Effect of Elevated Carbon Dioxide Concentration on Rice Quality: Nutritive Value,Color, Milling,Cooking, and Eating Qualities

Increase in the atmospheric carbon dioxide concentration ([CO₂]) enhanced the concentration of carbohydrates in rice grains, according to results of a previous study. However, its impact on other quality traits is little known. To investigate the effect of CO₂ levels (375 and 550 μmol/mol) on rice quality, a field experiment was conducted with open‐top chambers. Elevated [CO₂] affected several nutritional parameters of the grain. Whereas the concentration of α‐linolenic acid increased, that of linoleic and γ‐linolenic acids decreased. For example, reductions of 9 and 28% were observed for linoleic acid in the brown rice and for γ‐linolenic acid in the husk, respectively. Phytic acid concentration and zinc bioavailability were unaffected. Whereas iron bioavailability decreased in the brown rice (22%), calcium bioavailability increased in the bran and husk (5–11%). The concentrations of essential amino acids were also reduced; for example, the amount of isoleucine in the white rice, tyrosine in the brown rice, and phenylalanine in the bran decreased by 40, 57, and 23%, respectively. In contrast, elevated [CO₂] resulted in improved grain whiteness (3%) and starch viscosity (11%), with no effect on the milling quality. These data indicate that increased [CO₂] has both positive and negative effects on quality, depending on the specific end use of the rice grain.     

温度和二氧化碳浓度升高对青稞生长的影响

采用开顶式气室（OTC）模拟温度和二氧化碳（CO2）浓度升高的生长环境,以模拟大田环境为对照（CK）,通过大田原位模拟试验对“藏青2000”青稞品种在增温2℃（T2）、增温4℃（T4）和增温2℃同时增加CO2浓度100μL·L-1（T2+CO2）环境下进行观测,分析气候变化环境下青稞的生育期、光合作用、农艺性状及其耕层土壤养分的变化。结果表明：增温处理（T2、T4、T2+CO2）下青稞的生育期缩短5～7d。其中,T4处理的生育期最短,为92d,T2和T2+CO2处理为94d。增温处理中青稞叶片光合作用降低,其净光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Gs）均显著低于CK。增温处理使土壤耕层有机质和速效钾含量显著降低,速效磷含量提高。与CK相比,T2、T4和T2+CO2各处理青稞产量分别下降31.4%、46.9%和39.4%;增温2℃使青稞农艺性状（株高、干物质量、穗长）有所提高,在增温的基础上增加CO2浓度对青稞的影响并不显著,增温4℃严重影响青稞的正常生长和产量。     

长期大气CO2浓度升高对稻田CH4排放的影响

大气CO2浓度升高可直接或间接影响稻田CH4排放。深入研究长期大气CO2浓度升高对稻田CH4排放及其相关微生物的影响,对评估和应对未来气候背景下稻田CH4排放的响应具有重要意义。为探明长期大气CO2浓度升高对稻田CH4排放的影响及其机制,依托连续运行10年以上的中国稻田FACE（free-air CO2 enrichment）平台,观测2016—2017年正常大气条件（ACO2）和大气CO2浓度升高200 μmol?mol-1条件（ECO2）下稻田CH4排放通量、产甲烷菌和甲烷氧化菌群落丰度,并采用Meta分析方法定量研究CO2熏蒸年限对稻田CH4排放及其相关微生物群落丰度的影响。结果表明：对比ACO2处理,长期ECO2处理使稻田CH4排放降低28%（P<0.05）,产甲烷菌群落丰度降低39%（P<0.05）,同时甲烷氧化菌群落丰度增加21%（P>0.05）。Meta分析结果发现,随着CO2熏蒸年限的增加,大气CO2浓度升高对稻田CH4排放和产甲烷菌群落丰度的促进作用逐渐减弱,对甲烷氧化菌群落丰度的促进作用却逐渐增大。因此,未来气候条件下,长期大气CO2浓度升高会降低稻田CH4排放,这对缓解水稻种植带来的温室效应具有重要意义。     

