不同经营模式山核桃林地土壤pH值、养分与细菌多样性的差异

为探究土壤细菌多样性及其功能对山核桃(Carya cathayensis)经营模式的指导作用, 本文采用16S rRNA基因高通量测序技术检测并比较了生态经营和过度经营的山核桃林土壤中的细菌群落, 分析了山核桃干腐病发病期干腐病感病指数、土壤pH值、养分与细菌多样性的相关性。结果表明: (1)生态经营山核桃林的感病指数(3.3 ± 3.35)显著低于过度经营山核桃林(81.9 ± 1.27)。(2)生态经营山核桃林土壤pH (6.64 ± 0.06)显著高于过度经营山核桃林(5.80 ± 0.04)。(3)过度经营山核桃林土壤的速效磷、速效钾和速效氮含量分别为18.10 ± 0.58 mg/kg、698.63 ± 11.24 mg/kg和227.13 ± 3.81 mg/kg, 均分别显著高于三者在生态经营山核桃林土壤中的含量(14.94 ± 0.27 mg/kg、497.13 ± 6.19 mg/kg和195.28 ± 6.01 mg/kg)。(4)生态经营和过度经营山核桃林土壤分别有14和21个主要细菌属, 其中鞘氨醇单胞菌属(Sphingomonas)、Gaiella和溶杆菌属(Lysobacter)为生态经营山核桃林土壤的优势属, 其相对多度显著高于过度经营山核桃林; 而Bryobacter、Candidatus Solibacter和慢生根瘤菌属(Bradyrhizobium)为过度经营山核桃林土壤中的优势属, 其相对多度显著高于生态经营山核桃林。两种经营模式下山核桃林土壤的OTUs、Ace指数、Chao指数、Shannon指数和Simpson指数无显著差异。RDA分析与蒙特卡罗检验表明, pH值、速效磷和速效氮均对土壤细菌优势菌群群落结构有显著影响(P < 0.05)。     

天山雪莲SiSAD基因与拟南芥AtFAB2基因转化 烟草的抗寒性分析

通过转基因烟草(Nicotiana tabacum)验证天山雪莲(Saussurea involucrata) Δ9硬脂酰-ACP脱饱和酶基因SiSAD与拟南芥(Arabidopsis thaliana)中同源基因AtFAB2的抗寒性功能。利用农杆菌介导法将植物表达载体P_SiSAD:AtFAB2和P_SiSAD:SiSAD导入烟草, 然后将2种转基因和野生型烟草分别置于20°C、10°C、5°C、0°C及-2°C下处理2小时, 检测其相对电导率、丙二醛(MDA)含量、叶绿素荧光参数(F_v/F_m)及脂肪酸含量。将-2°C处理2小时后的植株置于25°C培养1周进行生长恢复实验。结果表明, 生长恢复实验中转SiSAD基因烟草的恢复效果显著优于转AtFAB2基因和野生型烟草。在0°C和-2°C处理2小时后, 转SiSAD、AtFAB2基因型和野生型烟草的相对电导率和丙二醛含量呈现显著递增趋势; 转SiSAD、AtFAB2基因型烟草的F_v/F_m显著高于野生型烟草, 其中, 转SiSAD基因烟草的F_v/F_m显著高于转AtFAB2基因烟草。转AtFAB2基因型和野生型烟草的油酸(C18:1)含量随着温度的降低逐渐升高后降低并在0°C时达到最高值; 而转SiSAD基因型烟草C18:1含量持续升高, 并在-2°C时达到最高值, 其含量分别是转AtFAB2基因型和野生型烟草的1.58倍和1.7倍。以上结果表明, 天山雪莲Δ9硬脂酰-ACP脱饱和酶基因SiSAD与拟南芥中同源基因AtFAB2均可以显著增强非低温驯化烟草的抗寒性, 但是SiSAD基因效果显著优于AtFAB2。     

