自由空气CO2浓度升高对水稻营养元素吸收和籽粒中营养元素含量的影响

 利用FACE（Free Air Carbon Dioxide Enrichment）平台技术，用水培试验研究了低氮（14 mg/L）和常氮（28 mg/L）水平下，大气CO2浓度升高对水稻（Oryza sativa L.）N、P、K、Ca、Mg、Cu、Zn、Fe、Mn的吸收和在植株不同部位的分配，并着重分析了CO2浓度升高对稻米中营养元素含量的影响。结果表明，按照当前CO2浓度条件下营养元素的正常供应水平，而且各元素都以有效态供给时，CO2浓度升高对多数被测元素吸收总量影响不大，只增加了K、Ca、Fe的吸收总量； N、P、Mg、Mn向穗部分配增加，K、Ca、Cu、Zn、Fe向穗部的分配比例不变；水稻籽粒中P、Ca、Mg、Cu、Zn、Fe和Mn含量无显著影响，N、K含量显著下降。还初步探讨了CO2浓度升高对稻米中人类必需营养元素的不足（或“隐性饥饿”）的影响。     

施氮和大气CO2浓度升高对春小麦拔节期光合作用的影响

为明确高大气CO2浓度下小麦叶片光合作用的适应机制及氮素的调控作用,利用开顶式气室,通过盆栽试验,测定和分析了不同大气CO2浓度和施氮量下小麦拔节期叶片的光合参数、叶绿素含量等指标.结果表明,高大气CO2浓度(760 μmol·mol-1)处理的小麦叶片的叶绿素含量、光合速率(Pn)、气孔导度(G5)和蒸腾速率(Tr)均随着施氮水平的升高而升高,平均增幅分别为31.6%、69.6%和57.6%,而胞间CO2浓度(Ci)和水分利用效率(WUE)随施氮水平的升高而呈先下降后上升的趋势.高大气CO2浓度下小麦叶片Pn、Ci和WUE显著高于正常CO2浓度(400 μmol·mol-1)处理,平均增幅分别为36.8%、74.O%和102.7%.在400 μmol·mol-1 CO2浓度下测定时,与正常大气CO2浓度下生长的小麦相比,高大气CO2浓度下生长的小麦拔节期叶片Pn在高施氮水平(0.2 g N·kg-1土)下未发生下调,而在低、中施氮水平(0和0.1 g N·kg-1土)下叶片Pn明显降低.因此,高大气CO2浓度下施氮可显著提高小麦叶片的Pn和WUE,且充分供氮可使叶片不发生光合适应现象,这可能与较高的施氮水平提高了高大气CO2浓度下小麦叶片的叶绿素含量有关.     

光照和施氮量对分蘖期水稻叶际氮氧化物(NO和NO2)交换的调控机制

 采用密闭箱法结合快速在线检测系统,研究了光 氮对分蘖期水稻叶际NOx(NO、 NO2 )交换的作用机制。结果表明：1）在叶际NOx(NO、 NO2 )交换过程中,试验用水稻品种有显著NO净挥发和NO2净吸收效应; 在严密控光和室内自然光条件下,水稻NO净挥发速率分别为2.48和2.84 μg/(桶·h),NO2 净吸收速率分别为0.116和0.175 μg/(桶·h),且在环境空气NO浓度为200 μg/m3 条件下也能挥发NO。 2）更换营养液后观测期(5 d)水稻NO挥发速率呈先升后降趋势,在供N 0~80 mg/L范围内提高供氮水平总体上增强了水稻NO挥发,但短期内（7 d）脱氮、缺氮(供N 10 mg/L)无明显抑制水稻NO挥发的作用;同期适度提高供氮浓度(供N 0~ 60 mg/L)增强了水稻NO2 吸收,但供氮6 d后外源氮源对水稻叶际NOx(NO、NO2 )交换的调控作用明显下降;3）更换营养液后短期内(1~2 d)控光处理下 6：00-10：00弱光和10：00-14：00 强光有刺激水稻NOx(NO、NO2 )挥发的作用,但14：00-18：00持续强光明显抑制了水稻NOx挥发;在更换营养液2 d后,延长光照时间能增强水稻NO2吸收,但光强变化对水稻NO2吸收调控作用不明显,晚上暗处理有同步抑制水稻NO挥发和NO2吸收效应;4）与基本不置换培养箱空气处理相比,置换培养箱空气同步增强了水稻NO挥发和NO2吸收。     

