水肥对高产无性系油茶果实产量的影响

以肥料氮(N)、磷(P)、钾(K)不同施用量和灌溉水量(H2O)为试验因子,采用二次通用旋转组合设计,研究了水肥对油茶鲜果产量的影响。结果表明,N、P、K和H2O的用量对油茶鲜果产量均存在显著的影响,且N与K、K与H2O对油茶鲜果产量存在显著的互作效应。试验因子间的交互作用使油茶鲜果产量明显提高,达到最大值时4个因子的编码值分别为:N为1.03、P为0.62、K为1.19、H2O为0.92,即全年每株油茶施有效养分N 181.8 g、P2O5 48.6 g、K2O 287.1 g,灌水29.2 kg,相当于每hm2施用N 795 kg、P2O5 80 kg、K2O 474 kg,灌水48 m3。采用该方案,油茶鲜果产量可达到最大为5 131 kg hm2。     

丛枝菌根真菌根内菌丝碱性磷酸酶活性与菌根共生效应的研究

试验研究 3种丛枝菌根真菌根内菌丝碱性磷酸酶活性与菌根共生效应的结果表明 ,3种丛枝菌根真菌对宿主植物的效应不同 ,与接种G .spp处理和未接种对照相比 ,接种G .m和G .i处理显著增加玉米地上部和根系干物质量、P浓度和吸P量 ,但后两者间无显著差异 ;而接种G .spp处理与对照无显著差异。播种后 35d时接种G .m和G .i处理根内菌丝碱性磷酸酶活性显著高于接种G .spp处理 ,而前二者间无显著差异 ,且随生长时间的变化趋势相似 ,35d时酶活性最高 ,35～ 5 0d呈迅速下降趋势 ,至 70d时酶活性仍下降且趋于平缓。G .spp酶活性则一直处于较低水平 ,随生长时间的延长略有起伏。即接种不同丛枝菌根真菌时 ,根内菌丝碱性磷酸酶活性高的菌根真菌对玉米生长促进作用较大 ,可提高玉米P营养状况 ;反之则对玉米生长和P营养状况无明显促进作用 ,且与对照无显著差异。出苗后 35d时根内菌丝碱性磷酸酶活性是预测丛枝菌根真菌对玉米生长效应的有效生理指标之一。     

Influence of mycorrhiza vs. soluble phosphate on growth,nodulation, and N2 fixation (15N) in alfalfa under different levels of water potential

Summary The legume Medicago sativa (+Rhizobium melilott) was grown under controlled conditions to study the interactions between soluble P in soil (four levels), or a mycorrhizal inoculum, and the degree of water potential (four levels) in relation to plant development and N₂ fixation. ¹⁵N-labelled ammonium sulphate was added to each pot for a qualitative estimate of N₂ fixation, in order to rank the effects of the different treatments.Dry-matter yield, nutrient content and nodulation increased with the amount of plant-available P in the soil, and decreased as the water stress increased, for each P-level. The mycorrhizal effect on dry matter, N yield, and on nodulation was little affected by the water potential. Since P uptake was affected by the water content in mycorrhizal plants, additional mechanisms, other than those mediated by P, must be involved in the mycorrhizal activity.There was a positive correlation between N yield and nodulation for the different P levels and the mycorrhizal treatment at all water levels. A high correlation between plant unlabelled N content and atom% ¹⁵N excess was also found for all levels of P. In mycorrhizal plants, however, the correlation between unlabelled N yield and ¹⁵N was lower. This suggests that mycorrhiza supply plants with other N sources in addition to those derived from the improvement on N₂ fixation.     

特色农业产业化与品牌化的协同关系研究

对特色农业产业化与品牌化的协同关系进行了研究,结果表明:产业化是品牌化的基础,产业化为品牌化提供了经济基础、影响力和品牌内涵;而产业化应当以品牌战略为指导,用品牌战略提升产业化的内涵和加速产业化进程。在研究的基础上指出特色农业在发展中应该坚持产业化和品牌化是同一过程、协同发展的指导思想。     

The complex symbiotic relationships of bark beetles with microorganisms: a potential practical approach for biological control in forestry

Bark beetles, especially Dendroctonus species, are considered to be serious pests of the coniferous forests in North America. Bark beetle forest pests undergo population eruptions, causing region wide economic losses. In order to save forests, finding new and innovative environmentally friendly approaches in wood-boring insect pest management is more important than ever. Several biological control methods have been attempted over time to limit the damage and spreading of bark beetle epidemics. The use of entomopathogenic microorganisms against bark beetle populations is an attractive alternative tool for many biological control programmes in forestry. However, the effectiveness of these biological control agents is strongly affected by environmental factors, as well as by the susceptibility of the insect host. Bark beetle susceptibility to entomopathogens varies greatly between species. According to recent literature, bark beetles are engaged in symbiotic relationships with fungi and bacteria. These types of relationship are very complex and apparently involved in bark beetle defensive mechanisms against pathogens. The latest scientific discoveries in multipartite symbiosis have unravelled unexpected opportunities in bark beetle pest management, which are discussed in this article.     