中国毛竹林碳氮磷生态化学计量特征

碳(C)、氮(N)、磷(P)生态化学计量比是生态系统过程与功能的重要特征, 开展种群生态化学计量学研究可以细化植物种群化学计量学内容, 确定限制植物生长的元素类型, 同时为大尺度模型的发展提供数据基础。为阐明我国毛竹(Phyllostachys edulis)林C、N、P化学计量学特征, 通过对毛竹主要产区文献数据的搜集整理与分析, 探索我国毛竹林“植物-土壤-凋落物”系统C、N、P及C:N、C:P、N:P生态化学计量特征, 以及不同组分生态化学计量特征与经纬度之间的关系。结果表明: 1)我国毛竹林叶片C含量为478.30 mg·g^-1, N含量为22.20 mg·g^-1, P含量为1.90 mg·g^-1, C:N为26.80, C:P为299.60, N:P为14.40; 毛竹林0-20 cm土层C含量为21.53 mg·g^-1, N含量为1.66 mg·g^-1, P含量0.41 mg·g^-1, C:N为14.20, C:P为66.74, N:P为4.28; 毛竹凋落物C含量为438.49 mg·g^-1, N含量为13.39 mg·g^-1, P含量为0.86 mg·g^-1, C:N为22.53, C:P为665.67, N:P为22.55。2)毛竹林“植物-土壤-凋落物”系统中, C:N表现为: 叶片>凋落物>土壤, C:P和N:P均表现为: 凋落物>叶片>土壤, 叶片N、P再吸收率分别为39.68%和54.74%, 我国毛竹林生长发育总体上可能受到P限制或者N和P两种元素的双重限制。3)纬度梯度: 叶片N含量、N:P随纬度增加而增加, C:N随纬度增加而降低。经度梯度: 叶片N:P随经度增加而增加, P含量、C:N随经度增加而降低; 土壤C:N随经度增加而增加, N含量随经度增加而降低; 凋落物N含量随经度增加而降低。4)叶片N含量与年平均气温和年降水量均存在明显负相关关系, 但对温度的响应比降水更敏感, 叶片N含量与纬度呈正相关关系, 支持“温度-植物生理假说”, 反映了植物对自然环境的适应。     

三种植物对土壤磷吸收和富集能力的比较

筛选磷富集植物是磷矿废弃地土壤与植被修复的关键。该文以向日葵(Helianthus annuus)、苏丹草(Sorghum sudanense)、南瓜(Cucurbita moschata)为研究对象, 采用盆栽试验, 设置5个磷浓度(0、100、300、500和700 mg·kg^-1), 分别在3个不同生长时段(4周、7周、10周)内采样, 对这3种植物的磷吸收和富集能力进行了比较。结果表明: (1)在相同生长时间内, 向日葵、苏丹草、南瓜的地上部磷含量均随磷处理浓度的升高而增大, 最大值分别为9.67 g·kg^-1、4.86 g·kg^-1、6.32 g·kg^-1; 相同浓度下, 向日葵地上部磷含量随着生长时间的延长呈上升趋势, 苏丹草则呈下降趋势, 南瓜无显著变化; (2) 3种植物的地上部磷累积量均在磷处理浓度为700 mg·kg^-1时, 生长10周后达到最大值, 分别为217.83 mg·plant^-1、93.92 mg·plant^-1、135.82 mg·plant^-1; (3)各浓度处理下, 向日葵、苏丹草的地上部磷富集系数和转移系数均大于1.00, 南瓜的地上部磷富集系数和转移系数波动较大; 向日葵的富集系数和转移系数最大值分别达11.39和4.09。综合比较可知, 3种植物磷吸收和富集能力的大小顺序为: 向日葵>南瓜>苏丹草。向日葵各项富磷特征基本符合磷富集植物的筛选标准, 可作为磷矿废弃地土壤与植被修复的备选物种。     

广东省胡颓子属植物种质资源及果实利用评价

在标本查阅和野外调查的基础上,对广东省胡颓子属（Elaeagnus L．）植物资源现状进行了综合评价,并对产量高且可生产性强的部分种类的果实矿质元素及氨基酸等营养成分的含量进行了分析测定。结果表明,广东产胡颓子属植物11种1变种,其中一些种类的果实中含有丰富的矿质元素;角花胡颓子（E．gonyanthes Benth．）和密花胡颓子（E．cottferta Roxb．）果实的营养价值较高、果实较大、有明显酸味,可作为第3代果品加工的生产资源;生存环境的保护对广东省胡颓子属植物资源的保护极其重要。     

