土壤水分条件对枫杨幼苗光合生理的影响

设定对照(CK,即常规生长)、轻度干旱(T1)、湿土壤(T2)和水淹(T3)4个处理组,研究枫杨(Pterocaryastenoptera C.DC.)幼苗在不同土壤水分条件下的光合生理反应.研完显示不同土壤水分对枫杨幼苗叶片净光合速率、气孔导度、水分利用效率和光合色素含量等参数有不同影响.胁迫初期(25 d),植株的各项生理指标变化较小,T3净光舍速率Pn比对照下降了25.4%.50天后,Pn下降比例大小为T1(60.3%)>T3(47.8%)>T2(28.1%),随后趋于稳定;蒸腾速率Tr和气孔导度Gs的变化趋势基本一致,T2和T3与对照无显著差异,T1则显著低于对照;T1有较高的水分利用效率(WUE),以对抗干旱缺水的逆境.T3光合色素含量持续处于最低状态,T1则与对照总体没有显著差异.各组叶绿素与类胡萝卜素含量之比界于4.475～6.920之间波动.而叶绿素a与叶绿素b的含量之比界于2.518～3.216之间波动.本实验证实枫杨幼苗兼具一定的耐水淹和耐旱的能力,也表明枫杨树种可用于三峡库区消落带的植被恢复构建.

Abstract：

In an experiment reported in this paper, Pterocarya stenoptera C.DC.seedlings were subjected to 4 water condition treatments, i.e.control (CK, normal water condition), T1 (light drought stress), T2 (wet soil) and T3 (soil submersion), and their photosynthetic responses were investigated.The results showed that different soil water conditions influenced, to different extents, the net photosynthetic rate (Pn), stomatal conductance (Gs), water use efficiency (WUE) and photosynthetic pigment content of the P.stenoptera seedlings.In the early period of stress (25d) of T3, these indices changed little and only Pn decreased by 25.4% compared with the control.Pn decreased by 60.3%, 47.8% and 28.1% in T1, T3 and T2, respectively, after 50 days and appeared relatively stable thereafter.Tr and Gs showed a similar change trend in various treatments.T2 and T3 had no significant difference from the control in the two in-dices, while T1 was significantly lower than it.T1 kept high water use efficiency against the drought stress.T3 had the lowest content of photosynthetic pigment, while T1 did not differ from CK in the con-tent of chlorophylls and carotenoids as a whole.The ratio of chlorophylls to carotenoids ranged from 4.475 to 6.920 and the ratio of chlorophylls a to b varied from 2.518 to 3.216 in these treatments.The above re-sults proved that P.stenoptera, seedlings are fairly tolerant to both waterlogging and drought stress and that P.stenoptera, can be a candidate species in the construction of the protection vegetation system of the Three Gorges Reservoir Region.     

A Study on Photosynthetic Physiological Characteristics of Six Rare and Endangered Species

The parameters of gas exchange and chlorophyll fluorescence in leaves of six rare and endangered species Neolitsea sericea, Cinnamomum japonicum var.chenii, Sinojackia microcarpa, Discocleidion glabrum var. trichocarpum, Parrotia subaequalis, Cercidiphyllum japonicum were measured in fields. The results showed that there were significant differences in photosynthetic capacity, intrinsic water use efficiency(WUEi), the efficiency of primary conversion of light energy of PSⅡ and its potential activity, the quantum yield of PSⅡ electron transport, and the potential capacity of heat dissipation among the six species. However, there was no significant difference in WUE. The highest values of net photosynthetic rate(Pn), transpiration rate(Tr) and stomatal conductance(gs) occurred in D. glabrum var. trichocarpum and the lowest in S. microcarpa. On the contrary, D. glabrum var. trichocarpum had the lowest WUE, intrinsic water use efficiency(WUEi) and S. microcarpa had the highest. The results indicated that D. glabrum var. trichocarpum had higher photosynthetic capacity and poorer WUE, while S. microcarpa had lower photosynthetic capacity and greater WUE. Furthermore, the mean values of maximal fluorescence(Fm), potential efficiency of primary conversion of light energy of PS Ⅱ(Fv/Fm),ΦPSⅡ, actual efficiency of primary conversion of light energy of PSⅡ(F′v/F′m)and non-photochemical quenching coefficient(NPQ) were the highest in S. microcarpa, indicating that its PS Ⅱ had higher capacity of heat dissipation and could prevent photosynthetic apparatus from damage by excessive light energy. Correlation analysis showed that there were significant correlations among photosynthetic physiological parameters. However, the initial fluorescence(Fo) was not significantly correlated with any other parameters. This study also revealed the extremely significant positive correlations between Pn and Tr, gs, apparent quantum yield(AQY), between Tr and gs, between light saturation point(LSP) and AQY, between Fv/Fm and Fm, between ΦPSⅡ and photochemical quenching coefficient(qp), between Tr,gs and LSP, AQY. However, WUEiwas significantly negatively correlated with Tr,gs, Pn, LSP and AQY.     