CO2浓度升高和氮素供应对黄瓜叶片光合色素的影响

本文通过N供应浓度[2(低N),7(中N)和14(高N)mmol/L]和CO_2浓度[400(C1),625(C2),1 200(C4)μmol/mol]处理的水培试验一,以及硝铵比[14/0(N1),13/1(N2),11/3(N3)和8/6(N4)]和CO_2浓度[400(C1),800(C3),1 200(C4)μmol/mol]处理的水培试验二,共同研究黄瓜叶片光合色素对CO_2升高、N供应浓度和形态的响应。研究结果表明:苗期时,低、中和高N下,C4处理使得植物干物质都明显增加;而初果期干物质提高程度下降,植株生长速率降低。中等CO_2浓度(C3)显著增加植物在各硝铵比处理的干物质量,但最高CO_2浓度(C4)有提高N3处理的干物质量的趋势。苗期时,在低N和中N供应时C4处理显著降低叶片叶绿素a、叶绿素b和胡萝卜素含量;但高N时,C3处理提高总色素含量,C4处理提高叶绿素b含量;初果期时CO_2浓度处理对色素含量无显著影响;N2硝铵比处理,中等CO_2浓度(C3)下叶片的3种色素含量最高。因此当苗期N素供应浓度较低时,CO_2浓度升高会显著降低叶片3种色素的含量,这主要可能与苗期植物生长速率显著提高产生的稀释作用有关。当N浓度为14 mmol/L时,CO_2浓度适当提高显著促进色素合成,其合成速率大于植物生长速率,导致色素含量提高,提高光合能力;初果期时,CO_2浓度升高的促进作用降低缓和了色素浓度的下降。适当提高NH4+-N供应比例也能达到提高色素含量的效果,但CO_2浓度不宜过高。故而植物光合色素含量可能受到CO_2浓度升高导致的植物干物质增加速率和光合色素合成速率改变的双重调节。中N和高N供应时,叶绿素a/b在苗期随着CO_2浓度的升高而降低,在初果期仅在高N时有显著降低。而在硝铵比试验中,植株种植稀疏时,C4处理提高叶绿素a/b。因此,CO_2浓度升高下的植物捕光能力的提高,可通过适当降低叶片光照强度和提高N供应浓度来实现。从实际生产角度出发,使用中等浓度CO_2施肥,提高N肥供应浓度和NH4+-N比例,结合植株的适当密植更有利于光合色素含量提高,优化其组成,从而有利于黄瓜生物量的提高。     

土壤酶活性对温度和CO2浓度升高的响应研究

作为土壤生态系统中的重要组成部分及生物元素循环的积极参与者,土壤酶在陆地生态系统地下生态过程中扮演着十分重要的角色。升高温度和(或)大气CO2浓度可能直接或者间接影响其活性。但目前对温度和(或)大气CO2浓度升高对土壤酶的影响机理、过程及土壤酶对其的响应机制研究相对薄弱。本文初步总结了国内外关于温度和(或)大气CO2浓度升高对土壤酶活性影响研究的现状,并指出了目前研究中存在的不足。     

大气CO_2浓度升高对粳稻稻米物性及食味品质的影响

在2009和2010年利用独特的稻/麦轮作系统FACE（Free Air CO2 Enrichment,开放式空气CO2浓度增高）平台,以武运粳21、扬辐粳8号、武香粳14和武粳15为供试材料,研究了高浓度CO（2比大气背景CO2浓度高200 μmol·mol-1）对粳稻蒸煮米的硬度、粘性、香气、光泽、完整性、味道和口感等的影响。物性分析仪测定结果表明,高浓度CO2环境下粳稻熟米的硬度和粘性总体呈增加趋势,其中扬辐粳8号两指标的增幅均达显著水平。食味计测定结果显示,高浓度CO2对蒸煮稻米香气、光泽度、完整性、味道和口感等食味品质指标均没有影响。相关分析表明,CO2与品种的互作对米饭硬度和粘性有显著影响,但对食味品质参数均没有影响。CO2与年度、CO2与年度和品种间的互作对所有测定参数均无显著影响。两年数据一致表明,未来高浓度CO2环境下粳稻蒸煮米的硬度和粘性将呈增加趋势,增幅因品种而异,但米饭食味品质无显著变化。     