不同施氮水平对冬小麦生长期土壤呼吸的影响

在目前全球氮沉降不断增加的背景下, 研究农田土壤呼吸对氮沉降的响应有助于理解未来生态系统碳循环对全球变暖的潜在影响。为探讨不同施氮浓度对华东地区冬小麦(Triticum aestivum)生长期土壤呼吸的影响, 该实验设计了对照组(不施加氮肥)和3种浓度施氮处理组(低浓度施氮15 g·m^-2·a^-1, 中等浓度施氮30 g·m^-2·a^-1, 高浓度施氮45 g·m^-2·a^-1)。使用便携式土壤CO₂通量观测仪LI-8100测定不同施氮浓度处理下冬小麦生长期(2013年12月至2014年5月)的土壤呼吸速率, 并探讨土壤呼吸与土壤温度、湿度等环境因素的关系。结果表明: 低、中、高3种浓度施氮处理的土壤呼吸速率平均值分别为5.29、6.17和6.75 μmol·m^-2 ·s^-1, 与对照组(土壤呼吸速率平均值为4.90 μmol·m^-2·s^-1)相比, 分别增加了7.8%、23.6%和37.8%; 地上生物量分别增加39.9%、104.4%和200.2%, 并与冬小麦生长季的总土壤呼吸正相关。5 cm深度土壤的温度与土壤呼吸速率呈指数关系(p < 0.05), 土壤呼吸季节变化的65%-75%由土壤温度引起, 其温度敏感性为2.09-2.32。结果表明, 添加氮肥促进了植物的生长, 增加了生物量, 从而增加了冬小麦农田的土壤呼吸速率。     

三种分离自冬虫夏草真菌及培养条件

对采自青海玉树、青海果洛和云南迪庆的冬虫夏草鲜品进行虫生真菌的分离、纯化,获得3种生长形态不同的真菌QH 2019、GL 2019和YN 2019。通过形态学及分子鉴定,菌株QH 2019为蝙蝠蛾拟青霉Samsoniella hepiali,菌株GL 2019为粉棒束孢Isaria farinosa,菌株YN 2019为玫烟色棒束孢Isaria fumosorosea。对这3株菌的培养条件初步研究,结果表明：菌株QH 2019在1/4 SDAY培养基上菌丝日生长速率最快,为(1.94±0.55)mm/d,且菌丝致密、粗壮,含水率高达(91.90±1.22)%,虫草素和虫草酸均以PDA培养的含量最高,分别为(0.47±0.022)mg/g和(3.24±0.021)mg/g;菌株GL 2019在PDA培养基上菌丝日生长速率、菌丝含水率、虫草素含量和虫草酸含量都最高,分别为(2.37±0.20)mm/d、(88.34±2.00)%、(0.23±0.013)mg/g和(6.92±0.019)mg/g,但其菌丝在1/4 SDAY培养基上生长最为致密、粗壮;菌株YN 2019在PDA培养基上菌丝日生长速率、虫草素和虫草酸的含量最高,分别为：(2.27±0.27)mm/d、(0.50±0.012)mg/g和(11.32±0.16)mg/g,但其菌丝在1/4 SDAY培养基上含水率最高(95.23±1.65)%,且生长最为致密、粗壮。综合评价表明3株真菌中YN 2019菌丝中虫草素和虫草酸的含量高、生长速率快,有较好的药用研究价值。     

