Prevalence and ecological factors affecting the distribution of plant-parasitic nematodes in Prunus groves in Spain

A wide survey was conducted to study plant-parasitic nematodes(PPNs)associated with Prunus groves in Spain.This research aimed to determine the prevalence and distribution of PPNs in Prunus groves,as well as the influence of explanatory variables describing soil,climate and agricultural management in structuring the variation of PPNs community composition.A total of 218 sampling sites were surveyed and 84 PPN species belonging to 32 genera were identified based of an integrative taxonomic approach.PPN species considered as potential limiting factors in Prunus production,such as Meloidogyne arenaria,M.incognita,M.javanica,Pratylenchus penetrans and P.vulnus,were identified in this survey.Seven soil physico-chemical(C,Mg,N,Na,OM,P,pH and clay,loamy sand and sandy loam texture classes),four climate(Bio04,Bio05,Bio13 and Bio14)and four agricultural management variables(grove-use history less than 10 years,irrigation,apricot seedling rootstock,and Montclar rootstock)were identified as the most influential variables driving spatial patterns of PPNs communities.In particular,younger plantations showed higher values for species richness and diversity indices than groves cultivated for more than 20 years with Prunus spp.Our study increases the knowledge of the distribution and prevalence of PPNs associated with Prunus rhizosphere,as well as on the influence of explanatory variables driving the spatial structure PPNs communities,which has important implications for the successful design of sustainable management strategies in the future in this agricultural system.

Parasitic Plants <i>Striga</i>and <i>Phelipanche</i>Dependent upon Exogenous Strigolactones for Germination Have Retained Genes for Strigolactone Biosynthesis

Strigolactones are plant hormones with multiple functions, including regulating various aspects of plant architecture such as shoot branching, facilitating the colonization of plant roots by arbuscular mycorrhizal fungi, and acting as seed germination stimulants for certain parasitic plants of the family Orobanchaceae. The obligate parasitic species Phelipanche aegyptiaca and Striga hermonthica require strigolactones for germination, while the facultative parasite Triphysaria versicolor does not. It has been hypothesized that P. aegyptiaca and S. hermonthica would have undergone evolutionary loss of strigolactone biosynthesis as a part of their mechanism to enable specific detection of exogenous strigolactones. We analyzed the transcriptomes of P. aegyptiaca, S. hermonthica and T. versicolor and identified genes known to act in strigolactone synthesis (D27, CCD7, CCD8, and MAX1), perception (MAX2 and D14) and transport (PDR12). These genes were then analyzed to assess likelihood of function. Transcripts of all strigolactone-related genes were found in P. aegyptiaca and S. hermonthica, and evidence points to their encoding functional proteins. Gene open reading frames were consistent with homologs from Arabidopsis and other strigolactone-producing plants, and all genes were expressed in parasite tissues. In general, the genes related to strigolactone synthesis and perception appeared to be evolving under codon-based selective constraints in strigolactone-dependent species. Bioassays of S. hermonthica root extracts indicated the presence of strigolactone class stimulants on germination of P. aegyptiaca seeds. Taken together, these results indicate that Phelipanche aegyptiaca and S. hermonthica have retained functional genes involved in strigolactone biosynthesis, suggesting that the parasites use both endogenous and exogenous strigolactones and have mechanisms to differentiate the two.

First genetic linkage map of Lathyrus cicera based on RNA sequencing-derived markers: Key tool for genetic mapping of disease resistance

The Lathyrus cicera transcriptome was analysed in response to rust(Uromyces pisi)infection to develop novel molecular breeding tools with potential for genetic mapping of resistance in this robust orphan legume species.One RNA-seq library each was generated from control and rust-inoculated leaves from two L.cicera genotypes with contrasting quantitative resistance,de novo assembled into contigs and sequence polymorphisms were identified.In toto,19,224 SNPs differentiate the susceptible from the partially resistant genotype’s transcriptome.In addition,we developed and tested 341 expressed E-SSR markers from the contigs,of which 60.7%varied between the two L.cicera genotypes.A first L.cicera linkage map was created using part of the developed markers in a RIL population from the cross of the two genotypes.This map contains 307 markers,covered 724.2 cM and is organised in 7 major and 2 minor linkage groups,with an average mapping interval of 2.4 cM.The genic markers also enabled us to compare their position in L.cicera map with the physical position of the same markers mapped on Medicago truncatula genome,highlighting a high macrosyntenic conservation between both species.This study provides a large new set of genic polymorphic molecular markers with potential for mapping rust resistances.It represents the first step towards genomics-assisted precision breeding in L.cicera.