Effect of Rice Residues on Carbon Dioxide and Nitrous Oxide Emissions from a Paddy Soil of Subtropical China

A pot incubation experiment with rice residues (straw and root) was conducted under aerobic condition (60% of WHC, water holding capacity) for a period of 55 days in a greenhouse. The emissions of carbon dioxide (CO₂) and nitrous oxide (N₂O) were determined by the closed chamber method in a paddy soil. The soil was derived from quaternary red clay, and collected from the Ecological Station of Red Soil, the Chinese Academy of Sciences, located in Jiangxi Province, a subtropical region of China. The emissions of CO₂ and N₂O were increased by the amendment of rice residues. Significantly positive correlation was found between N₂O and CO₂ fluxes (R = 0.650*?0.870*, P ≤ 0.05). The cumulative emissions during the early stage of the incubation (<25 days after residue addition) accounted for about 67%–86% and 67%–80% of the total amount of CO₂ and N₂O emissions, respectively. Cumulative emissions and emission factors of the two gases were higher in the soils amended with rice straw than those with rice root. The two gas fluxes were positively correlated with microbial biomass C and N, as well as soluble organic C. N₂O flux was positively correlated with NH₄ ⁺–N content at the early stage (<25 days), and negatively with NO₃ ^?–N content at the later stage of this incubation (25–55 days), implying that both nitrification and denitrification may have contributed to N₂O production.     

空气温度和CO2浓度升高对晚稻生长及产量的影响

人类活动所导致的气候变化将使大气CO2浓度和温度上升,研究空气温度和CO2浓度升高对晚稻生长和产量的影响,可为评估未来气候条件下粮食安全提供依据。采用改进后的开顶式气室（OTC）大田原位模拟CO2浓度增加60μL·L-1和温度升高2℃的未来气候情景,研究气候变化对晚稻生长及产量的影响,试验设对照(气室内温度和CO2浓度与大田一致,CK)、增温2℃(IT）和增温2℃+CO2浓度增加60μL·L-1（IT+IC）3个处理,对晚稻的株高、分蘖数、叶绿素含量、叶面积指数以及产量构成进行监测。结果表明：（1）IT处理能显著增加晚稻的株高,全生育期株高平均增加约3cm,而IT+IC处理对株高无影响;（2）移栽20d后IT处理对水稻分蘖产生促进作用,每穴约增加1个分蘖茎,IT+IC处理对分蘖数无显著影响;（3）IT处理增加叶绿素含量约0.8个SPAD单位,并显著增加晚稻叶面积指数,而全生育期IT+IC处理对叶绿素含量无影响;（4）IT+IC处理使水稻显著增产,增产率达14.0%,而单纯增温使晚稻空秕率增加,降低千粒重从而导致产量增加不显著。     

大气CO2浓度升高条件下稻稗共生系统中稗草对水稻光合生理的影响

稗草是水稻田的恶性杂草之一,严重影响水稻的生长发育和产量形成。为明确CO2浓度升高条件下稗草和水稻的光合生理响应及其竞争关系变化,以吉粳88为研究对象,利用开放式CO2浓度富集系统（FACE系统）开展模拟试验。试验设置2个CO2浓度,分别为自然大气CO2浓度（400µmol·mol−1）和高CO2浓度（550µmol·mol−1）,高CO2浓度环境应用FACE系统进行调控;每种CO2浓度处理中设2种种植方式,分别为清种水稻和水稻与稗草混种,稗草与水稻种植密度比为1:5,在水稻各生育期测定相应的光合生理指标并进行分析。结果表明：CO2浓度升高使水稻每穴穗数显著增加,结实率也有所提高,最终使水稻产量显著提高;稗草与水稻混种使水稻结实率显著降低,水稻千粒重显著增加,最终使水稻产量显著降低;CO2浓度升高和稗草互作使水稻千粒重显著提高,但对产量影响并不显著。CO2浓度升高使水稻干物质量显著提高,稗草使水稻干物质量显著降低;而CO2浓度升高和稗草互作对水稻干物质影响不显著。CO2浓度升高使水稻剑叶净光合速率、胞间CO2浓度及SPAD值显著升高,使水稻剑叶气孔导度和蒸腾速率显著降低,稗草显著降低了水稻剑叶净光合速率、胞间CO2浓度、气孔导度、蒸腾速率、瞬时水分利用效率及SPAD值;CO2浓度和稗草互作使水稻剑叶净光合速率先降低后升高。水稻抽穗后CO2浓度升高对水稻光合作用的影响大于稗草对水稻光合作用的影响。     

