The influence of tillage on the structure of rhizosphere and root-associated arbuscular mycorrhizal fungal communities

Soil environmental factors affect the structure of arbuscular mycorrhizal (AM) fungal communities present in soil. However, it is not understood to which degree management practices such as tillage lead to dissimilarities between intra- and extraradical AM fungal communities. This study aims to assess the influence of two different soil management practices (conventional tillage and no-till) on the diversity of AMF communities, both in rhizosphere soil and inside corn roots. We hypothesized that under no-till, roots are colonized as they grow through the undisturbed fungal mycelia left from the previous crop whereas under conventional tillage they are colonized by those propagules that survived disturbance and can re-establish in their new relocated and mixed environment. We predicted that the degree of similarity of AM fungal communities inside versus outside the roots would be greater under no-till than under tillage. Using terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis we observed a different AM fungal community present in roots under no-till than under conventional tillage. Moreover, the communities present in the rhizosphere soil were different than in the roots of the corn plants. These results suggest that soil management does alter the diversity of AM fungal communities associated with corn roots and that plants influence the structure of the AMF community colonizing their roots. Sequencing results indicated that the majority of AMF species found in this agricultural soil was Glomus spp. However, further work is required to determine the extent to which AM fungal genotypic alterations by soil management influences competitive relationships.     

有机肥与控释复合肥配施对茶叶产量、品质和土壤化学性质的影响

合理施肥对于提高茶叶产量和品质具有重要作用。通过3年田间试验,对比研究了6种施肥模式（常规化肥、控释复合肥、常规化肥 + 有机肥、控释复合肥 + 有机肥、70%常规化肥 + 有机肥、70%控释复合肥 + 有机肥）对茶叶产量、品质和土壤化学性质的影响。结果表明,一次性施用茶树专用控释复合肥能够达到常规化肥1年4次施用的增产效果,并显著提高了夏茶茶叶品质。与单施常规化肥相比,增施有机肥处理的茶叶产量提高10.6% ~ 14.0%,达显著水平（P < 0 .05),净收益增加8.0% ~ 18.3%,并显著提高了茶叶水浸出物和游离氨基酸总量,降低茶多酚含量和酚氨比。与常规化肥增施有机肥相比,控释复合肥增施有机肥茶叶产量提高了3.0%（P < 0.05),净收益增加7.6% ~ 8.5%,夏茶水浸出物含量提高1.34% ~ 1.39%,茶多酚含量降低了2.7% ~ 4.7%,达显著水平（P < 0.05)。70%常规化肥 + 有机肥或70%控释复合肥 + 有机肥处理的茶叶产量及品质与全量施肥增施有机肥处理相比均无显著性差异。在培肥土壤方面,增施有机肥处理显著提高了茶园0 ~ 20?cm土层土壤pH、有机质、全氮和速效氮含量。因此,从施肥方便性、茶叶产量、经济效益、茶叶品质和培肥土壤方面综合考虑,与施用常规化肥相比,控释复合肥减少用量30%并增施有机肥是最优推荐施肥措施。     

High colonization by native arbuscular mycorrhizal fungi (AMF) of rubber trees in small-holder plantations on low fertility soils in North East Thailand

Rubber tree is a very important crop in Thailand, representing an essential source of income for farmers. In the past two decades, rubber tree plantations have been greatly expanding in unfavorable areas, where climate conditions are difficult and soil fertility is very poor. To optimize latex yields, mineral fertilizers have been widely used. A better understanding of the roles of the biological compartment in soil fertility is essential to determine alternative management practices to sustain soil fertility and optimize latex yields. Arbuscular mycorrhizal fungi (AMF) are widely recognized as beneficial for plants, mainly through their role in improving plant nutrient uptake. The objective of this study was to assess the AMF populations in rubber tree plantations and the impact of both soil characteristics and plantation age on these communities. Our results showed that all rubber trees were highly colonized, regardless of the soil structure and nutrient contents. AMF colonization was not affected by the age of the trees, suggesting that maintaining the symbiosis is likely to be beneficial at all stages. A better understanding and management of the microbial communities would contribute to maintaining or restoring soil fertility, leading to a better tree growth and optimized latex yield.     

