Grassland Science最新文献

Mixed seeded plots of timothy (Phleum pratense L.) and galega (Galega orientalis Lam.) were established in multiple seeding times from 2014 to 2017 to determine the latest sowing limit in the Konsen region, northern Japan, where growing conditions are severe. Although low yields were observed in some cases when the soil freezing depth was deeper than average, the dry matter yield of the first crop of galega in the year after sowing was higher under conditions that ensured pre-overwintering plant length growth of 30 cm or more, as compared with growth of less than 30 cm. Galega rhizomes were observed under conditions of pre-overwintering plant length of 28 cm or more, but not under conditions of less than 28 cm in length. Therefore, achieving 30 cm plant length prior to overwintering is desirable when sowing galega in the Konsen region. Furthermore, the effective cumulative temperature (ECT) required for pre-overwintering galega to reach 30 cm in plant length was 1079°C, for which seeding dates were calculated to be July 10 and June 29 in terms of calendar days, with 80% and 90% probability. In the Konsen region, galega should be sown earlier than in other regions of Hokkaido to ensure the growth rate because of the effects of soil freezing on overwintering performance.

It is common in southern China that rice (Oryza sativa L.) fields are sown with a cover crop like Italian ryegrass (Lolium multiflorum L.) following autumn harvest. The objective of the present research was to compare the effects of different no-tillage methods on the yield, nutritive composition and silage fermentation quality of Italian ryegrass. Italian ryegrass was planted in winter fallow paddy fields on 9 days (NT9) and 5 days (NT5) prior to rice harvest and on 1 day after rice harvest for 2 years. Sowing prior to harvest was no-tillage, and sowing after rice harvest was either no-tillage (NT1) or conventional tillage (CK). The grass was harvested and ensiled two times each year. The growing year had no significant effects on the yield and most nutrition components, while it had significant effects on pH value, butyric acid and NH₃-N contents of silage. There were no differences in the yield, nutritional composition and silage fermentation quality among sowing methods. The neutral detergent fiber and acid detergent fiber of NT1 decreased slightly compared with NT9, NT5 and CK (p > .05). There was no difference in silage fermentation quality among the four treatments. The best sowing method for Italian ryegrass with second cut in winter fallow paddy was no-tillage sowing after rice harvest.

Crown vetch (Coronilla varia L.) is a widely spread legume species that can be used as a forage crop for herbivores. The crown vetch herbage was ensiled with 0, 4, or 8% of crushed barley grain on a wet basis. The crude protein (CP) and neutral detergent fiber in organic matter (NDFom) contents of crown vetch herbage were higher than those of crown vetch silages (p < .05). The malondialdehyde (MDA) concentrations of herbage and silages with barley grain were lower than that of silage without barley grain (p < .05). The linoleic acid (C18:2) percentage of total fatty acids in forage decreased with the ensiling process (p < .05). The addition of crushed barley grain in the ensiling process of crown vetch herbage preserved the α-linolenic acid (C18:3) percentage of total fatty acids (p < .05). The crushed barley grain positively affected dry matter (DM) and ammonia-nitrogen levels, acidity value (pH and lactic, acetic and propionic acids) and in vitro ruminal fermentation values (cumulative gas production, metabolic energy [ME], net energy lactation [NEL] and organic matter digestion [OMd]) of crown vetch silage (p < .05). The concentration of volatile fatty acids (acetic, butyric, propionic, iso-valeric and iso-butyric acids) in the in vitro ruminal fermentation fluid was similar in herbage and silages of crown vetch (p > .05). Consequently, crushed barley grain (especially 4% rate) in the ensiling process of crown vetch increased hemicellulose, easily digestible carbohydrates, linoleic acid, α-linolenic acid in silage and in vitro ruminal digestion parameters, positively affected silage acidity and decreased lipid peroxidation.

This study monitored spatiotemporal variation in aboveground biomass of a paddock (1.1 ha) in a sown tropical grass pasture under cattle grazing over a 22-year period (1995–2016) by nondestructively estimating biomasses of 182 fixed locations (0.5 × 0.5 m each) in the paddock at about monthly intervals during the annual stocking season (May to October or November). The mean aboveground biomass of the paddock varied seasonally and interannually between 33 and 605 g DM/m² and was explained by a regression model including positive effects of mean air temperature, N fertilizer rate and total precipitation during the preceding 60 days (R² = 0.311, P < 0.001). The coefficient of variation of aboveground biomass, as an indicator of spatial (within-paddock) variability, varied seasonally and interannually between 0.16 and 0.94, and was described by a model incorporating a positive effect of cumulative stocking density during the preceding 40 days and negative effects of mean air temperature, total precipitation during the preceding 20 days and N fertilizer rate during the preceding 60 days (R² = 0.277, P < 0.001). The spatial distribution pattern of aboveground biomass in the paddock was persistent (P < 0.05) or not persistent over the study period, almost without being reversed. In detail, patterns in the mid stocking season tended to maintain mutual similarity in the entire range of the intervals between the measurements (364–7,694 days), whereas those at the beginning and near end of the stocking season lost mutual similarity as the interval increased. There was no indubitable evidence that the changes in botanical composition destabilized the spatial distribution pattern of aboveground biomass. The results indicate the need for assessing how the long-term stability of the within-paddock distribution pattern of aboveground biomass affects agronomic and ecological performance of the grazing system.