环境温度和CO2浓度升高对湖北早稻氮素含量及产量的影响

采用改进后的开顶式气室（OTC）,大田原位模拟温度升高2℃和CO₂浓度增加60μL·L^-1的未来气候情景,观测其对湖北地区早稻植株全氮、土壤氮素及产量的影响。试验设置对照(CK)、增温（增2℃,IT）、增CO2 (增60μL·L^-1,IC)以及增温+CO^₂（增2℃+增60μL·L^-1,IT+IC）4个处理,3次重复,随机区组排列,对早稻各生育期植株全氮含量、土壤NH4⁺-N和NO₃--N含量以及产量构成进行监测。结果表明：（1）温度和CO^₂浓度升高以及二者同增会增加早稻生育早期（特别是分蘖期）植株体内全氮含量,分蘖期以后各处理间差异不显著,籽粒全氮含量差异亦不显著;土壤NH4⁺-N含量与植株全氮变化规律类似,在早稻生育早期,温度和CO^₂浓度升高以及二者同增会增加土壤NH4⁺-N含量,分蘖期以后各处理间差异不显著;（2）温度升高使拔节期、成熟期土壤NO₃--N含量降低,抽穗期土壤NO₃--N含量增加;CO₂浓度增加会提高拔节期、成熟期,降低抽穗期土壤NO₃-N含量;（3）CO₂浓度升高,早稻增产13.4%,与CK差异极显著（P<0.01）,而单独增温或增温+增CO₂处理早稻产量与CK差异不显著。     

大气CO_2浓度升高对陆地生态系统土壤固碳的可能影响

陆地生态系统碳循环是全球碳循环的重要组成部分,在全球碳收支中占主导地位。大气CO2浓度升高直接或间接地影响土壤碳的固定,碳在土壤的不同固定机理反映了碳的稳定性和周转过程,本文综述了影响碳固定的物理、化学和生物学机理,土壤碳固定的不同状态发生的主要机理不同;受大气CO2浓度升高影响时间长短不一,主要过程有所侧重,但三种机理相互影响。     

Environmental Controls on Fallow Carbon Dioxide Flux in a Single‐Crop Rice Paddy,Japan

Soil organic carbon (SOC) is one of the important measures of soil fertility and sustainability in arable lands. With continuous CO₂ flux measurements, this study assessed the SOC decomposition and its environmental controls at both half‐hourly and season‐long scales in a single‐crop rice (Oryza sativa L.) paddy during three fallow periods between 2004 and 2007. Measurements were made on a gray lowland soil sited in eastern Japan using the eddy covariance method. Ecosystem respiration was strongly affected by soil water content measured at 0–0·1 m depth. At 0·5 m³ m^{− 3} or more of soil water content, the baseline of ecosystem respiration decreased by 50% compared with that at 0·2 m³ m^{− 3} . The effect was quantified at half‐hourly scale using an empirical multiple regression model, together with the soil surface temperature and the time after residue incorporation. At season‐long scale, net biome production, which is equivalent to the change in the SOC pool during the fallow period, was estimated from the flux and ancillary data at 150 g C m^{− 2} in 2004–2005, 70 g m^{− 2} in 2005–2006, and 270 g C m^{− 2} in 2006–2007. Apparently, as much as 46 to 79% of the soil organic matter incorporated (crop residues, ratoon, and stable manure) was decomposed during the fallow period. Precipitation, or associated soil water content, was important for the carbon balance of the field at season‐long scale because of its large interannual variability and relatively low permeability of the paddy soil. Copyright © 2013 John Wiley & Sons, Ltd.     