Conservation agriculture based sustainable intensification of basmati rice-wheat system in North-West India

Continuous mono-cropping of rice-wheat (RW) system with conventional tillage (CT) based management practices have led to decline in soil health, groundwater table and farmers profit in north-west India. A medium-term (4 years) farmer’s participatory strategic research trial of basmati RW system was conducted to evaluate the effects of conservation agriculture (CA) based management practices on crop yields, water productivity, profitability and soil quality. Six treatments were compared varied in the cropping system, tillage, crop establishment and residue management. CA-based management under zero-till direct seeded rice-wheat-mungbean recorded 36% higher system yield than conventional till rice-wheat system (14.91 Mg ha^?1). CA-based rice-wheat system and rice-wheat-mungbean system saved ~35% irrigation water compared to conventional RW system (2168 mm ha^?1). Total water productivity (WP_I+R) was improved by 67% with CA-based rice-wheat-mungbean system (0.90 kg grain m^?3) over the conventional system. On system basis, 42% higher net return was recorded with CA-based rice-wheat-mungbean system compared to conventional system (USD 2570 ha^?1). Mungbean integration in basmati RW system contributed 29% share in system net returns across the treatments. Soil chemical and biological properties were improved by ~40% and 150%, respectively, with CA-based management system.     

Effects of long-term contrasting lime and phosphorus applications on barley grain yield,root growth and abundance of mycorrhiza

Lime and phosphorus (P) applications are common agricultural management practices. Our aim was to quantify the effects of long-term application practices on root growth and abundance of arbuscular mycorrhizal fungi (AMF) under field conditions. We assessed the effects of lime and P fertilizer applications on barley yield, root growth and AMF abundance in 2016. Treatments were no, low, medium and high liming rate corresponding to application of 0, 4, 8 and 12 Mg lime ha⁻¹ every 5–9 years since 1942 combined with no or yearly application of 15.6 kg P ha⁻¹ since 1944. At harvest, grain yield, root intensity (core-break) and AMF abundance at different soil depths were estimated. Root development was monitored during early growth with minirhizotrons in treatments receiving low, medium and high liming rates and P fertilization. A quadratic model relating grain yield to liming rate estimated yields to peak at 6.4 Mg lime ha⁻¹ with yields of 4.2 and 3.2 Mg grain ha⁻¹ with and without P fertilization, respectively. Low and medium liming rates resulted in greater AMF abundance, especially in the no P treatments. During early growth in P-fertilized treatments, 77% and 65% more roots developed in the soil profile when treated with medium and high liming rate, respectively, compared to low liming rate. We conclude that long-term application of lime in soils receiving yearly P fertilization improved conditions for root growth in soil layers below 30 cm, but at the high liming rate, this did not translate into higher yield.     

Soil tillage and herbicide applications in pea: arbuscular mycorrhizal fungi,plant growth and nutrient concentration respond differently

ABSTRACT

We conducted a field- and pot experiment with peas to investigate the impact of soil tillage and herbicide applications on arbuscular mycorrhizal fungi (AMF), plant growth, phosphorus concentrations, C:N ratio in plants and yield. The field study was carried out in a long-term soil tillage experiment where four tillage treatments have been compared. Field soil from the experimental plots were used for the pot experiment. AMF were not affected by herbicide (MCPB) application, neither in the field nor in the pot experiments. However, AMF root colonization was enhanced by reduced tillage, minimum tillage and no-tillage practices, compared to conventional tillage. In the pot experiment, plant growth and nodulation of pea roots was negatively affected by the high herbicide dosage. In the field experiment neither tillage nor herbicide treatment exert specific effects on root growth parameters, phosphorus concentrations, C:N ratio and plant dry matter. This work demonstrates that an appropriate herbicide usage coupled with conservation soil tillage techniques can favour AMF root colonization and benefit plant growth.