高浓度CO2条件下水稻叶片氮含量下降与氮代谢关键酶活性的关系

利用FACE（Free Air Carbon Dioxide Enrichment）平台技术,研究了低氮（125 kg/hm2,以纯N计）和常氮（250 kg/hm2）水平下,高浓度CO2（周围大气CO2浓度+200 μmol/mol）对水稻不同生育期功能叶N代谢关键酶活性的影响。结果表明,高浓度CO2提高了叶片硝酸还原酶和蛋白水解酶的活性,两者在常N下的响应程度大于在低N下的响应程度;高浓度CO2降低了低N下叶片谷氨酰胺合成酶和谷氨酸脱氢酶（NADH GDH）活性,常N水平下酶活性的下降趋势得到改变或缓解。由此可见,高浓度CO2条件下NO3-转化为NH4+加速,而NH4+进一步同化为有机N却受阻,而且,由于后期蛋白水解加速,将进一步加剧叶片N含量的下降。这是水稻叶片N含量下降的内在因素。而增施N肥,有利于同化酶的表达,降低叶片蛋白水解酶活力,从而缓解叶片N含量的下降。     

黄淮海地区大豆光合特性及高光效种质筛选

本文旨在研究黄淮海大豆种质资源的光合气体交换特性,从中筛选高光效种质,为开展培育大豆高光效品种等研究奠定基础。在大田条件下,以150份来自黄淮海地区的大豆种质资源为试材,利用LI-6400便携式光合仪测定其盛花期的光合气体交换参数,包括叶片净光合速率、气孔导度、胞间CO2浓度、蒸腾速率、叶片饱和水汽压亏缺、蒸腾效率以及叶片瞬时水分利用效率。结果表明,150份大豆种质光合气体交换参数间存在较大差异。7个参数的变异系数范围为5.54%~29.56%,其中,蒸腾效率变异系数最高,胞间CO2浓度最低。净光合速率与气孔导度、叶片瞬时水分利用效率呈显著正相关,与叶片饱和水汽压亏缺呈显著负相关;气孔导度与胞间CO2浓度、蒸腾速率呈显著正相关,与叶片饱和水汽压亏缺、蒸腾效率、叶片瞬时水分利用效率呈显著负相关;胞间CO2浓度与叶片饱和水汽压亏缺、蒸腾效率呈显著负相关;蒸腾速率与叶片饱和水汽压亏缺呈显著正相关,与蒸腾效率、叶片瞬时水分利用效率呈显著负相关;蒸腾效率与叶片瞬时水分利用效率呈显著正相关。进一步利用主成分分析选出3个主成分（气孔因子、水分因子、光合因子）,方差累积贡献率达93.64%。聚类分析将150份大豆种质划分为12个类群,其中第Ⅱ类群包括23份大豆种质,表现高气孔导度、高水分利用率和高光合效率。因此第Ⅱ类群可作为适合育种需要的高光效大豆种质。     

施氮量对开花期超高产小麦旗叶CO2响应曲线的影响

为给未来大气CO2浓度升高条件下超高产小麦的氮肥管理提供技术支撑,在大田条件下利用LI-6400便携式光合作用测定仪,采用开放式气路测定了不同CO2浓度下小麦旗叶的净光合速率(Pn)、气孔导度(Gs)、胞问CO2浓度(Ci)、蒸腾速率(Tr)、水分利用效率(WUE)等相关指标,分析了施氮量对开花期起高产小麦旗叶CO2响应曲线的影响.结果表明,氮素对开花期超高产小麦旗叶的CO2响应有较大的调节作用,随着外界CO2农度的升高,小麦旗叶的先合参数Pn、WUE,逐渐上升并在800 μmol CO2·mol-1左右趋于稳定.但施氮量在375kg/ha条件下Pn、WUE反而较施氮量为300 kg/ha的降低.说明在合理的施氮范围内,施氮和提高外界CO2浓度能通过增强小麦旗叶对胞间CO2的利用能力来提高光舍速率、降低蒸腾速率、提高水分利用效率,从而改善旗叶的光合性能.     

