Field performance in northern Spain of Douglas-fir seedlings Inoculated with ectomycorrhizal fungi

 Experimental plantations were established in northern Spain to determine the effects of different ectomycorrhizal fungi on growth and survival of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) under field conditions. Douglas-fir seedlings were inoculated with Laccaria bicolor S238 mycelia in two bareroot nurseries in central France or with spore suspensions of three hypogeous ectomycorrhizal species: Melanogaster ambiguus, Rhizopogon colossus and R. subareolatus, in a Spanish containerised nursery. The effects of ectomycorrhizal inoculation on plant survival after outplanting were limited, being only significant at the Guipuzkoan (Spain) site, when plants inoculated with L. bicolor S238 were compared to non-inoculated plants grown in non-fumigated soil. L. bicolor S238 had a significant effect on plant growth during the phase of bareroot nursery growth and this difference was maintained after field outplanting. Nursery inoculations with M. ambiguus, R. colossus and R. subareolatus improved plant growth during the first 2 and 3 years after field outplanting. The positive effects of the inoculation treatment on seedling height, root collar diameter and stem volume persisted after 5 years of field growth. Inoculation with these ectomycorrhizal fungi may improve the field performance of Douglas-fir seedlings in northern Spain. Accepted: 12 February 1999     

Studies on the Chemical Constituents of Limonium aureum (L.) Hill

Five different crystals have been obtained for the first time from the aerial parts of Limonium aureum (L.)Hill ex kuntze. They were identified as follows: (Ⅰ) homoeriodictyol, (Ⅱ) naringenin, (Ⅲ) eriodictyol (Ⅳ) myricetin-3-O-β-D-glucoside and (Ⅴ) myricetin-3-O-β-D-galactoside.     

Diversity of nifH gene pools in the rhizosphere of two cultivars of sorghum (Sorghum bicolor) treated with contrasting levels of nitrogen fertilizer.

The diversity of nitrogen-fixing bacteria was assessed in the rhizospheres of two cultivars of sorghum (IS 5322-C and IPA 1011) sown in Cerrado soil amended with two levels of nitrogen fertilizer (12 and 120 kg ha(-1)). The nifH gene was amplified directly from DNA extracted from the rhizospheres, and the PCR products cloned and sequenced. Four clone libraries were generated from the nifH fragments and 245 sequences were obtained. Most of the clones (57%) were closely related to nifH genes of uncultured bacteria. NifH clones affiliated with Azohydromonas spp., Ideonella sp., Rhizobium etli and Bradyrhizobium sp. were found in all libraries. Sequences affiliated with Delftia tsuruhatensis were found in the rhizosphere of both cultivars sown with high levels of nitrogen, while clones affiliated with Methylocystis sp. were detected only in plants sown under low levels of nitrogen. Moreover, clones affiliated with Paenibacillus durus could be found in libraries from the cultivar IS 5322-C sown either in high or low amounts of fertilizer. This study showed that the amount of nitrogen used for fertilization is the overriding determinative factor that influenced the nitrogen-fixing community structures in sorghum rhizospheres cultivated in Cerrado soil.     

二色补血草的耐盐性研究

通过NaCl胁迫发芽试验、盆栽浇灌NaCl盐水试验、不同含盐量土壤的种植试验,研究二色补血草(Limonium bicolor)3个时期的耐盐能力。结果表明:高浓度NaCl对二色补血草种子的萌发有明显的抑制作用,种子的发芽率与盐浓度之间呈显著的负相关,种子萌发时盐胁迫的适宜值、临界值、极限值分别是0.49%、1.30%、2.11%;盆栽试验结果表明,二色补血草在2.0%以下的NaCl盐水胁迫下没有表现明显的盐害症状,只表现高浓度NaCl胁迫下,生长量低于低浓度处理的,当处理浓度达到2.4%时,多数植株濒临死亡;不同含盐量土壤的种植试验结果表明,在自然条件下,二色补血草成株耐盐临界值为1.7%~1.8%。试验结果说明二色补血草具有较强的耐盐能力,适合在滩涂盐碱地推广种植。     

二色补血草的耐盐性研究

通过NaCl胁迫发芽试验、盆栽浇灌NaCl盐水试验、不同含盐量土壤的种植试验,研究二色补血草（Limoniumbicolor）3个时期的耐盐能力。结果表明：高浓度NaCl对二色补血草种子的萌发有明显的抑制作用,种子的发芽率与盐浓度之间呈显著的负相关,种子萌发时盐胁迫的适宜值、临界值、极限值分别是0.49%、1.30%、2.11%;盆栽试验结果表明,二色补血草在2.0%以下的NaCl盐水胁迫下没有表现明显的盐害症状,只表现高浓度NaCl胁迫下,生长量低于低浓度处理的,当处理浓度达到2.4%时,多数植株濒临死亡;不同含盐量土壤的种植试验结果表明,在自然条件下,二色补血草成株耐盐临界值为1.7%～1.8%。试验结果说明二色补血草具有较强的耐盐能力,适合在滩涂盐碱地推广种植。     

Apparent survival and return rate of breeders in the southern temperate White‐rumped Swallow Tachycineta leucorrhoa

Life‐histories and demographic parameters of southern temperate bird species have been little studied. We estimated return rates between years and sexes, and adult apparent survival and recapture probabilities with mark–recapture data on White‐rumped Swallows and found a lower return rate of unsuccessful females. There was little support for influences of sex or year on survival rates. The estimates were equivalent to the lowest value reported for a northern congener, in contrast to the prediction of geographical variation under life‐history theory.     

