温度精细调控对哺乳仔猪局部供暖节能的影响

随着哺乳仔猪日龄增加,仔猪对温度的需求逐渐降低。为了探究精细调控保温灯温度对局部供暖的影响,满足仔猪对温度的需求、降低供暖能耗,试验选择河北承德某猪场2个试验单元共48栏仔猪,分为四梯度温差2 ℃组、四梯度温差1 ℃组和两阶段功率组,监测仔猪生长性能、行为和能耗。结果表明,在仔猪日龄1～3、4～7、8～14和15～21 d,四梯度温差2 ℃组保温灯下的平均空气温度分别为30.5、28.1、27.6和26.1 ℃,四梯度温差1 ℃组保温灯下的空气温度分别为29.7、27.9、27.2和26.9 ℃,两阶段功率组保温灯下的空气温度分别为31.4、27.3、27.7和27.8 ℃。3组之间哺乳仔猪平均日增质量差异不显著（P>0.05）,哺乳仔猪成活率基本一致（约为97%）。四梯度温差2 ℃组和四梯度温差1 ℃组保温灯的日均耗电量较两阶段功率组分别降低16.7%和26.2%。从节能角度来说,设置四个温度梯度变温度精细调控保温灯较两阶段功率控制对仔猪局部供暖的效果更优。该研究为优化仔猪保温灯温度精细调控效果、提升猪场经济效益提供了一定的理论依据。     

北京市猪舍节能改造的节能及保温效果

为了寻找北京市猪场节能的途径,对北京市既有供暖猪舍建筑围护结构保温性能进行了调查,并对370 mm厚墙、黏土瓦屋顶猪舍进行了墙体外贴保温板、黏土瓦屋顶上增加彩钢夹芯板保温层等节能改造,对节能潜力进行了估算,然后通过温度实测试验比较了节能改造舍与对照舍冬季的热环境状况。结果表明,北京市猪舍墙体、屋顶、窗户均不够节能;在假设供暖猪舍舍内冬季温度为20℃,供暖期为125 d的情况下,370 mm厚墙、黏土瓦屋顶猪舍1个采暖季的耗煤量为72 kg/m2,经过节能改造后,可节能69%。节能改造的投资回收期约为7.4 a。在舍外日平均温度为2.6~9.3℃情况下,试验节能改造舍舍内日平均温度较对照舍高1~3℃。舍外逐时温度越低,节能改造舍与对照舍内逐时温度差越大。试验期间,舍外逐时温度最低值为-2.3℃时,节能改造舍较对照舍逐时温度提高3.6℃。该文可为北京市既有供暖猪舍改造方案提供参考。     

冬季漏缝地板羊舍温热参数的时空分布规律

为研究冬季寒冷地区漏缝地板羊舍温热参数空间和时间变化规律。该研究选择两栋南北朝向且结构相同的传统漏缝地板羊舍,舍A的出粪口未作封堵处理,而舍B的出粪口进行密闭封堵,对两舍漏缝地板上部空间的温湿度进行时间和空间(水平和垂直)的动态测定,试验周期2个月,并利用红外热像仪对漏缝地板下部空间结构进行成像分析。结果表明:1)两舍日均温和湿度虽未表现出显著性差异(P0.05),舍A温度和湿度为-3.07℃和38.08%,但出粪口封堵的舍B温度呈现升高趋势,均温达-2.76℃,两舍最大温差可达1.05℃。2)从垂直空间看,漏缝地板上方1.5 m处温度(T1.5)显著高于漏缝地板处温度(T0)(P0.01),舍A的两处垂直温差达1.71℃,而舍B温差降至1.35℃,且舍B T0平均温度提高了0.49℃。另外,舍A的T0最低可降至-7.40℃,且每天有16.0h温度低于-3℃。3)从水平空间看,两栋舍南侧的温度均高于北侧,尤其是漏缝地板处,两侧温差为0.59(舍A)和0.39℃(舍B),且舍东西方向的水平温差较大,尤其舍北侧,其水平温差舍A达2.11℃,而舍B降至0.92℃。所有测点中,两舍西北侧出粪口的漏缝地板处温度最低,舍B T0和T1.5分别较舍A提高了1.33和0.47℃。4)从漏缝地板下部结构的红外热成像图分析,舍A漏缝地板和粪沟底部温差达2.1℃,而舍B温差降至0.7℃,且两舍地板下部结构中侧壁温度最低,分别达-9.3(舍A)和-7.2℃(舍B)。5)从风寒温度(Wind Chill Temperature,WCT)分析,舍B的WCT显著高于舍A(P0.05),且舍A出粪口处风速显著高于舍B(P0.05),最高达0.682 m/s。传统漏缝地板羊舍的出粪口进行密闭封堵可提高舍内温度,降低舍内水平和垂直温差,建议羊舍设置漏缝地板时增加出粪口的密闭性和保温性。     

