毛乌素沙地若干植物光合作用,蒸腾作用和水分利用效率种间及生境间差异

报道了内蒙古毛乌素沙地不同生境下66种不同科属植物的光合作用、蒸腾作用和水分利用效率特征。这几种生境包括流动沙丘、固定沙丘、滩地和湿地,所分布的植物与表现的生理生态特征不同。研究结果表明:藜科、禾本科、豆科等具有C4光合碳同化途径或具固氮能力的植物具有较高的光合能力,其净光合速率20～30μmolCO2·m-2·s-1;而松柏科的常绿植物具最低的光合速率,0～5μmolCO2·m-2·s-1。菊科、玄参科、禾本科等具C3途径和无固氮能力的植物蒸腾作用最高,为20～30mmolH2O·m-2·s-1;松柏科、杨柳科和菊科的个别植物蒸腾速率很低,为0～5mmolH2O·m-2·s-1。豆科、禾本科和藜科中具C4光合途径或固氮能力的一些植物(灌木或草本植物)具有较高的水分利用效率。然而,植物的这些生理生态指标随不同季节和生境表现出不同的特点,在晚夏季所测的净光合速率、蒸腾速率分别比初夏季高26%和40%,而水分利用效率下降12%。从总体趋势来看,随着生境沿着由湿到干的不同水分供应等级,如从湿地、滩地、固定沙丘至流动沙丘,光合作用和蒸腾作用呈现减弱的趋势,而水分利用效率则呈现升高的趋势     

米瓦罐的光合特性研究

采用美国LI-COR生产的LI-6400便携式光合系统研究了米瓦罐的光合特性。结果表明,米瓦罐光 合速率的日变化呈单峰曲线,上午10:00时光合速率达到最大值;在大气CO2浓度下,米瓦罐的光饱和点为 1 800μmol·m-2·s-1,光补偿点为30μmol·m-2·s-1;在光饱和点的光强下,米瓦罐的CO2饱和点为1 200 μmolCO2·mol-1,CO2补偿点为40μmolCO2·mol-1。     

梨树叶片蒸腾特性研究

采用CIRAS-1红外气体分析仪研究梨树不同时期蒸腾速率及水分利用效率变化特征。结果表明:梨树蒸腾速率日变化为单峰型,峰值出现在11:00～P15:00;蒸腾速率的季节变化呈"V"字形,其中5～P8月份逐渐降低,8～P9月份迅速升至最高,生长季平均蒸腾速率为2.66mmol.m-2.s-1;决定蒸腾速率日变化的主要因子为空气温度、叶面温度和水汽压差,且各因子对蒸腾速率日变化的贡献率分别为85%～P96%、76%～P86%和98%。水分利用效率日变化峰值出现在早上7:00～P9:00,然后逐渐降低;水分利用效率的季节变化峰值(5.38μmolCO2/mmolH2O)出现在8月份,5、6、7、9月份的水分利用效率相当,其值在2.86～P3.05μmolCO2/mmolH2O之间,生长季平均为3.44μmolCO2/mmolH2O;相关分析结果表明,水分利用效率受光合有效辐射、空气温度、叶片温度、空气湿度、以及叶片-大气水气压差等各因子的综合作用。     