稻米外观与加工品质对大气CO2浓度升高的响应

【目的】大气CO2浓度升高会降低水稻的外观与加工品质。为探明其下降机制并予以缓解，【方法】采用开放式大气CO2浓度升高(FACE)平台、两种栽培品种及其三种不同的基因调控遗传材料 (中花11及其蒸腾调节材料ZmK2.1-15、ZmK2.1-20、OsKAT3-26、OsKAT3-30; 中花11及其促冠根生长材料ERF3-7和ERF3-12; 日本晴及其促硝酸盐吸收材料NIL)，研究稻米外观与加工品质对CO2浓度升高的响应。【结果】稻米外观品质与加工品质对CO2浓度升高的响应因品种不同而异。CO2浓度升高下，中花11的垩白粒率和垩白度增加9.2%和4.4%，整精米率降低5.3%；而日本晴的垩白粒率和垩白度降低11.1%和7.9%，整精米率提升9.8%。蒸腾调节材料显著改善了CO2浓度升高对中花11外观与外观品质的负面效应，与当前CO2浓度相比，CO2浓度升高，ZmK2.1-15、 ZmK2.1-20、OsKAT3-26、OsKAT3-30的垩白粒率相对变化量为−2.7%、−16.3%、−14.8%，+7.4%，垩白度为−8.7%、−22.3%、−15.1%、−3.0%，整精米率为+2.1%、+6.4%、+3.6%、−7.0%。促冠根生长材料加大了CO2浓度升高对中花11号外观与加工品质的负面效应，ERF3-7、ERF3-12的垩白粒率在CO2浓度升高下分别增加17.7%和11.5%，垩白度增加34.4%和19.1%，整精米率分别降低10.1%和0.8%。促硝酸盐吸收材料(NIL)的垩白粒率和垩白度在CO2浓度升高下无明显变化，整精米率下降4.2%。NIL的外观品质较日本晴明显改善，CO2浓度升高下垩白粒率和垩白度分别下降16.5%和17.9%，当前CO2浓度条件下分别下降26.3%和28.9%。【结论】未来CO2浓度升高条件下，通过基因改良促进水稻蒸腾作用和硝酸盐吸收是提升稻米外观与加工品质的有效途径之一。     

稻米外观与加工品质对大气CO2浓度升高的响应

【目的】大气CO2浓度升高会降低水稻的外观与加工品质。为探明其下降机制并予以缓解,【方法】采用开放式大气CO2浓度升高(FACE)平台、两种栽培品种及其三种不同的基因调控遗传材料(中花11及其蒸腾调节材料ZmK2.1-15、ZmK2.1-20、OsKAT3-26、OsKAT3-30;中花11及其促冠根生长材料ERF3-7和ERF3-12;日本晴及其促硝酸盐吸收材料NIL),研究稻米外观与加工品质对CO2浓度升高的响应。【结果】稻米外观品质与加工品质对CO2浓度升高的响应因品种不同而异。CO2浓度升高下,中花11的垩白粒率和垩白度增加9.2%和4.4%,整精米率降低5.3%;而日本晴的垩白粒率和垩白度降低11.1%和7.9%,整精米率提升9.8%。蒸腾调节材料显著改善了CO2浓度升高对中花11外观与外观品质的负面效应,与当前CO2浓度相比,CO2浓度升高,ZmK2.1-15、ZmK2.1-20、OsKAT3-26、OsKAT3-30的垩白粒率相对变化量为?2.7%、?16.3%、?14.8%,+7.4%,垩白度为?8.7%、?22.3%、?15.1%、?3.0%,整精米率为+2.1%、+6.4%、+3.6%、?7.0%。促冠根生长材料加大了CO2浓度升高对中花11号外观与加工品质的负面效应,ERF3-7、ERF3-12的垩白粒率在CO2浓度升高下分别增加17.7%和11.5%,垩白度增加34.4%和19.1%,整精米率分别降低10.1%和0.8%。促硝酸盐吸收材料(NIL)的垩白粒率和垩白度在CO2浓度升高下无明显变化,整精米率下降4.2%。NIL的外观品质较日本晴明显改善,CO2浓度升高下垩白粒率和垩白度分别下降16.5%和17.9%,当前CO2浓度条件下分别下降26.3%和28.9%。【结论】未来CO2浓度升高条件下,通过基因改良促进水稻蒸腾作用和硝酸盐吸收是提升稻米外观与加工品质的有效途径之一。     