装配式配种妊娠猪舍冬季保温与能耗特征

为了解规模化猪场装配式配种妊娠猪舍冬季保温以及能源消耗情况,通过对试验猪舍围护结构传热系数、墙体内表面温度以及耗热量理论计算与现场试验监测相结合的方法,对猪舍围护结构热工性能与猪舍能耗特征进行分析。结果表明：试验猪舍复合保温墙体主体部位和外保温砖墙墙体的理论计算值分别为0.31和0.23 W/(m2·K),实测传热系数分别为0.39和0.69 W/(m2·K),复合保温墙体钢梁部位传热系数的实测值为0.97 W/(m2·K)。在试验期间舍外平均温度下,墙体各部位不会产生结露现象,而围护结构彼此的连接处、屋架下弦和钢柱与天棚连接部位则易发生冷凝情况。试验期间,猪舍理论总耗热量和理论+实测总耗热量的平均值分别为10.73和11.84 W/m2,该类猪舍围护结构耗热量平均值小于通风耗热量平均值的20%。所需供热量和实际天然气供热量的每日平均值分别为0.28和0.39 kW·h/m2。该研究可为猪舍设计的节能保温方案提供理论依据。     

空气源热泵用作北京保育猪舍地暖的供暖效果研究

中国"2+26"城市禁煤供暖,猪场迫切需要找到可以替代燃煤、满足供暖需求的供暖方式。为了解空气源热泵在猪舍地暖的供暖效果,选择北京猪舍,配置空气源热泵设备,进行供暖期间保育猪舍热环境效果试验。结果表明:试验期间,室外最低和最高温度分别为-11.0和12.1℃;在地暖供暖猪舍中,地面温度与供水温度、室外温度都呈正比例相关关系,与供暖距离呈反比例线性关系;在系统供水温度范围为30.0～41.0℃时,猪舍无猪单元距离分水器最近(24 m)测点和最远(60 m)测点地面温度为19.1～28.6℃;实际供水温度平均值较设定温度降低1.8～4.0℃;距离分水器最近(24 m)测点地面温度较实际系统供水温度下降8.3～13.1℃;距离分水器最远(60 m)测点较最近测点(24 m)地面温度下降0.5～1.8℃。无猪时,0.3 m高温度较地面温度降低5.0℃;距离地面0.3 m以上不同高度温度变化不明显。对于北京保育猪舍适宜采用空气源热泵地暖供暖,推荐蓄水罐设定温度宜为43～32℃,实际供水温度宜为40.6～29.9℃。     

日光温室固定保温被遮阴对光热环境及产量影响分析

为了避免日光温室中卷式卷帘机械在工作时损坏前屋面覆盖层薄膜，通常会在卷帘机下方铺垫一条固定保温被。日间，这条保温被会遮挡进入日光温室的太阳光线并在室内形成阴影。针对固定保温被对室内光热环境分布和作物产量的影响，该研究对固定保温被下方的光照、温度和作物的产量进行测试，同时利用太阳直射辐射理论提出固定保温被阴影宽度的计算方法。结果表明，在试验期间固定保温被正下方的光照强度平均值为198 μmol/(m²·s)，距离固定保温被4.0～5.0 m位置处的光照强度是固定保温被正下方的2.0倍以上。日间，固定保温被正下方的空气温度、墙面温度和土壤温度相比于固定保温被两侧最大降低2.2、5.8和2.3 ℃。夜间，墙面温度和土壤温度最大降低1.2和1.3 ℃。固定保温被正下方单垄番茄相比于其他垄平均减产36.2%，植株茎粗平均减小2.0～4.0 mm。不同地理位置和不同方位角的日光温室受到固定保温被遮阴在室内形成的阴影宽度范围为11.0～14.0 m。该研究定量分析了使用中卷式卷帘机械的日光温室中固定保温被对室内光热环境和作物产量的影响。     

