Grassland Science最新文献

Root system characteristics are of fundamental importance to soil improvement and underground resource acquisition in riparian buffer strips. Root architectural traits determine the in situ space-filling properties of a root system. The aims of this study were to examine the grassland root morphological characteristics in the vegetation zone from the lower reaches of Yellow River. Five natural homogeneous grasslands including Imperata cylindrica, Phragmites australis, Cynodon dactylon, Artemisia argyi and Juncellus serotinus were selected. Seven root architecture parameters including fractal dimension, total root length, total root surface area, total root volume, average diameter, root crossing number and root tip number were analyzed, and comprehensive scores were evaluated using principal component analysis. The results showed that average root diameter of the five herbaceous plants was ranged from 0.42 to 0.78 mm. The total root length, total root surface area, total root volume, root crossing number and root tip number of I. cylindrica and P. australis were significantly higher than those of C. dactylon, A. argyi and J. serotinus. The main factors influencing root architecture were average diameter, total root surface area and total root volume through principal component analysis. I. cylindrica had the highest comprehensive score, followed by P. australis, A. argyi, C. dactylon and J. serotinus. I. cylindrica and P. australis would be good competitors for both soil resource acquisition and soil quality improvement due to their root traits. These results could provide a scientific basis for evaluating the ecological function of riparian vegetation.

To explore the effects of saline-alkali stress on the functional and physiological characteristics of Leymus chinensis leaves, L. chinensis plants were subjected to severe saline-alkali (pH = 9.73, electrical conductivity [EC] = 0.637 mS/cm), moderate saline-alkali (pH = 8.76, EC = 0.451 mS/cm), and control (pH = 7.37, EC = 0.22 mS/cm) soil treatments. Leaf functional traits, ion content, photosynthetic parameters, and antioxidant enzyme activity were determined, and the relationship between the functional traits and physiological characteristics was analyzed. With an increase in saline-alkali stress, the leaf density of L. chinensis decreased significantly (p < 0.05), the leaf mass per area (LMA) did not change significantly, and the leaf biomass ratio decreased significantly (p < 0.05). The Na⁺ mass fraction increased, and the K⁺ and Ca²⁺ contents and K⁺/Na⁺ and Ca²⁺/Na⁺ ratios decreased in response to saline-alkali stress. Except for intercellular CO₂ concentration, net photosynthetic rate, stomatal conductance, and transpiration rate were lower under saline-alkali stress. Except for dehydroascorbate reductase, the antioxidant enzymes increased significantly as a result of saline-alkali stress. Leaf density and leaf biomass ratio were significantly correlated with the measured physiological indicators except for net photosynthetic rate and peroxidase. Further study on large-scale cultivation of L. chinensis would be beneficial for the ecological recovery and exploitation of the saline-alkali soil.

Sorghum (Sorghum bicolor [L.] Moench) is an important annual forage crop. Multiple harvests per year not only increase the total yield of sorghum but also help to avoid its injury and damage by biotic and abiotic stresses. It is well known that S. bicolor subsp. drummondii, or sudangrass, regrows vigorously after cutting. To elucidate the genetic mechanisms underlying this ability, we evaluated recombinant inbred lines and advanced populations of bmr (brown midrib) sorghum × sudangrass under different environments and identified quantitative trait loci (QTLs) controlling regrowth ability. Although the dry matter weight at the second harvest varied among years, significant QTLs for increased regrowth ability were detected on chromosomes (Chrs.) 3, 6, 7 and 10. In particular, the sudangrass alleles of two QTLs detected on Chrs. 7 and 10 showed a positive effect on regrowth ability. We named the QTL on the short arm of Chr. 7 qRG7-1 and verified it in the QTL analysis of F₃ and BC₂F₃ populations. QTL analysis by using an F₃ population segregating for regrowth ability also showed a clear LOD peak in the qRG7-1 region. Substitution mapping using two BC₂F₃ populations placed qRG7-1 at 3.81–9.75 Mb on Chr. 7.