水稻苗期根系铵钾离子吸收的交互作用研究

【目的】为探讨水稻幼苗根系NH_4~+、K~+吸收的交互作用,深化水稻养分吸收理论,【方法】采用溶液培养的方法,对低钾及高钾浓度下水稻在有铵和无铵时的K~+吸收动力学特征进行了研究,对不同钾浓度下水稻根系NH_4~+的吸收速率进行了比较。【结果】1)当K~+0.2 mmol/L时,水稻根系通过高亲和转运系统吸收K~+服从Michaelich-Menten动力学方程;NH_4~+的存在显著降低K~+的最大吸收速率(Vmax),且降幅随着NH_4~+浓度的增加而增大;NH_4~+对水稻根表载体与K~+的亲和力(Km)影响较小,在1.62 mmol/L NH_4~+浓度下,水稻品种齐粒丝苗和沪科3号的Km分别下降了12.33%和16.46%,远低于Vmax 47.30%和39.21%的降幅。2)当K~+0.5 mmol/L时,水稻根系K~+低亲和转运系统发挥作用,K~+吸收速率随浓度的增加而不断增加,呈不饱和特征;但在相同K~+浓度下,水稻根系的K~+吸收速率随NH_4~+浓度的增加而下降。3)水稻根系对NH_4~+的吸收速率随着NH_4~+浓度的增加而增加;在相同NH_4~+浓度下,水稻根系对NH_4~+的吸收速率受K~+浓度的影响很小。【结论】NH_4~+抑制水稻苗期根系K~+的高亲和转运和低亲和转运,NH_4~+对K~+高亲和吸收的影响主要是由于铵竞争细胞膜上的钾载体所致;外界K~+浓度的变化对水稻幼苗的NH_4~+吸收速率影响很小。水稻铵钾的交互作用主要表现在NH_4~+对K~+吸收的抑制作用。     

大气CO2浓度升高对茶树光合生理特性的影响

通过对不同大气CO2浓度水平下的茶树观测试验,研究了大气CO2增长对茶树新梢叶片净光合速率、蒸腾气孔导度、水分利用效率、叶绿素含量和营养元素含量等光合生理特性的影响。结果表明,在大气CO2浓度为550、750μmol·mol-1时,比正常大气CO2水平下茶树叶片日平均净光合速率提高17.9%和25.8%,并缓解和消除了光合午休现象;茶树叶片气孔导度降低7.6%和13.0%,蒸腾速度稍有下降,水分利用效率提高21.6%和35.8%;同时使茶树新梢叶绿素a、叶绿素b、叶绿素总量和类胡萝卜素含量分别提高12.8%～18.4%、14.0%～22.0%、13.1%～19.4%和17.2%～20.1%,但叶绿素a与叶绿素b的比值有所降低。大气CO2浓度的升高使新梢营养元素N、K、Ca含量有不同程度降低,而Mg、Fe、Zn、Mn、Cu含量有所增加。     

