渭北黄土区农林复合系统中大豆辣椒的光合生理特性

研究了农林复合系统不同处理对大豆、辣椒的光合特性和叶绿素荧光参数的影响.结果表明,从单作到距李子1m处,随着距李子树越近,遮光愈多.各处理大豆、辣椒的光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)表现出与光合有效辐射(PAR)基本一致的日变化模式,且与单作相比,各处理大豆、辣椒的光合速率、气孔导度和蒸腾速率均有不同程度的降低.相关性分析结果表明二者的光合速率、气孔导度及蒸腾速率均与光合有效辐射呈正相关关系.随着遮荫程度的提高,大豆、辣椒叶绿素含量和表观量子效率(Ф)升高,光饱和点(LSP)和光补偿点(LCP)降低.二者叶绿素荧光参数最大光能转换效率( Fv / Fm ) 、PSⅡ电子传递量子效率(ФPSⅡ ) 以及光化学猝灭系数( qP)均有不同程度的升高,而非光化学猝灭系数( qN P)却逐渐降低.说明大豆、辣椒能适应弱光环境,在较低的光照条件下正常生长.     

黄土区农林复合生态系统中大豆和绿豆的光合生理特性

用Li-6400光合测定系统和FMS-2.02荧光仪测定了单作及间作农林复合系统中大豆和绿豆的光合荧光参数日变化特征,进一步解析复合系统光能竞争机理.结果表明:(1)从单作到间距核桃1 m间作模式,距核桃树越近,遮光愈多,各处理大豆、绿豆的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)表现出与光合有效辐射(PAR)基本一致的先升后降的日变化模式.(2)随着遮荫程度的提高,大豆、绿豆叶绿素含量和表观量子效率(Ф)升高,而光饱和点(LSP)和光补偿点(LCP)降低.(3)随着遮荫程度的提高,大豆、绿豆叶绿素荧光参数最大光能转换效率(Fv/Fm)、PSⅡ电子传递量子效率(ФPSⅡ)以及光化学猝灭系数(qP)均有不同程度的升高,而非光化学猝灭系数(qN)却逐渐降低.研究发现,大豆和绿豆能适应间作系统的弱光环境,在较低的光照条件下正常生长,植物的光合特性与其生境特点相符.     

外源Ca~(2+)对高温强光下西葫芦幼苗形态特征、光合特性及荧光参数的影响

选用西葫芦(Cucurbita pepo)品种"阿兰"一代为试验材料,研究了外源Ca2+处理对高温强光交叉胁迫下西葫芦幼苗生长特征、光合特性及叶绿素荧光参数的影响.结果表明:高温强光胁迫下,5～20mmol·L-1Ca2+处理的西葫芦幼苗具有较高的株高和较大的叶面积,其叶绿素、类胡萝卜素含量及光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)和光化学猝灭系数(qP)均较高,而胞间CO2浓度(Ci)和非光化学猝灭系数(NPQ)较低,其中以10mmol·L-1Ca2+处理效果最好.说明5～20mmol·L-1Ca2+处理能有效缓解高温强光对西葫芦光合机构的不可逆伤害,使其保持较快的光合电子传递速率和较高的PSⅡ电子传递活性.Ca2+处理浓度超过40mmol·L-1时对高温强光胁迫没有缓解效应.     

γ-氨基丁酸(GABA)对低氧胁迫下甜瓜幼苗光合作用和叶绿素荧光参数的影响

采用营养液水培方法,研究了低氧胁迫下外源γ-氨基丁酸(GABA)对甜瓜幼苗光合色素含量、光合作用及叶绿素荧光参数的影响.结果表明:低氧胁迫导致甜瓜幼苗光合色素含量显著下降,光合作用降低;外源GABA能显著提高正常通气和低氧胁迫下甜瓜幼苗的光合色素含量、净光合速率、气孔导度、胞间CO2浓度、CO2羧化效率、最大光化学效率、光化学猝灭系数、表观光合电子传递速率和PSⅡ光合电子传递量子效率,而气孔限制值、初始荧光和非光化学猝灭系数显著降低,GABA在低氧胁迫下的提高效果更明显;同时添加GABA和GABA转氨酶抑制剂γ-乙烯基-γ-氨基丁酸(VGB)处理显著降低了低氧胁迫下GABA对甜瓜幼苗光合特性的缓解效果.     