烟曲霉TMS-26产紫杉醇补料分批发酵条件初步探索

内生真菌发酵法是解决紫杉醇药源短缺问题的有效途径之一。本研究以摇瓶分批发酵为基础,进行摇瓶补料分批发酵研究,探究了苯丙氨酸、甘氨酸、苯甲酸钠乙酸钠混合液、3,5-二硝基水杨酸、H₂O₂、CuSO₄在发酵周期（13d）中,不同添加时间点对TMS-26菌体量及紫杉醇产量的影响,发现在第8天添加苯丙氨酸、甘氨酸、3,5-二硝基水杨酸时,其产量分别达到了(664.80±40.34)µg/L、(628.72±30.44)µg/L、(641.36±19.62)µg/L;在第9天添加CuSO₄时,其产量达到了(697.46±15.76)µg/L;在第10天添加H₂O₂、苯甲酸钠乙酸钠混合液,其产量分别达到了(615.78±36.28)µg/L、(792.54±10.04)µg/L。在摇瓶补料分批发酵研究结果的基础上,进行了5L罐发酵工艺放大研究,探究了前体和诱导子通过进行一次补加和恒速补加的方式对Aspergillus fumigatus TMS-26菌体量及紫杉醇产量的影响,结果表明恒速补加苯丙氨酸乙酸钠混合液,紫杉醇产量达到了746.17µg/L。通过本次研究,优化了TMS-26产紫杉醇摇瓶补料分批发酵和5L罐发酵工艺,为后续实现紫杉醇工业化生产奠定基础。     

杭州湾内外海域秋季浮游动物群落的比较

本文比较了杭州湾湾外海域(122.10°-122.58° E, 30.54°-30.93° N)和湾内不同海域(北岸东侧: 121.67°- 121.87° E, 30.68°-30.83° N; 南岸东侧: 121.60°-121.85° E, 29.95°-30.24° N; 北岸西侧: 121.31°-121.56° E, 30.58°- 30.77° N)秋季浮游动物的群落组成、累积优势度曲线以及多样性指数(H')等群落结构特征, 并进行了差异性分析。结果表明: 湾外海域的群落组成与湾内海域的3个群落之间均有较大的差异。湾外海域的群落I是以中华假磷虾(Pseudeuphausia sinica)等近海种、背针胸刺水蚤(Centropages dorsispinatus)等沿岸低盐种为主, 其次是外海种。湾内南岸东侧海域的群落II主要以左突唇角水蚤(Labidocera sinilobata)等沿岸低盐种为主, 近海种次之。湾内北岸东侧海域的群落III是以真刺唇角水蚤(Labidocera euchaeta)等沿岸低盐种、虫肢歪水蚤(Tortanus vermiculus)等河口半咸水种组成的混合群落。湾内北岸西侧海域群落IV是以虫肢歪水蚤为代表的河口半咸水种为主的群落。总的说来, 这一水域向西和向北方向出现更低盐度适应性的群落。从累积优势度曲线来看, 湾外海域群落I与湾内北岸东侧群落III的累积优势度上升趋势均相对平缓, 但群落III的初始累积优势度略高于群落I; 而与群落I相比, 湾内南岸东侧的群落II与北岸西侧的群落IV的初始累积优势度均很高。湾外海域群落I的初始累积优势度较低, 显示出群落I的优势种较多, 而单一优势种优势度低于湾内3个群落。方差分析结果表明: 湾外海域的浮游动物多样性指数与湾内3个海域均有极显著差异(P < 0.01), 而湾内各海域之间均无显著性差异(P > 0.05)。说明湾外浮游动物群落的多样性高于湾内海域。湾内外海域浮游动物群落特征之间有较大差异, 其主要原因是影响各自群落的主导水团明显不同。     

秦巴山区野生胡颓子属植物资源及研究

胡颓子是胡颓子科、胡颓子属(Elaeagus L)常绿、落叶灌木或小乔木,其果实成熟从四月下旬延续到十月中旬,浆果色泽艳丽,营养丰富,具有显著的医疗保健功能。秦巴山区是我国胡颓子属植物的集中分布地区,种类繁多,资源蕴藏量大,仅陕西商洛地区年采集量即可达1千万公斤,是一种颇有开发价值的野生果树。目前国内对胡颓子属植物的系统开发研究报导较少,资源的流失和破坏现象十分严重。为了开发利用野生胡颓子资源,我们对秦巴山区胡颓子属植物资源及利用价值进行了较为系统的研究和分析。     

