Heat stress threatens rice yield and quality at flowering stage. In this study, average relative seed setting rate under heat stress (RHSR) and genotypes of 284 varieties were used for a genome-wide association study.

【目的】研究水稻产量对不同时期不同类型高温的响应差异,为耐热水稻品种的筛选与培育提供依据。【方法】在桶栽条件下,于人工气候室内,以耐热水稻品种Nagina 22、汕优63和热敏感品种两优培九为材料,设置三个处理时期,即穗分化期、开花期和灌浆期;四种处理温度,即白天高温、夜间高温、全天高温和适宜温度,研究水稻产量和产量构成因子对不同时期高温的响应。【结果】汕优63在三个时期均表现出较强的耐热性;Nagina 22在花期和灌浆期对高温耐性较强,但易受穗分化期高温影响;两优培九对不同时期高温均较敏感。汕优63在不同时期高温下均表现出稳定的伤流强度,而高温敏感品种两优培九的伤流强度受高温影响均显著下降。【结论】水稻对不同时期的高温耐性并不具有相关性,筛选或培育耐热品种时应考虑其对不同时期高温的综合耐受性。

为了掌握广西水稻高温热害的变化规律特征,为水稻生产制定防灾减灾对策提供决策依据,本研究利用广西89个气象观测站1958—2018年观测资料及地理信息数据,采用GIS技术、M-K突变分析和Morlet小波周期分析等方法,探究广西早稻高温热害发生的时间变化规律和空间分布等特征。结果表明：（1）1958—2018年广西早稻高温热害呈增长趋势,20世纪90年代为发生低谷期,21世纪10年代为高发期;（2）高温热害发生次数在2009年发生增多突变,除重度高温热害外,轻、中度高温热害次数变化均有突变发生;（3）高温热害发生频次存在18、32年左右的显著周期变化,预计2018年之后广西早稻高温热害仍处于高发期;（4）高温热害高发区位于左、右江河谷,桂中盆地和西江—浔江—郁江等流域区域,沿海地区发生频次少于内陆。以上研究结论对实现水稻丰产稳产优产具有重要的现实意义。

农业种质资源主要包括农作物、畜禽、农业微生物和药用植物等种质资源。截止到2023年，我国保存的作物种质资源有超过54万份，其中有8万多份是水稻种质资源，如何对这么庞大的水稻种质资源进行精确评价与利用，这将对今后水稻种质创新与育种具有重要意义。本文梳理了我国水稻种质资源收集、评价与精确鉴定、水稻新品系创制、水稻杂种优势利用、水稻种质创制新技术、新方法以及水稻优异基因资源的挖掘与利用等方面的进展，并归纳形成了水稻种质资源创制与利用的新模式。最后，本文就当前水稻核心种质构建、种质资源鉴定与挖掘以及种质资源共享共赢机制等方面的问题进行了探讨，并就如何加强专用型核心种资的构建、种质资源的精确鉴定、种质资源的创新研究、种质资源的共享机制以及种质资源的合作交流进行了分析与展望，以期为进一步深入开展水稻种质资源鉴定评价与创新利用提供一定的参考和帮助。

为研究耐热水稻品种“Nagina 22”（N22）开花结实期高温胁迫下的主要生理响应，采用温室盆栽试验，在各供试材料的开花期，利用人工气候室进行高温胁迫处理。研究结果表明：N22在高温胁迫下不改变开花期但表现出日开花量的“转峰”；与N22相比，水稻感热品种“Moroberekan”花药开裂显著受阻，柱头上萌发的花粉数显著减少；花粉萌发数与花药开裂状况呈极显著的相关关系，进而表现出主穗结实率与柱头上花粉萌发数呈显著的相关关系；主穗日结实率在高温下呈递减趋势，且“Moroberekan”较N22的下降速率显著加快，表明耐热品种与表明高温胁迫对结实率存在“累积效应”，而且高温胁迫效应发生在开花授粉之前。