Photosynthetic Characteristics and Ultrastructure of Chloroplast of Cucumber Under Low Light Density in Solar-Greenhouse

The photosynthetic characteristics and ultrastructure of chloroplast of cucumber in solargreenhouse were studied. The result showed that the photosynthetic rate (Pn), photosynthetic ability (A350), carboxylation efficiency, light saturation point and light compensation point all declined remarkablyunder low light density, indicating that the photosynthetic characteristics of cucumber were closely related to light environment. Under low light density, the minimal fluorescence (Fo), alterable fluorescence (Fv), photochemical efficiency of PSⅡ(Fv/Fm), steady fluorescence in hight (Fs), maximal fluorescence (Fm‘) and actual efficiency of PSⅡ (ΦpsⅡ)etc increased, indicating that the photochemical activity and efficiency for solar energy transformation enhanced, thus the light proportion used to electron transport also increased. The chlorophyll a, b, a/band carotenoid of shading leaves decreased. However, the depressed extent of Chl a and Chl a/b were obviously larger than that of Chl b. The number of chloroplast and starch grain in cucumber leaves descended, but that of grana and lamella increased as a shaded result. The size of chloroplast and starch grain of shading leaves minished.     

Exogenous GSH protects tomatoes against salt stress by modulating photosystem Ⅱ efficiency,absorbed light allocation and H_2O_2-scavenging system in chloroplasts

The effects of exogenous GSH(reduced glutathione)on photosynthetic characteristics,photosystem Ⅱ efficiency,absorbed light energy allocation and the H_2O_2-scavenging system in chloroplasts of salt-stressed tomato(Solanum lycopersicum L.)seedlings were studied using hydroponic experiments in a greenhouse.Application of exogenous GSH ameliorated saline-induced growth inhibition,the disturbed balance of Na~+ and Cl~- ions and Na~+/K~+ ratios,and the reduction of the net photosynthetic rate(P_n).GSH also increased the maximal photochemical efficiency of PSⅡ(F_v/F_m),the electron transport rate(ETR),the photochemical quenching coefficient(q_P),and the non-photochemical quenching coefficient(NPQ).In addition,GSH application increased the photochemical quantum yield(Y(Ⅱ))and relative deviation from full balance between the photosystems(β/α–1)and decreased the PSⅡ excitation pressure(1–q_P)and quantum yield of non-regulated energy dissipation(Y(NO))in leaves of salt-stressed tomatoes without BSO(L-buthionine-sulfoximine,an inhibitor of key GSH synthesis enzymeγ-glutamylcysteine synthetase)or with BSO.Further,the addition of GSH depressed the accumulation of H_2O_2 and malondialdehyde(MDA),induced the redistribution of absorbed light energy in PSⅡ reaction centers,and improved the endogenous GSH content,GSH/GSSH ratio and activities of H_2O_2-scavenging enzymes(including superoxidase dismutase(SOD),catalase(CAT),peroxidase(POD)and key enzymes in the AsA-GSH cycle and Grx system)in the chloroplasts of salt-stressed plants with or without BSO.Therefore,GSH application alleviates inhibition of salt-induced growth and photosynthesis mainly by overcoming stomatal limitations,improving the PSⅡ efficiency,and balancing the uneven distribution of light energy to reduce the risk of ROS generation and to mediate chloroplast redox homeostasis and the antioxidant defense system to protect the chloroplasts from oxidative damage.Thus,GSH may be used as a potential tool for alleviating salt stress in tomato plants.     