开放式空气CO2浓度增高和施氮量对水稻结实期叶片内肽酶活力的影响

 利用农田开放式空气CO2浓度增高 (free air CO2 enrichment,FACE) 系统,CO2浓度设正常CO2 (ambient, AMB) 和高CO2 (FACE,AMB + 200 μmol/mol) 2个水平,施N量设低氮 (LN,15 g/m2,以纯氮计)、中氮 (NN,25 g/m2)和高氮 (HN,35 g / m2) 3个水平,对水稻品种武香粳14结实期剑叶和倒2叶的内肽酶活力变化情况进行了研究。结果表明: 1) 同AMB相比,FACE处理使剑叶抽穗后10 d、20 d以及倒2叶抽穗到抽穗后20 d内肽酶活力明显提高,但使剑叶成熟期内肽酶活力明显下降;使剑叶抽穗后10 d、20 d和成熟期以及倒2叶抽穗到成熟期内肽酶比活力明显提高;FACE对抽穗后10 d、20 d叶片内肽酶活力和比活力影响较大,而对抽穗期和成熟期的影响较小。同LN相比,HN使灌浆前期叶片内肽酶活力明显降低,灌浆中后期则呈增加趋势;HN降低了叶片各期内肽酶比活力,灌浆前期降幅大于后期。 2) 同AMB相比,FACE使叶片抽穗后10 d至成熟期可溶性蛋白含量明显降低;同LN相比,HN明显减缓FACE处理对抽穗后10 d至成熟期功能叶片可溶性蛋白含量的影响。 3）除成熟期叶片可溶性蛋白含量与内肽酶活力呈正相关外,结实期剑叶及倒2叶可溶性蛋白含量与对应时期内肽酶活力呈显著负相关。上述结果说明,FACE处理下水稻剑叶及倒2叶结实中后期可溶性蛋白含量明显下降与结实期叶片内肽酶活力的变化关系密切。     

空气中CO2浓度升高条件下水稻抽穗期的QTL定位

以65个水稻染色体片段置换系(chromosome segment substitution lines,CSSLs)为材料,对比分析了正常大气CO2浓度（对照）和开放式空气CO2浓度升高（free air CO2 enrichment,FACE,大气CO2浓度增加200 μmol/mol）下水稻抽穗期的变化,并定位了相关QTL(quantitative trait loci)。供试株系的抽穗期对CO2浓度升高表现为提早、延迟和不变等3种响应,抽穗期两极变化最大的株系为AI46（提前11 d）和AI63（延迟6 d）。两种条件下,共检测到9个控制抽穗期的QTL,分布在第3、4、6、7、8、10和11染色体上。其中位于第6和第8染色体上的 qHD6 4和 qHD8 4在两种CO2浓度下都检测到,但在FACE下的贡献率均显著增大;而 qHD3A 3和 qHD11A 7只在正常条件下检测到, qHD4F 4、 qHD10F 4和 qHD11F 4则只在FACE下检测到。 暗示控制水稻抽穗期的基因表达易受环境CO2浓度的影响。     

Effects of Elevated Atmospheric Carbon Dioxide Concentration on Silica Deposition in Rice (Oryza sativa L.) Panicle

Abstract

The effects of elevated carbon dioxide concentration ([CO₂]) on silica deposition on husk epidermis of rice (Oryza sativa L. cv. Akitakomachi) during the flowering stage were investigated in this study. The study was motivated by the concept that the rice yield maybe affected by global warming as a result of elevated [CO₂] environment since sterility of rice is related to the panicle silica content that influences transpiration, and elevated [CO₂] could affect plant transpiration. Silica deposition analysis was focused on the flowering stage of the rice crop grown hydroponically under two [CO₂] conditions: 350 μmol mol-¹ (ambient) and 700 μmol mol-¹ (elevated). Silica deposition on the husk epidermis from three parts of the panicle at four flowering stages were examined using a scanning electron microscope (SEM) combined with an energy dispersive X-ray microanalyzer (EDX). The results demonstrated that elevated [CO₂] significantly suppressed silica deposition on the husk epidermis at the lower part of the panicle, and at the early flowering stage when 1/3 of the panicle emerged from the leaf sheath. In the transverse section analysis of the husk, silica deposition on the husk epidermis under elevated [CO₂] was less than that under ambient [CO₂] at the late flowering stage. The less silica deposition observed on the husks at the late flowering stage under elevated [CO₂] might be related to the suppressed transpiration from the panicle by elevated [CO₂] found in a previous study.     