干旱胁迫对两种油桐幼苗生长、气体交换及叶绿素荧光参数的影响

为了探究干旱胁迫对两种油桐(三年桐和千年桐)幼苗光合生理特性的变化及响应,采用盆栽试验,研究不同水分处理(正常供水、轻度干旱、中度干旱、重度干旱)对油桐幼苗生长、叶片气体交换及叶绿素荧光参数的影响。结果表明:与对照相比,轻度干旱胁迫对两种油桐生长、气体交换及叶绿素荧光参数无明显影响(P0.05);中度干旱及重度干旱使两种油桐的叶绿素SPAD值、生长量、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、气孔限制值(L_s)、最大净光合速率(P_(nmax))、光饱和点(LSP)、表观量子效率(AQY)、暗呼吸速率(R_d)、最大光化学效率(F_v/F_m)、实际光化学量子效率(Φ_(PSⅡ))、电子传递速率(ETR)及光化学猝灭系数(q_P)显著下降(P0.05),且在重度干旱胁迫下迅速下降,胞间CO_2浓度(C_i)、水分利用效率(WUE)、光补偿点(LCP)、初始荧光(F_o)、非光化学猝灭系数(NPQ)显著升高(P0.05);中度干旱胁迫下油桐幼苗P_n的降低是由气孔因素及光合机构活性降低的非气孔因素共同引起的,而重度干旱胁迫下光合作用的下降主要是由光合机构活性降低的非气孔因素引起的。三年桐的光合机构活性及光合效率高于千年桐,对干旱胁迫的适应性较千年桐强。     

低温胁迫对广玉兰幼苗光合及叶绿素荧光特性的影响

以广玉兰幼苗为材料,对其进行0,-4℃、-8℃,-12℃和-16℃ 5个梯度低温处理,研究了广玉兰幼苗的光合作用与叶绿素荧光特性变化.结果表明:随着温度降低,广玉兰幼苗叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(G3)、叶肉细胞间隙CO2浓度(Ci)、叶绿素含量均逐步降低,最大光化学效率(Fv/Fm)、潜在光化学效率(Fv/F0)、最大量子产额(Yield)、光合电子传递速率(ETR)、光化学猝灭系数(qp)也均同时下降,而初始荧光(F0)、非光化学猝灭系数(qN)则逐步上升.可见,低温胁迫除导致光合作用的气孔抑制外,还直接损伤光合机构使PSⅡ反应中心失活,引起其光能原初捕捉能力和光能同化率减弱,增加了通过热辐射消耗的光能比例,最终导致广玉兰幼苗光合作用能力减弱.     

模拟酸雨对龙眼叶片气体交换和叶绿素a荧光参数的影响（英文）

 研究了模拟酸雨对龙眼(Dimorcarpus longana)叶片气体交换和叶绿素a荧光参数的影响,结果表明：酸雨胁迫抑制龙眼光合作用,受胁迫叶片光补偿点上升。pH 3.0的酸雨处理6 h后叶片气体交换和叶绿素a荧光参数下降,停止处理后72 h可以恢复。pH 2.5的酸雨处理6 h后净光合速率（Pn）、气孔导度(Cs)、蒸腾速率（Tr）,叶绿素a荧光参数Fv/Fo、Fv/Fm、PSII非环式电子传递的量子产量（ΦPSⅡ）、荧光下降比值（Rfd）、非光化学猝灭系数（qN）和光化学猝灭系数（qP）急剧下降,停     

土壤水分对冬小麦生育后期叶片气体交换及叶绿素荧光参数的影响

通过防雨棚小区栽培,控制土壤供水系数(Kw)分别为0.8、0.6、0.4、0.2,以自然状况下的小区为对照(CK),研究土壤水分条件对冬小麦生育后期叶片气体交换及叶绿素荧光参数的影响。结果表明:Kw为0.6处理的冬小麦叶片叶绿素含量与0.8处理接近,且显著高于其他处理(P<0.05);Kw为0.6处理对冬小麦叶片的气孔导度和蒸腾速率有轻度抑制,但其光合速率却高于0.8处理,而Kw为0.2处理的光合速率、气孔导度及蒸腾速率均为最低;气孔限制值在Kw为0.4处理下最高,其次为0.2处理,0.8处理下最低;冬小麦叶片的表观量子效率在Kw为0.4处理下最高,光补偿点总体上随着土壤水分含量的降低呈下降趋势,而光饱和点及最大光合速率则以Kw为0.6处理最高,其次为0.8处理,0.2处理最低;冬小麦叶片的天线转化效率Fv’/Fm’、电子传递速率ETR、实际量子效率ФPSII及光化学猝灭qP均以Kw为0.6处理最高,其次为0.8处理,0.2处理下最低;在Kw为0.2处理下,冬小麦光合作用主要受非气孔因素限制,而在0.4处理下,则主要受气孔因素限制。     