转Bt基因水稻"克螟稻"淀粉食用品质与稻米营养成分的研究

对转Bt基因抗虫水稻（Oryza sativa subsp.japonica）与原亲本的淀粉食用品质和稻米关键性营养成分进行了检测与比较,发现这两种水稻在表观直链淀粉含量、胶稠度和淀粉粘滞特性等淀粉食用品质方面基本相同;在粗蛋白、粗脂肪、总灰分、氨基酸和矿物质等关键性营养成分上差异不显著.表明在水稻遗传转化操作过程中T-DNA（Transferred DNA）并未改变原亲本的品质性状.     

秸秆还田与水分管理对稻田土壤微生物量碳、氮及溶解性有机碳、氮的影响

采用田间小区试验,于2011年晚稻季在湖南省长沙县金井镇研究水分管理方式(间歇灌溉和长期淹水)和秸秆还田量(无秸秆还田,低量秸秆还田和高量秸秆还田)对稻田土壤微生物量碳、氮和可溶性有机碳、氮含量的影响。结果表明,在长期淹水的条件下,高量秸秆还田较无秸秆还田可提高土壤微生物量碳、氮和土壤可溶性有机碳、氮的含量;间歇灌溉条件下,低量秸秆还田较高量秸秆还田可提高土壤微生物量碳、氮和土壤可溶性有机碳、氮的含量。无秸秆还田条件下,间歇灌溉处理比长期淹水处理土壤微生物量碳、氮和可溶性有机氮含量高,可溶性有机碳含量低;高量秸秆还田下,长期淹水处理比间歇灌溉处理土壤微生物量碳、氮和可溶性有机碳、氮含量高。不同水分管理方式对不同秸秆还田量下稻田土壤微生物量碳、氮和可溶性有机碳、氮含量影响不同。     

不同耕作措施对黑土碳排放和活性碳库的影响

农田耕地土壤碳的动态变化是陆地生态系统碳循环的研究热点,明确人为干预下土壤碳固定及排放的主导途径和因素,可以为制定农田固碳减排管理措施提供理论基础。为探究不同耕作措施下农田土壤碳循环特征,在东北典型黑土区黑龙江省青冈县设置不同耕作措施和秸秆还田方式的玉米种植田间试验,包括深松25 cm(T1),深松25 cm+秸秆粉碎还田(T2),深松35 cm(T3),深松35 cm+秸秆粉碎还田(T4),深松35 cm+秸秆粉碎覆盖还田(T5);对5种处理下土壤呼吸速率及碳累积排放量、土壤活性有机碳库组分和作物产量进行了分析。结果表明,秸秆粉碎还田显著增加了土壤碳排放,并且秸秆粉碎翻埋还田在增加土壤有机碳库和提高作物产量方面的效果优于秸秆粉碎覆盖还田。     

The Influence of Carbon Dioxide or Ozone Concentration on Growth and Assimilate Partitioning in Seedlings of Nine Conifers

Abstract

Seedlings of nine different conifers were exposed to 355 and 730 μmol mol-1 CO₂, or low (> 15 nmol mol^?1) and elevated 0₃ concentration (70 nmol mol^?1) for 81–116 days. The experiments were conducted in growth chambers placed in a greenhouse. Increased CO₂ concentration enhanced the mean relative growth rate (RGR) and total plant dry weight by 4 and 33% in Larix leptolepis, by 4 and 38% in Larix sibirica, by 7 and 47% in Picea glauca and by 3 and 16% in Picea sitchensis, respectively. The growth rates and dry weights of Pimis contorta, Pinus mugo and Pseudotsuga menziesii were not significantly affected. Carbon dioxide enrichment enhanced RGR of two provenances of Picea abies by 4 and 6%, respectively, while a third provenance was unaffected. In Pimis sylvestris, only the RGR of one of three provenances was stimulated by CO₂ enrichment (4%).