Abbreviations: AMF: arbuscular mycorrhizal fungi; CT: conventional tillage; RT: reduced tillage; MT: minimum tillage; NT: no tillage; P: Phosphorus; C:N ratio: carbon:nitrogen ratio     

菌根对紫色土上间作玉米生长及磷素累积的影响

丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)在土壤与植物系统的磷素循环中发挥着关键的作用。本文通过盆栽模拟试验研究了不同AMF接种状况[不接种(NM)、接种Glomus mosseae(GM)、接种G.etunicatum(GE)]和玉米/大豆间作体系不同根系分隔方式(不分隔、尼龙网分隔、塑料膜分隔)对间作玉米植株生长及磷素吸收累积的影响。研究结果表明:GM处理下的间作玉米根系侵染率在不同根系分隔方式之间的差异不显著,而GE处理则在塑料膜分隔处理下对玉米的侵染率最高。接种不同AMF对间作玉米促生效果不同,GM和GE处理在不同根系分隔情况下表现出各自的优势,与未接种处理相比,GM处理能使玉米生物量、株高有一定程度增加并在根系不分隔处理下玉米磷吸收较多、生长较好;GE处理能使植株生物量有一定程度增加并在尼龙网分隔处理下的玉米磷吸收较多、生长较好。间作体系不同根系分隔方式对玉米的影响也不同,其中玉米地上部生物量在根系分隔处理下普遍小于不分隔处理,但根系生物量的大小情况则刚好相反。另外,无论何种接种状况,玉米根系磷含量及吸收量均以尼龙网分隔处理显著较高。而根系磷吸收效率则以接种G.mosseae且不分隔根系处理显著高于分隔处理。所有复合处理中,以接种G.etunicatum与尼龙网分隔根系组合处理对间作玉米的生长及磷素累积的促进作用最好,若应用于滇池流域,可望有效控制坡耕地土壤磷素的迁移。     

Effects of different management practices on arbuscular mycorrhizal fungal diversity in maize fields by a molecular approach

As obligate mutualistic symbionts, arbuscular mycorrhizal fungi (AMF) colonize the roots of many agricultural crops, and it is often claimed that agricultural practices are detrimental to AMF. As a result, agroecosystems impoverished in AMF may not get the fully expected range of benefits from these fungi. Using molecular markers on DNA extracted directly from soil and roots, we studied the effects of different management practices (tillage and N fertilization) on the AMF communities colonizing an experimental maize field in Central Italy. Our molecular analysis based on three different nuclear rRNA regions (18S, 28S and ITS) allowed us to assess AMF biodiversity. Glomeraceae members were the main colonizer, and they co-occurred with Gigasporaceae and Paraglomus regardless of the management practices applied. Diversisporaceae and Entrophosporaceae members were instead detected in the N-fertilized soils and in the untreated soil, respectively. The results obtained indicated that the general AMF assemblages structure and composition in the maize field plots appear to be primarily influenced by N fertilization and, to a lesser extent, by tillage. This study also validates the usefulness of multiple molecular markers to consolidate and refine the assessment of the environmental AMF diversity.     

不同复合生态模式茶园的经济效益及生态效益研究

【目的】研究不同类型复合生态茶园经济效益及茶园土壤肥力的差异,为茶园管理与决策优化提供科学指导。【方法】试验地位于浙江省,始于2012年。供试茶园包括单一种植(CK)、茶草复合(GT)、茶菌复合(BT)和茶禽复合(PT) 4种生态模式,均已持续经营10年。2019—2021年调查了茶叶产量、收入与支出明细,2021年采集0—60 cm茶园土壤测定pH、有机质、养分含量等指标,利用模糊综合评判法对土壤进行了综合肥力评价。以茶园收入作为经济指标,土壤pH、土壤有机质(SOM)、综合肥力作为生态指标,对不同类型茶园经济与生态效益进行了对比分析。【结果】1)CK模式茶园3年茶叶平均产量为189 kg/hm²,净收入为65000元/hm²。GT、PT和BT模式的茶叶平均产量分别较CK模式提高了63.5%、79.4%和99.2%,3年平均净收入提高了66.7%、99.7%和83.7%,BT模式中的黑木耳和PT模式中的散养鸡带来的附加收入,分别占该模式总收入的40.9%和22.1%。CK、GT、PT和BT模式下茶园的产投比分别是2.57、3.23、3.69...     