不同诱导子对怀牛膝细胞生长及多糖含量的影响

为提高怀牛膝(Achyranthes bidentata)悬浮培养细胞中牛膝多糖的含量,以酵母提取物、榆黄蘑(Pleurotus citrinopileatus)及水杨酸作为诱导子,分别在同一时期以不同浓度或在不同时期以相同浓度添加至细胞培养物中,收获时测定细胞生长量和牛膝多糖含量。结果显示,在培养12天时添加2.5%(v/v)酵母诱导子,细胞干重最大,可达46.75 g·L–1,多糖含量为5.76 mg·g~(–1);在培养9天时添加5 mg GE·L–1榆黄蘑诱导子,收获时细胞中多糖含量可达6.56 mg·g~(–1),细胞干重达28.3g·L–1;1 mg·g~(–1)水杨酸对牛膝多糖的诱导效果不如以上2种诱导子明显。     

Stoichiometric characteristics of carbon,nitrogen and phosphorus of Sibiraea angustata shrub on the eastern Qinghai-Xizang Plateau

Aims Little is known about the stoichiometric characteristics of carbon (C), nitrogen (N) and phosphorus (P) in plateau shrubs across China. Sibiraea angustata is a typical and representative shrub species on the eastern Qinghai- Xizang Plateau, and exploring its C, N and P distribution patterns and stoichiometric properties in different organs (including root, shoot, leaf, twig and fruit) would help us better understand the mechanisms of C, N and P cycling and balance in the S. angustata dominated shrub ecosystem.
Methods Sixteen sampling sites were selected on the eastern Qinghai-Xizang Plateau by the stratified sampling method. The height and coverage of the dominant shrubs, latitude, longitude and altitude of the sites were recorded. Three 5 m × 5 m plots were selected at each site. At least 128 biological samples of plant organs of S. angustata were collected and measured, respectively. The C and N concentrations of plant samples were analyzed using an elemental analyzer (2400 II CHNS). The P concentration was analyzed using the molydate/ascorbic acid method after H₂SO₄-H₂O₂ digestion.
Important findings The C, N and P concentrations of different organs followed the order of: shoot (495.07 g·kg^-1) > twig (483.37 g·kg^-1) > fruit (480.35 g·kg^-1) > root (468.47 g·kg^-1) > leaf (466.33 g·kg^-1); leaf (22.27 g·kg^-1) > fruit (19.74 g·kg^-1) > twig (7.98 g·kg^-1) > shoot (4.54 g·kg^-1) > root (4.00 g·kg^-1) and fruit (2.85 g·kg^-1) > leaf (1.92 g·kg^-1) > twig (0.96 g·kg^-1) > root (0.52 g·kg^-1) > shoot (0.45 g·kg^-1), respectively. The ranges of the coefficient of variation (CV) for C, N and P concentrations were 1.71%-4.44%, 14.49%-25.50% and 11.46%-46.15%, respectively. Specifically, the C concentration was relatively high and stable, and the maximum CV values for N and P were found in roots. The N:P value of different organs varied from 7.12-12.41 and the minimum CV for N:P was found in twig, which indicated that N:P in twig had higher internal stability. In addition, correlation analysis indicated that the C concentration was significantly negatively correlated with N and P concentrations and correlation coefficients were -0.407 and -0.342, respectively. However, N concentration had dramatically positive correlation with P concentration and the correlation coefficient was 0.814. These results also could indicate that the C, N and P stoichiometric characteristics in the S. angustata shrub accorded with the homeostatic mechanism and growth rate hypothesis to some extent, the distributions of C, N and P concentrations were closely related to the function of the organs and it should be prudent to use ecological stoichiometric ratios to judge the condition of nutrient limitation at the species level.     

Stoichiometric characteristics of carbon,nitrogen and phosphorus in Phyllostachys edulis forests of China