Appraising trapping efficiency of vegetative barriers in agricultural landscapes:Strategy based on a probabilistic approach based on a review of available information

Vegetative barriers have proven their effectiveness in controlling water erosion and enhancing other ecosystem services in agricultural areas.This characteristic has led to the conservation and promotion of vegetative barriers as landscape elements by the Common Agricultural Policy and other policy initiatives.Numerous reviews have dealt with the trapping efficiency of vegetated barriers,although they usually focus on studies from humid climates where their implantation and survival are more favourable.However,vegetated barriers are also an attractive alternative in arid and semi-arid climates.They limit competition for water and nutrients with crops to a reduced area compared to other best management practices,such as cover crops.This study presents a review of trapping efficiency of sediment,runoff,and nutrients(P and N)by vegetative barriers in regions of humid and arid,and semi-arid,climates,and a strategy based on sediment trapping efficiency probability,which in turn is based on the results obtained from our review.Different types of independent variables were grouped and identified for the review:related to the vegetative barrier dimension(buffer width,slope of the plot,and buffer area ratio),and related to the experimental conditions(type of vegetation in the buffer,soil protection of the non-buffered area,type of climate,type of experimental measurement and origin of rainfall).An explor-atory analysis evaluated the significance of the experimental variables,which identified the need to focus on experiments under natural rainfall since those carried out with simulated rainfall presented statis-tically significant differences.In general,average trapping efficiencies for runoff and sediment were 40.1 and 62.6%,respectively.For nutrients,values of trapping efficiencies had an average of 44.9%for phosphorus and 38.4%for nitrogen.Runoff and sediment trapping efficiency in arid and semi-arid re-gions tended to be higher than in humid regions.Regarding dimensional variables,a positive trend was observed in the runoff and sediment trapping efficiency with the width of the vegetative barrier,with a large variability across all the width range.Finally,based on the results of our review,we developed a probabilistic model for sediment trapping efficiency as a normalised cumulative probability distribution function for the two climatic regions separately.Also,we developed it as a function of the width of the vegetative barrier for each climatic region,to facilitate decision-making.This model shows that in 92%of the cases,a vegetative barrier will reduce erosion in humid climates,while this trapping efficiency will be 100%in semi-arid and arid conditions.This analysis showed that vegetative barriers are an alternative to other best management practices,e.g.cover crops,when there are operational or agronomic impedi-ments to their implementation,having a high success rate in reducing erosion in any agricultural area.

Morphological and molecular characterization of the rice root-knot nematode, Meloidogyne graminicola, Golden and Birchfeild, 1965 occurring in Zhejiang, China

The rice root-knot nematode Meloidogyne graminicola is a severe pest of rice. In China, it was first reported from Hainan Province, and later from several other provinces. In the present study, a rice root-knot nematode population found from the rice cultivation areas of Zhejiang Province, China is characterized via molecular analysis using internal transcribed spacer(ITS) and cytochrome c oxidase subunit Ⅱ(coxⅡ)-16 S rRNA genes and scanning electron microscopy(SEM) observations of males and the second-stage juveniles. Morphometric data and molecular sequence comparisons for all M. graminicola populations occurring in China are also provided. The overall morphology of M. graminicola found in Zhejiang match well with the original description, though males have a slightly longer body and stylet, and a shorter tail, while the second-stage juvenile is also slightly longer than in the original description. This is the first report of M. graminicola from Zhejiang. Phylogenetic studies based on coxⅡ suggest that all the Chinese populations belong to Type B. This study expands knowledge of the increasing distribution and phylogenetic relationships of M. graminicola that occur in China.

Shared and tailored common bean transcriptomic responses to combined fusarium wilt and water deficit

Common bean(Phaseolus vulgaris L.),one of the most consumed food legumes worldwide,is threatened by two main constraints that are found frequently together in nature,water deficit(WD)and fusarium wilt(Fop).To understand the shared and unique responses of common bean to Fop and WD,we analyzed the transcriptomic changes and phenotypic responses in two accessions,one resistant and one susceptible to both stresses,exposed to single and combined stresses.Physiological responses(photosynthetic performance and pigments quantification)and disease progression were also assessed.The combined FopWD imposition negatively affected the photosynthetic performance and increased the susceptible accession disease symptoms.The susceptible accession revealed a higher level of transcriptional changes than the resistant one,and WD single stress triggered the highest transcriptional changes.While 89 differentially expressed genes were identified exclusively in combined stresses for the susceptible accession,35 were identified in the resistant one.These genes belong mainly to“stress”,“signaling”,“cell wall”,“hormone metabolism”,and“secondary metabolism”functional categories.Among the up-regulated genes with higher expression in the resistant accession,the cysteine-rich secretory,antigen 5 and Pr-1(CAP)superfamily protein,a ribulose bisphosphate carboxylase family protein,and a chitinase A seem promising targets for multiple stress breeding.