为研究杂交稻对开花结实期高温胁迫的生理生态适应性，选用具代表性的主栽杂交稻组合国稻6号、协优46，人工设计极值高温40~42℃，自始穗期至此后15 d每天6 h行热害处理，以自然气候条件为对照，比较研究高温胁迫对国稻6号与协优46结实的生理影响。结果表明，国稻6号具较高的受孕小穗成粒效应，即不仅不孕小穗率低，而且秕谷率也低。国稻6号对开花结实期高温较协优46钝感，两者在小穗育性和热害指数上的差异达到显著水平(P<0.05)。究其生理原因, (1)成熟期间稻株剑叶光能转化效率及光合效率较高，茎鞘储藏物质较丰；(2)成熟期间稻株仍具较强根系吸水能力与叶片蒸腾水平，维持蒸腾流利于光合物质运输；(3)成熟灌浆期稻株自动调节粒间顶端优势，增进迟开花的弱势粒充实成实粒。

以两个耐热性不同的籼稻品种为材料，在减数分裂期进行高温(白天温度>35℃)处理，以同期自然温度(白天温度<33℃)为对照，研究减数分裂期高温对产量的影响及其生理机制。结果表明，高温处理与对照相比，显著降低了热敏感品种双桂1号的花药开裂率及花粉育性，对耐热品种黄华占影响较小；明显降低了每穗颖花数、结实率和粒重，从而使产量显著下降，其中耐热品种下降幅度小于热敏感品种；热敏感品种粒宽显著缩短，长宽比显著增大，而对耐热型品种影响不大；明显降低了水稻的根系活力和幼穗的核糖核酸(RNA)含量，显著增加了叶片丙二醛(MDA)含量和幼穗的乙烯释放速率，热敏感品种变化幅度大于耐热品种；显著增加了耐热品种叶片的抗氧化酶活性，对热敏感品种无显著影响。总之，根系活力和抗氧化保护系统能力强、RNA含量高、MDA含量低及乙烯合成少是耐热性品种在高温胁迫下保持较高产量的重要生理原因。

Studies on heat tolerance in rice (Oryza sativa L.) have focused on a range of accessions that are currently not grown or cultivated in small localized geographic regions, while popular rice cultivars occupying millions of hectares have not been tested for their response to heat stress. Hence, 18 popular rice cultivars grown across tropical and subtropical regions were subjected to 38°C for 6 h of heat stress at anthesis and five selected contrasting entries were exposed to six consecutive days (6 h each day) of stress coinciding with both gametogenesis and anthesis. Among the tested entries, Ciherang was the most tolerant, after both 6 h at anthesis and 6 d of stress across both gametogenesis and anthesis, whereas Moroberekan and KDML‐105 were the most susceptible. Using a quick and easy phenotyping protocol and by considering all the sterile spikelets across target panicles, the crucial physiological window “spikelets with exserted anthers but with no ovule enlargement” was identified as the most sensitive stage with exposure to heat stress at both critical reproductive stages. Geographic origin of rice varieties was not clearly related to the degree of tolerance or susceptibility to heat stress because both conditions were observed in cultivars from each target region. Our findings complement other ongoing efforts that are using heat‐tolerant landraces and wild rice as donors to further increase tolerance to sustain global rice production under future warmer climate.

Oryza meridionalis Ng. is a wild relative of Oryza sativa L. found throughout northern Australia where temperatures regularly exceed 35 degrees C in the monsoon growing season. Heat tolerance in O. meridionalis was established by comparing leaf elongation and photosynthetic rates at 45 degrees C with plants maintained at 27 degrees C. By comparison with O. sativa ssp. japonica cv. Amaroo, O. meridionalis was heat tolerant. Elongation rates of the third leaf of O. meridionalis declined by 47% over 24 h at 45 degrees C compared with a 91% decrease for O. sativa. Net photosynthesis was significantly higher in O. sativa at 27 degrees C whereas the two species had the same assimilation rates at 45 degrees C. The leaf proteome and expression levels of individual heat-responsive genes provided insight into the heat response of O. meridionalis. After 24 h of heat exposure, many enzymes involved in the Calvin Cycle were more abundant, while mRNA of their genes generally decreased. Ferredoxin-NADP(H) oxidoreductase, a key enzyme in photosynthetic electron transport had both reduced abundance and gene expression, suggesting light reactions were highly susceptible to heat stress. Rubisco activase was strongly up-regulated after 24 h of heat, with the large isoform having the largest relative increase in protein abundance and a significant increase in gene expression. The protective proteins Cpn60, Hsp90, and Hsp70 all increased in both protein abundance and gene expression. A thiamine biosynthesis protein (THI1), previously shown to act protectively against stress, increased in abundance during heat, even as thiamine levels fell in O. meridionalis.

