Wheat streak mosaic virus： incidence in field crops, potential reservoir within grass species and uptake in winter wheat cultivars

Wheat streak mosaic virus（WSMV）has become a re-emerging pathogen in cereal crops in the Czech Republic.WSMV was first reported in the former Czechoslovakia in the early 1980s,and then no record of the virus was documented until 2009.The incidence of the virus was recorded in recent years in several winter wheat fields and many grass species.Here,we surveyed the incidence of WSMV in cereal crops.The results demonstrated the existence of the virus in winter wheat and volunteer wheat during each year of the monitoring period,which spanned from 2013–2016.Although the range of infected samples was low（6.4%of the total tested samples）,a high incidence of well-distributed virus was recorded.In at least six fields,the virus reached severe and potentially epidemic levels.In accordance with our previous report detailing WSMV infection of native grasses,we tested several grass species commonly grown in the Czech Republic.We found that some grass species acted as experimental hosts and possible reservoirs of the virus;these included Anthoxanthum odoratum（sweet vernal grass）,Arrhenatherum elatius（false oat-grass）,Lolium multiflorum（Italian rye-grass）,Bromus japonicus（Japanese chess）,Echinochloa crus-galli（barnyard grass）,Holcus lanatus（meadow soft grass）and Holcus mollis（creeping soft grass）.Some of these grass species are also important weeds of cereals,which may be the potential source of WSMV infection in cereal crops.Several widely used winter wheat cultivars were tested in the field after artificial inoculation with WSMV to evaluate virus titre by RT-qPCR.Overall,the tested cultivars had a low virus titre,which is associated with mild disease symptoms and may provide a good level of crop resistance to WSMV.

Intraspecific trait variation in three common grass species reveals fine-scale species adjustment to local environmental conditions

Aims Studies along environmental gradients have shown that intraspecific trait variation(ITV)may contribute considerably to community-level trait variation.However,we lack knowledge about how the extent of ITV varies on a local scale and whether a varying extent of ITV is related to differences in local environmental site and plant commu-nity characteristics.Methods We investigated plant height,specific leaf area(SLA),leaf dry mat-ter content(LDMC)and leaf greenness of three common grass spe-cies(Arrhenatherum elatius,Dactylis glomerata,Poa pratensis)in 12 mown grasslands in a local study area around Jena(Thuringia,Germany)across three spatially hierarchical sampling levels:between sites,between subplots within site and within subplots.Important Findings Arrhenatherum elatius and D.glomerata had higher means in plant height and a lower variation in leaf traits than P.pratensis.The major proportions of variation in leaf traits of P.pratensis and D.glomerata were found within subplots,while the traits of A.elatius varied mainly between sites.Trait correlations across the hierarchical sam-pling levels were highly consistent in A.elatius,but more variable in D.glomerata and P.pratensis.Environmental site and plant commu-nity characteristics mostly explained a larger proportion of variation in trait means in A.elatius than in D.glomerata and P.pratensis,while metrics of ITV were generally less predictable.Our results suggest that trait variation in P.pratensis and D.glomerata is more strongly related to within-site conditions(i.e.biotic interactions),while differences in local environmental conditions between sites have a strong impact on trait variation in A.elatius.Since our study was limited to three grass species,further studies with a greater number of species are required to make generalizations about the importance of biotic interactions and environmental conditions as drivers of ITV at local scale.

Impacts of livestock grazing on a savanna grassland in Kenya

The dynamics of most rangelands in Kenya remain to be poorly understood. This paper provides baseline information on the response of a semiarid rangeland under different livestock grazing regimes on land inhabited by the Massai people in the east side of Amboseli National Park in Kenya. The data were collected from grasslands designated into four types： （1） grassland from previous Massai settlements that had been abandoned for over twenty years; （2） grassland excluded from livestock grazing for eight years; （3） a dry season grazing area; and （4） a continuous grazing area where grazing occurred throughout all seasons. Collected data included grass species composition, grass height, inter-tuft distance, standing grass biomass and soil characteristics. The results indicated that continuous grazing area in semiarid rangelands exhibited loss of vegetation with negative, long-term effects on grass functional qualities and forage production, whereas grassland that used traditional Maasai grazing methods showed efficiency and desirable effects on the rangelands. The results also showed that abandoned homestead sites, though degraded, were important nutrient reservoirs.

Construction of Forest and Grass Industry Economic Belt Using Land Resources in Road Side Slope

The construction of expressway and high-speed rail is at the sacrifice of the soil ecological environment. It brings about much damaged land and bare slope. It is necessary to restore vegetation and rebuild landscape. In the design of target plant community and configuration plants,it is required to select as far as possible plants that can blossom and bear fruit or pods. Then seeds of these plants can be harvested,processed and sold,and applied for other projects,so as to develop into a complete forest and grass seed industry chain. This not only reasonably utilizes land resources,but also provides a new approach to the problem of insufficient fine forest seed sources in China. This paper discussed the use of land resources in road side slope and forest and grass seed selection and breeding technology,and elaborated the industrialized development paths for forest and grass seed industries in road side slope. Finally,it arrived at following recommendations.( i) The construction of forest and grass industry economic belt using land resources in road side slope can realize maximum land value. Building a road can help people there get rich,and the type of land and water cultivates its type of forest and grass.( ii) It can make up for the losses incurred from construction of expressway and high-speed rail or destroying forest land,and it can increase farmers' income.( iii) It can increase the supply of domestic seeds,reduce seed import,save foreign exchange,and partly solve the problem of insufficient supply of forest and grass seeds.( iv) It is able to form a complete forest and grass seed industry economic cycle chain,increase employment,and provide new approaches for enriching and benefiting farmers.

