Grassland Science最新文献

Agropyron is an important germplasm material of the genetic improvement for Gramineae forage and Triticeae crops. In the present research, in order to determine the stable and major quantitative trait loci (QTLs) controlling five significant quality traits, a total of 115 individuals from F₂ segregation population of tetraploid hybrid crested wheatgrass and their parents were used as materials. On the basis of the ultra-high density molecular genetic linkage map of tetraploid crested wheatgrass constructed with single nucleotide polymorphism (SNP) markers, we first determined QTLs for the phenotypic data of five quality traits in three different environments (Hohhot-2018, Hohhot-2019 and Tongliao-2019) in 2 years (2018 and 2019) by Map QTL 6.0 software. The results showed that a total of 28 QTLs controlling quality traits of wheatgrass were located on 11 linkages (LGs), including LG1, LG2, LG3, LG4, LG6, LG7, LG8, LG9, LG12, LG13 and LG14. Among them, there were two QTLs for crude protein content (CPC), four QTLs for water-soluble carbohydrate content (WSCC), 12 QTLs for starch content (SC), five QTLs for phosphorus content (PC) and five QTLs for calcium content (CC), which accounted for 10.1% to 21.6% of the phenotypic variation and all were major QTLs of genetic contribution rate >10%. However, only six stable QTLs were detected at least in two environments and in the mean environment data, including one for CPC (qCpc4-1), one for WSCC (qWscc4-2), two for SC (qSc1-2, qSc9-12), one for PC (qPc4-4) and one for CC (qCc4-2). These QTLs determining five traits would provide a theoretical basis for further fine mapping and the molecular marker-assisted selection of elite gene in tetraploid crested wheatgrass.

Soil acidity affects botanical compositions and pasture production, but the relationship between orchardgrass persistence and the soil nutrients in acidic soils with different management methods is understudied in production fields. Here, using exchangeable acidity (y₁) as an indicator of exchangeable aluminum (Al), we conducted a survey to investigate the relationship between orchardgrass dominance and the soil characteristics in sown pastures under different management practices. The botanical composition and soil chemical conditions were investigated in six orchardgrass–tall fescue mixed pastures (two cutting meadows and four cattle grazing pastures) from June 18 to July 17, 2018. Six- and three-line transects were fixed in each meadow or pasture, respectively, and five measurement locations were set along each transect at 10-m intervals. Each location had three square plots (20 × 20 cm) for the vegetation survey and three consecutive soil sampling plots (4-cm diameter) adjacent to the middle square plot. The dominant plant species in each plot was recorded, and soil samples were collected at 0- to 5-cm depth to measure y₁ and major soil nutrients. The y₁ ranged from 3.55 to 25.83 in the cutting meadows, which was wider than in the grazing pastures (1.85–16.29). In the cutting meadows, the dominance frequency of orchardgrass increased with the rise in y₁, whereas that of tall fescue decreased in cutting meadows. No significant relationship was found between dominance frequencies and y₁ in the grazing pastures. Although concentration of some soil nutrients varied with y₁, these nutrients were not related to the dominance frequencies of orchardgrass for either management strategy. These results suggest that orchardgrass declines are prevented at high exchangeable Al sites by the non-establishment of less Al-tolerant plant species under cutting conditions.

Urochloa (syn. Brachiaria) cultivars are widely used as forage for ruminants in tropical countries and also in Thailand. Two new Urochloa cultivars, OKI-1 and Br-203, have high forage yield and digestibility compared with other cultivated Urochloa grasses. Seed production is a fundamental requirement for widespread sowing, and it can be increased by optimizing agronomic practices, such as changing plant spacing. Two field trials were conducted in 2018–2020 at Lampang Animal Nutrition Research and Development Center, Northern Thailand, to determine the optimal plant spacing for seed production of these Urochloa cultivars. In both trials, four plant-spacing regimes (50 × 100, 75 × 100, 100 × 100 and 125 × 100 cm) were used in a randomized complete block design with four replicates. In two consecutive harvests of both trials, plant spacing did not significantly affect seed yield and quality but affected tiller and inflorescence densities. Specifically, significant higher numbers of tillers and inflorescences were produced per unit area at the narrowest plant spacing (i.e., 50 × 100 cm). OKI-1 and Br-203 tended to have higher pure seed yields (PSY) at plant spacings of 100 × 100 (136.46 kg/ha) and 75 × 100 cm (79.59 kg/ha), respectively. Both cultivars showed similar trends in PSY, filled seed percentage and a thousand seed weight, which tended to be higher in the first-year crops than the second-year crops. This difference could be attributed to a reduction in available soil N resulting from a large amount of N utilization during vegetative growth, combined with inadequate and erratic rainfall. In addition to the recommended optimum plant spacing, sufficient fertilizer and suitable environmental factors could increase seed yield.

