NaCl渐进胁迫对啤酒大麦幼苗生长、离子分配和光合特性的影响

砂培条件下,对啤酒大麦幼苗在等量NaCl 梯度(每周以17.1 mmol/L NaCl递增)渐进胁迫下生长和生理的响应进行研究。结果表明,随着盐浓度的递增,啤酒大麦地上生物量、株高显著低于对照组,而根系生物量和根冠比高于对照组,低盐分、短时间盐胁迫能刺激根系生长。盐分胁迫至高浓度(≥85.5 mmol/L NaCl)时,随着胁迫时间的持续,大麦幼苗生长受到抑制,地上含水量明显下降;短时间内适应低浓度盐胁迫后,一定程度上提高了啤酒大麦的净光合速率(P_n),而高浓度盐分能显著抑制大麦的净光合速率,气孔导度(G_s),胞间CO₂浓度(C_i)和蒸腾作用(T_r);高浓度、长时间盐分渐进胁迫下,影响大麦光合特性的主要是非气孔因素。大麦地上部Na⁺和Cl^-含量随介质中NaCl浓度的递增和胁迫时间的延续呈逐渐上升趋势,而根系中Na⁺含量呈下降趋势,Cl^-含量则呈逐渐上升的趋势。处理组大麦地上部K⁺/Na⁺明显低于对照,且随着盐浓度的递增而减小,说明在盐分胁迫过程中,地上部分优先积累 Na⁺。选择性吸收和运输K⁺是啤酒大麦适应渐进盐胁迫的生理生态机制。     

连作条件下间作模式对当归生长特性和产量的影响

为缓解当归连作障碍问题,在甘肃省岷县连作2年当归田,设置当归与油菜、蚕豆、大蒜、小麦和燕麦5种植物间作种植试验,以当归单作为对照,测定不同时期当归生长发育状况及产量,探讨利用作物间作缓解当归连作障碍的可行性。结果表明,在各生育时期,当归/大蒜的当归株高最高。在当归苗期和根膨大期,当归/大蒜的当归地上部干物质重比单作当归分别高31.51%和21.28%;在当归苗期、根膨大期和收获期,当归/大蒜的当归地下部干物质重比单作当归分别高25.00%,36.65%和54.75%。在苗期、根膨大期和收获期,当归/大蒜的当归根茎粗分别比单作当归提高12.26%,4.80%和24.38%。当归/燕麦对各生育期当归地上和地下部干物质具有明显抑制作用,并且其抑制作用最强。油菜、蚕豆、大蒜、小麦、燕麦与当归间作的麻口病发病率分别比当归单作降低46.05%,43.31%,25.24%,2.34%和12.82%。当归/大蒜的一等归出成率和二等归出成率比当归单作分别提高118.62%和27.82%。当归/大蒜的当归产量(1 946.53 kg/hm²)比当归/油菜、当归/蚕豆、当归/小麦、当归/燕麦和当归单作分别提高67.29%,143.31%,207.57%,683.06%和34.71%。不同间作模式对当归出苗率和抽薹率产生影响,但影响不显著。当归/大蒜能提高当归产量和优等归出成率,并能适当减少当归麻口病,因此当归/大蒜对减缓当归连作障碍有一定作用。     

祁连山高山草地毒杂草侵入对蝗虫相对多度的影响

为研究祁连山高山草地毒杂草侵入对蝗虫群落组成、相对多度以及群落数量的影响,2008-2009年6-9月在野外调查基础上,对毒杂草(狼毒、甘肃臭草和披针叶黄华)侵入型草地和天然草地植被群落、土壤理化特性以及蝗虫多样性及群落数量进行调查分析。结果表明,毒杂草侵入显著降低草地物种丰富度、Shannon-Wiener指数和均匀度指数(P<0.05),植被群落高度和生物量明显增加(P<0.05);甘肃臭草侵入型草地土壤有机质和含水量最高,狼毒侵入型草地土壤紧实度和天然草地全N含量显著大于其他样地(P<0.05);毒杂草侵入影响蝗虫群落组成、降低物种多样性、改变物种相对多度。但蝗虫群落数量因杂草种类呈现较大差异,蝗虫群落数量因甘肃臭草侵入而降低、随狼毒和披针叶黄华侵入而增加。高山草地毒杂草侵入通过改变植被结构和营养价值、影响蝗虫土壤理化特性和栖息生境,而草地蝗虫群落组成、数量和多样性对此做出积极响应。该研究不仅为研究高山草地毒杂草型退化对昆虫以及无脊椎动物的影响提供参考,而且也为高山草地生物多样性维持和保育提供有益依据。     

Estimation of water balance in the source region of the Yellow River based on GRACE satellite data