Aims Stoichiometric ratios of carbon (C), nitrogen (N) and phosphorus (P) are important characteristics of the ecological processes and functions. Studies on population ecological stoichiometry can refine the content of flora chemometrics, determine the limited nutrient, and provide data for process-based modeling over large scale. Phyllostachys edulis is an important forest type, whose area accounts for 74% of total bamboo forest area in Southern China. However, little is known about the ecological stoichiometric in P. edulis. This study aimed to reveal C:N, C:P and N:P stoichiometry characteristics of the “plant-soil-litter” continuum and to provide a better understanding nutrient cycling and stability mechanisms in P. edulis forest in China. Methods The data were collected from the published literature containing C、N、P content in leaf or surface soil (0-20 cm) or littefall in P. edulis forests. Important findings 1) The leaf C, N, P content were estimated at 478.30 mg·g^-1, 22.20 mg·g^-1, 1.90 mg·g^-1 in P. edulis, and the corresponding C: N, C: P and N: P were 26.80, 299.60 and 14.40, respectively. Soil C, N, and P content in 0-20 cm were 21.53 mg·g^-1, 1.66 mg·g^-1, 0.41 mg·g^-1, with ratios of 14.20 for C:N, 66.74 for C:P and 4.28 for N:P. The C, N and P contents were 438.49 mg·g^-1, 13.39 mg·g^-1, 0.86 mg·g^-1 for litterfall, with the litter C:N, C:P and N:P being 25.53, 665.67, 22.55, respectively. 2) In the plant-soil-litter system in P. edulis forest, leaf had higher C:N, litter had higher C:P and N:P, while soil were the lowest. The N, P resorption rate was 39.68% and 54.74%, indicating that P. edulis forest growth and development was constrained by P or by both of N and P in China. 3) N content and N:P in leaf showed a tendency to increase with latitude, while the C:N of leaf declined with latitude. N:P of leaf increased with longitude, but the P content and the C:N of leaf showed a opposite trend. C: N of soil increased with longitude, whereas the N content of soil declined longitude. The N content of litter declined with longitude. 4) The leaf N content was negatively correlated with mean annual temperature and mean annual precipitation, but being more sensitive to temperature than precipitation. The positive correlations between N content and latitude support “Temperature-Plant Physiological” hypothesis, reflecting an adaptive strategy to environmental conditions.     

匀浆法提取沙枣果总黄酮工艺研究

沙枣常用于治疗脾胃虚弱、消化不良、肠炎腹泻、肺热咳嗽等疾病。为更好的开发利用沙枣植物资源,本研究通过传统水浴提取法和匀浆提取法的单因素对比实验,确定了匀浆法提取沙枣果总黄酮的提取方案。通过正交优化,获得匀浆法最优提取工艺为：乙醇浓度55%、料液比1∶30 g·mL^-1、匀浆时间5 min。在优化工艺条件下,沙枣果总黄酮的得率为6.57%。本研究为沙枣果的综合开发利用提供理论依据。     

Spatio-temporal characteristics of evapotranspiration and water use efficiency in grasslands of Xinjiang

Aims Xinjiang is located in the hinterland of the Eurasian arid areas, with grasslands widely distributed. Grasslands in Xinjiang provide significant economic and ecological benefits. However, research on evapotranspiration (ET) and water use efficiency (WUE) of the grasslands is still relatively weak. This study aimed to explore the spatio-temporal characteristics on ET and WUE in the grasslands of Xinjiang in the context of climate change.Methods The Biome-BGC model was used to determine the spatio-temporal characteristics of ET and WUE of the grasslands over the period 1979-2012 across different seasons, areas and grassland types in Xinjiang.Important findings The average annual ET in the grasslands of Xinjiang was estimated at 245.7 mm, with interannual variations generally consistent with that of precipitation. Overall, the value of ET was lower than that of precipitation. The higher values of ET mainly distributed in the Tianshan Mountains, Altai Mountains, Altun Mountains and the low mountain areas on the northern slope of Kunlun Mountains. The lower values of ET mainly distributed in the highland areas of Kunlun Mountains and the desert plains. Over the period 1979-2012, average annual ET was 183.2 mm in the grasslands of southern Xinjiang, 357.9 mm in the grasslands of the Tianshan Mountains, and 221.3 mm in grasslands of northern Xinjiang. In winter, ET in grasslands of northern Xinjiang was slightly higher than that of Tianshan Mountains. Average annual ET ranked among grassland types as: mid-mountain meadow > swamp meadow > typical grassland > desert grassland > alpine meadow > saline meadow. The highest ET value occurred in summer, and the lowest ET value occurred in winter, with ET in spring being slightly higher than that in autumn. The higher WUE values mainly distributed in the areas of Tianshan Mountains and Altai Mountains. The lower WUE values mainly distributed in the highland areas of Kunlun Mountains and part of the desert plains. The average annual WUE in the grasslands of Xinjiang was 0.56 g·kg^-1, with the seasonal values of 0.43 g·kg^-1 in spring, 0.60 g·kg^-1 in summer, and 0.48 g·kg^-1 in autumn, respectively. Over the period 1979-2012, the values of WUE displayed significant regional differences: the average values were 0.73 g·kg^-1 in northern Xinjiang, 0.26 g·kg^-1 in southern Xinjiang, and 0.69 g·kg^-1 in Tianshan Mountains. There were also significant differences in WUE among grassland types. The values of WUE ranked in the order of mid-mountain meadow > typical grassland > swamp meadow > saline meadow > alpine meadow > desert grassland.     