华北冬季密闭兔舍显热回收通风系统应用效果研究

针对华北地区常见围护结构的冬季不供暖密闭种兔舍保温与通风的矛盾问题,该文通过试验研究该类型兔舍不通风及运行显热回收通风系统(sensible heat recovery ventilation,SHRV)2种状态下的舍内空气质量、SHRV节能通风效果,并对比分析了SHRV结合均匀开孔送风和一端开口送风方式对舍内温度及气流分布的影响,探究SHRV在该兔舍的适用性。结果表明,相比于舍内不通风状态,运行SHRV时,舍内平均温度无显著波动;运行1 h后NH_3和CO_2浓度分别从9.9 mg/m~3和0.23%下降到4.2 mg/m~3和0.09%,湿度从84%下降到56%适宜水平,舍内空气质量改善明显。在该地区舍外温度-6～5℃时,SHRV可使新风温度平均提高3.4℃,平均显热回收效率和能效比(coefficient of performance,COP)分别为65%和5.1,达到了国家节能标准(60%和2.5)。比较分析风管一端开口送风与管道均匀开口送风发现,均匀开口送风可使舍内平均风速降低到0.2 m/s以下,减少舍内气流和温度分层,提高送风均匀性,降低动物冷应激。研究表明,在该地区常见围护结构不供暖密闭种兔舍使用SHRV可有效缓解通风与保温的矛盾,但若要达到更理想的节能通风效果,需采取适宜的芯体片间距,增加饲养密度、加强畜舍围护结构的密闭性提高保温效果。     

浅层地热联合太阳能集热墙系统冬季室内供暖试验

该文提出一种浅层地热联合太阳能集热墙系统,并在石河子地区对采用该系统的被动式太阳房进行了供暖测试研究,对比分析了试验房在不同供暖模式(C1对比房无任何采暖措施的模式、C2试验房未开地下室顶板通风口的供暖模式、C3试验房采用浅层地热联合太阳能集热墙系统的供暖模式)、不同天气状况(晴天、阴天)下的室内热环境。试验结果显示:试验房C3模式下室内平均温度比对照房室内平均温度高6.45℃,日较差为3.5℃;晴天时,试验房白天室内温度有5 h超过了12℃;阴天时,试验房室内外温差仍然达到9.52℃;当室外天气状况为晴天且空气质量指数(air quality index,AQI)符合二级标准限值情况下,试验房在采暖期内10月、11月、及次年的3月、4月,可仅依靠浅层地热联合太阳能集热墙系统满足室内温度的要求,节能效果显著。     

不同节能改造方式猪舍的供暖能耗和经济性比较

为降低猪舍冬季供暖能耗,以12头母猪的分娩猪舍常见围护结构为基础,理论与试验相结合分析了不同节能改造方式的供暖能耗和经济指标。结果表明:未保温猪舍、外墙保温猪舍、外墙天棚保温门窗进风猪舍和外墙天棚保温天棚进风猪舍1个供暖季总能耗分别为118.2、45.2、35.3和0.2 kW·h/m~2。4种猪舍不需要供暖的时长占供暖期总时长的比例分别为10%、28%、33%和96%。外墙保温猪舍与未保温猪舍相比、外墙天棚保温门窗进风猪舍与外墙保温猪舍相比、外墙天棚保温天棚进风猪舍与外墙天棚保温门窗进风猪舍相比、外墙天棚保温天棚进风猪舍与外墙保温猪舍相比,节约的单位能耗的改造成本分别为1.2、40.4、0.2和9.0 Yuan/(kW·h)。以节约单位能耗所需投资最小目标选择猪舍节能改造方式,以墙体保温节能改造最好;以猪舍总能耗最低为目标,则猪舍墙体和天棚均需节能改造并进行天棚预热新风通风。     

复合保温卷帘改善寒区开放式牛舍冬季热湿环境

针对北方寒区卷帘牛舍冬季舍内温度过低、影响奶牛健康和生产的现状,该文结合黑龙江地区的气候特点,以牛舍温度不低于(5 ℃为设计目标,通过对卷帘材料的传热性能、厚度和面密度等进行测试,研究筛选了2种传热系数小于1.23 W/(m2(℃)的复合保温卷帘：1号白色保温卷帘（白色涤纶布+珍珠棉+喷胶棉+珍珠棉+白色涤纶布,1.01 W/(m2(℃)）和2号灰色保温卷帘（PE编织布+喷胶棉+针刺棉毡+镀铝PE编织布,0.89 W/(m2(℃)）。将2种保温卷帘分别安装在同一栋试验舍内,以原有的单层卷帘牛舍为对照舍进行了为期2个月的现场应用效果试验。试验结果表明,2种保温卷帘的透光性存在显著差异（P<0.05）,但保温效果不存在显著差异（P>0.05）;试验舍和对照舍在两侧卷帘开启25 cm、南侧开启25 cm和两侧封闭3种工况下,试验舍的平均温度和相对湿度均显著高于对照舍和舍外（P<0.05）,其舍内平均温度范围是(12.45～(16.70 ℃,平均相对湿度范围是88.53%～97.73%。因此,新型保温卷帘虽然比单层卷帘具有更好的保温性能,但是奶牛依旧处于低温高湿的状况下,表明只改善卷帘的保温性能并不能保证使寒区奶牛舍内温度高于最低温度的要求,寒区应慎重采用可封闭开放式的牛舍建筑形式。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。