乌兰布和沙漠东北部8种沙生灌木生长季末期的光合生理特性

以乌兰布和沙漠东北部的甘蒙柽柳、沙木蓼、霸王、沙冬青、花棒、白刺、梭梭和柠条8种沙生灌木为材料,对沙生灌木生长季末期的光合生理特性进行了研究。结果表明:(1)8种沙生灌木秋季的气孔导度日变化有明显的峰谷;气孔导度日均值最大的为梭梭(0.71 mol.m-2.s-1),最小的为柠条(0.08 mol.m-2.s-1);(2)8种沙生灌木秋季的光合速率日变化均呈现单峰曲线,影响光合速率变化的因素以非气孔限制因素为主;光合速率峰值出现时间以柠条最早(11:30),甘蒙柽柳和沙木蓼最晚(15:30);光合速率日均值最大的为沙木蓼(7.99μmol.m-2.s-1),最小的为柠条(3.40μmol.m-2.s-1);(3)蒸腾速率的日变化除梭梭和柠条呈现单峰曲线外,其余6种灌木呈现出准双峰曲线或双峰曲线;蒸腾速率日均值最大的为梭梭(4.42 mmol.m-2.s-1),最小的为柠条(0.47mmol.m-2.s-1);气孔运动因素对蒸腾作用的影响占据优势;(4)8种沙生灌木的光合水分利用效率在白昼普遍高于早晚,且以柠条的光合水分利用效率日均值最大(7.18μmol.mmol-1),梭梭最小(1.23μmol.mmol-1);蒸腾速率日均值高的沙生灌木光合水分利用效率日均值低,反之亦然。     

内蒙古浑善达克沙地97种植物的光合生理特征(英文)

 报告了内蒙古浑善达克沙地不同生境下97种不同科、属植物的光合速率、蒸腾速率和水分利用效率特征。结果表明：猪毛菜（Salsola collina）、沙米（Agriophyllum pungens）、黑沙蒿（Artemisia ordosica）、狗尾草（Setaria viridis）、柠条（Caragana microphylla）等具有C4光合碳同化途径或具固氮能力的植物种具有较高的光合能力,其净光合速率大于30 μmol CO2·m-2·s-1, 而大部分具C3途径和无固氮能力的植物种的净光合速率较低,为1.29～10 μmol CO2·m-2·s-1;71%的植物种蒸腾速率集中在2～10 mmol H2O·m-2·s-1。所选出的高光效植物种在当地植被恢复与重建过程中应有很高利用价值。C4植物种占所测植物种的1/5左右,主要分布于固定沙丘上,且随着生境土壤湿度的增大其与C3植物种的光合速率差异逐渐缩小。在3种生境条件下,灌木和草本植物的光合速率和蒸腾速率顺序为：低湿地> 滩地 > 固定沙丘(p<0.01),而乔木为固定沙丘>滩地 (p<0.01) 。不同功能型植物的气体交换特征随生境的不同而异, 在固定沙丘上, 草本的蒸腾速率最高,乔木的水分利用率最高,三者光合速率相差不大。     

荒漠植物梭梭和沙拐枣光合作用、蒸腾作用及水分利用效率特征

运用开放式气体交换LI-6400便携式光合作用测定系统,研究了梭梭(Haloxylonammodendron)和沙拐枣(Calligonummongolicum)的净光合速率(Pn)、蒸腾速率(E)及水分利用效率(WUE)特征。结果表明:梭梭和沙拐枣在湿润状况下的Pn日变化呈单峰型,梭梭低于沙拐枣,日平均分别为19.60±0.12μmol·m-2·s-1和24.06±0.50μmol·m-2·s-1;E也是梭梭低于沙拐枣,日平均分别为5.53±0.08mmol·m-2·s-1和8.21±0.26mmol·m-2·s-1;WUE则不同,日平均梭梭高于沙拐枣,分别为3.28±0.05mmolCO2·mol-1H2O和2.84±0.06mmolCO2·mol-1H2O。WUE年均值也是梭梭高于沙拐枣,二者最高值都出现在9月,次高值出现在7月,WUE的高低变化与年降水量的高低分布一致。在湿润和干燥两种状况下,梭梭和沙拐枣Pn对光强的响应表明,水分条件好时Pn明显增大,光能利用率提高。从湿润状况时的净光合速率、光饱和点和CO2补偿点,以及干燥状况时也具有低CO2补偿点,确定梭梭和沙拐枣具有C4光合途径。     