Baseline of the Use of Solar Irrigation Pump in the Niayes Area in Senegal

Solar irrigation pumps are considered as an alternative to the use of diesel and electric pumps due to the high cost of energy. These pumps are now increasingly used in the Niayes area. Thus, a more in-depth knowledge about the components of a solar pumping system and their characteristics available on the market as well as prices can be beneficial. This study was conducted to have an idea on the baseline of the use of solar irrigation pumps in this area. To perform this study, surveys were conducted among 12 suppliers and 10 service providers located in Dakar, Thies, Louga and Saint-Louis region and among 53 users located in Potou area which is in Louga region. Results show a wide range of pump brands and characteristics. Brands found were Lorentz, LIKOU, SHIMGE, Grundfos, Solar pump, Feili, Difful, JUQIANG, Solar tech, and Asaman. The pumps’ flow rate varies between 2.5 m3/h and 45 m3/h, the pressure ranges from 15 m to 160 m and the power is between 0.072 kW and 10 kW. The price of these pumps varies depending on the brand used and their characteristics. In addition, other materials are available, such as panels with power ranging from 80 W to 330 W and electric cables. The price of these components varies according on the type used. Thus, the investment cost for implementation varies between 640 euros (420,000 CFA) and 25,087 euros (16,455,919 CFA). The cost of installation varies between 76.3 euros (50,000 CFA) and 1219.6 euros (800,000 CFA). Concerning maintenance, it is generally free during the warranty period when the equipment is supplied and installed by the same company. However, the cost of maintenance varies between 152.5 euros and 457.4 euros/year or is estimated at 45.7 euro/maintenance after the warranty years. Investigations conducted among users show that farmers in general do not perform pump maintenance due to a lack of knowledge and financial means. Thus, according to farmers, factors that impact pumps operation are the low sunshine that occurs between December and January and the iron in the water and low well discharge.

Technical and Economic Feasibility of Solar Pump Irrigation in the North-Niayes Region in Senegal

Northern Niayes is an area where agriculture is the main activity. Water used for irrigation in this area comes exclusively from groundwater. Farmers do not have access to electricity, thus fuel is the main source of energy used, which is very expensive. The objective of this study was to assess the techno-economic feasibility of solar irrigation pumps. Regarding technical feasibility, pump sizing was carried out on the basis of irrigation management, irrigation techniques, and water distribution. Also, the economic feasibility was studied on the basis of the Net Present Value, Benefit-Cost Ratio, Internal Rate of Return and Payback Period. Results showed for cultivated area ranging from 0.05 ha to 1.91 ha, pumps’ flow rate does not vary greatly from one irrigation technique to another. It varies between 2.5 m3/h and 31 m3/h. However, pressure and power are higher when using drip and sprinkler irrigation techniques, ranging from 27.8 m to 39.9 m for drip and 40.1 m to 58.5 m for sprinkler irrigation. The power varies between 0.05 kW and 1.6 kW for manual, between 0.05 kW and 2.5 kW for drip and between 0.1 kW and 4.75 kW for sprinkler irrigation. The investment cost is variable (669 euros to 21,400 euros), depending on the cultivated area, pump brands and characteristics, and irrigation techniques. Results show that the investment cost ranges from 669 euros (438,500 CFA) to 4090 euros (2,683,000 CFA) when using the manual irrigation technique, from 1281 euros to 20,600 euros when using the drip irrigation technique and from 819 euros to 21,403 euros when using sprinkler irrigation technique for individual pumps. The investment cost is higher when using reservoirs. In this case, the investment cost varied between €722 and €6062 for manual irrigation, €1532 and €25,882 for drip irrigation and €900 and €28,000 for sprinkling. However, the total investment cost at the entire lowland scale is higher when farmers use the pumps individually and lower when farmers use the pumps in groups when using manual and drip irrigation techniques. NPV varies between 15,993€ (0.75 ha) and 103,139€ (1.41 ha) and between 13,064€ and 86,139€ when using sprinkler irrigation techniques with PVC pipes and when using the drip irrigation technique, respectively. BCR is estimated to average 2.2, 2, and 2 respectively when using manual, drip, and sprinkler irrigation techniques. In addition, PBP is reached more rapidly when using the manual irrigation technique.