Rice, a staple crop that feeds more than one-third of the world’s population, encounters a wide range of biotic and abiotic stresses due to climate change. Rising temperature is one of the significant abiotic stresses affecting rice productivity worldwide. The development of heat-tolerant rice cultivars is critical in this regard. Weedy rice could potentially serve as a natural resource for genes conferring agronomically important traits beneficial to cultivated rice. However, heat tolerance in both cultivated and weedy rice is still understudied. This study screened a set of 180 weedy rice accessions for heat stress tolerance and further characterised them using genome-wide single-nucleotide polymorphisms (SNPs) analysis. Five heat-tolerant (HT) accessions (MU244, MU235, MU249, MU260 and MU237), along with five heat-susceptible (HS) accessions (MU100, MU114, MU264, MU251 and MU005), were subjected to relative electrical conductivity (REC) test and reactive oxidative species assay (ROS). These tests verified that the five HT accessions performed better under heat stress than their HS counterparts. In addition, whole-genome sequences of three HT (MU235, MU237 and MU066) and four HS (MU100, MU114, MU022 and MU005) accessions were selected for the genome-wide SNPs comparison, revealing substantial amino acid variation in the heat-tolerance-related genes between the HT and HS rice groups. The proposed genes and genome-wide SNP markers may help rice breeders better understand how different rice cultivars respond to heat stress.

Global warming threatens crop production. G proteins mediate plant responses to multiple abiotic stresses. Here we identified a natural quantitative trait locus, TT2 (THEROMOTOLERANCE 2), encoding a Gγ subunit, that confers thermotolerance in rice during both vegetative and reproductive growth without a yield penalty. A natural allele with loss of TT2 function was associated with greater retention of wax at high temperatures and increased thermotolerance. Mechanistically, we found that a transcription factor, SCT1 (Sensing Ca Transcription factor 1), functions to decode Ca through Ca-enhanced interaction with calmodulin and acts as a negative regulator of its target genes (for example, Wax Synthesis Regulatory 2 (OsWR2)). The calmodulin-SCT1 interaction was attenuated by reduced heat-triggered Ca caused by disrupted TT2, thus explaining the observed heat-induced changes in wax content. Beyond establishing a bridge linking G protein, Ca sensing and wax metabolism, our study illustrates innovative approaches for developing potentially yield-penalty-free thermotolerant crop varieties.© 2021. The Author(s), under exclusive licence to Springer Nature Limited.

How the plasma membrane senses external heat-stress signals to communicate with chloroplasts to orchestrate thermotolerance remains elusive. We identified a quantitative trait locus, (), consisting of two genes, and, that interact together to enhance rice thermotolerance and reduce grain-yield losses caused by heat stress. Upon heat stress, plasma membrane-localized E3 ligase TT3.1 translocates to the endosomes, on which TT3.1 ubiquitinates chloroplast precursor protein TT3.2 for vacuolar degradation, implying that TT3.1 might serve as a potential thermosensor. Lesser accumulated, mature TT3.2 proteins in chloroplasts are essential for protecting thylakoids from heat stress. Our findings not only reveal a genetic module at one locus that transduces heat signals from plasma membrane to chloroplasts but also provide the strategy for breeding highly thermotolerant crops.

Global warming would deteriorate rice (Oryza sativa L.) quality, especially chalk characteristic. To better cope with the challenges from global warming, the effects of nitrogen (N) fertilizer at heading stage on rice quality under elevated temperature during grain‐filling stage were investigated. Four different growth regimes, including no warming without N fertilizer at heading stage (CK), elevated temperature without N fertilizer at heading stage (ET), elevated temperature with N fertilizer at heading stage (ET+N), no warming with N fertilizer at heading stage (CK+N), were conducted. Elevated temperature during grain filling was achieved by a free‐air temperature enhancement facility with the increase of 4°C in ET and 3.7°C in ET+N. Results showed that elevated temperature decreased rice appearance quality and cooking quality and increased rice nutritional quality and eating quality. Grain‐filling rate and amyloplast development for both superior and inferior spikelets were obviously accelerated during early grain‐filling stage by elevated temperature. The application of N fertilizer at heading stage could inhibit the deterioration of rice quality, particularly for chalk performance, and may be associated with the alleviation of grain‐filling rate and amyloplast development. The above evidence indicated that the application of N fertilizer at heading stage is efficient to mitigate rice quality deterioration under higher temperatures in the Yangtze River Valley.