Photosynthetic Characteristics of a Super High Yield Cultivar of Winter Wheat During Late Growth Period

The mechanism of high yield of winter wheat in the field at late growth period was investigated by measuring the photosynthetic characteristics of photosystem Ⅱ （PSⅡ） and xanthophylls cycle, which could provide physiological reference for breeding. Weimai 8 （W8）, a super high yield cultivar, and Lumai 14 （L14）, a control cultivar were object. The photosynthetic rate （Pn）, parameters of chlorophyll fluorescence and chlorophyll content were measured. The Pn, maximum photochemical efficiency of PSII （Fv/Fm）, quantum yield of PSII electron transport （ΦPSⅡ）, efficiency of excitation energy capture by open PSII reaction centers （Fv＇/Fm＇）, and photochemical quenching coefficient （qP） were higher in Weimai 8 compared to that in Lumai 14, a commercial high yield cultivar. Furthermore, Weirnai 8 showed a lower non- photochemical quenching coefficient and a lower de-epoxidized ratio of the xanthophyll cycle pigments than of Lumai 14 at late growth period. At mature stage, chlorophyll content of different leaves decreased both in Weimai 8 and Lumai 14. Chlorophyll content in flag, second and third leaf from the top of plant decreased more in Lumai 14 than in Weimai 8. These results suggested that Weimai 8 had more antenna pigments to absorb light energy, and had higher photosynthetic capability and photochemical efficiency of PSⅡ. The yield of Weimai 8 was also higher than that of Lumai 14.     

Photosynthetic Characteristics and Antioxidative Metabolism of Flag Leaves in Responses to Nitrogen Application During Grain Filling of Field-Grown Wheat

A two-factorial experiment was conducted with two wheat cultivars, SN1391 （large spike and large grain） and GC8901 （multiple spike and medium grain）, and two nitrogen （N） application rates （12 and 24 g N m^-2）, to investigate the responses of photosynthetic characteristics and antioxidative metabolism to nitrogen rates in flag leaves of field-grown wheat during grain filling. The results showed that the content of N and chlorophyll （Chl） in wheat flag leaves decreased after anthesis and the net photosynthetic rate （Pn）, effective quantum yield of PS Ⅱ （Фps n）, efficiency of excitation capture by open PS Ⅱ reaction centers （Fv′/Fm′）, and photochemical quenching coefficient （qp） began to decrease at 14 days after anthesis. However, the maximal efficiency of PS Ⅱ photochemistry （Fv/Fm） decreased slightly until the late period of senescence and the nonphotochemical quenching coefficient （NPQ） increased during flag leaves＇ senescence, As a result, a conflict came into being between absorption and utilization to light energy in flag leaves during senescence, which might accelerate the senescence of flag leaves. Compared with GC8901, the lower plant population of SN1391 during grain filling was helpful to maintain the higher content of photosynthetic pigment, activity of PS II, and Pn in flag leaves during senescence, The delayed decrease in antioxidative enzyme activity and the lower degree of membrane lipid peroxidation in the senescing leaves of SN1391 were beneficial to protect the photosynthetic apparatus, which lead to the prolonged duration of CO2 assimilation. With the increase of N application, the Chl content of SN1391 flag leaves and the efficiency of excitation captured by open PS Ⅱ centers increased. At the same time, the thermal dissipation in SN1391 flag leaves at high N （HN） treatment decreased and Фps Ⅱ improved greatly, which were favorable to the increase of Pn. The SOD, POD, CAT and APX activities in the flag leaves of SN1391 increased     

Photosynthetic performance of switchgrass and its relation to field productivity:A three-year experimental appraisal in semiarid Loess Plateau

To reveal photosynthetic characteristics and biomass yield is important for evaluating introduced species adaptation to local environments. A field experiment was conducted over three consecutive years(2011–2013) to evaluate photosynthetic characteristics, soil water content, aboveground biomass accumulation, and water use efficiency(WUE) in switchgrass(Panicum virgatum L.) populations exposed to three row spacing(20, 40 and 60 cm) treatments in two growth months(June and August) on the semiarid Loess Plateau of China. Results indicated that net photosynthetic rate(P_n), transpiration rate(T_r), instantaneous water use efficiency(WUEi) and plant height of switchgrass showed an increased trend, but aboveground biomass production and WUE showed an decreased trend with enlarged row spacings over the three years. The maximum daily mean Pn values(17.9, 18.4 and 19.7 μmol CO_2 m~(-2) s~(-1)) were observed in 2011, and the highest aboveground biomass production(67 771.8, 6 976.8 and 6 609.2 kg ha~(-1)) were recorded in 2012 for 20, 40 and 60 cm, respectively. A close correlation between tiller numbers and aboveground biomass production(r=0.907) was observed. Pn was positively and significantly correlated with biomass per tiller, but it showed a negative correlation with aboveground biomass production. Our results confirm that wide row spacing is beneficial for single plant development, while narrow row spacing favors biomass production and water use of switchgrass in the region. It also implies that single leaf growth and performance could explain the switchgrass community density differences, while fails to account for the aboveground biomass production.     