Exploring optimal soil mulching to enhance maize yield and water use efficiency in dryland areas in China

Water and nutrient availability significantly limits global crop production, especially for dryland agriculture in arid and semi-arid regions. To explore the optimal soil mulching options for the Loess Plateau in China, a 3-year field study was conducted to investigate the effects of various soil mulching practices on soil temperature and the water use and grain yield of spring maize. The treatments included traditional flat farming (CK), narrow plastic film mulch (NM), wide plastic film mulch (WM) and narrow plastic film mulch?+?maize straw mulch between rows (MS). The results showed that MS treatment increased consistently soil temperature during the initial stages of maize growth, and more importantly, it reduced diurnal temperature variation. MS also increased in soil water storage by 10.1%, leading to the highest water use efficiency (WUE?=?30.9?kg?ha^?1?mm^?1) over CK on 3 year average. MS significantly increased maize yield and net income of farmers by up to 20%, compared to CK. In conclusion, optimisation of soil mulching strategies significantly enhanced crop yield and water productivity in dryland agriculture in China. Our study provides important guidance for exploring better soil management practice for dryland agriculture in the other regions of the world.     

Morphological and molecular characterization of arbuscular mycorrhizal fungal communities inhabiting the roots and the soil of saffron (Crocus sativus L.) under different agricultural management practices

Crocus sativus L. cultivation is expanding to areas with low soil fertility, where mycorrhizal fungi are supposed to be essential for plants growth and ecosystems functioning. Agricultural practices applied under these conditions should lead to good saffron productivity and quality. Our objective was to study the density and diversity of mycorrhizal fungi populations associated with saffron grown in Taliouine (Morocco) under different agricultural management practices (fertilization type, age and plantation method). Morpho-anatomical studies identified rhizospheric mycorrhizal spores and assessed root colonization by arbuscular mycorrhizal fungi (AMF). Molecular identification of AMF was realized by sequencing the Large Subunit (LSU) rDNA gene region. Among the eleven species of AMF spores identified, Funneliformis and Rhizoglomus species were the most abundant (> 35%). Modern saffron plantation showed higher roots colonization rates (mycorrhization intensity (100%) and frequency (51.6%)), while in traditional plantations lower mycorrhization frequency values were found (17.4%). LSU sequencing identified five AMF genera and three unknown genomic groups, whereas Shannon diversity index indicated that AMF community composition changed significantly according to plantation age and fertilization type. Our results contribute to a better knowledge of saffron AMF communities and open new perspectives for a rational utilization of the agricultural practices for organic saffron production.     

Effects of organic and other management practices on soil nematode communities in tea plantation: a case study in southern China

Four major tea management practices (organic, pollution‐free, conventional, and semi‐natural) are employed in Chinese tea plantations at present. These practices can induce changes in the physiochemical parameters, microorganism community and enzyme activity in tea plantation soil. However, understanding of their effects on soil nematodes is still scarce. This study aimed to investigate whether and how different management practices affect the biodiversity, function, and structure of soil nematode communities in tea plantation habitats. The soil nematode community structures and ecological indices were determined from the soil samples collected more than 6 y after their respective farming practices were first applied, and different management practices did not greatly affect soil nematode community evenness or species diversity, but organic practice increased nematode trophic diversity, common species diversity, and species richness. Pollution‐free practice considerably increased fungivorous nematodes, and both pollution‐free and conventional practice decreased bacterivorous nematodes markedly in the subsurface layers of soil. Predator and omnivorous nematodes were found to be more abundant in semi‐natural plantation. Organic practice was more sustainable and suitable for tea cultivation, with the greatest biodiversity, best nutrient conditions, higher and more stable C/N ratio and lower interference in the food web.     