【目的】研究灌浆期高温胁迫对早籼稻碾磨、外观和蒸煮食味品质的影响，揭示早籼稻品质性状对灌浆期高温胁迫的响应规律。【方法】以R996、湘早籼45号和6个新育成的早籼稻品系为试验材料，以分期播种方式利用自然高温进行胁迫处理，分析了供试品系的碾磨、外观和蒸煮食味品质，筛选出对高温钝感和敏感的水稻品系，探究稻米品质性状对灌浆期高温胁迫的响应规律。【结果】稻米品质性状对灌浆期不同时段温度的敏感性不同，始穗后10 d内温度对稻米碾磨品质和蒸煮食味品质影响最显著，始穗后30 d内温度对稻米外观品质影响最显著。稻米品质对灌浆期高温胁迫的响应因性状而异，灌浆期高温胁迫显著降低糙米率、精米率、整精米率和粒长，显著提高垩白粒率、垩白度，劣化了稻米碾磨品质和外观品质；显著降低直链淀粉含量，提高米饭外观、米饭口感和米饭黏度，提升了米饭适口性。水稻品系对高温胁迫的响应因稻米品质性状而异，Q3、Q8、Q11、Q13属于碾磨品质高温钝感品系，Q3、Q4、Q5和Q11属于外观品质高温钝感品系且高温下蒸煮食味品质优。【结论】灌浆期高温胁迫会降低稻米的碾磨品质和外观品质，提高米饭适口性。水稻品系Q3和Q11碾磨品质、外观品质好且高温钝感，蒸煮食味品质优良，可望为早籼稻优质育种提供新的种质资源。

【目的】近年来极端高温天气频发，严重抑制水稻产量品质形成，优化植株营养状态，改善能量代谢可减缓高温热害，但高温下不同施肥量对籽粒能量代谢的影响及其与产量、品质及耐热性形成的影响仍未见报道，其作用机制的阐明可为水稻耐热性抗风险栽培技术研发提供重要理论依据。【方法】以浙江省推广大面积较大的单季杂交籼稻品种中浙优8号为材料，采用人工气候室盆栽的试验方法开展研究。设置不施肥(0-NPK)、1/2肥料(1/2-NPK)和正常施肥(1-NPK)三个肥料用量处理，开花当天移至人工气候室高温处理15d(高温处理设置昼/夜分别为36/28℃，常温对照设置昼/夜分别为28/25℃)。【结果】无论常温或高温下，在供试肥料水平下随着施肥量增加，中浙优8号产量、结实率及千粒重均呈逐渐增加的趋势；高温下，结实率、千粒重的下降幅度随施肥量增加而下降。然而，整精米率随施肥量增加而下降，垩白度则呈增加的趋势。高温处理后籽粒可溶性糖、MDA、H₂O₂、腺苷三磷酸酶(ATPase)及PARP [poly(ADP-ribose) polymerase]含量高于常温对照处理，淀粉、非结构性碳水化合物、抗氧化酶活性及ATP含量则低于常温对照。无论常温或高温下非结构性碳水化合物、抗氧化酶活性、ATP及ATPase均随着施肥量的增加而提高，而MDA、H₂O₂及PARP含量则呈下降趋势。常温下，能量感受器基因SnRK1A及SnRK1B相对表达量随施肥量增加而下降，而TOR则呈增长趋势。与常温对照相比，高温处理后SnRK1A上调表达，而TOR相对表达量随施肥量增加而上调。【结论】增施肥料能有效缓解花期高温对水稻结实率及千粒重的影响，但外观品质与加工品质存在变劣的趋势。常温下，增施肥料品质变劣可能与籽粒灌浆速率加快有关，而高温导致品质下降主要在于能量不足，难以满足产量及品质形成的需求。