几种野生银莲花生殖生长期的光合作用特性初探

采用LI-6400便携式光合仪对室外栽培的几种野生银莲花光合作用特性进行了研究.结果表明,净光合速率 Pn 和蒸腾速率 Tr 日变化均呈单峰曲线,前者的峰值出现在10:00～11:00时,后者的峰值出现在13:00时前后.在光强0～2000μmol·m-2·s-1条件下,Pn呈S曲线,光补偿点为60～80μmol·m-2·s-1,光饱和点为800μmol·m-2·s-1左右,但光强继续增加到1800μmol·m-2·s-1,Pn仍有少许提高;Tr随PAR的增加而缓慢增加.在环境CO2浓度为0～350μmol·mol-1条件下,Pn直线上升,草玉梅、秋牡丹和野棉花的光合CO2补偿点均为50μmol·mol-1左右;Tr在环境CO2浓度25～350μmol·mol-1范围内几乎呈水平线.野生银莲花的Pn和Tr表现出较明显的种间差异.     

不同砧木嫁接番茄光合特性的研究

采用LI-6400便携式光合作用系统对田间条件下嫁接番茄(珍红/砧木1号,珍红/桂砧1号)以及接穗(珍红)的光合作用特性进行了系统研究。结果表明:自根苗的光饱和点显著高于嫁接苗;自根苗和嫁接苗的光补偿点差异不显著,以珍红/桂砧1号最高(31.8μmolphotons·m-2·s-1),珍红/砧木1号最低(17.6μmolphotons·m-2·s-1);嫁接苗的CO2补偿点显著低于自根苗,且珍红/桂砧1号与自根苗的差异达极显著水平;表观量子效率变化范围为0.062~0.073;CO2饱和点在844~971μmolCO2·mol-1左右,CO2羧化效率变化范围为0.055~0.086molCO2·m-2·S-1;光合作用CO2补偿点珍红、珍红/砧木1号和珍红/桂砧1号分别为74.0、60.8和50μmolCO2·mol-1。嫁接苗的日平均光合速率和蒸腾速率高于自根苗,但两者的日进程曲线均为“单峰型”,其光合作用不存在“午休现象”。     

秦艽与小秦艽光合日变化的研究

运用光合作用测定系统,对野生秦艽(Gentiana macrophylla Pall．)和小秦艽(G．dahurica Fisch．)的开花期的光合特性进行研究。结果表明,2种秦艽的净光合速率、蒸腾速率、气孔导度日变化曲线都呈双峰型,有明显的光合“午休”现象。小秦艽的光合速率、蒸腾速率、气孔导度照著高于秦艽,分别高出2．7 μmolCO2·m-2·s-1、1．5 mmol·m-2·s-1和140．7 mmol．m-2·s-1而叶温则低于秦艽2．8C。相关分析表明,开花期的温度、光照对2种秦艽的光合都有一定影响,蒸腾速率、气孔导度调节光合作用,而引起2种秦艽光合速率降低的主要因素为非气孔因素。     

米瓦罐光合日变化的研究

采用LI-6400便携式光合系统研究了米瓦罐的光合日变化.结果表明,米瓦罐光合速率的日变化呈单峰曲线,上午10:00时光合速率最大,为31.5μmolCO2/(m2·s);7:00时的表观量子效率最高,为0.032 CO2/quantum;气孔导度的变化趋势与光合速率一致,10时出现最大值,为0.521 molH2O/(m2·s);11时蒸腾速率最快,为6.82mmolH2O/(m2·s);水分利用效率8时最高,为7.07μmolCO2/mmolH2O.     

On-station comparative analysis of reproductive and survival performance between Red Maasai,Dorper, and Merino sheep breeds