We investigated whether the intercropping of maize and soybean could improve the silage nutritional content without reducing the forage yield or worsening silage fermentation process and aerobic stability. Three crop arrangements were studied: maize monoculture, soybean monoculture and maize-soybean intercropping. The experimental design was completely randomized with 5 replicates per treatment. Maize-soybean intercropping decreased the dry matter (DM) and grain yield as well as the production of digestible dry matter per hectare. The crude protein content of maize-soybean intercropped silage was higher compared with maize in monoculture (by 40%), but, on average, both silages presented similar fermentation profile, in vitro digestibility (600 g/kg DM), dry matter loss (37.1 g/kg DM), gas loss (36 g/kg DM) and aerobic stability (60 hr). Soybean-crop silage presented an elevated content of volatile organic compounds, low lactic acid concentration (2 g/kg DM), high pH (5.26), and greater losses of dry matter (73 g/kg DM) and gas (98.5 g/kg DM) during fermentation. Aerobic stability was higher in soybean-crop silage (192 hr) due to the high content of volatile fatty acids (butyric acid > 87 g/kg DM) and low contents of residual sugar and lactic acid. In conclusion, maize and soybean intercropping increased crude protein content, but contrary to our hypothesis, the crop association did not result in greater silage digestibility or higher aerobic stability, nonetheless reduced both crop productivity. Additionally, ensiling direct-cut soybean crop with low DM content is not recommended due to the high risk of undesirable fermentation and nutrient losses.

The aim of this study was to reveal the potential impact of botanically diverse pasture on the nutritional, physiological, and immunological status of grazing cattle using multifaceted indices. Ten Japanese black beef cows (325.5 ± 40.6 kg of body weight [BW], 7.9 ± 3.8 years of age) were used in this experiment. Five of them grazed on a 1.8-ha grassland (botanically diverse pasture: DP) that was composed of sown grassland and grazable forestland (approximately 34 plant species). The other five cows grazed on 1.0 ha of sown grassland with only a few plant species (botanically monotonous pasture: MP, approximately 5 plant species) for 2 months. Blood samples were collected approximately every 2 weeks. In DP cows, the hemoglobin (HGB) concentration, hematocrit (HCT) ratio, and superoxide dismutase (SOD) activity increased linearly after the start of grazing, as did plasma sodium (Na), calcium (Ca), and potassium (K) concentrations. Urea nitrogen (UN) levels were higher in DP than in MP cows throughout the grazing period, whereas in MP cows, the red blood cell (RBC) count, HGB concentration, and HCT ratio decreased quadratically after the start of grazing. The DP cows gained more BW than the MP cows throughout the grazing period. Thus, the increased intake and/or the change in the ingested plant species in DP cows might have promoted the increase in the plasma UN concentration. In summary, the present study showed that grazing in botanically diverse pasture improved the nutritional and physiological status of cows; however, it aggravated the imbalance of protein and energy intake induced by grazing within 2 months.

Paspalum atratum is a tropical grass with potential to contribute to forage availability in areas dominated by waterlogged acidic soils. However, little is known of the interactive effect of N fertilization and stage of harvest on its nutritive value. Therefore, the objectives of this study were to evaluate the interactive effects of N fertilization and harvesting stage on herbage characteristics and nutritive value of P. atratum (Cv. Ubon) and to determine the optimum N fertilization rate at each stage of regrowth. P. atratum seedlings were planted in 18,631-cm³ plastic pots containing growth media amended with 0, 25, 50, and 75 kg N/ha. Forage was harvested after 6- and 12-weeks regrowth. Nitrogen fertilizer had a significant effect (p < 0.05) on herbage yield, sward height, crude protein yield, crude protein concentration, and 12- and 24-h in vitro ruminal organic matter digestibility (IVOMD). P. atratum fertilized with 50 kg N/ha produced the highest dry matter yield (1,133 kg DM/ha) at 12-week regrowth. Crude protein (CP) was highest (133 g/kg DM) in 6-week regrowth forage that received 50 kg N/ha. IVOMD at 12 and 24 h of incubation was highest in 6-week regrowth forage amended with 0 and 50 kg N/ha, respectively. Herbage characteristics and nutritive value of P. atratum showed a quadratic response to N fertilization at both regrowth stages. Response surface optimization indicated that N fertilizer application rates of 56.0 and 52.3 kg N/ha maximized P. atratum herbage yield, CP content, and 12-h IVOMD at 6- and 12-week regrowth, respectively. It was, therefore, concluded that the herbage yield and nutritive value of 6- and 12-week regrowth P. atratum is optimized with N fertilizer rates of 56.0 and 52.3 kg N/ha, respectively.