西北地区退耕还林工程对粮食生产与农民生计的影响

[目的]评估西北地区退耕还林工程对粮食生产与农民收入的影响,为西北地区退耕还林工程实施的有效性和可行性提供依据。[方法]以西北地区各省(区)退耕还林面积、粮食播种面积、粮食产量、农民纯收入、黄河流域径流量和土壤侵蚀总量为基础数据,运用SPSS及Excel数据库技术开展分析。[结果]退耕还林直接造成西北地区粮播面积减少,粮食总产量下降,但农民纯收入逐年增加;退耕还林面积大小与粮播面积大小和粮食产量多少呈负相关关系,与农民纯收入呈正相关关系;黄河流域径流量随着退耕还林面积的增加而增加,二者呈正相关关系;土壤侵蚀量随着退耕还林面积的增加而减少,二者之间呈负相关关系。[结论]退耕还林生态工程对西北地区粮食生产的影响不大,促进农户增收的同时起到了保持水土,改善生态环境的重要作用。     

Influences of non-herbaceous biochar on arbuscular mycorrhizal fungal abundances in roots and soils: Results from growth-chamber and field experiments

Biochar holds promise as an amendment for soil quality improvement and sequestration of atmospheric carbon dioxide. However, knowledge of how biochar influences soil properties, especially soil microorganisms, is limited. Three separate studies were conducted, with two studies using Plantago lanceolata as the AMF hosting plant, and a third being conducted in the field. Each of the three studies employed a different soil type. Furthermore, a total of five different biochars, and ten different biochar application rates, were used across the three experiments. All experiments had the goal to examine biochar influences on arbuscular mycorrhizal fungal (AMF) abundance in roots and AMF abundance (hyphal lengths) in soils. AMF abundance was either decreased or remained unchanged across all biochar treatments. When AMF abundances decreased, significant changes in soil properties, primarily in soil P availability, were observed. Application of large quantities (2.0% and 4.0%, w/w) of a lodgepole pine biochar, led to significant declines in AMF abundance in roots of 58% and 73% respectively, but not in soils. These declines in AMF abundance were accompanied by significant declines (28% and 34%) in soil P availability. After addition of a peanut shell biochar produced at 360 °C, P increased by 101% while AMF root colonization and extraradical hyphal lengths deceased by 74% and 95% respectively. Field application of mango wood biochar at rates of 23.2 and 116.1 t C ha⁻¹ increased P availabilities by 163% and 208% respectively and decreased AMF abundances in soils by 43% and 77%. These findings may have implications for soil management where the goal is to increase the services provided by AMF.     

干旱条件下墨西哥中部高地不同耕作措施和农作物残留物管理对玉米产量和净收益的影响

In the subtropical highlands of Central Mexico, where the main crop is maize （Zea mays）, the conventional practice （CP） involves tillage, monoculture and residue removal, leading to soil degradation and unsustainable use of natural resources and agricultural inputs. Conservation agriculture （CA） has been proposed as a viable alternative in the region, based on reduction in tillage, retention of adequate levels of crop residues and soil surface cover and use of crop rotation. This study began in 2009 when the highlands of Central Mexico suffered from a prolonged drought during vegetative maize growth in July-August, providing an opportunity for the on-farm comparison of CA with CP under severe drought conditions which 21 climate change models projected to become more frequent. Under dry conditions, CA resulted in higher yields and net returns per hectare as early as the first and second years after adoption by farmers. As an average of 27 plots under farmers＇ management in 2009, the maize yields were 26% higher under CA （6.3 t ha-1） than under CP （5.0 t ha-l）. 2010 was close to a normal year in terms of rainfall so yields were higher than in 2009 for both practices; in addition, the yield difference between the practices was reduced to 19% （6.8 t ha-1 for CA vs. 5.7 t ha-1 for CP）. When all the 2009 and 2010 observations were analyzed in a modified stability analysis, CA had an overall positive effect of 3 838 Mexican Pesos ha-1 （320 $US ha-1） on net return and 1.3 t ha-1 on yield. After only one to two years of adoption by farmers on their fields, CA had higher yields and net returns under dry conditions that were even drier than those predicted by the analyzed 21 climate change models under a climate change scenario, emission scenario A2.     