Water storage has important significance for understanding water cycles of global and local domains and for monitoring climate and environmental changes.As a key variable in hydrology,water storage change represents the sum of precipitation,evaporation,surface runoff,soil water and groundwater exchanges.Water storage change data during the period of 2003-2008 for the source region of the Yellow River were collected from Gravity Recovery and Climate Experiment(GRACE)satellite data.The monthly actual evaporation was estimated according to the water balance equation.The simulated actual evaporation was significantly consistent and correlative with not only the observed pan(20 cm)data,but also the simulated results of the version 2 of Simple Biosphere model.The average annual evaporation of the Tangnaihai Basin was 506.4 mm,where evaporation in spring,summer,autumn and winter was 130.9 mm,275.2 mm,74.3 mm and 26.1 mm,and accounted for 25.8%,54.3%,14.7% and 5.2% of the average annual evaporation,respectively.The precipitation increased slightly and the actual evaporation showed an obvious decrease.The water storage change of the source region of the Yellow River displayed an increase of 0.51 mm per month from 2003 to 2008,which indicated that the storage capacity has significantly increased,probably caused by the degradation of permafrost and the increase of the thickness of active layers.The decline of actual evaporation and the increase of water storage capacity resulted in the increase of river runoff.     

Soil water and salt distribution under furrow irrigation of saline water with plastic mulch on ridge

Furrow irrigation when combined with plastic mulch on ridge is one of the current uppermost water-saving irrigation technologies for arid regions.The present paper studies the dynamics of soil water-salt transportation and its spatial distribution characteristics under irrigation with saline water in a maize field experiment.The mathematical relationships for soil salinity,irrigation amount and water salinity are also established to evaluate the contribution of the irrigation amount and the salinity of saline water to soil salt accumulation.The result showed that irrigation with water of high salinity could effectively increase soil water content,but the increment is limited comparing with the influence from irrigation amount.The soil water content in furrows was higher than that in ridges at the same soil layers,with increments of 12.87% and 13.70% for MMF9(the treatment with the highest water salinity and the largest amount of irrigation water) and MMF1(the treatment with the lowest water salinity and the least amount of irrigation water) on 27 June,respectively.The increment for MMF9 was gradually reduced while that for MMF1 increased along with growth stages,the values for 17 August being 2.40% and 19.92%,respectively.Soil water content in the ridge for MMF9 reduced gradually from the surface layer to deeper layers while the surface soil water content for MMF1 was smaller than the contents below 20 cm at the early growing stage.Soil salinities for the treatments with the same amount of irrigation water but different water salinity increased with the water salinity.When water salinity was 6.04 dS/m,the less water resulted in more salt accumulation in topsoil and less in deep layers.When water salinity was 2.89 dS/m,however,the less water resulted in less salt accumulation in topsoil and salinity remained basically stable in deep layers.The salt accumulation in the ridge surface was much smaller than that in the furrow bottom under this technology,which was quite different from traditional furrow irrigation.The soil salinities for MMF7,MMF8 and MMF9 in the ridge surface were 0.191,0.355 and 0.427 dS/m,respectively,whereas those in the furrow bottom were 0.316,0.521 and 0.631 dS/m,respectively.The result of correlation analysis indicated that compared with irrigation amount,the irrigation water salinity was still the main factor influencing soil salinity in furrow irrigation with plastic mulch on ridge.     

牛源性无乳链球菌血清型分布及抗生素耐药性研究

本研究旨在查明牛源性无乳链球菌血清型分布及对常见抗生素的耐药情况,指导临床合理用药。对从中国部分地区奶牛场采集的临床型乳房炎病牛乳中分离鉴定出78株无乳链球菌地方菌株,制备沉淀反应抗原及6株标准血清型无乳链球菌单因子血清抗体,采用环状沉淀试验,对78株无乳链球菌地方菌株进行了血清学分型鉴定;同时采用K-B纸片法测定了这些菌株对抗生素的耐药情况。结果表明,引起奶牛乳房炎的无乳链球菌血清型主要为X型(60.26%),其次为Ⅲ型(10.26%)、R型(7.69%)、Ⅱ型(7.69%)和Ⅰb型(5.13%),Ⅰa型尚未发现。无乳链球菌对目前临床上使用的大部分抗生素,如头孢唑啉、头孢噻肟、丁胺卡那霉素、卡那霉素、庆大霉素、四环素、强力霉素、氟苯尼考、多黏菌素B、环丙沙星、氟哌酸和头孢他啶/棒酸均较敏感;但对氨苄青霉素、链霉素、恩诺沙星、阿莫西林/棒酸和复方新诺明,有一定的耐药性,其耐药率达50%~100%。本研究对进一步研制有效的药物及疫苗,指导临床合理用药具有重要的意义。     

The impact of land use change on soil organic carbon and labile organic carbon stocks in the Longzhong region of Loess Plateau