怀山药类原球茎的诱导形成与植株再生

为提高山药离体繁殖的速度, 缩短繁殖周期, 以铁棍山药(Dioscorea opposita cv. ‘Tiegun’)带腋芽茎段为材料, 对类原球茎的诱导、增殖、分化与植株再生进行了研究。结果表明, 铁棍山药类原球茎诱导的最适培养基为MS+1.0 mg·L^-1 TDZ+30 g·L^-1蔗糖, 增殖的最适培养基为MS+9 mg·L^-1 6-BA+30 g·L^-1蔗糖, 分化的最适培养基为MS+2 mg·L^-1 KT+0.02 mg·L^-1 NAA+30 g·L^-1蔗糖, 最适生根培养基为1/4MS+0.05 mg·L^-1 NAA+1.0 mg·L^-1 PP333+15 g·L^-1蔗糖, 生根率达80%, 移栽成活率可达85%。类原球茎的诱导形成及植株再生体系的建立为怀山药种苗的快速繁殖提供了一条新途径。     

绒毛白蜡体胚诱导和植株再生

该文探讨了基本培养基、外植体、培养条件以及植物生长调节剂配比对绒毛白蜡(Fraxinus velutina)体胚诱导的影响。结果表明,胚根是诱导体胚发生的最佳外植体;体胚诱导的最适培养基为改良MS+2 mg·L~(–1) 6-BA+0.1 mg·L~(–1) NAA、30g·L~(–1)蔗糖、5.0 g·L~(–1)琼脂;暗培养20天后进行光照培养(14小时光照/10小时黑暗),光密度为100~(–1)20μmol·m~(–2)·s~(–1),昼温度(25±2)°C,夜温度(18±2)°C;成功诱导出体细胞胚并获得再生植株,体胚诱导率可达59.8%,体胚萌发率达81.2%。壮苗最适培养基为改良WPM+0.5 mg·L~(–1) 6-BA+0.2 mg·L~(–1) ZT+0.01 mg·L~(–1) NAA。生根最适培养基为改良1/2MS+1.0 mg·L~(–1)IBA+0.05 mg·L~(–1) NAA+20 g·L~(–1)蔗糖,生根率高达97.3%,试管苗移栽成活率达97.8%。     

Effects of nitrogen addition on soil respiration of Rhododendron simsii shrubland in the subtropical mountainous areas of China

