Grassland Science最新文献

The propagation and seed multiplication of site-adapted and drought-tolerant grass varieties are essential to provide high-quality forage in temperate grasslands. A field experiment was conducted from 2016–2019 on orchardgrass (Dactylis glomerata L.) in the province of Styria, Austria. Treatment effects of sulfur, fungicide application and a plant growth regulator, singly and in combination, on seed yield and its reproduction parameters were tested under two different fertilizer nitrogen management systems (single application [N1] and split application [N2]). In terms of seed yield, a combination of all treatments compared to fertilization-only treatment showed a significant increase of 22% under N2 fertilization. In terms of the thousand seed weight, the fungicide treatments and a combination of all treatments performed significantly better than other treatments within N1 and N2. The use of fungicide and a combination of all treatments also significantly increased the germination capacity in N1. Therefore, a combination of all plant protection treatments is recommended to optimize seed yield, thousand seed weight and germination capacity.

The aim of this study was to explore the response of the stoichiometric and photosynthetic characteristics of a dominant plant species in a typical grassland to changes in precipitation. Rain shelter technology was used to simulate 50%, 100%, and 150% of natural rainfall. The photosynthetic rate (Pn), intercellular CO₂ concentration (Ci), transpiration rate (Tr), stomatal conductance (Gs), and ecological stoichiometry of the rhizosphere soil and Stipa bungeana at different growth stages were measured in May, July), and September, 2019 after 2 years of rainfall control. The results showed that the aboveground carbon (C) content of plants grown under 150% precipitation was significantly higher than that of plants grown under 100% precipitation in September. The aboveground nitrogen (N) content of plants under 50% precipitation was significantly higher than the plants grown under 100% precipitation. Under all different precipitation treatments, the aboveground C:N ratio was the lowest (16.4–19.6) in May. The range of average aboveground C: phosphorous (P) ratio was 373.7–617.8, and the N:P ratio in the descending order was July > May > September. The 50% precipitation treatment promoted the highest accumulation of underground C at all the growth stages. The productivity of the grassland under the 100% and 150% precipitation treatments was limited by the rhizosphere soil N and P. The underground C, P, C:P, and aboveground C:N ratios were sensitive indicators. Aboveground and underground N:P ratio showed the strongest significant correlation (P < 0.001), and the correlation between underground stoichiometry and rhizosphere soil P (P < 0.001) was stronger than that with rhizosphere soil N (P < 0.05). The correlation between Ci and stoichiometry was opposite in direction to the correlation between Pn, Tr, Gs, and stoichiometry. The research results will provide a scientific reference for understanding of the material cycle and judgment of vegetation nutrient limitations in the Loess Plateau.

To reveal the genetic diversity and structure of cultivars and breeding materials of diploid Italian ryegrass (Lolium multiflorum Lam.) in Japan, using genome-wide allele frequency data obtained by genotyping by random amplicon sequencing, direct of pooled DNA, we investigated genetic diversity among and within 89 accessions. We selected 2629 reliable alleles at 456 polymorphic loci to evaluate allele frequency in each accession. Results of hierarchical cluster analysis based on Nei's standard genetic distance and of principal component analysis and nonhierarchical cluster analysis based on the complete set of allele frequencies classified the accessions into a large group including major Japanese cultivars and their ancestral landraces with a wide range of maturity, and a small group with mainly medium maturity, including ‘Gulf’, introduced from overseas. The genetic relationships fully reflected the kinship inferred from the breeding history in Japan. Mean expected heterozygosity (H_E) and number of alleles per locus (A) were evaluated as indices of genetic diversity within each accession. We found a significant negative correlation between the year of application for varietal registration and H_E or A in 14 early-maturing Japanese cultivars. The genetic diversity profile can be used for breeding to maintain or increase the diversity within cultivars or breeding materials.

Root and stalk rot (RSR) of maize (Zea mays L.) plants, caused by soil-borne disease pathogens of the genus Pythium, can get worse in global warming. It has been known that the resistance of F₁ hybrids often disaccords with those of their parental inbreds, which makes it difficult to develop resistant hybrids effectively. Best linear unbiased prediction (BLUP) is a standard mixed model equation, which is fitted for predicting hybrid performance by the parental inbreds of maize. The objective of this study was to evaluate simple parental-progeny-based BLUP in predicting single-cross performance and to determine the importance of general combining ability of the resistance to Pythium RSR. The performance prediction of the parental inbreds from BLUP was consistent with empirical knowledge and was determined mostly useful, despite not using a coefficient of coancestry. Correlation coefficients between breeding values from BLUP and actual field data for hybrids, across different experiments from 2018 to 2019, were relatively high (R = 0.854 and 0.703, respectively). These results indicate the potential of the parental-progeny-based BLUP for maize single-cross performance. This is the first report in predicting the resistance to this disease with BLUP, and the findings can be applied to routine breeding programs as well as to genome-wide molecular polymorphism data to contribute to the future breeding programs.

Insufficient forage supply from natural rangelands during the dry season hampers ruminants' performance in the derived savanna zone of Nigeria. Therefore, to provide alternative feed resources, we evaluated silage potential of Columbus grass (Sorghum almum Parodi) at boot, dough and maturity stages for 4-, 8-, 12- and 16-week ensiling durations, in a 3 × 4 factorial experiment. The dry matter yield (DMY) was determined at each harvest stage, and the forages were subsequently ensiled. The results revealed that the DMY of S. almum at maturity was 8.98% and 18.67% higher than at dough and boot stages, respectively (p < 0.05). The silages were ranked “good silage” based on physical characteristics. Silage pH decreased with advancing ensiling duration from 4 to 16 weeks in boot (5.25–4.63), dough (5.63–4.11) and maturity (5.42–4.91), with a corresponding increase in lactic and volatile fatty acids. Crude protein (CP) was higher in forages ensiled at maturity and increased with ensiling duration after initial decline from 4 to 8 weeks. Neutral detergent fiber (NDF) and hemicellulose increased quadratically from boot to dough and subsequently declined at maturity. Growth stage, ensiling duration and their interactions influenced the macrominerals' content (p < 0.05). Silages' dry matter intake (DMI) declined from boot to dough stage across the ensiling durations, and except for 8 weeks, the DMI increased at maturity by 6.71%, 5.54% and 7.19% in 4, 12 and 16 weeks, respectively. Therefore, owing to the lower NDF and high DMY, CP and DMI of S. almum ensiled at maturity for 16 weeks, it could guarantee a quantitative and qualitative forage supply to maintain optimum animal performance throughout the dry season.

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.