Land use change (LUC) is widely recognized as one of the most important driving forces of global carbon cycles. The soil organic carbon (SOC) and labile organic carbon (LOC) stores were investigated at arable land (AL), artificial grassland (AG), artificial woodland (AW), abandoned arable land (AAL) and desert steppe (DS) in the Longzhong region of the Loess Plateau in Northwest China. The results showed that conversions from DS to AL, AL to AG and AL to AAL led to an increase in SOC content, while the conversion from DS to AW led to a decline. The differences in SOC content were significant between DS and AW at the 20-40 cm depth and between AL and AG at the 0-10 cm depth. The SOC stock in DS at the 0-100 cm depth was 39.4 t/hm 2 , increased by 28.48% after cultivation and decreased by 19.12% after conversion to AW. The SOC stocks increased by 2.11% from AL to AG and 5.10% from AL to AAL. The LOC stocks changed by a larger magnitude than the SOC stocks, which suggests that it is a more sensitive index of carbon dynamics under a short-term LUC. The LOC stocks increased at 0-20 cm and 0-100 cm depths from DS to AW, which is opposite to that observed for SOC. The proportion of LOC to SOC ranged from 0.14 to 0.20 at the 0-20 cm depth for all the five land use types, indicating low SOC dynamics. The allocation proportion of LOC increased for four types of LUC conversion, and the change in magnitude was largest for DS to AW (40.91%). The afforestation, abandonment and forage planting on arable land led to sequestration of SOC; the carbon was lost initially after afforestation. However, the carbon sink effect after abandonment may not be sustainable in the study area.     

西北碱性土壤施肥对东方百合“索邦”光合及种球产量的影响

西北冷凉气候适合百合的生长,但其偏碱性的土壤是影响种球产量和质量的重要因素。本研究以东方百合“索邦”为试材,采用裂区设计试验,研究了冷凉气候下碱性土壤中施入不同量草炭和N、P、K、Ca肥对“索邦”百合种球产量、光合特性、光合色素含量、不同生长指标和不同器官干物质积累量的影响。结果显示,施用草炭对百合生物量、种球产量、个体种球鲜重没有显著影响,但会显著降低种球干鲜比;不同施肥处理下,单纯不施N、Ca肥的处理种球产量、鲜重和干重、光合效率、叶面积指数、生物量等指标高于施用了N、Ca肥的处理,单纯不施P、K肥处理下各指标总体较低。研究表明,百合品种索邦在试验地区(宁夏隆德县)生长状况良好,该地的气候条件较为适宜百合的生长;施用草炭对百合产量影响不显著,不能对碱性土壤起到有效地改良作用;碱性土壤下N、Ca肥的过量施用会影响微量元素的吸收,造成百合的生理性缺素,从而降低了百合产量和品质,因而碱性土壤下种植百合需要合理施肥,以保障百合的品质和产量。     

灌溉与施氮对留茬免耕春小麦耗水规律、产量和水分利用效率的影响

在甘肃省石羊河流域绿洲灌区,研究了不同灌溉量(常规灌溉327 mm,节水20%灌溉261 mm和节水40%灌溉196 mm)和施氮量 (0,140,221和300 kg N/hm²) 对留茬免耕绿洲农田0～120 cm 土壤水分动态、小麦耗水规律、籽粒产量和水分利用效率的影响。结果表明,灌溉影响灌水前24 h深层(80～120 cm)土壤含水量和灌水后24 h浅层(0～80 cm)土壤含水量,施氮处理对深层(0～120 cm)土壤含水量影响不显著。就全生育期而言,土壤贮水量和植株耗水强度随灌水量增加而增加,不施氮处理的土壤贮水量高于施氮处理,施氮对植株耗水强度影响不显著。当施氮量达到221 kg N/hm²时,春小麦水分利用效率(14.51 kg/hm²·mm)和春小麦籽粒产量(6 365 kg/hm²)达到最大值。春小麦籽粒产量随灌溉量增加而增加,常规灌溉的平均籽粒产量比节水20%灌溉和节水40%灌溉分别增加8.2%和32.2%。不同灌溉之间的水分利用效率相差不显著。     

白刺对干旱胁迫的生理生化反应

研究白刺幼苗抗旱特性的生理学机制,期望为干旱农业生产提供理论依据。实验采用盆栽,用控制浇水的方法对不同强度的干旱胁迫梯度上对白刺幼苗叶片相对含水量、丙二醛、脯氨酸、可溶性蛋白质、叶绿素含量、超氧离子自由基产生速率和抗氧化酶活性的变化特点进行了研究。试验结果表明：在干旱胁迫下,白刺叶片相对含水量降低、脯氨酸含量呈增加趋势;可溶性蛋白质、叶绿素含量在轻度和中度干旱胁迫时上升,在重度干旱胁迫时显著下降;随着干旱胁迫的加剧,膜透性上升,丙二醛含量和超氧离子自由基产生速率增加。抗氧化系统酶活性测定结果表明,SOD、POD、CAT 3个酶能配合协同作用,降低膜脂过氧化程度,减少水分胁迫造成的伤害。