Aims As the second largest C flux between the atmosphere and terrestrial ecosystems, soil respiration plays a vital role in regulating atmosphere CO₂ concentration. Therefore, understanding the response of soil respiration to the increasing nitrogen deposition is urgently needed for prediction of future climate change. However, it is still unclear how nitrogen deposition influences soil respiration of shrubland in subtropical China. Our objectives were to explore the effects of different levels of nitrogen fertilization on soil respiration, root biomass increment, and litter biomass, and to analyze the relationships between soil respiration and soil temperature and moisture.
Methods From January 2013 to September 2014, we conducted a short-term simulated nitrogen deposition experiment in the Rhododendron simsii shrubland of Dawei Mountain, located in Hunan Province, southern China. Four levels of nitrogen addition treatments (each level with three replicates) were established: control (CK, no nitrogen addition), low nitrogen addition (LN, 2 g·m^-2·a^-1), medium nitrogen addition (MN, 5 g·m^-2·a^-1) and high nitrogen addition (HN, 10 g·m^-2·a^-1). Soil respiration was measured by LI-8100 soil CO₂ efflux system. At the same time, we measured root biomass increment and litter biomass in each plot.
Important findings Soil respiration exhibited a strong seasonal pattern, with the highest rates found in summer and the lowest rates in winter. Annual accumulative soil respiration rate in the CK, LN, MN and HN was (2.37 ± 0.39), (2.79 ± 0.42), (2.26 ± 0.38) and (2.30 ± 0.36) kg CO₂·m^-2, respectively. Annual mean soil respiration rate in the CK, LN, MN and HN was (1.71 ± 0.28), (2.01 ± 0.30), (1.63 ± 0.27) and (1.66 ± 0.26) μmol CO₂·m^-2·s^-1, respectively, and it was 17.25% higher in the LN treatment compared with CK (p = 0.06). The root biomass increment was increased by LN, MN, and HN treatments by 18.36%, 36.49% and 61.63%, respectively, compared to CK. The litter biomass was increased by LN, MN, and HN treatments by 35.87%, 22.17% and 15.35%, respectively, compared with CK. Soil respiration exhibited a significant exponential relationship with soil temperature (p < 0.01, R² is 0.77 to 0.82) and a significant linear relationship with soil moisture at the depth of 5 cm (p < 0.05, R² is 0.10 to 0.15). The temperature sensitivity (Q₁₀) value of CK, LN, MN and HN plots was 3.96, 3.60, 3.71 and 3.51, respectively. These results suggested that nitrogen addition promoted plant growth and decreased the temperature sensitivity of soil respiration. The increase of root biomass under N addition may be an important reason for the change of soil respiration in the study area.     

Responses of apical ion fluxes to NaCl stress in Elaeagnus angustifolia seedlings

Aims Elaeagnus angustifolia is one of the most salt-tolerant species. The objective of this study was to understand the mechanisms of ion transporation in E. angustifolia exposed to different salt concentrations through manipulations of K⁺/Na⁺ homeostasis.
Methods Seedlings of two variants of the species, Yinchuan provenance (YC, salt-sensitive type) and the Alaer provenance (ALE, salt-tolerant type), were treated with three different NaCl application modes, and the ion fluxes in the apical regions were measured using non-invasive micro-test technology (NMT). In mode 1, Na⁺ and K⁺ fluxes were measured after 150 mmol·L^-1 NaCl stress lasted for 24 h. In mode 2, K⁺ and H⁺ fluxes were quantified with a transient stimulation of NaCl solution. In mode 3, Amiloride (Na⁺/H⁺ antiporters inhibitor) and tetraethylammonium (TEA, K⁺ channel inhibitor) was used to treat apical regions of E. angustifolia seedlings after NaCl stress for 24 h, respectively.
Important findings Under NaCl stress for 24 h, net effluxes of Na⁺ and K⁺ were increased significantly. The net Na⁺ effluxes of YC provenance seedlings (720 pmol·cm^-2•s^-1) were lower than that of ALE provenance (912 pmol·cm^-2·s^-1), but the net K⁺ efflux was higher in YC provenance. Under the instantaneous NaCl stimulation, net K⁺ efflux was remarkably increased, with the net K⁺ efflux of YC provenance always higher than that of ALE provenance. Interestingly, H⁺ at the apical regions was found from influx to efflux, with the net H⁺ efflux of ALE provenance greater than that of the YC provenance. Under the NaCl and NaCl + Amiloride treatment, the net Na⁺ efflux of ALE provenance seedlings was higher than that of YC provenance, while the net K⁺ efflux was less in ALE provenance seedlings. On the other hand, the differences in net Na⁺ and K⁺ effluxes were insignificant between the two provenances under the control group and NaCl + TEA treatment. In conclusion, NaCl stress caused Na⁺ accumulation and K⁺ outflows of E. angustifolia seedlings; The E. angustifolia seedlings utilize Na⁺/H⁺ antiporters to reduce Na⁺ accumulation by excretion; and the maintenance of K⁺/Na⁺ homeostasis in salt-tolerant E. angustifolia provenance seedlings roots accounted for a greater Na⁺ extrusion and a lower K⁺ efflux under NaCl stress. Results from this study provide a theoretical basis for further exploring salt-tolerant E. angustifolia germplasm resource.