Effects of Root Pruning on Non-Hydraulic Root-Sourced Signal, Drought Tolerance and Water Use Efficiency of Winter Wheat

Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals (nHRS), drought tolerance and water use efficiency of winter wheat (Triticum aestivum). The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots (1.06 and 0.94 mmol g-1 s-1, respectively). The soil water content (SWC) at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants (61.1-44.6% field water capacity) than for intact root plants (57.9-46.1% field water capacity). At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield (F PS II ), the maximum photochemical efficiency of PS II (F v /F m ), coefficient of photochemical quenching (qP), and coefficient of non-photochemical quenching (NPQ), in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency (WUE) than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This suggests a possible direction of drought- resistance breeding and potential agricultural measure to improve WUE of winter wheat under semiarid conditions.     

A Comparative Study on Photosynthetic Characteristics of Dryopteris fragrans and Associated Plants in Wudalianchi City,Heilongjiang Province,China

While comparing photosynthetic characteristics of Dryopteris fragrans(L.)Schott to those of several commonly associated plants in its native community,coordination between D.fragrans and its environment was observed.The diurnal net photosynthetic rate(Pn)varied dramatically for all the plants studied.D.fragrans,Woodsia ilvensis and Urtica angustifolia all exhibited unimodal type Pn variation,with low Pn,weak photosynthetic capacity,and dramatic maximal photosynthesis(Pmax)changes.When compared to values for its associated plants,D.fragrans values were of intermediate level,indicating difficulty in adapting to its environment. Moreover,the nitrate reductase activity of D.fragrans was higher than that of only one species,Artemisia gmelinii.With increasing leaf maturity and chlorophyll content,D.fragrans exhibited declining LCP(light compensation point)and a relatively low LSP(light saturation point).Because of its overall relatively weak photosynthetic capacity,D.fragrans exhibited narrow ecological amplitude with respect to light adaptation.     

Increased sink capacity enhances C and N assimilation under drought and elevated CO_2 conditions in maize

The maintenance of rapid growth under conditions of CO_2 enrichment is directly related to the capacity of new leaves to use or store the additional assimilated carbon(C) and nitrogen(N). Under drought conditions, however, less is known about C and N transport in C_4 plants and the contributions of these processes to new foliar growth. We measured the patterns of C and N accumulation in maize(Zea mays L.) seedlings using 13 C and 15 N as tracers in CO_2 climate chambers(380 or 750 μmol mol~(–1)) under a mild drought stress induced with 10% PEG-6000. The drought stress under ambient conditions decreased the biomass production of the maize plants; however, this effect was reduced under elevated CO_2. Compared with the water-stressed maize plants under atmospheric CO_2, the treatment that combined elevated CO_2 with water stress increased the accumulation of biomass, partitioned more C and N to new leaves as well as enhanced the carbon resource in ageing leaves and the carbon pool in new leaves. However, the C counterflow capability of the roots decreased. The elevated CO_2 increased the time needed for newly acquired N to be present in the roots and increased the proportion of new N in the leaves. The maize plants supported the development of new leaves at elevated CO_2 by altering the transport and remobilization of C and N. Under drought conditions, the increased activity of new leaves in relation to the storage of C and N sustained the enhanced growth of these plants under elevated CO_2.     

浅谈饲料中有效能的测定技术

饲料中有效能是供动物生长发育的基础.不同动物所用的有效能体系不同,目前大多数动物采用消化能、代谢能体系,但随着研究的发展与深入,发现最能反映饲料有效能的是净能体系.无论哪种体系,采用合理的测定技术准确测定饲料中的有效能值显得尤其重要,通过对饲料有效能值的准确测定可以实现动物所需能量的精确供给,减少养殖成本,使经济效益最大化.文章综述了几种有效能评价体系的测定技术.     

《河北农业大学学报》创刊年代考

清光绪二十八年(1902)河北农业大学前身—直隶农务学堂诞生,经几易其名,于1958年更名为河北农业大学至今。清光绪三十一年(1905)直隶高等农业学堂时期创办了《北直农话报》,清光绪三十四年(1908)更名为《直隶农务官报》,中华民国七年(1918)改出《农学月刊》,中华民国十七年(1928)易名为《河大农刊》,中华民国二十三年(1934)更名为《河北通俗农刊》,中华民国二十四年(1935)易名为《河北农林学刊》,1948年更名为《河北农学院研究专刊》,1959年更名为《河北农业大学学报》至今。《河北农业大学学报》前身诸刊都与现时的《河北农业大学学报》有着一脉相承的历史渊源,各刊之间联系紧密,连续性、继承性强。因此,《河北农业大学学报》的创刊时间应追溯至1905年创办的《北直农话报》。     