高CO2浓度对水稻叶片膜脂过氧化和抗氧化酶活性的影响

 以4个栽培稻品种和2种野生稻为材料,比较了长期生长在高浓度CO₂(600 μL/L)和普通空气CO₂浓度(350 μL/L)下抽穗期水稻叶片抗氧化酶活性的变化以及对甲基紫精光氧化的响应。在自然条件下其抗氧化酶(SOD、CAT和POD)活性因品种和种性的不同而存在一定的差异。与生长在普通空气CO₂浓度的水稻相比,高浓度CO₂下叶片的膜脂过氧化产物MDA含量和POD活性都有不同程度下降,SOD和CAT活性则因品种的不同而呈不同的变化趋势。光氧化条件下,生长在普通空气CO₂浓度下的水稻叶片CAT活性增加了1.7～6.5倍,高浓度CO₂下则增加了1.0～3.8倍,而SOD和POD活性在光氧化条件下都降低。光氧化导致了水稻叶片的MDA含量的增加,高浓度CO₂下生长的水稻叶片MDA含量增加的幅度小于在普通空气CO₂浓度下生长的水稻,显示高浓度CO₂对光氧化损伤具防护效应。     

The impact of free-air CO2 enrichment (FACE) and nitrogen supply on grain quality of rice

Because CO₂ is needed for plant photosynthesis, the increase in atmospheric CO₂ concentration ([CO₂]) has the potential to enhance the growth and yield of rice (Oryza sativa L.), but little is known regarding the impact of elevated [CO₂] on grain quality of rice, especially under different N availability. In order to investigate the interactive effects of [CO₂] and N supply on rice quality, we conducted a free-air CO₂ enrichment (FACE) experiment at Wuxi, Jiangsu, China, in 2001–2003. A long-duration rice japonica with large panicle (cv. Wuxiangging 14) was grown at ambient or elevated (ca. 200 μmol mol⁻¹ above ambient) [CO₂] under three levels of N: low (LN, 15 g N m²), medium (MN, 25 g N m²) and high N (HN, 35 g N m² (2002, 2003)). The MN level was similar to that recommended to local farmers. FACE significant increased rough (+12.8%), brown (+13.2%) and milled rice yield (+10.7%), while markedly reducing head rice yield (−13.3%); FACE caused serious deterioration of processing suitability (milled rice percentage −2.0%; head rice percentage −23.5%) and appearance quality (chalky grain percentage +16.9%; chalkiness degree +28.3%) drastically; the nutritive value of grains was also negatively influenced by FACE due to a reduction in protein (−6.0%) and Cu content (−20.0%) in milled rice. By contrast, FACE resulted in better eating/cooking quality (amylose content −3.8%; peak viscosity +4.5%, breakdown +2.9%, setback −27.5%). These changes in grain quality revealed that hardness of grain decreased with elevated [CO₂] while cohesiveness and resilience increased when cooked. Overall, N supply had significant influence on rice yield with maximum value occurring at MN, whereas grain quality was less responsive to the N supply, showing trends of better appearance and eating/cooking quality for LN or MN-crops as compared with HN-crops. For most cases, no [CO₂] × N interaction was detected for yield and quality parameters. These data suggested that the current recommended rates of N fertilization for rice production should not be modified under projected future [CO₂] levels, at least for the similar conditions of this experiment.     

Seasonal changes in the effects of free-air CO2 enrichment (FACE) on phosphorus uptake and utilization of rice at three levels of nitrogen fertilization