γ-氨基丁酸（GABA）对低氧胁迫下甜瓜幼苗光合作用和叶绿素荧光参数的影响

采用营养液水培方法,研究了低氧胁迫下外源γ-氨基丁酸（GABA）对甜瓜幼苗光合色素含量、光合作用及叶绿素荧光参数的影响.结果表明：低氧胁迫导致甜瓜幼苗光合色素含量显著下降,光合作用降低;外源GABA能显著提高正常通气和低氧胁迫下甜瓜幼苗的光合色素含量、净光合速率、气孔导度、胞间CO₂浓度、CO₂羧化效率、最大光化学效率、光化学猝灭系数、表观光合电子传递速率和PSⅡ光合电子传递量子效率,而气孔限制值、初始荧光和非光化学猝灭系数显著降低,GABA在低氧胁迫下的提高效果更明显;同时添加GABA和GABA转氨酶抑制剂γ-乙烯基-γ-氨基丁酸（VGB）处理显著降低了低氧胁迫下GABA对甜瓜幼苗光合特性的缓解效果.     

接种AMF对弱光环境及盐胁迫下甜瓜光合特性的影响

以甜瓜(Cucumis melo L.)品种"中蜜3号"为试材,摩西球囊霉菌(Glmous mosseae,GM)为供试菌种,采用温室盆栽试验研究了丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)对弱光及盐胁迫下甜瓜幼苗叶绿素含量、光合气体交换参数、叶绿素荧光参数和光响应曲线的影响。结果表明:弱光及盐胁迫下接种AMF可显著增强甜瓜幼苗叶绿素含量、净光合速率(P_n)、光合电子传递速率(ETR)、水分利用率(WUE)和气孔限制因子(L_s);气孔导度(G_s)、蒸腾速率(T_r)、胞间CO_2浓度(C_i)则随胁迫时间延长不断增强;光化学猝灭系数(qP)与实际光化学效率(Φ_(PSⅡ))变化趋势基本一致且均显著高于未接菌处理;接种AMF显著增强了最大光化学效率(F_v/F_m),但处理之间差异不显著;并进一步提高了宿主的最大羧化速率(A_(max))、光饱和点(LSP)和表观量子效率(AQE),降低了光补偿点(LCP)和暗呼吸速率(R_d)。研究发现,AMF可通过改善叶绿素荧光、气体交换参数和光响应参数来减轻弱光及盐胁迫对植株造成的伤害,从而提高甜瓜对弱光及盐胁迫的耐性。     

Pollen,ovules, and pollination in pea: Success,failure, and resilience in heat

Field pea (Pisum sativum), a major grain legume crop, is autogamous and adapted to temperate climates. The objectives of this study were to investigate effects of high temperature stress on stamen chemical composition, anther dehiscence, pollen viability, pollen interactions with pistil and ovules, and ovule growth and viability. Two cultivars (“CDC Golden” and “CDC Sage”) were exposed to 24/18°C (day/night) continually or to 35/18°C for 4 or 7 days. Heat stress altered stamen chemical composition, with lipid composition of “CDC Sage” being more stable compared with “CDC Golden.” Heat stress reduced pollen viability and the proportion of ovules that received a pollen tube. After 4 days at 35°C, pollen viability in flower buds decreased in “CDC Golden,” but not in “CDC Sage.” After 7 days, partial to full failure of anthers to dehisce resulted in subnormal pollen loads on stigmas. Although growth (ovule size) of fertilized ovules was stimulated by 35°C, heat stress tended to decrease ovule viability. Pollen appears susceptible to stress, but not many grains are needed for successful fertilization. Ovule fertilization and embryos are less susceptible to heat, but further research is warranted to link the exact degree of resilience to stress intensity.     