The reproductive performance of ewes and the survivability of lambs to weaning have a critical economic impact on sheep farming worldwide. Further, knowledge of major mortality causes allows an opportunity for improved flock management to evade financial losses. The maximum likelihood estimates for generalised linear mixed models and chi-square test methods were used to examine 971 mating records, 839 and 763 lambs born and weaned (singles or twins) from the Naivasha Sheep and Goats station in Kenya for the years 2011 to 2020 consisting of Dorper, Red Maasai (RedM), and Merino breeds. The RedM (P < 0.05) outperformed Dorper and Merino in weaning rate, whereas reproductive performance between the three breeds was not significantly different (P > 0.05) in litter size and multiple lambings per ewe lambing. On the one hand, Dorper significantly (P < 0.05) outperformed the other two breeds only in weaning weight per lamb born. In addition, among all the major causes of death, pneumonia appeared to be the one to which Dorper breeds were most susceptible (chi-square test, P < 0.05). According to the findings of this study, neither the Dorper nor the Merino sheep breeds were reproductively superior to the RedM in an extensive semi-arid production environment. In addition, Dorper's susceptibility to the leading causes of mortality, particularly pneumonia and sheep pox, were relatively high compared to other breeds and could be a precursor to massive economic losses for Dorper sheep producers. In contrast to the indigenous RedM breed, imported sheep breeds appeared to be more susceptible to major mortality-related under an extensive production system. Therefore, regardless of weaning weight, RedM breed production appears to be a more viable investment for small-scale farmers, particularly in semi-arid regions.     

Time dependency of molecular rate estimates and systematic overestimation of recent divergence times

Studies of molecular evolutionary rates have yielded a wide range of rate estimates for various genes and taxa. Recent studies based on population-level and pedigree data have produced remarkably high estimates of mutation rate, which strongly contrast with substitution rates inferred in phylogenetic (species-level) studies. Using Bayesian analysis with a relaxed-clock model, we estimated rates for three groups of mitochondrial data: avian protein-coding genes, primate protein-coding genes, and primate d-loop sequences. In all three cases, we found a measurable transition between the high, short-term (< 1-2 Myr) mutation rate and the low, long-term substitution rate. The relationship between the age of the calibration and the rate of change can be described by a vertically translated exponential decay curve, which may be used for correcting molecular date estimates. The phylogenetic substitution rates in mitochondria are approximately 0.5% per million years for avian protein-coding sequences and 1.5% per million years for primate protein-coding and d-loop sequences. Further analyses showed that purifying selection offers the most convincing explanation for the observed relationship between the estimated rate and the depth of the calibration. We rule out the possibility that it is a spurious result arising from sequence errors, and find it unlikely that the apparent decline in rates over time is caused by mutational saturation. Using a rate curve estimated from the d-loop data, several dates for last common ancestors were calculated: modern humans and Neandertals (354 ka; 222-705 ka), Neandertals (108 ka; 70-156 ka), and modern humans (76 ka; 47-110 ka). If the rate curve for a particular taxonomic group can be accurately estimated, it can be a useful tool for correcting divergence date estimates by taking the rate decay into account. Our results show that it is invalid to extrapolate molecular rates of change across different evolutionary timescales, which has important consequences for studies of populations, domestication, conservation genetics, and human evolution.     

Predation rate and numerical response of Aphidoletes aphidimyza feeding on different densities of Aphis craccivora

Predation rate and numerical response are basic to any investigation of predator–prey relationships and key components in the selection of predators for biological control. The density-dependent predation rate and numerical response of Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) to varying densities (5, 10, 20, 40, 60 and 80) of third-instar Aphis craccivora (Koch) (Hemiptera: Aphididae), were studied in laboratory conditions [23±1°C, 70 ± 5% relative humidity (RH), and a photoperiod of 16:8 h L:D. Predation rate data were analysed using the age-stage, two-sex consumption rate software. Net consumption rate (C₀) increased by increasing prey density. The lowest and highest net consumption rates were 20.75 and 190.8 prey nymphs at densities of 5 and 80 A. craccivora. The transformation rate from prey population to predator offspring (Q_p) increased by increasing prey density. The reproductive numerical response, in terms of eggs laid, increased curvilinearly with increasing prey density. Females laid 121.375 ± 4.301 eggs when exposed to the highest prey density (80) and 52.5 ± 1.544 eggs at lowest prey density (5). It can be concluded that different densities of A. craccivora influenced the reproductive performance of A. aphidimyza in terms of predation rate and numerical response.     