We proposed a mixture of animal husbandry and fruit tree industry: livestock grazing under an orchard layer to increase agricultural productivity per area and reduce the costs of feed, fertilizer, and weed control. Lambs were reared in-house for 1 month and then moved to a pear orchard for 1 month of grazing. We recorded the changes in body weight, blood properties (e.g., albumin, cholinesterase, and nonesterified fatty acids), and parasitic infection to compare the in-housed lambs with the grazing lambs in the orchard. Additionally, we conducted field investigations for changes in vegetation and soil properties before and after grazing. Grazing caused significant increases in body weight, helminth eggs in dung, and soil water retention, and significant decreases in plant biomass, grass digestibility, and soil hardness. In contrast, the nutritional values of the feed, blood properties, and soil chemical properties (e.g., pH, P, N, and C) were not significantly changed after grazing. These results highlighted that the fruit tree industry combined with livestock production would be an acceptable management approach for Japanese agriculture, although further case studies are required.

Lactic acid bacteria (LAB) naturally present on forage crops are responsible for the silage fermentation quality. However, there are few reports on the factors affecting the distribution of epiphytic LAB on the crops. Therefore, the influences of spraying sugars, growth temperatures and nitrogen application levels on the amounts and species of LAB on Italian ryegrass (Lolium multiflorum) were evaluated in this study. Spraying xylose, fructose, glucose, sucrose and galactose significantly increased (p < 0.05) the population sizes and species of LAB on Italian ryegrass. Spraying sucrose made Italian ryegrass epiphyte the most LAB. As for the effect of temperatures, Leuconostoc mesenteroides dominated on Italian ryegrass grown at 10 and 15°C, while Lactobacillus plantarum dominated at 20°C, and Weissella paramesenteroides dominated at 25°. The population sizes and species of LAB on Italian ryegrass were the most at 15°C. When N (0, 35, 70, 105, 140 or 175 kg/ha) was applied to Italian ryegrass, LAB population sizes and species were the most at N 35 kg/ha (p < 0.05). Lactobacillus plantarum was detected in all the treatments of Italian ryegrass except the growth temperatures of 10 and 25°C.

Grassland ecosystem functions are affected to a large extent by grazing activities. However, owing to the associated spatial heterogeneity, the influence of grazing intensity on grassland ecosystem biomass and the underlying mechanisms remains unclear. In this study, we analyzed data from 335 field data to clarify the response of grassland ecosystem biomass to grazing activities in China. We established that the size of the priming effect of grazing activities on total biomass, aboveground biomass and belowground biomass is −0.25 ± 0.09 (95% confidence interval [CI]: −0.42 to −0.07), −0.47 ± 0.05 (−0.57 to −0.37) and −0.18 ± 0.04 (−0.29 to −0.10), respectively. Grazing was found to significantly reduce both the biomass of grassland ecosystems (p < 0.01) and the average effect value of temperate, meadow and desert steppes with respect to vegetation type (p < 0.05). The descending order of the effects of grazing intensity on biomass was heavy, light and moderate, with light and heavy grazing significantly reducing grassland biomass (p < 0.01), whereas moderate grazing made a comparatively smaller contribution. Furthermore, explained heterogeneity analysis revealed that soil water content was positively associated with the effect size, and path analysis indicated that soil bulk density, precipitation and average annual temperature have a significant direct influence on the effect value (p < 0.05). Given the minimal impact of moderate grazing on biomass, we suggest that stocking at moderate densities could represent an effective approach for restoring degraded grasslands. Moreover, increasing soil water content could contribute to effectively reducing grazing-related damage to the biomass of grassland ecosystems.

The present study was aimed to investigate the protective role of silicon (Si) from salt-induced damages in alfalfa. Seedlings were treated with 200 mM NaCl plus three silicon levels (0, 0.75 and 1.5 mM) for 1 week. We observed that salt stress impacted plant growth remarkably, including height, root length, stem and leave weight, aboveground biomass and total biomass, chlorophyll a (chl a), chlorophyll b (chl b), total chlorophyll (total chl), chlorophyll fluorescence, K concentration and K/Na ratio. Consequently, electrolyte leakage (EL), superoxide dismutase (SOD) activity, Na concentration, proline, malondialdehyde (MDA), soluble sugar (SS) and soluble protein (SP) content were found to be raised significantly. After exogenously applying Si under salt stress, the EL, MDA, proline and Na content, except SOD activity, were observed to be dropped. Meanwhile, the chl a, chl b, and total chl and SS content, and chlorophyll fluorescence were found to be elevated. In terms of Si concentration, we found that the protective effects of Si were considerably better at lower concentration (0.75 mM) than higher (1.5 mM) one. Collectively, our results suggested that Si alleviate salt-induced damage and promote alfalfa growth by changing physiological characteristics.