Arbuscular mycorrhizal fungi pre-inoculant identity determines community composition in roots

Pre-inoculation of seedlings with commercial, typically non-indigenous, AMF inoculants is common practice in horticultural and land reclamation industries. How these practices influence AMF community composition in pre-inoculated seedlings after they are planted in soil containing a resident AMF community is almost completely unknown. However, there may be important implications regarding success of horticultural practices, as well as unexpected ecological consequences. In this study we exposed Leucanthemum vulgare seedlings to five different AMF treatments (pre-inoculation with a representative of Glomus group A and Glomus group B, one of two Gigaspora spp., or no AMF) prior to exposure to a whole-soil, mixed-AMF community inoculum. After a growth period of 75 additional for 28 days, AMF community composition within the roots was analyzed using an approach combining LSU rDNA sequencing and T-RFLP analysis. Our results indicate that the AMF communities that assemble within roots were strongly influenced by AMF pre-inoculant identity. Pre-inoculation with either Glomus spp., unlike what was found for Gigaspora, greatly restricted numbers of other AMF ribotypes able to subsequently colonize roots after exposure to our Glomeraceae-dominated field soil; this suggested that phylogenetic relatedness and life history strategies may play a role in AMF community assembly. Our results further revealed concurrent changes in AMF community functions, as indicated by differences in plant biomass and foliar nutrients. These results serve to highlight the importance of considering life history differences when designing AMF inoculants and may have important implications regarding the introduction of non-indigenous AMF.     

Effects of double drilling of small grains on soil erosion by concentrated flow and crop yield

Soil erosion on agricultural land and its detrimental environmental and economical effects has aroused increased interest among both the research and policy-making communities. The call for erosion control measures adapted to local farming practices is high, especially in Europe where farmers are reluctant to adopt soil conservation techniques. This study investigates a new technique for controlling concentrated flow erosion rates in the loess belt of central Belgium: i.e. double drilling of cereals in zones of concentrated flow. Cross-sectional areas of erosion channels as well as crop yield parameters in single- and double-drilled zones were compared. The technique is based on the combined effect of the increased density of plant shoots and roots for reducing soil loss. Results indicate that double drilling can reduce soil loss through concentrated flow by 25% on average and by up to 40% under optimal conditions. No net change in wheat grain yield was observed, and farmers who participated in the experiments were satisfied with the results and the easy application of the technique. Globally, benefits were larger than costs. However, the effectiveness of the technique in reducing soil loss by concentrated flow erosion seems to be topographically restricted. For positions in the landscape with a contributing drainage area larger than ca. 0.75 ha, the effectiveness of double drilling can be doubted. Double drilling should therefore be regarded as one possibility amongst others to reduce concentrated flow erosion rates in farmers’ fields.     