光周期和温度对虎斑蝶卵、幼虫及蛹存活的影响

通过在人工气候箱内设定不同光周期和温度梯度单虫饲养观察个体发育史,研究了光周期和温度对虎斑蝶Danaus genutia幼期存活的影响,研究结果可为该高观赏价值蝶种的规模化养殖提供依据。结果表明,在长光照(L∶D=15∶9)条件下,17.5、20.0、22.5、25.0、27.5、30.0℃时虎斑蝶卵的孵化率分别为63.72%、71.67%、65.75%、75.00%、67.12%、59.56%,幼虫的存活率分别为85.67%、85.96%、91.19%、89.20%、80.86%、68.78%,蛹的存活率分别为82.76%、100.00%、96.00%、97.06%、100.00%、100.00%;在短光照(L∶D=9∶15)条件下,17.5、20.0、25.0、30.0℃时虎斑蝶卵的孵化率分别为86.36%、67.06%、75.00%、77.50%,幼虫的存活率分别为85.05%、84.59%、85.74%、80.78%,蛹的存活率分别为93.30%、94.12%、100.00%、100.00%。结果表明,17.5℃和30.0℃均不利于虎斑蝶幼期的存活,20.0～27.5℃是其幼期生长发育适宜的温度范围。长光照利于幼虫的存活,短光照利于卵的孵化和蛹的羽化;在17.5～30.0℃内,较高的温度利于蛹的羽化,而较低的温度利于卵的孵化和幼虫的存活;温度对虎斑蝶卵的孵化、幼虫的存活及蛹的羽化影响大于光周期;在养殖生产上,建议将幼期养殖温度控制在20.0～27.5℃,幼虫期饲养在长光照下为宜,卵和蛹期置于短光照下为宜。     

光合单位的周转率与叶片光合速率的关系

利用闪光技术,测得若干高等植物叶片的光合单位为 1450～2050 Chl/CO_2。在含O_2 2％及CO_2浓度和光通量密度都饱和的条件下,测得叶片的连续光合速率为25～70μmol CO_2 m~(-2) s~(-1)。从上述数据及叶片叶绿素含量计算,得叶片光合单位的周转率已达80～160次/s。这样的周转速率与Emerson当初用改变闪光间暗间隔而测到的光合单位周转时间相似(即<10 ms/次,或>100次/s),从而证实了光合单位的周转与光合速率直接有关。这样的速率可称之为叶片光合的理论速率。     

沙埋对两种一年生藜科植物存活及光合生理的影响

为了解沙埋对沙生植物存活的影响及其光合生理响应特征,比较不同藜科沙生植物耐沙埋能力及其光合响应,在内蒙古科尔沁沙地研究了沙米(Agriophyllum squarrosum)和大果虫实(Corispermum marocarpum)在不同沙埋深度下第5、10、15天的净光合速率、气孔导度、蒸腾速率、水分利用效率的变化,并于植物生长末期对存活率进行了测定。结果表明:沙米较大果虫实具有较强的耐沙埋能力,其中沙米幼苗最大耐沙埋深度超过苗高10 cm,大果虫实在埋深等于其苗高时全部死亡;随沙埋深度增加,沙米和大果虫实的存活率均显著下降,但沙米的下降幅度明显小于大果虫实;沙埋后,2种植物的气孔关闭或开放程度减小,通过降低蒸腾速率和提高水分利用效率来适应沙埋胁迫;随着沙埋胁迫的加剧,2种植物的净光合速率下降,表明沙埋胁迫对植物的光合作用破坏较大;相比于大果虫实,沙米对于沙埋胁迫有着更好的光合适应,随着胁迫的时间增加,其净光合速率有所恢复。     

Nutrient requirements and stress response of Populus simonii and Paulownia tomentosa

