Grassland Science最新文献

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.

Genetic relatedness and diversity of 62 cultivars and breeding lines of tetraploid Italian ryegrass (Lolium multiflorum Lam.; 39 accessions) and its interspecific hybrids, Festulolium (18 accessions), and hybrid ryegrass (Lolium × hybridum Hausskn.; 5 accessions), mainly from Japan, were revealed based on 2,824 genome-wide allele frequencies obtained by the genotyping by random amplicon sequencing-direct (GRAS-Di) method using bulk genomic DNA testing. Genomic composition of each accession was estimated according to the occurrence of 77,373 unique GRAS-Di sequences in the reference population consisting of diploid Italian ryegrass, meadow fescue (Festuca pratensis Huds.), and perennial ryegrass (Lolium perenne L.). The high correlation coefficient (0.98) between the fescue-specific reads ratio and the previously obtained f-ratio of genomic in situ hybridization in Festulolium cultivars suggests the usefulness of this simple method. Both cluster analysis based on Nei's standard genetic distance (D_ST) and principal component analysis (PCA) showed that groups were formed largely by species. However, the complex heritage of Lolium-Festuca (Festulolium) materials could not be determined by species registration or breeding history alone. Some Festulolium accessions were closely related to Italian ryegrass, whereas some defined as Italian ryegrass may actually be interspecific hybrids. The high genetic diversity of Festulolium compared to Italian ryegrass and hybrid ryegrass revealed by PCA seems due to the wide range of fescue-specific read ratios (0.04–33.0%). Tetraploid Italian ryegrass did not show clear structural differentiation, but some genetic relationships attributable to breeding history were demonstrated. Mean pairwise D_ST of tetraploid Italian ryegrass cultivars was significantly lower than that of diploids. Tetraploids and diploids could be separated by PCA plot. Although mean expected heterozygosities of tetraploid and diploid cultivars were not significantly different, the results suggest that the utilization of diploid genetic resources is effective in maintaining and increasing the genetic diversity of breeding populations of tetraploid Italian ryegrass.

This study aimed to investigate the effect of a soil ammonia-oxidizing bacterial (AOB) strain on Italian ryegrass (Lolium multiflorum Lam.) regrowth. Potted Italian ryegrass was used as test material. We isolated and screened an AOB strain from the soil for use in inoculation of other soils to increase nitrification. The sequence of the two isolated and screened AOB strains (S2_8_1 and S2_7_25) were 100% similar to that of Ensifer sesbaniae and Acinetobacter pittii. The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) was also added to the soil to inhibit nitrification. The experimental design involving the inoculation of the soils with the AOB strain included seven treatments: (1) regrowth without any additives, (2) regrowth with blank enrichment medium added to the soil, (3) regrowth with S2_8_1 strain inoculation, (4) regrowth with S2_7_25 strain inoculation, (5) regrowth with DMPP added to the soil, (6) regrowth with DMPP added to the soil and with S2_8_1 strain inoculation, and (7) regrowth with DMPP added to the soil and with S2_7_25 strain inoculation. Compared with regrowth treatment without any additives, the regrowth treatment with S2_8_1 and S2_7_25 inoculations significantly increased leaf biomass by 23.5–48.6%, the leaf net photosynthetic rate by 27.9–48.5%, the rhizosphere soil nitrification rate by 43.0–144.2%, leaf cytokinin concentrations by 23.7–24.9%, and xylem sap cytokinin concentrations by 32.5–43.2%. The increase of nitrate nitrogen content in rhizosphere soil induced by S2_8_1 and S2_7_25 promoted the transfers of cytokinin from roots to leaves, resulting in the increase of cytokinin concentration in leaves. This increase in leaf cytokinin concentrations improved Italian ryegrass regrowth. However, the S2_8_1 and S2_7_25-induced increases in the nonrhizosphere soil nitrification rate were not closely related to Italian ryegrass regrowth. The tested AOB strains have considerable potential to increase Italian ryegrass regrowth.

Low temperature is one of the abiotic factors that limit the biomass of Medicago ruthenica (L.), and carbon and nitrogen have important roles in the plant's growth and development. However, the information on the distribution of carbon and nitrogen under low temperature conditions is limited. In this study, we investigated the influence of carbon and nitrogen distribution on M. ruthenica (L.) Trautv. cv. ‘Zhilixing’ based on ¹³C and ¹⁵N isotope tracers in two temperature-controlled chambers (4–10°C and 25°C, respectively) for 30 days. Results showed that under low temperature, plant height significantly decreased by 22.74%, whereas the ratio of underground to aboveground biomass considerably increased by 146.31% compared to the control plants at 30 days. Moreover, low temperature stress significantly increased the activities of sucrose synthase and glutamine synthase in leaves, shoots and roots. The total carbon content and the abundance of ¹⁵N increased in leaves, shoots and roots under low temperature, with a greater level of increase in shoots than in leaves and roots. The weight of leaves, shoots and roots was correlated with δ¹⁵N. Hence, low temperature inhibited growth and promoted the transport of carbon and nitrogen.

The methods used to evaluate kinetic parameters of ruminant feeds can be in situ and in vitro. For both methods, it is necessary to maintain cannulated animals in order to collect the inoculum from the rumen, which has been under strong pressure from society, in terms of animal welfare policies, to avoid this type of practices. This work aimed to evaluate the estimation of in vitro digestibility and fermentation of elephant grass forage by near infrared reflectance spectroscopy (NIRS), as a fast and noninvasive alternative to the in vitro method. The experimental design was in randomized blocks with three repetitions. The treatments were arranged in a split-plot scheme, with 13 genotypes in the plot and 15 regrowth ages in the subplot. Crude protein (CP) and neutral detergent fiber (NDF) contents; in vitro dry matter (IVDMD) and NDF (IVNDFD) digestibilities; and total volume (V_t), gas production rate (μ) and half-life conventional analyses were determined for pre-dried elephant grass forage samples. For the evaluation of NIRS models performance, coefficient of determination (R²cv) and standard error of cross validation (SECV) were used. As the regrowth age advanced, there was a linear increase in the NDF content and a linear reduction in the IVDMD, IVNDFD and V_t values. The NIRS estimates proved to be adequate for IVDMD (R²cv = .95), IVNDFD (R²cv = .85), V_t (R²cv = .81) and gas production at 48 (R²cv = .82), 72 (R²cv = .85) and 96 h (R²cv = .84), confirming as an alternative to the in vitro methods that dispense with the use of cannulated animals.