Orchardgrass (Dactylis glomerata) persists poorly in acidic soils. Not many studies have looked into the effects of fertilizers in improving orchardgrass persistence within acidic soils. We conducted experiments on 64 individual potted orchardgrass plants, which were defoliated to 5 cm and assigned to one of the following four treatment groups: unfertilized control (CNT), chemical fertilizer (CHE), grazing cattle dung (DNG), and cattle manure compost (CMP). Half the pots in each treatment received aluminum sulfate solution to induce further soil acidification (Al-add), while the others received water (no-Al). On days 20 and 47, after defoliation, soil properties and dry weights of aboveground biomass (AGB) (separated into leaves and stubble) and roots of four pots in each treatment group were measured. Al-add induced soil acidification in all fertilizers across the experiment (p < 0.05). On day 20, AGB and leaves in CHE was increased by acidification (p < 0.05), which was not observed in other fertilizer treatments (p > 0.1). Stubble growth increased following acidification in all fertilizer treatments (p < 0.05). Acidification did not increase AGB on day 47; no effect was seen on root growth at either day 20 or 47 (p > 0.1). On day 20, soil concentrations of inorganic nitrogen (IN), nitrate-nitrogen (NO₃-N), and ammonium-nitrogen (NH₄-N) were significantly elevated in Al-add pots (p < 0.05). The increment was greater in CHE and CMP than in CNT and DNG on day 20, with a similar trend being observed for IN and NH₄-N concentrations at day 47. IN and NH₄-N concentrations in DNG with no-Al increased over the regrowth period. These results indicate that orchardgrass regrowth in acidic soils can be improved by fertilizer addition, depending on fertilizer type. The increased concentration of soil IN, induced by soil acidification, is likely to be one of the factors encouraging growth. This increase of regrowth may favor the persistence of orchardgrass in strongly acidic soils.

Naturally occurring forage species in the high-altitude pasturelands of Western Himalaya are traditionally being utilized for feeding of livestock. However, the nutritional quality evaluation and validation of their potential as feed for livestock needs to be undertaken. Here, we evaluated proximate compositions, minerals and amino acids (AAs) of five high-altitude forage species, namely, Festuca kashmiriana L., Medicago sativa L., Trifolium pratense L., Medicago falcate L. and Melilotus indica L. The results revealed that proximate compositions, mineral and AAs varied significantly among the forage species. The carbohydrate, crude protein, moisture content, crude fat, crude fiber, crude ash, total phenol, oil absorption capacity and water absorption capacity were found in the range of 17.44–37.27 mg/100 mg, 3.34–14.71 mg/100 mg, 88.73%–90.72%, 0.98–2.32 mg/100 mg, 11.16–24.16%, 7.71–34.49%, 292.50–488.12 μg/100 mg, 3.91–4.67 g/g and 2.64–3.41 g/g, respectively. Elemental composition showed that calcium was the predominant element among the minerals (13.91–132.05 mg/kg DM) followed by magnesium (4.60–12.92 mg/kg DM), iron (2.04–76.13 mg/kg DM) and zinc (1.07–2.17 mg/kg DM). Furthermore, we found that these high-altitude forage species are rich in essential AAs like histidine, tryptophan, valine, leucine, phenylalanine and to some extent isoleucine and tyrosine. In addition, these five species showed distinct proteomes but shared a similar functional group. The proteome profiling of these forage species will help to understand the molecular basis of nutritional enrichment and stress tolerance potential against harsh environmental conditions of high altitudes. Overall, we conclude that traditionally used high-altitude forage species are nutritionally rich and can be recommended as part of the daily nutritive feed for livestock animals.

In order to make good use of Pennisetum grasses to relieve the shortage of animal feed, the nutrients, silage fermentation quality, and Cornell Net Carbohydrate and Protein System (CNCPS) protein fractions of Pennisetum spp. were evaluated in this study. Four Pennisetum cultivars of Reyan-4, Mott, Guimu-1, and MT-1 were harvested at the first cut and second cut, and they were wilted and ensiled for the analyses of fermentation quality and protein fractions. The first-cut grasses had higher crude protein (CP), water-soluble carbohydrate (WSC) contents, and lower detergent fiber contents than the second cut ones. Mott had higher CP content. Reyan-4 and MT-1 contained higher WSC contents, and their silages had lower pH and ammonia nitrogen (NH₃-N) content, higher lactic acid content than Mott and Guimu-1 silages. Wilting increased pH and NH₃-N contents and decreased lactic acid contents of both cut silages. The CNCPS analysis showed that fresh MT-1 of either first or second cut had more evenly distributed protein fractions than other three grasses. Wilting and ensiling increased nonprotein nitrogen contents and decreased unavailable protein contents of four grasses. Four cultivars at the first cut contained more CP and less fiber than those at the second cut. