Cadmium Accumulation and Tolerance of Two Salix Genotypes Hydroponically Grown in Presence of Cadmium

Abstract

In general, according to previous studies, pioneer species do not require arbuscular mycorrhizal fungi (AMF) to increase their growth and survival in tropical systems. The aim of this study was to determine the dependence response to AMF of Heliocarpus appendiculatus, a pioneer species, at different phosphorus (P) levels. In a greenhouse experiment, H. appendiculatus seedlings were grown in pots with a sterile vermiculite-sand mixture (1:1). Two sets of pots were set up: One set was inoculated (150 spores per pot) with indigenous AMF from a tropical rain forest at “Los Tuxtlas” (Veracruz, Mexico); the other set was not inoculated. To each set, 0, 0.02, 0.2, and 2 g L^?1P was added. All pots were watered with 250 mL of nutrient solution. Mycorrhizal plants showed a higher total dry weight and relative growth rate in 0.02 g L^?1P concentration, while nonmycorrhizal plants responded positively at 0.2 g L^?1P; a decrease in plant responses at higher P levels was observed in both treatments. H. appendiculatus showed to have higher relative dependence at lower P concentration (≈50%). As levels of P increased, mycorrhizal colonization decreased. Successful growth of pioneer species during succession process may be improved if there is AMF content in soils, prior to disturbance.     

基于防风效益的毛乌素沙地沙柳灌丛平茬方法优选

针对当前毛乌素沙地沙柳灌丛衰退问题,设计维持丛状结构特征可持续的生态平茬方法,研究不同平茬方法下沙柳灌丛的风场结构与防风效益,为今后毛乌素沙地沙柳生态平茬提供理论指导。试验设定6种平茬强度(0、0.2Ф、0.4Ф、0.6Ф、0.8Ф、1.0Ф,Ф为灌丛蓬径),3种平茬模式(模式A:按平茬强度沿主风向从灌丛迎风面向背风面平茬、模式B:按平茬强度沿主风向从灌丛两侧向中间同时平茬、模式C:按平茬强度沿主风向从灌丛中间1/2处同时向两侧平茬,下同)来维持灌丛结构的可持续存在,分析平茬后灌丛保留结构的自身形态参数和防风效益的关系,并依此选出最优平茬方法。试验结果表明:平茬强度在0～0.4Ф范围内,模式A和B的灌丛形态参数和防风效益指标均无显著变化,但模式B防风效益优于模式A;而强度为0.6Ф及以上,3种平茬模式下,背风面的风速降幅均明显减小,防风距离逐渐缩短,与原灌丛防风效益差异显著,强度为0.4Ф是防风效益发生突变的临界点。对防风效益影响最大的形态参数是疏透度。研究得出合理的平茬方法为:沙柳灌丛以模式B进行平茬,平茬强度为0.4Ф。     

Soil bacterial community response to sulfadiazine in the soil–root zone

Sulfonamide antibiotics reach soil via manure and adversely affect microbial diversity. Clear effects of these bacteriostatic, growth‐inhibiting antibiotics occur in the presence of a parallel input of microbial activity stimulating manure. Natural hot spots with already increased soil microbial activity are located in the rhizosphere, comprising microorganism such as Pseudomonas with plant growth promoting and pathogenic strains. The hypothesis was therefore that the antibiotic activity of sulfonamides is promoted in the rhizosphere even in the absence of manure, followed by shifts of the natural plant‐specific microbial community structure. This was evaluated by a laboratory experiment with Salix fragilis L. and Zea mays L. After 40 d of incubation, sub‐areas such as non‐rhizosphere soil, rhizosphere soil and plant roots were sampled. Effects on microbial community structure were analyzed using 16S rRNA gene fragment patterns of total bacteria community and Pseudomonas. Selected exoenzymes of N‐, P‐, and C‐cycling were used to test effects on microbial functions. Compared to the factors soil sub‐area and sulfadiazine (SDZ) content, plant species had the largest influence on the bacterial community structure and soil exoenzyme activity pattern. This was also reflected by an up to 1.5‐fold higher acid phosphatase activity in samples from maize‐ compared to willow‐planted soil. We conclude that antibiotic effects on the bacterial community structures are influenced by the antibiotic concentration and root influence.     

土壤生物工程在北京山区公路绿化中的应用

山区公路边坡绿化不仅可以保护边坡,防治水土流失,而且还可以改善公路施工过程中对环境造成的创伤,已经成为公路边坡治理的重要内容。以北京市怀柔区琉璃河岸坡为试验示范区,以旱柳(Salix matsudana)作为主要的绿化植物,采用扦插、埋根、灌丛垫、柳篱挡墙、梢捆等土壤生物工程措施,对沿河公路路基边坡进行治理,并对施工完成5个月后的生长状况、护坡效果等进行观测调查。结果表明:5种土壤生物工程中旱柳的成活率均在90%以上,在试验区具有很好的适应性;在不同的工程类型、水淹与否等条件下,旱柳的生长状况表现出明显的差异,各措施按旱柳生长状况由好到差排序依次为梢捆、灌丛垫、埋根、扦插、柳篱挡墙;水淹1个月的旱柳基径和株高较未水淹的平均值分别小13.2%和21.4%。     

基于去趋势分析的中国温带旱柳开花始期对气候变暖的响应

为了更准确地揭示植物在物候水平上对气温变化的响应与适应机制,在去气温和物候时间序列趋势的基础上,建立日尺度的气温?物候回归模型,分析中国温带地区40个站点1986-2011年旱柳开花始期对气温变化的响应与适应机理。结果表明：中国温带地区77.5%的站点旱柳开花始期呈提前趋势,相应的敏感时段春季气温则呈上升趋势（0.8±0.5℃·10a-1）。其中,75%的站点物候期或气温时间序列存在显著变化趋势。进行去趋势处理后,17.5%的站点相关性发生变化,去趋势前其相关性较低,去趋势后,表现为显著负相关;模拟的均方根误差（RMSE）从去趋势前的5.5d降至去趋势后的4.9d,说明去趋势方法能提高气温-物候响应关系诊断的精确度。基于去时间序列线性趋势的气温－物候回归模型,得到92.5%的站点旱柳开花期与敏感时段春季气温呈显著负相关关系,即随着气温的升高,旱柳开花期呈提前趋势,其线性响应速率为-2.5±2.1d·℃-1。     

Revegetation of copper mine tailings with ryegrass and willow

To restore vegetation on metal mine tailings is very difficult because they often contain high concentrations of heavy metals, low nutrient content and low water retention capacity. This study involved 3 experiments that evaluated the effects of 4 treatment amendments: montmorillonite, rice straw, organic manure and chemical fertilizer on the growth of ryegrass (Loliurn perenne L.) and willow (Salix virninalis L.) with Cu and Zn mine tailings from two mining areas. The results showed that ryegrass was the most tolerant of 4 crops to Cu toxicity. Also when organic manure, which contained high concentrations of inorganic salts, was added to the mine tailings, it significantly hindered ryegrass growth (P=0.05).Meanwhile, with ryegrass organic manure significantly increased (P=0.05) the extractable Cu concentration in both mine tallings. When montmorillonite was used as a mine tailings amendment with willow, the height and tress number at the 1st cut were significantly greater (P = 0.05) than a control without montmorillonite. However there was no significant difference for height, tress number, dry weight or root dry weight at the 2nd cut. So, amendment applications to reduce metal toxicity and increase nutrients retention in mine tailings were essential during revegetation of mine tailings.     

干旱胁迫对5个种源沙柳(Salix psammophila)气体交换及水分利用效率的影响

在盆栽条件下,对5个种源沙柳进行了水分胁迫处理,在不同干旱阶段对苗木叶水势、土壤含水率、蒸腾速率、光合速率等气体交换特性及水分利用效率进行了研究.结果表明:沙柳属于亚低水势忍耐脱水耐旱树种,叶水势随土壤含水量的下降而下降,变化趋势可用双曲线方程y=a b/x(0.389 0＜a＜0.520 3,8.906 6＜b＜11.466 9)拟合,其中民勤种源沙柳的双曲线方程中b值最低,为8.91,表现出较强的耐旱特性.在正常水分供应条件下,榆林种源沙柳的光合速率为23.89 μmol/(m2·s),水分利用效率为3.44 μmol/mmol,表现出很强的光合生产能力.随着干旱胁迫的加剧,各种源沙柳苗木的水分利用效率均有不同程度增加,民勤种源沙柳的增加值最大,为0.75 μmol/mmol,表现出了较强的抵抗干旱的能力,而榆林种源沙柳对水分亏缺则非常敏感,光合速率、蒸腾速率都急剧下降.这充分表明在水分供应充足的条件下,榆林种源沙柳具有最大的光合生产潜力;而当遇到干旱胁迫时,民勤种源沙柳则表现出极强的维持体内水分平衡的能力,是5个种源中最耐旱的种源.     

垂柳故土考

垂柳（蜀柳）原产于蜀（今成都一带地区）。从南北朝时期（420～589）开始,它被逐渐广泛地栽植于长江、黄河流域以及其他地区。它曾被向东引种至日本、朝鲜。它也曾被向西传入中亚和西亚;大约在17世纪从近东传入欧洲;后来大约在18世纪从欧洲传入北美洲。     

不同处理对旱柳扦插育苗的影响

本文通过对旱柳(Salix matsudana koidz)插条不同长度、不同粗度、不同扦插日期、不同扦插深度、插穗不同处理方式进行了扦插试验,分析得出,4月初用粗度为0.5-1.0cm、长度为22cm、浸水24h的旱柳插穗在外露1-2cm的情况下扦插成活率比较高.     

灌丛植物-乌柳

通过对乌柳生长状况及与柽柳生物量的比较分析，结果表明，乌柳虽然在林区广泛生长，在共和盆地干旱半干旱沙地引种也能很好生长，是干旱半干旱区的生态治理好帮手。