Over time, the relative effect of elevated [CO₂] on the photosynthesis and dry matter (DM) production of rice crops is likely to be changed with increasing duration of CO₂ exposure. However, there is no systemic information on interactive effects of elevated [CO₂] and nitrogen (N) supply on seasonal changes in phosphorus (P) nutrient of rice crops. In order to investigate the interactive effects of these two factors on seasonal changes in plant P concentration, uptake, efficiency and allocation, a free-air CO₂ enrichment (FACE) experiment was conducted at Wuxi, Jiangsu, China, in 2001–2003. A japonica cultivar with large panicle was grown at ambient or elevated (ca. 200 μmol mol⁻¹ above ambient) [CO₂] and supplied with three levels of N: low (LN, 15 g N m²), medium (MN, 25 g N m²) and high N (HN, 35 g N m² (2002, 2003)). The MN level was similar to that recommended to local farmers. FACE significantly increased shoot P concentration (dry base) over the season, the average responses varied between 7.3% and 16.2%. Shoot P uptake responses to FACE declined gradually with crop development, with average responses of 57%, 51%, 37%, 26% and 11% on average during the growth periods from transplanting to early-tillering (Period I), early-tillering to mid-tillering (Period II), mid-tillering to panicle initiation (Period III), panicle initiation to heading (Period IV) and heading to grain maturity (Period V), respectively. Seasonal changes in shoot P uptake ratio (i.e., the ratio of shoot P uptake during a given growth period to final shoot P acquisition at grain maturity) responses to FACE followed a similar pattern to that of shoot P uptake, with average responses of 19%, 14%, 3%, −5% and −16% in Periods I, II, III, IV and V of the growth period, respectively. As a result, FACE enhanced shoot P uptake by 33% at grain maturity. P allocation patterns among above-ground organs were not altered by FACE before heading, but it was modified after heading, with a shift in P allocation patterns towards vegetative organ. FACE resulted in the significant decrease in P-use efficiency for biomass across the season and P-use efficiency for grain yield and P harvest index at grain maturity. Generally, there were no interactions between [CO₂] and N supply on above P nutrient variables measured. Data from this study has important implications for P management in rice production systems under future elevated [CO₂] conditions.     

Analysis of QTLs for Flag Leaf Shape and Its Response to Elevated CO2 in Rice （Oryza sativa）

To understand the responses of flag leaf shape in rice to elevated CO2 environment and their genetic characteristics,quantitative trait loci(QTLs)for flag leaf shape in rice were mapped onto the molecular marker linkage map of chromosome segment substitution lines(CSSLs)derived from a cross between a japonica variety Asominori and an indica variety IR24 under free air carbon dioxide enrichment(FACE,200μmol/mol above current levels)and current CO2 concentration(Ambient,about 370μmol/mol).Three flag-leaf traits,flag-leaf length(LL),width(LW)and the ratio of LL to LW (RLW),were estimated for each CSSL and their parental varieties.The differences in LL,LW and RLW between parents and in LL and LW within IR24 between FACE and Ambient were significant at 1%level.The continuous distributions and transgressive segregations of LL,LW and RLW were also observed in CSSL population,showing that the three traits were quantitatively inherited under both FACE and Ambient.A total of 16 QTLs for the three traits were detected on chromosomes 1,2,3,4,6,8 and 11 with LOD(Log10-likelihood ratio)scores ranging from 3.0 to 6.7.Among them,four QTLs (qLL-6*,qLL-8*,qLW-4*,and qRLW-6*)were commonly detected under both FACE and Ambient.Therefore,based on the different responses to elevated CO2 in comparison with current CO2 level,it can be suggested that the expressions of several QTLs associated with flag-leaf shape in rice could be induced by the high CO2 level.     

水稻孕穗期不同叶位叶片的气体交换与叶绿素荧光特性

研究了6个水稻品种孕穗期不同叶位的气体交换和叶绿素荧光特性,结果表明净光合速率([i]P[/i][sub]n[/sub]）、气孔导度（[i]g[/i]）、蒸腾速率（[i]E[/i]）和水分利用效率（[i]WUE[/i]）均随叶位降低而明显下降;而胞间CO[sub]2[/sub]浓度（[i]C[/i][sub]i[/sub]）基本维持不变,说明叶片衰老时[i]P[/i][sub]n[/sub]的下降主要不是气孔因素引起的。叶绿素含量降低与[i]P[/i][sub]n[/sub]下降的表现一致,叶绿素荧光分析表明[i]F[/i][sub]v[/sub]/[i]F[/i][sub]m[/sub]和[i]F[/i]'[sub]v[/sub]/[i]F[/i]'[sub]m[/sub]没有随叶位发生变化,而PSⅡ的光化学效率[i]Ф[/i][sub]PSⅡ[/sub]和电子传递速率([i]ETR[/i]）随叶位降低明显下降,这表明可能是PSⅠ电子传递受阻导致CO[sub]2[/sub]同化下降。