丛枝菌根真菌提高植物非生物胁迫耐受性研究进展

丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF或AM真菌)是一种在土壤中广泛存在的有益真菌,能与地球上80％左右陆生植物根系共生形成丛枝菌根结构.AM真菌能通过与宿主植物交换碳源,促进宿主植物对N和P等无机营养元素的吸收,提高植株生产力和抵抗非生物胁迫的能力.全球气候变化和化肥农药的使用...     

内生真菌与高羊茅之间的共生关系

从内生真菌的涵义及其基本生物学特征出发,着重对国内外近10 年来有关内生真菌与高羊茅关系的研究情况作了综述,主要包括内生真菌对高羊茅生长发育及其抗逆性的影响、内生真菌对高羊茅植物群落及生态系统的影响等,并对内生真菌研究的实际意义及其应用前景作了总结。     

Symbiotic Associations in Ascidians: Relevance for Functional Innovation and Bioactive Potential

Associations between different organisms have been extensively described in terrestrial and marine environments. These associations are involved in roles as diverse as nutrient exchanges, shelter or adaptation to adverse conditions. Ascidians are widely dispersed marine invertebrates associated to invasive behaviours. Studying their microbiomes has interested the scientific community, mainly due to its potential for bioactive compounds production—e.g., ET-73 (trabectedin, Yondelis), an anticancer drug. However, these symbiotic interactions embrace several environmental and biological functions with high ecological relevance, inspiring diverse biotechnological applications. We thoroughly reviewed microbiome studies (microscopic to metagenomic approaches) of around 171 hosts, worldwide dispersed, occurring at different domains of life (Archaea, Bacteria, Eukarya), to illuminate the functions and bioactive potential of associated organisms in ascidians. Associations with Bacteria are the most prevalent, namely with Cyanobacteria, Proteobacteria, Bacteroidetes, Actinobacteria and Planctomycetes phyla. The microbiomes of ascidians belonging to Aplousobranchia order have been the most studied. The integration of worldwide studies characterizing ascidians’ microbiome composition revealed several functions including UV protection, bioaccumulation of heavy metals and defense against fouling or predators through production of natural products, chemical signals or competition. The critical assessment and characterization of these communities is extremely valuable to comprehend their biological/ecological role and biotechnological potential.     

Mycorrhizal Associations and Their Manipulation for Long-Term Agricultural Stability and Productivity

Summary

Mycorrhizae refer to an association (largely symbiotic) between plants and fungi that colonize the cortical root tissue of most agricultural crops during the period of active plant growth. The contribution of these symbioses to plant growth and soil fertility maintenance has been well-recognized for past several years. In spite of these benefits to agriculture, at present, the realization of the full potential of these fungi has not yet been reached. It must also be recognized that recent research on the possible application of the mycorrhizal symbiosis in agriculture has revealed many gaps in knowledge of fungal biology and ecology. Scientific knowledge on the role of these fungi in plant development and protection, soil stabilization, aggregate formation and creation of nutrient reserves is still limited. For efficient use and manipulation of these fungal symbioses for long-term agricultural stability and productivity, our understanding of their physiology, function and interactions with existing crops and environmental conditions should be improved. Besides, effects of different agronomic practices, application of chemical fertilizers and pesticides on their ecology and function should be elucidated before their successful utilization in agriculture.

This paper presents information on the morphology of different my-corrhizal fungi, their physiology and functions. Methods presently used to produce mycorrhizal inocula, their application in the field, problems to be resolved for their massive exploitation and future research needs have also been described. References have been selected to explain the recent advances in our understanding on these beneficial fungi.     

Effects of mycorrhizal fungi on root-hair growth and hormone levels of taproot and lateral roots in trifoliate orange under drought stress

A pot experiment was used to evaluate the effects of an arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae on plant growth performance, root-hair growth, and root hormone levels in trifoliate orange (Poncirus trifoliata) seedlings under well-watered (WW) and drought stress (DS). A 9-week mild DS treatment significantly reduced mycorrhizal colonization of 2nd- and 3rd-order lateral roots. Root mycorrhizal colonization was relatively higher in the 2nd- and 3rd-order lateral roots than in the taproot and the 1st-order lateral root under WW and DS. AMF seedlings exhibited significantly higher root-hair density, length (except for the taproot) and diameter in taproot and 1st-, 2nd-, and 3rd-order lateral roots under WW, and considerably higher root-hair density (except for 1st-order lateral root), length (except for 2nd-order lateral root) and diameter under DS. Mycorrhizal inoculation remarkably increased root abscisic acid (ABA), indole-3-acetic acid (IAA), methyl jasmonate, and brassinosteroids (BRs) concentrations under DS, in company with the decrease in root zeatin riboside and gibberellins levels and root IAA effluxes. Root-hair traits were significantly positively correlated with root colonization and root ABA and BRs levels. It is concluded that mycorrhizal plants possessed better root-hair growth to adapt mild DS, which is associated with mycorrhizal colonization and endogenous hormone changes.