月光花素对彩叶芋愈伤组织细胞生长和分化的影响

在含有NAA0.2mg/L,2.4-D 0.2mg/L的MS基础培养基中添加月光花素培养彩叶芋愈伤组织,结果显示,低浓度的月光花素能促进愈伤组织生长,高浓度则有明显的抑制作用,最适浓度为1.0~2.0mg/L;培养两个月后,添加适宜浓度的月光花素(0.2~2.0mg/L)的培养基能促进体细胞分化和植株再生,而高浓度(10.0mg/L)处理和对照均未能分化出绿苗。表明适宜浓度的月光花素在合适的生长素剂量的协同作用下,对植物愈伤组织细胞的生长和分化有较强的调节作用。     

离体条件下日本冷杉/二色蜡蘑的外生菌根合成

本实验报道了以离体培养方式诱导日本冷杉(Abies firma Sieb.et Zucc.)与二色蜡蘑(Laccaria bicolor(Maire)Orton)的外生菌根合成的方法.日本冷杉能否与广谱性的外生菌根菌二色蜡蘑形成人工菌根?菌根结构的诱导是否只发生在植物体整体水平上?这些是本实验的关注点.研究结果显示:无菌幼苗接种10周后,在光学显微镜下可观察到典型的外生菌根的特征,即由高度分叉的外延菌丝体形成的厚实的菌套以及由内延菌丝体形成的哈蒂氏网.将来源于下胚轴的愈伤组织与二色蜡蘑的菌丝体进行共同培养,3周后,菌丝体开始接触愈伤组织的表面,并且侵入到愈伤组织的细胞间,形成拟哈蒂氏网结构.愈伤组织可以作为一种菌根学研究的有效的培养体系.这一方法可望为冷杉类植物菌根学的研究提供有效的实验工具.     

盐胁迫对盐生植物黄花补血草种子萌发和幼苗生长的影响

盐生植物黄花补血草广泛分布于我国西北地区、东北西部以及华北北部,对改良盐碱土壤具有重要的生态作用。以黄花补血草(Limonium aureum(L.)Hill)为材料,研究分析了不同浓度NaCl胁迫对其种子萌发和幼苗生长产生的抑制效应及作用机制。结果表明:低浓度NaCl(25 mmol/L和50 mmol/L)处理不影响黄花补血草种子萌发和幼苗生长,25 mmol/L NaCl甚至促进了根生长,而高浓度NaCl(100 mmol/L和150 mmol/L)处理明显抑制种子萌发及幼苗生长。利用荧光探针的检测结果表明,NaCl处理的幼苗根中过氧化氢(H2O2)和一氧化氮(NO)含量明显高于对照水平。碘化丙啶(PI)染色结合激光共聚焦显微镜观察及检测相对电导率结果显示,高浓度NaCl处理抑制了幼苗根尖伸长区细胞的伸长生长,增加了细胞膜的通透性,对根细胞造成了明显的伤害。此外,高浓度NaCl处理诱导叶片丙二醛(MDA)含量显著升高。以上结果说明,黄花补血草对低浓度的盐具有一定的耐盐性,但高浓度盐降低了种子的萌发率,使幼苗根中H2O2产生增加,抑制根尖伸长区细胞的伸长生长,对根、叶造成明显氧化损伤,从而抑制黄花补血草幼苗的生长。     

Cs phytoremediation by Sorghum bicolor cultivated in soil and in hydroponic system

Cs accumulation characteristics by Sorghum bicolor were investigated in hydroponic system (Cs level at 50–1000 μmol/L) and in soil (Cs-spiked concentration was 100 and 400 mg/kg soil). Two varieties of S. bicolor Cowly and Nengsi 2# grown on pot soil during the entire growth period (100 days) did not show significant differences on the height, dry weight (DW), and Cs accumulation. S. bicolor showed the potential phytoextraction ability for Cs-contaminated soil with the bioaccumulation factor (BCF) and the translocation factor (TF) values usually higher than 1 in soil system and in hydroponic system. The aerial parts of S. bicolor contributed to 86–92% of the total removed amounts of Cs from soil. Cs level in solution at 100 μmol/L gave the highest BCF and TF values of S. bicolor. Cs at low level tended to transfer to the aerial parts, whereas Cs at high level decreased the transfer ratio from root to shoot. In soil, the plant grew well when Cs spiked level was 100 mg/kg soil, but was inhibited by Cs at 400 mg/kg soil with Cs content in sorghum reaching 1147 mg/kg (roots), 2473 mg/kg (stems), and 2939 mg/kg (leaves). In hydroponic system, average Cs level in sorghum reached 5270 mg/kg (roots) and 4513 mg/kg (aerial parts), without significant damages to its biomass at 30 days after starting Cs treatment. Cs accumulation in sorghum tissues was positively correlated with the metal concentration in medium.