高校贫困生认定工作面面观

国家贫困生资助政策实施以来,对贫困生帮助很大,同时在实际运行中还存在着一些问题。本文提出贫困生认定工作仍需要进一步采取各种相关配套措施,以推动和保障贫困生资助工作更好地开展。     

生态旅游潜在客源市场特征的调查研究--以湖南永州金洞森林旅游开发为例

为探明客源市场生态旅游消费的潜在特征,采用问卷调查的形式,就长沙市居民对湖南金洞生态旅游开发的意向等问题进行抽样调查．结果显示,生态旅游符合人们“回归自然”的旅游新时尚,有着极大的开发空间,指出生态旅游的开发要注重环境保护和可持续发展．开发的产品要以休闲度假类的大众产品为主,开发生态旅游都市客源市场还要多种渠道并用,尤其是要注重媒体的宣传．     

动物疫苗接种异常反应的处理

动物疫病是畜牧业生产的大敌,要发展畜牧业生产就要防治动物疫病。但在疫苗接种时,经常出现正常反应外的其他不利于机体的反应,如废食、皮疹、休克、死亡等,正确处理或避开这些问题,对推行动物疫病的计划免疫,实施强制免疫,保护人畜安全具有十分重要的现实意义和作用。     

探究板栗的科学贮藏方法

板栗属壳斗科栗属(Castanea mollisima Blume),其种子属于顽拗型种子,不耐贮藏。基于近年来板栗贮藏保鲜技术研究成果,从合理采收、贮前处理、贮藏方法等方面进行论述。     

厚胶合板弹性模量预测模型

为了预测厚胶合板弹性模量,通过简化层合板理论,该文建立了胶合板弹性模量预测模型,并以单板条、经过涂胶热压处理的单板条和相同工艺条件下的单板层积材的弹性模量,采用4种不同铺层方式的19层桉树胶合板对模型进行了验证。结果表明:3种预测值与实测值的趋势一致,相关系数R2顺纹在0.86以上,横纹在0.88以上,但是精度不同。采用单板条弹性模量预测的胶合板弹性模量比实测值偏低;采用经过涂胶热压处理后的单板条弹性模量预测的胶合板弹性模量比实测值偏高;采用相同工艺条件下的单板层积材弹性模量预测的胶合板弹性模量与实测值偏差较小,顺纹平均误差为4.64%,横纹平均误差10.94%。因此,采用相同工艺条件下的单板层积材的弹性模量来预测胶合板的弹性模量是可行的。      

增强我国水果业出口竞争力的思考

分析了入世4年来,我国水果出口在量上实现了突破,但并没有实现质变的主要原因,指出我国水果业存在的问题。论述了引进外资对发展我国水果业的意义,并提出了具体可行的对策与建议。     

黑豆不同部分馏油的体外抗氧化性比较

[目的]通过体外抗氧化体系比较黑豆不同部分馏油抗氧化性活性。[方法]通过正交试验优化索氏提取黑豆馏油的最佳工艺,提取黑豆不同部分馏油;研究黑豆不同部分馏油对羟基自由基(·OH)、DPPH自由基(DPPH·)的清除能力。[结果]在样品浓度为1.0 mg/mL时,黑豆不同部分馏油对·OH的清除率分别为全豆馏油83.9%、豆黄(黑豆去皮部分)馏油64.8%、豆皮馏油17.3%,对DPPH·的清除率分别为全豆馏油41.3%、豆黄馏油33.2%、豆皮馏油77.9%。[结论]黑豆不同部分馏油均具有较好的抗氧化性,是良好的天然抗氧化剂。黑豆不同部分馏油对·OH的清除能力从大到小依次为全豆馏油、豆黄馏油、豆皮馏油,对DPPH·的清除能力从大到小依次为豆皮馏油、全豆馏油、豆黄馏油。     

水牛梭形住肉孢子虫包囊抗原的纯化技术

应用萄聚糖凝胶柱层析对水牛梭形住肉孢子虫包囊包溶性抗原进行了纯化。结果表明：纯化水牛梭形住肉孢子虫包囊抗原的最适条件为：选用萄聚糖凝胶Ｇ—１００柱层析系统；洗脱液为０３ＭＰＢＳ（ｐＨ７２），床体积为１０ｃｍ×１６５ｃｍ，上样体积为５００ＨＬ；流速为１２ｍＬ／ｈ。纯化抗原可使琼脂凝胶双扩散试验的阳性检出率提高３０％。