The interactive effect of temperature and fertilizer types determines the dominant microbes in nitrous oxide emissions and the dicyandiamide efficacy in a vegetable soil

Heat waves associated with global warming and extreme climates would arouse serious consequences on nitrogen(N)cycle.However,the responses of the functional guilds to different temperatures,especially high temperature and the cascading effect on N_(2)O emissions remain unclear.An incubation study was conducted to examine the effect of different temperatures(20°C,30°C,and 40°C)and fertilizer types(urea and manure)on N_(2)O-producers and N_(2)O-reducers,as well as the efficacy of dicyandiamide(DCD)on N_(2)O emissions in a vegetable soil.Results showed that ammonia oxidizers and nirS-type denitrifiers were well adapted to high temperature(40°C)with manure application,while the fungal nirK-denitrifiers had better tolerance with urea application.The nosZ clade I microbes had a strong adaptability to various temperatures regardless of fertilization type,while the growth of nosZ clade II group microbes in non-fertilized soil(control)were significantly inhibited at higher temperature.The N_(2)O emissions were significantly decreased with increasing temperature and DCD application(up to 60%,even at 40°C).Under high temperature conditions,fungal denitrifiers play a significant role in N-limited soils(non-fertilized)while nirS-type denitrifiers was more important in fertilized soils in N_(2)O emissions,which should be specially targeted when mitigating N_(2)O emissions under global warming climate.

Evaluation of soil erosion risk and identification of soil cover and management factor (C) for RUSLE in European vineyards with different soil management

Vineyards show some of the largest erosion rates reported in agricultural areas in Europe.Reported rates vary considerably under the same land use,since erosion processes are highly affected by climate,soil,topography and by the adopted soil management practices.Literature also shows differences in the effect of same conservation practices on reducing soil erosion from conventional,bare soil based,management.The Revised Universal Soil Loss Equation(RUSLE)is commonly adopted to estimate rates of water erosion on cropland under different forms of land use and management,but it requires proper value of soil cover and management(C)factors in order to obtain a reliable evaluation of local soil erosion rates.In this study the ORUSCAL(Orchard RUSle CALibration)is used to identify the best calibration strategy against long-term experimental data.Afterwards,ORUSCAL is used in order to apply the RUSLE technology from farm based information across different European wine-growing regions.The results suggest that the best strategy for calibration should incorporate the soil moisture sub-factor(Sm)to provide better soil loss predictions.The C factor,whose average values ranged from 0.012 to 0.597.presented a large spatial variability due to coupling with local climate and specific local management.The comparison across the five wine-growing regions indicates that for the soil protection management,permanent cover crop is the best measure for accomplishing sustainable erosion rates across the studied areas.Alternate and temporary cover crops,that are used in areas of limited water resources to prevent competition with vines,failed to achieve sustainable erosion rates,that still need to be addressed.This raises the need for a careful use of C values developed under different environmental conditions.

Spatial variability of soil organic carbon stock in an olive orchard at catchment scale in Southern Spain

Orchards have a high potential for carbon sequestration.However,little research is available on the spatial variability at catchment scale and on the difference between the tree area and the lanes.We analyzed theik spatial variability of soil organic carbon stock,SOCstock at 90 cm depth in an 8-ha catchment in Southern Spain with olives on a vertic soil.Results showed higher soil organic carbon concentration,SOC,in the tree area as compared to the lane up to 60 cm depth,but its impact on SOCstock was negligible since it was compensated by the higher soil bulk density in the lane.SOC at different depths was correlated with that in the top 0-5 cm.The overall SOCstock of the orchard was 4.14 kg m^(-2),ranging between 1.8 and 6.0 kg m^(-2).This SOCstock is in the mid-lower range of values reported for olive orchards,measured at smaller scale,and similar to those other intensive field crops and agroforestry under comparable rainfall conditions.The spatial variability in SOCstock was correlated to several geomorphological variables:elevation,cumulative upstream area,topographic wetness index,sediment transport index,and tillage erosion.Differences in SOC and SOCstock are driven by the sediment redis-tribution downslope,mainly by tillage erosion,and higher soil water availability in lower areas allowing higher biomass production.These topographic indexes and the correlation between SOC in the topsoil and SOCstock up to 90 cm should be further explored in other typology of olive orchards for facilitating the mapping of SOC_(stock).