Love, careers, and heights in France, 2001

Short men are less likely to be married or live in a permanent relationship than their taller counterparts. This pattern is not due to their social status. While blue-collar workers are shorter on average than managers, the effects of height on finding a mate are similar in the two social groups. Being tall is also economically advantageous for men. With identical educational attainment levels, tall men have better careers than short men as they are given greater supervisory responsibilities. In making a commitment, some women might take height into account as an anticipated indicator of future resources of the household. Choice of partner is also influenced by social norms--i.e., partners should be physically well-matched--which is more difficult for shorter men.     

Distribution of N,P, K,Ca, Mg,S, Zn,Fe, Mn and Cu in groundnut

Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.     

Correlations of calcium accumulations in arteries, veins, cartilages, ligaments, and bones in single humans

To show the relationships of calcium accumulation in the thoracic aorta to the other tissues, calcium contents were determined with a microwave-induced plasma-atomic emission spectrometer on arteries, veins, cartilages, ligaments, and bones. These tissues were resected from 18 individuals, consisting of 11 men and 7 women who died in the age range 59–91 yr. As thoracic and abdominal aortas are routinely used for radiographic examination of arterial calcification, they appear to be standard tissues of the calcium accumulation. The calcium accumulations were determined in the femoral artery, the superior and inferior venae cavae, the internal jugular vein, cartilages of the articular disk of the temporomandibular joint and the intervertebral disk, both the ligaments of the anterior cruciate ligament and the ligamentum capitis femoris, and the calcaneus, in contrast with the thoracic aorta. As calcium increased in the thoracic aorta, it increased in the femoral artery, the articular disk of the temporomandibular joint, the intervertebral disk, both ligaments of the anterior cruciate ligament, and the ligamentum capitis femoris, but it did not increase in veins, such as the superior and inferior venae cavae and the internal jugular vein. In contrast, it decreased in the calcaneus.     

Seroepidemiology of human parechovirus types 1, 3, and 6 in Yamagata,Japan, in 2014

To clarify the seroepidemiology of human parechovirus type 1 (HPeV1), 3 and 6, neutralizing antibodies (NT Abs) were measured in 214 serum specimens collected in 2014 in Yamagata, Japan. The seroprevalence against HPeV1 was 100% in all age groups, while that against HPeV3 and HPeV6 was 79.4% and 66.8%, respectively, overall. The geometric mean titers of NT Abs against HPeV1, 3 and 6 were 755.2, 255.0 and 55.9, respectively, overall. Our findings indicate that HPeV1 is the most prevalent HPeV circulating in Yamagata, followed by HPeV3 and HPeV6.     

Diet,intestinal morphology,and nitrogen assimilation efficiency in the damselfish,Stegastes lividus,in Guam

Synopsis Analysis of stomach contents of Stegastes lividus revealed a shift from omnivory in juveniles to herbivory in adults. Red algae, primarily Polysiphonia spp., Gelidiopsis intricata and Ceramium spp., formed the bulk of the diet in all size classes. Foraminifera and small crustaceans were of particular importance in the diet of juveniles. Net nitrogen assimilation efficiency of field-fed S. lividus was approximately 61%, and did not vary with fish size. The net assimilation efficiencies of fish fed on Enteromorpha in the laboratory ranged from size-class means of 36–79% for nitrogen and from 29–72% for total organic material, and increased from juveniles to adults. Apparently, juveniles compensate for a lower efficiency in assimilating plant food by including a higher percentage of animal material in their natural diets. The ratios of intestine length to standard length (IL/SL) and to intestine diameter (IL/ID) increased rapidly in juveniles and leveled off in adults. The retention time for ingested food items may only be about one-half as long in juveniles as in adults. The combination of observed IL/ID ratios and estimated retention times proved most valuable in the interpretation of ontogenetic changes in feeding habits and assimilation efficiency.     

Magnesium,calcium, copper,and zinc in meals

Meals of 12 diets were prepared from conventional foods with precautions against contamination by metallic elements because of epidemiologic associations between ischemic heart disease and the metabolism of magnesium, calcium, copper, and zinc. Magnesium, calcium, copper, and zinc were measured by atomic absorption spectrometry with satisfactory accuracy and precision. The mean daily amount of copper in the diets was less than the apparent adult requirement. Mean amounts of magnesium and zinc were close to apparent requirements; however, adults consuming amounts less than one standard deviation below these means may be depleting body stores and be at risk of pathology. Magnesium and copper were highly correlated (r=0.849,P=0.0001) in meals. This and other significant correlations probably will prevent the relationships of these elements to ischemic heart disease from being elucidated by epidemiology. Metabolic experiments will be necessary to differentiate among several hypotheses.