After two growth seasons CO₂ enrichment enhanced RGR and total plant dry weight by 11 and 35% in Picea abies and by 12 and 36% in Pinus sylvestris, respectively. Elevated CO₂ decreased the shoot:root ratio in Larix leptolepis, and decreased the needlerstem ratio in Picea glauca, but increased it in Pseudotsuga menziesii.

Elevated O₃ significantly decreased the plant dry weight in Picea sitchensis, Pseudotsuga menziesii and in one of three provenances of Pinus sylvestris, while the other species and provenances were unaffected. Increased O₃ concentration increased the shoot:root dry weight ratio in one of three Picea abies provenances, in all three Pinus sylvestris provenances and in Pinus contorta. The needle:stem ratio was enhanced by O₃ in seven of the nine species. The O₃ exposure caused chlorosis of needles in all species except Pseudotsuga menziesii.     

Effect of Silicon on Arsenic Concentration and Speciation in Different Rice Tissues

Rice is a major source of inorganic arsenic (As) exposure for billions of people worldwide. Therefore, strategies to reduce As accumulation in rice should be adopted. Silicon (Si) application can effectively mitigate As accumulation in rice. In this study, a pot experiment was performed to investigate the effect of Si on As speciation and distribution in different rice tissues. The results showed that Si addition significantly increased As and Si concentrations in soil solution and Si concentration in iron plaque formed around rice root surface, whereas As in the iron plaque was significantly decreased. Total As concentrations in the stem, leaf, husk, and brown rice were remarkably decreased by 51.9%, 31.9%, 33.8%, and 24.1%, respectively, after Si addition, and inorganic As concentrations were reduced by 52.3%, 35.5%, 50.1%, and 20.1%, respectively. Moreover, both dimethylarsinic acid concentration and percentage in rice grain were significantly elevated by Si application. Therefore, Si application is promising as a way to mitigate inorganic As accumulation in rice and to reduce consumer health risk.     

协调水稻产量和品质的植株临界氮浓度的确定

根据植株氮营养状况指导优质米生产具有重要意义。试验以五优稻4号为供试材料,以密度为主区(密度分别为每平方米18穴和25穴),氮量为副区(氮量分别为0、75、105、135 kg hm^-2),测定水稻植株全氮、籽粒无机氮含量、水稻产量和品质等指标,以期为实现水稻丰产优质提供理论依据。结果表明:施氮量和水稻产量呈2次曲线关系,最高产量施氮量为113～126kg hm^-2,经济合理施氮量为110～125 kg hm^-2;随着施氮量增加,各个时期水稻植株含氮量,收获期籽粒铵态氮和硝态氮含量显著提高,N105处理与N0处理间上述指标差异均显著(P <0.05),而N105和N135处理间只有籽粒无机氮含量差异显著;施氮后籽粒蛋白质含量有增加趋势,随着施氮量增加稻米食味值下降,N135处理食味降低超过10%(P <0.05),其他处理间差异不显著。密度增加,水稻氮素积累量增加,产量提高了11.4%;稀植有利于提高地上部含氮量、籽粒铵态氮和硝态氮含量;稀植出米率提高了4.77个百分点(P <0.05),食味值有降低趋...     

CO_2浓度、氮素和水分对春小麦碳素固定的影响

试验设350μmolmol-1和700μmolmol-12种CO2浓度水平,湿润、干旱2种水分处理和施N0、50、100、150和200mgkg-15个水平。结果表明,CO2浓度增加,春小麦地上部碳固定量和碳固定总量均增加,但与氮肥施用水平有关。在中氮和高氮时,CO2浓度增高,地上部碳固定量和碳固定总量明显增加,而不施氮肥和低氮时,增加则不明显。不同水分处理地上部碳固定量和碳固定总量也没有明显差别,这表明,CO2浓度升高对氮素和水分胁迫及对春小麦碳固定并没有补偿作用。