The aim of this investigation was to estimate the optimum nutrient requirements and responses to low relative nutrient addition rates of seedlings of two important broadleaf tree species in China, Populus simonii Carr. and Paulownia tomentosa (Thunb.) Steud. In preliminary experiments the optimum nutrient proportions were estimated under high concentration conditions. The nutrients consumed were replaced by means of daily additions determined by pH and conductivity titrations without changing the nutrient solutions. A relatively high K level was needed in relation to nitrogen; higher than in birch or grey alder seedlings. To obtain a high relative growth rate, suitable proportions by weight were 100 N:70 K:14 P:7 Ca:7 Mg for the Populus seedlings and 100 N:75 K:20 P:8 Ca:9 Mg for the Paulownia seedlings.
In studies of nutrient stress responses the relative nutrient addition rate was used as the treatment variable under low conductivity conditions. The responses and relationships were similar to those described for birch, grey alder and Salix . The relative addition rate, and there was also a strong linear regression between relative growth rate and nitrogen status. Relative growth rates were high and the maximum weight increase was about 19% day⁻¹ in Populus and over 25% day⁻¹ in Paulownia . The nitrogen productivity of Paulownia was very high, 0.26 g dry weight (g N)⁻¹ h⁻¹, and for Populus it was 0.16 g dry weight (g N)⁻¹ h⁻¹.     

新疆野生郁金香与栽培品种的杂交性状

为研制具有自主知识产权的郁金香（Tulipa gesneriana）新种质，本实验选择6种栽培郁金香品种为母本，5种野生郁金香为父本进行杂交试验。结果显示，平均受精率为（84．8±3．5）％，母本受精率最高的是克斯奈丽斯，平均为（94．0±2．3）％，受精率最低的是蒙特卡罗，平均为（71．0±3．8）％。果实发育1个月最高坐果率为100．0％，平均为（75．2±4．1）％，2个月最高坐果率为（90．0±3．6）％，平均为（47．0±3．4）％；杂交种子平均结实率为24．3％。研究结果表明，母本与杂交组合对受精率、坐果率和结实率有显著影响，父本则没有显著影响：杂交组合小黑人×伊犁郁金香、小黑人×柔毛郁金香及小黑人X天山郁金香亲合性较好，其杂交种子结实率分别为78．2％、68．4％和57．5％。     

Altitudinal and seasonal effects on aerobic metabolism of deer mice

Summary I compared the maximal aerobic metabolic rates ( ), field metabolic rates (FMR), aerobic reserves ( -FMR), and basal metabolic rates (BMR) of wild and recently captured deer mice from low (440 m) and high (3800 m) altitudes. To separate the effects of the thermal environment from other altitudinal effects, I examined mice from different altitudes, but similar thermal environments (i.e., summer mice from high altitude and winter mice from low altitude). When the thermal environment was similar, , FMR, and aerobic reserve of low and high altitude mice did not differ, but BMR was significantly higher at high altitude. Thus, in the absence of thermal differences, altitude had only minor effects on the aerobic metabolism of wild or recently captured deer mice.At low altitude, there was significant seasonal variation in , FMR, and aerobic reserve, but not BMR. BMR was correlated with , but not with FMR. The significant positive correlation of BMR with indicates a cost of high , because higher BMR increases food requirements and energy use during periods of thermoneutral conditions.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - partial pressure of oxygen - T _a ambient temperature - T _b body temperature - T _e operative temperature - maximal aerobic metabolic rate     

Growth and social interactions of wild and sea-ranched brown trout and their hybrids

A laboratory study of the social behaviour and growth performance of juvenile brown trout Salmo trutta of wild and sea-ranched origin and their crosses, indicated that the social behaviour of wild and sea-ranched fish differed. Male and female parents seemed to have a different impact on the juveniles. The category having wild mother and sea-ranched father were less aggressive, less active in general, but active in feeding, and therefore had higher growth rates. This pattern arose despite that the feeding rate and the motivation to first get a food item when food was provided did not differ between the groups of fish. Wild fish tended to be most aggressive. If sea-ranched and wild fish have different intrinsic (genetically based) 'life styles', the crosses between wild and sea-ranched fish indicate that there is likelihood for an introgression of genes adapted to hatchery environment into the genetics of wild conspecifics. This is particularly serious when hatchery-reared fish invades wild populations over many years.