Semiarid grasslands contribute significantly to global soil carbon (C) storage. Carbon loss from these systems via microbial decomposition is controlled by abiotic and biotic factors such as soil moisture and temperature and C input. Plant litter in these systems can be present above the soil surface or mixed with surface soil by trampling, especially in intensively grazed areas. A quantitative understanding of abiotic factors' interactive effect is critical for predicting soil C dynamics in response to grassland management and environmental conditions changes. Therefore, we conducted a 3-month laboratory incubation experiment to quantify the impact of litter placement and soil moisture on soil carbon dioxide (CO₂) emissions under three controlled temperatures. The treatments including three litter placements (no litter, litter on top and litter mixed with surface soil) and three soil moisture levels (23%, 37% and 50% water-filled pore space [WFPS]) were incubated at three temperatures (10°C, 20°C and 30°C). Carbon dioxide fluxes were measured every 2 weeks. Soil CO₂ fluxes were higher for all moisture and litter treatments initially and declined overtime at 20°C and 30°C. Mixing litter with soil increased the cumulative CO₂ emissions by 24% and 19.5% at 20°C and 30°C, respectively, compared to no litter. Also, soil-litter mixing compared with litter on top showed a 14.3% and 21.6% increase in cumulative CO₂ emissions at temperatures of 20°C and 30°C, respectively. At all temperatures, 37% and 50% WFPS resulted in similar cumulative CO₂ emissions. The results from this study indicate that rising temperatures from 10°C to 30°C accelerate the effect of soil litter mixing on increasing CO₂ emissions compared to litter on top and no litter.

This study investigated the possibility of a reduced-fumonisin corn cultivation method using two fungicides, azoxystrobin and propiconazole. A field-based cultivation experiment was conducted, wherein Kimimaru and LG3490 corn were cultivated for 2 years with a fungicide applied. In the first year, the use of fungicides reduced the concentration of fumonisin in corn, but in the following years, no fumonisin-reducing effect was observed. Differences in precipitation may be the cause, but details were unknown. Although a minor effect was observed, the results suggested that the method was not wholly effective. Next, in an in vitro incubation experiment, the relationship between fumonisin-producing fungi (Fusarium fujikuroi) and fumonisin production was examined in the presence of two fungicides. Both fungicides reduced F. fujikuroi cell mass in a concentration-dependent manner. Fumonisin production did not decrease noticeably at low fungicide concentrations but at high concentrations. This indicates that a fungicide concentration above a certain threshold is required to suppress fumonisin production. The fumonisin produced per fungal cell mass remained almost constant between 0.1 and 10 mg/L propiconazole, although it decreased to zero at higher propiconazole concentrations. Thus, the propiconazole-induced decrease in fumonisin production was likely caused by a reduction in fungal cell mass. In contrast, fungal cell mass decreased as azoxystrobin concentration increased, and the azoxystrobin produced per cell mass reduced. Thus, fumonisin production was synergistically suppressed by decreased cell mass and production. The results of both experiments did not exhibit the desired level of reduction effect likely because a sufficiently high concentration of fungicide could not be maintained for outdoor cultivation. Various other factors, such as weather conditions, may have affected the disinfectant concentration, leading to the reduced fungicide concentration.

Paspalum dilatatum is an excellent warm-season forage grass and soil conservation plant in subtropical regions. However, information on P. dilatatum cultivation in southwestern China is limited. A preliminary evaluation of the genetic diversity and adaptability of six P. dilatatum germplasms was conducted in Guizhou based on inter simple sequence repeat (ISSR) markers and field trials. Fifteen polymorphic primers were screened from 50 ISSR primers. A total of 141 bands were generated, 124 of which were polymorphic, yielding 88.63% polymorphic bands. The number of polymorphic loci detected for the different germplasms ranged from 23 to 61, and the percentage of polymorphic loci was 40.67%. The mean number of alleles was 1.23, and the effective allele number was 1.15. Nei's genetic diversity index was 0.08. The Shannon information index was 0.12, and the genetic similarity coefficient (GSC) ranged from 0.6002 to 0.8955, indicating a relatively rich genetic base among the germplasms. The unweighted pair group method with arithmetic mean approach was used to construct the clustering map. Using a GSC of 0.83 as the threshold value, the six germplasm materials were divided into four clusters, indicating that ISSR molecular markers can be effectively applied to analyze the genetic diversity of P. dilatatum germplasms. Cluster analysis of 12 growth characteristics of the germplasms of P. dilatatum showed that germplasm 4 exhibited strong tillering ability and a high crude protein content. Germplasm 3 showed high plant height, fresh yield and hay yield. Germplasm 1 showed the lowest forage yield and crude protein content. Germplasms 2, 5 and 6 showed excellent crude protein and crude fat contents; the remaining indicators showed intermediate performance. This study provides important references for the utilization and variety selection of introduced P. dilatatum resources in the karst areas of Guizhou.