Application of Hoof Tillage Method to Improve Degraded Mountain Grassland

Four seeding methods, including broadcast sowing, feeding seeds to sheep, putting seed bag on sheep and cattle, and mix-seeding were combined with hoof tillage method to improve the degraded mountain grassland where large gradient limited the use of machine. The results showed that the most suitable grassland type for hoof tillage was mountain meadow steppe. The optimum reseeding period was early spring, followed by late autumn ; and Sainfoin （Onobrychis sativa） was the most suitable herbage species. The optimum reseeding method was artificial broadcasting in the slope with the gradient 〈 20°, followed by putting seed bag on sheep and cattle. After improvement of hoof tillage, the vegetation coverage increased by 35%, the proportion of high quality herbage increased by 25%, and the fresh yield increased by three to four times.

Impacts of native vegetation on the hydraulic properties of the concentrated flows in bank gullies

To quantify the impacts of native vegetation on the spatial and temporal variations in hydraulic properties of bank gully concentrated flows,a series of in situ flume experiments in the bank gully were performed at the Yuanmou Gully Erosion and Collapse Experimental Station in the dry-hot valley region of the Jinsha River,Southwest China.This experiment involved upstream catchment areas withone-and two-year native grass(Heteropogon contortus)and bare land drained to bare gully headcuts,i.e.,Gullies 1,2 and 3.In Gully 4,Heteropogon contortus and Agave sisalana were planted in the upstream catchment area and gully bed,respectively.Among these experiments,the sediment concentration in runoff in Gully 3 was the highest and that in Gully 2 was the lowest,clearly indicating that the sediment concentration in runoff obviously decreased and the deposition of sediment obviously increased as the vegetation cover increased.The concentrated flows were turbulent in response to the flow discharge.The concentrated flows in the gully zones with native grass and bare land were sub-and supercritical,respectively.The flow rate and shear stress in Gully 3 upstream catchment area were highest among the four upstream catchment areas,while the flow rate and shear stress in the gully bed of Gully 4 were lowest among the four gully beds,indicating that native grass notably decreased the bank gully flow rate and shear stress.The Darcy–Weisbach friction factor(resistance f)and flow energy consumption in the gully bed of Gully 4 were notably higher than those in the other three gully beds,clearly indicating that native grass increased the bank gully surface resistance and flow energy consumption.The Reynolds number(Re),flow rate,shear stress,resistance f,and flow energy consumption in the gully beds and upstream areas increased over time,while the sediment concentration in runoff and Froude number(Fr)decreased.Overall,increasing vegetation cover in upstream catchment areas and downstream gully beds of the bank gully is essential for gully erosion mitigation.

Identification and Chemical Composition of Major Camel Feed Resources in Degahbur District of Jarar Zone, Somali Regional State, Ethiopia

This study was conducted to identify major available camel feed resources and determine their chemical composition in Degahbur district. A total of 120 respondents were selected using purposive sampling technique. Data from the selected actors were collected using a semi-structured questionnaire survey, focus group discussion and field observations. The study revealed that the majority (82.5%) of the respondents in the study area were male headed households. Browsing trees and shrubs were the major available livestock feed resources both in dry (51.6%) and wet (68%) season, and followed by herbaceous species (26.6 and 23.7% for dry and wet season, respectively). The study identified about 20 herbaceous, 24 trees, 11 shrubs, 7 bush and 17 grass species which are used as camel feed in the study area. Chemical composition analyses of the sampled feeds indicated that there was a significant difference in crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) between species in different seasons. The NDF contents in the current study were above the critical value of 60% which was reported to result in decreased voluntary feed intake, feed conversion efficiency and longer rumination time. In general, the findings indicated that the use of improved forages and agro-industrial by-products as camel was minimal;thus, camels were fed on available feed resources which are poor in nutritional quality without any supplementation. Therefore, the study suggests the need for improving camel feeding practices in the study area to enhance camel productivity.

Soil Carbon, Nitrogen and Microbial Dynamics of Pasturelands: Impacts of Grazing Intensity and Planting Systems

Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well understood yet ir the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen （N） dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems （ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand） at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0 30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.

Mind the gap among patches in arid plant communities:rapid root proliferation in response to N addition

Aims In arid communities,it has been proposed that individual plants can extend their roots beyond their canopy exploring neighbour-ing bare ground areas.This becomes relevant in systems where the vegetation is distributed in patches surrounded by bare soil.However,whether roots of different species may be overlapping under bare ground areas is still controversial.The factors control-ling root responses when no plants appear to be directly influ-encing the gap among patches are still unclear.The aim of our study was to detect perennial grasses responses to an N enrich-ment pulse.Methods In a semi-arid steppe(Patagonia,Argentina),we buried root traps filled with sieved soil with and without N addition,under bare soil patches.Traps were harvested after 4 and 6 months.Trap neighbour-hoods(30 cm in diameter)included at least three of the dominant tussock species.After harvests,we identified species in the traps by root traits and quantified diversity,biomass and specific relative growth rates.Important Findings Bare ground areas show simultaneous root growth of different spe-cies.Diversity of perennial grass roots was higher with N addition than without it in the first harvest(4 months),but this difference disappeared in the second harvest(6 months).Root biomass was maximal after 6 months in N addition traps.Species preferred by herbivores(Bromus pictus and Poa ligularis)showed rapid growth and responses to N addition.Differences between harvests may be an indicative that N pulses interact with rising temperatures and soil water content as growing season progress.