Grassland Science最新文献

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.

Elucidating the effect of γ-aminobutyric acid (GABA) on seed germination and seedling growth of Medicago ruthenica under low-temperature could provide a reference for alleviating the harmful effects of low temperatures on legumes in alpine meadows. We set up different temperatures to screen three low temperatures that inhibit seed germination of Medicago ruthenica, and six aqueous concentrations of GABA (0, 0.1, 0.5, 1, 5, 10 mM) were set up to screen out the best GABA seed soaking concentration that can promote the seed germination at low-temperature. The three temperatures of 10 °C, 20/5 °C and 15/5 °C inhibited seed germination of Medicago ruthenica. Soaking seeds with 1 mM GABA could significantly increase seed germination rate of Medicago ruthenica at low-temperature (10 °C). Soaking seeds only with 0.1 mM GABA could promote germination of Medicago ruthenica at 20/5 °C, but there is no significant difference compared with distilled water soaking. Whereas, all GABA seed soaking concentrations delayed seed germination time and inhibited seed germination at 15/5 °C. Pre-spraying seedlings with 1 mM GABA at 10 °C reduced the production of superoxide anion, hydrogen peroxide and malondialdehyde content, and increased the activities of catalase, peroxidase, superoxide dismutase and ascorbate peroxidase in leaves of Medicago ruthenica on days 7. Simultaneously, Pre-spraying seedlings with 1 mM GABA at 10 °C significantly increased the net photosynthetic rate and decreased intercellular CO₂ concentration. These data suggest that GABA could enhance the cold tolerance of Medicago ruthenica by promoting seed germination, regulating the antioxidant system, and increasing photosynthetic efficiency. However, the mitigation effect of GABA on low-temperature is only applicable to a certain temperature. The mitigation effect of GABA on low temperature will be weakened as the low temperature of plants is less than 10 °C

Sorghum–sudanense is a hybrid of sorghum and Sudanese grass and is widely used in animal husbandry and aquaculture because of its high yield, excellent quality and wide adaptability. Using high-throughput sequencing, we constructed a high-density genetic map of sorghum Tx623A × sudangrass S722 with 103 recombinant inbred lines (RILs) in this study and mapped quantitative trait loci (QTLs) for plant height (PH), stem diameter (SD), tiller number (TN), fresh weight (FW) and dry weight per plant (DW). The map included 1610 markers with a total length of 2329 cM and QTL mapping identified 19 QTLs, including two for PH, three for SD, four for TN, four for FW and five for DW. We detected two QTL clusters containing overlapping QTLs for PH, FW and DW. Orthologs of three SD candidate genes from maize were found within two SD QTLs. The identification of these QTLs will be useful for cloning the corresponding genes for these traits and developing marker-assisted selection (MAS) in future sorghum breeding programs.

Drought is a major environmental stress that limits growth and development of plants. Strigolactone, a kind of carotenoid-derived sesquiterpenoid hormone, plays an important role in resisting abiotic stress for plants. In this study, alfalfa (Medicago Sativa L.) WL-712 was sprayed with GR24 (a synthetic strigolactone analog) at the concentration of 0.1 μM for 3 days under drought stress for 1 week. The results showed that GR24 treatment could increase the contents of soluble protein and soluble sugar and decrease the content of malondialdehyde, which negatively affected by drought stress in alfalfa. In addition, GR24 treatment significantly enhanced superoxide dismutase and the activities of peroxidase and catalase in alfalfa. The JIP test analysis also indicated that GR24 could alleviate photosynthesis negatively affected by drought stress. The expressions of genes related to photosynthesis were consistent with the changes of physiological indexes in alfalfa. This study indicated that GR24 could alleviate the adverse effects of drought stress on physiology and photosystem II function in alfalfa leaves.

Secondary origin grasslands are widespread habitats that provide a wide array of ecosystem services. Their conservation relies on management practices that can, in turn, alter their soil carbon cycle to result in higher soil respiration rates. In the perspective of social and climate change scenarios, there is the need to seek the best management practices for conservation of secondary origin grasslands, climate mitigation and economic sustainability for farmers. The aim of this study was to investigate whether increasing the customary practice of mowing twice a year to monthly mowing through the growing season (when herbage production was feasible; i.e., >0.5 t/ha dry matter) generates changes to the drivers and rates of soil respiration of fertilized Bromus erectus-dominated grasslands. Soil CO₂ efflux, temperature and moisture were recorded over 3 years (2016–2018) under these “customary” and “monthly” mowing frequencies (twice per year; 4–6 times per year, respectively). Soil CO₂ efflux, temperature and moisture were not affected by the higher mowing frequency over the study period. Independent of mowing frequency, soil water content was the main driver of soil CO₂ emissions during the growing season (April to October, inclusive), whereas soil temperature was the main driver during the nongrowing season (November to March, inclusive). Therefore, increasing the customary mowing of twice a year to the monthly mowing frequency through the growing season does not impact upon soil respiration of B. erectus-dominated grasslands, at least over a 3-year period.

Alfalfa (Medicago sativa L.) as a perennial forage grass is widely adapted to favorable environmental conditions with wide range of soils including acid soils. The productivity traits of alfalfa in the soil without and with 1.8–14.7 mgAl/kg concentration of mobile Al were investigated. The study site was conducted at the Vėžaičiai Branch of the Lithuanian Research Centre for Agriculture and Forestry, 55°70 N lat., 21°49 E long. The experiment featuring 19 cultivars was established on a Balthygleyic Dystric Retisol in 2018. In 2019 and 2020, the productivity traits were evaluated: spring regrowth, plant height before flowering, stem number, seed yield, and fresh and dry matter yield. The mobile Al negatively influenced productivity traits of alfalfa in 2019 and 2020. Several cultivars of alfalfa were distinguished by tolerance to mobile Al and will be used for further selection for breeding. In 2020, the cultivar Europe from France was distinguished by spring regrowth, number of stems and fresh matter yield in the soil with mobile Al. The cultivar Ludelis from France differed by spring regrowth and height before flowering time in the soil with mobile Al in 2019–2020. The cultivar Skriveru from Latvia was the most yielding by seed yield in the soil without and with mobile Al in 2019. The Lithuanian cultivar Antanė was yielding by dry matter yield in the soil with and without mobile Al in 2019. The cultivar Žydrūnė from Lithuania was yielding by fresh and dry matter yield in the soil with and without mobile Al in 2020. This study on acid soils with and without mobile Al concentrations has revealed the differences of productivity traits under different environmental conditions of experimental years. Results of this study are important not only for Lithuania but also for the other lands of Europe where Retisol are prevails.