耕作对坡耕地水土流失和冬小麦产量的影响

在模拟降雨和自然降雨条件下研究长期（6年）定位耕作措施对豫西早区坡耕地水分保持、土壤流失以及冬小麦产量的影响。耕作措施包括少耕、免耕覆盖、深松覆盖和常规耕作。田间模拟降雨试验用来测定不同耕作措施对径流和土壤流失的影响，自然降雨小区主要用来验证模拟试验结果，同时测定不同耕作措施对冬小麦产量的影响。模拟试验结果表明：不同耕作措施下的土壤饱和导水率没有明显差异，雨前土壤含水量和降雨强度均显著影响地表径流。在试验条件下，免耕覆盖处理未产生径流和土壤流失，水土保持效果最好。与常规耕作比较，深松覆盖处理分别减少径流和土壤流失50％和90％。尽管少耕可以有效降低土壤流失，但其产生的径流量和常规耕作相近。在自然降雨条件下，免耕覆盖和深松覆盖的水土保持效果从第3年开始显著。深松覆盖在任何年型均能够显著提高冬小麦的产量。相比较常规耕作，深松覆盖平均增产9．4％。免耕覆盖除丰水年也能显著提高冬小麦产量．但增产效果不如深松覆盖显著。少耕无明显增产效果。由于产量对农民来说是评判一个耕作措施效果的重要依据，同时考虑到深松覆盖显著的水土保持效果，我们认为深松覆盖是适合当地早作农业的一个有效耕作措施。     

Adoption of technologies that enhance soil carbon sequestration in East Africa. What influence farmers’ decision?

The last two decades have seen a rise of interest in the adoption and diffusion of agricultural technologies aimed at improving the sustainability of agricultural lands among smallholder farmers in developing countries. This papers set out to understand factors that influence the adoption of technologies that enhance soil carbon sequestration among smallholder farmers, using secondary data recorded in the World Overview of Conservation Approaches and Technologies (WOCAT) database from 45 to 50 smallholders’ farmers in selected places in Kenya and Ethiopia respectively. A Probit model was used to analyse whether socio-economic, institutional, off-farm income, technical know-how, farmers’ perceptions, and land use characteristics influences the adoption of technologies that enhance soil carbon sequestration. The results show that smallholder farmers that positively perceived net benefits of the soil carbon enhancing technologies were more likely to adopt such technologies that enhance soil carbon sequestration in both countries. Access to off-farm income and land ownership with title deeds were also found to be positively associated with adoption. Off-farm income positively influences adoption among farmer with a moderate income (100-500US$ per year) but not the rich (>500US$) farmers. Moderate to high level of skills and technical know-how required for implementing and maintaining a technology on the farm had a negative influence on adoption. This shows that interventions, aimed at addressing specific factors such as inadequate skills and knowledge, change in perception among farmers, and off-farm income are likely to have the greatest impact in decisions relating to the adoption of the soil carbon enhancing practices among farmers in East Africa.     

丛枝菌根对酸枣实生苗耐盐性的影响

本文研究了在土中加入不同量NaCl条件下 (0、1 5、3 0、4 5gkg-1干土 )接种丛枝菌根真菌 (AMF)Glomusmosseae对盆栽酸枣 (ZizyphusspinosusHu)实生苗生长及耐盐性的影响。结果表明 ,无论接种与否 ,植株的高度、根茎叶的干鲜重均随土壤NaCl浓度的增加而降低 ,而根、茎、叶和整株的Na浓度及Na全量均随土壤NaCl浓度的增加而增大。在土壤盐浓度相同的条件下 ,接种AMF植株的生长量 (株高、鲜重、干重等 )和叶片的叶绿素含量显著高于不接种植株。接种AMF的植株茎、叶中Na浓度低于不接种植株 ,而根中Na浓度、植株Na总量显著高于不接种植株。盐浓度最大的接种处理 ,其植株生长量和叶片叶绿素含量均高于不加盐不接菌处理。播种时进行盐胁迫处理和播种后 4 0d开始进行盐胁迫处理对菌根的侵染率、植株生长的影响差异不显著。上述四种盐浓度播种时进行盐处理的接种AMF植株的总干重比不接种植株分别提高 16 4 %、14 9%、4 8%、35 % ,在播种后 4 0d进行盐处理的接种AMF的植株比不接种植株分别提高 194 %、12 7%、72 %、4 6 %。结果证明 ,酸枣实生苗具有较强的耐盐性 ,其生长对菌根真菌有很强的依赖性 ,接种菌根真菌提高了其耐盐能力。