Mulching as best management practice to reduce surface runoff and erosion in steep clayey olive groves

No-tillage and soil mulching with pruning residues,applied in olive groves of the semi-arid Mediter-ranean environment,as erosion control practices still practice not fully studied.This study has evaluated the saturated hydraulic conductivity(Ksat),surface runoff(SR)and soil erosion(SL)under rainfall at plot scale throughout two years in four different management practices,total soil cover with a net(SP),mechanical tillage(MT)and mulching by vegetal residues at 3,5·10^(3) and 17,5·10^(3) kg ha^(-1) of dry matter(NTR350 and NTR1750),in an olive grove of Southern Italy.Ksat varied between 1.6(MT)and 25.1(NTR1750)mm/h.A clear reduction in runoff and soil losses was detected for the mulch-based practices when compared to MT,from 20 to 32%in the runoff coefficient and 75-80%in SL,with higher reductions in the NTR1750.This reduction in SL can be mainly explained by the reduction in SR and rain-splash,interrill and rill erosion,due to protection by mulch residues,which increased the vegetal cover and organic matter content of mulched plots.The vegetal cover was on average higher in SP(33%),NTR1750(25%)and NTR350(22%),and lower in MT(12%).The mean organic matter content of soil was 2.01%,1.69%,1.34%and 0.82%for NTR1750,NTR350,SP and MT respectively.Overall,the results quantify the impact of soil mulching with pruning residues at different doses,which will provide guidelines to control and mitigate the hydrological response of clayey and steep soils in Mediterranean olive groves,analysing the associated environmental and economic benefits.

In-depth analysis of soil management and farmers’perceptions of related risks in two olive grove areas in southern Spain

This manuscript presents a questionnaire-based study aimed to provide a detailed analysis on the different soil management carried out by olive farmers in two representative olive-growing areas in southern Spain(Cordoba and Estepa),their perceptions on cover crop use and the possible influence of the different types of farms and farmers’typologies on these perceptions.Our results show a relatively large variability of soil management,with fourteen options,as a result of a combination of different alternatives for bare soil and cover crops with the use or not of pruning residues,but with a great similarity between both areas.The results indicate a high adoption of soil conservation measures in the two study areas,with 63%of farmers using cover crops and 80%a mulch of pruning residues,higher than that reported in previous studies in Southern Spain,and a trend of lower use of these techniques by less experienced and younger farmers.This high penetration of soil conservation measures resulted in a significant reduction of soil erosion risk,as indicated by the relatively low values for the cover and management factor(C)of RUSLE,also calculated and presented in this study,but also the possibility of focusing further efforts on fanners with less experience.Our results indicate the persistence of a minor,but relevant,percentage of farmers using bare soil management(37%)and no mulching(20%),with a moderate concern on the impact of soil erosion on soil degradation and provision of ecosystem services.This suggests the need to concentrate efforts also on this cluster of farmers to enhance the success of what seems to be a remarkable expansion of the use of soil conservation measures in recent decades in Southern Spain,but also in similar areas in the Mediterranean basin.

SHui, an EU-Chinese cooperative project to optimize soil and water management in agricultural areas in the ⅩⅪ century

This article outlines the major scientific objectives of the SHui project that seeks to optimize soil and water use in agricultural systems in the EU and China,by considering major current scientific challenges in this area.SHui(for Soil Hydrology research platform underpinning innovation to manage water scarcity in European and Chinese cropping systems)is large cooperative project that aims to provide significant advances through transdisciplinary research at multiple scales(plot,field,catchment and region).This paper explains our research platform of long-term experiments established at plot scale,approaches taken to integrate crop and hydrological models at field scale;coupled crop models and satellite-based observations at regional scales;decision support systems for specific farming situations;and the integration of these technologies to provide policy recommendations through socio-economic analysis of the impact of soil and water saving technologies.It also outlines the training of stake-holders to develop a basic common curriculum despite the subject being distributed across different disciplines and professions.As such,this article provides a review of major challenges for improving soil and water use in EU and China as well as information about the potential to access information made available by SHui,and to allow others to engage with the project.