Zoysia matrella (L.) Merrill is a perennial C4 warm-season turfgrass grown for landscapes, golf courses, sports fields and recreation parks. To create a new breeding method by genome editing, an efficient genetic transformation system is essential. In this study, we report the efficient protocol of Agrobacterium-mediated transformation through the establishment of a stable tissue culture system for Z. matrella ‘Wakaba’. The embryogenic callus was induced from shoot apices of nodal segments incubated in Murashige and Skoog (MS) medium containing 2 mg/l 2,4-dichlorophnoxyacetic acid (2,4-D), 0.1 mg/l 6-benzylaminopurine (BAP) and 5 μM CuSO₄ (MS-DBC). Repeated subculture of compact high-quality callus in MS-DBC medium produced a highly regenerative callus with dense pre-embryogenic clusters, and it was used as a transformation target. Agrobacterium strain EHA105 harboring pANIC8B vector containing the β-glucuronidase gene (GUS) and hygromycin B phosphotransferase gene was used. Agrobacterium-infected calli were cocultured for 5 days with 100 μM acetosyringone and then subjected to selection pressure of 50 mg/l hygromycin. This optimized protocol yielded transformation efficiencies of up to 6.6%. Southern blot analysis verified one to three copies of the GUS gene in different independent transgenic plants. All transgenic plants were morphologically normal, and the GUS expressions were stable. Our optimized in vitro and transgenic system will facilitate the new breeding technology of genome editing in zoysiagrass.

The slow initial growth of hybrid brachiariagrass (Urochloa spp.) can require some months to achieve complete ground cover of a newly seeded area, leading to decreased forage production and increased weed infestation in the establishment year. To solve these problems, we attempted to sow seeds by mixing warm-season annual forages with brachiariagrass at a brachiariagrass pasture establishment (University of Florida, USA, 2017 and 2018). Treatments were single seeding of ‘Cayman’ brachiariagrass solo (BR), sorghum sudangrass solo (Sorghum bicolor (L.) Moench; SD), and sunn hemp solo (Crotalaria juncea L.; SH) and two mixtures of these three forages at half (HSR) or full (FSR) of the recommended seeding rate. The seeding rates of FSR were, respectively, 10, 20, and 25 kg/ha for brachiariagrass, sudangrass, and sunn hemp. The treatments were distributed in a randomized complete block design with four replicates. Plots were harvested at 6, 12, 18, and 24 weeks after seeding. The number of brachiariagrass seedlings in the HSR and FSR treatments was less than half that in the BR (P < .05). The BR treatment had greater brachiariagrass herbage accumulation (HA) at all harvests than HSR (4%–75% of BR) or FSR (7%–66% of BR). This difference between the BR and mixture treatments became narrower in later harvests. In addition to the decreased number of brachiariagrass seedlings, light and nutrient competition between annual forages are considered to be the causes of lower brachiariagrass HA in the mixture treatments. Sunn hemp increased forage HA and crude protein concentrations at 6 weeks. Sudangrass provided overyielding forage until 18 weeks after seeding, with a similar nutritive value as brachiariagrass. Mixing warm-season annual forages with brachiariagrass at the establishment, especially half of the seeding rates of sunn hemp and sudangrass, is a feasible management practice to increase HA during the first 12 weeks after seeding.

We investigated the changes in vegetation responses following fertilization in abandoned farmland in Mongolia. Nitrogen (N), phosphorus (P) and potassium were sprayed alone or in combination on abandoned farmland on a typical steppe in Mongolia, and changes in soil nutrients, species composition and vegetation cover were investigated. Abandoned farmland had lower vegetation cover and soil N and P levels than natural grassland. Phosphorus fertilization significantly affected soil phosphate levels. Nitrogen fertilization in abandoned farmland effectively increased vegetation cover. Moreover, combined N and P fertilization increased plant cover over either element alone, possibly via improved uptake of nitrate ions and the promotion of growth. The effect of increasing cover following fertilization was primarily observed in the genus Artemisia. These results suggest that fertilization of abandoned farmland might not contribute to a return to natural steppe vegetation but rather increase the vegetation cover of annual forbs such as field weeds. Species composition did not appear to be affected by fertilization. This speaks to the difficulty of promoting species regeneration in abandoned farmland using fertilization alone. However, combining fertilization with the introduction of native plant material, e.g., seed sowing, may be beneficial in early restoration treatments, given the promotion of plant growth via fertilization and the importance of reducing wind erosion via the establishment of ground cover.