43的结实率较低;但在大田高温和人工气候室模拟高温胁迫下,D43的开花时间避开了日高温段,从而表现出较高的结实率;花器官形态性状包括花药开裂率、柱头上的花粉附着数、花粉萌发数与结实率之间呈显著正相关,因此可用于评价水稻的花期耐热性。