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）。

以 303 份黄淮海地区大豆种质资源为研究对象，利用变异系数和 Shannon-Weaver 多样性指数对 11 个农艺性状和2 个品质性状进行多样性分析，通过主成分、相关性以及逐步回归分析对大豆种质资源进行综合评价和评价指标筛选，为黄淮海大豆种质创新和品种选育提供参考。结果表明：13 个性状变异系数的变化范围为 5.52%~27.61%，生育日数、每荚粒数、蛋白含量、脂肪含量等 4 个性状较稳定，株高、单株粒数、单株荚数、单株粒重、百粒重等 5 个性状变异丰富；13 个性状多样性指数变化范围为 1.9906~2.0956。聚类分析将 303 份大豆种质资源分为 7 个类群，其中第Ⅴ类群综合性状最好，可作为黄淮海大豆育种的优质亲本。主成分分析将 13 个性状简化为 4 个主成分，累积贡献率为 75.051%，第 1 主成分与单株荚数、粒数有关；第 2 主成分与蛋白质、脂肪含量有关；第 3 主成分与籽粒大小有关；第 4 主成分与单株产量有关。303 份大豆种质资源综合评价 F 值均值为 0.549，ZDD04189 涟水天鹅蛋的 F 值最高（0.935），ZDD23089 晋品 42 的 F 值最低（0.207）。通过逐步回归分析得到生育日数、株高、单株粒数、单株粒重、蛋白质含量等 5 个表型性状，可以作为黄淮海大豆种质表型综合评价的主要指标。

目的 华南双季稻区是我国优质籼稻的主产区之一，研究气候变暖对华南双季稻稻米品质的影响具有重要意义。方法 采用稻田开放式主动增温系统对早稻(合丰丝苗，2020年；粤禾丝苗，2021年)和晚稻(粤禾丝苗，2020和2021年)进行全生育期昼夜不间断增温处理，分析增温对早、晚稻加工、外观、营养和食味品质的影响。结果 与不增温处理相比，增温(早稻，1.5~1.8 ℃；晚稻1.9~2.0 ℃)对早、晚稻糙米率均无显著影响。增温条件下，早稻精米率和整精米率均显著降低，而晚稻精米率和整精米率无显著变化。增温对垩白粒率和垩白度的影响在早、晚稻之间呈相反趋势；增温显著提高早稻垩白粒率和垩白度，而降低晚稻垩白粒率。增温条件下，早、晚稻直链淀粉含量均显著降低，而蛋白质含量呈升高趋势。此外，增温提高早、晚稻稻米峰值黏度和米饭黏性，降低其消减值及晚稻糊化温度和米饭硬度。相关分析表明，增温条件下，早、晚稻糊化特性和米饭质构的改变主要与直链淀粉含量的降低有关。结论 增温导致早稻加工和外观品质变差，而有利于改善其营养和食味品质。增温条件下，晚稻外观、营养和食味品质均有改善。

高温热害已成为影响我国特别是长江流域水稻生长发育及高产稳产的主要限制因素之一。本研究利用大田自然高温、温室高温两种环境对2018—2020年的1 379份水稻材料的开花期耐热性进行了鉴定和评价，系统分析了不同年份间、不同品种类型间、不同来源渠道品种间耐热性情况。结果表明，供试材料中耐热性达到1、3、5、7、9级的品种比例分别为11.96%、66.78%、18.06%、2.76%和0.44%，且耐热品种呈逐年增多的趋势；两系杂交稻、三系杂交稻、常规稻中开花期耐热性达到强至较强（1级和3级）的品种占比分别为82.57%、73.45%和60.00%，不同类型品种的耐热性表现为两系杂交稻>三系杂交稻>常规稻；国家（省）区试、绿色通道、联合体渠道来源的品种的开花期耐热性整体表现相似。本试验综合利用大田自然高温、温室高温两种环境建立了一套水稻开花期耐热性鉴定规程和评价方法，可以对供试材料在不同年份、不同环境、不同程度热胁迫下的耐热性做出相对一致、客观的评价。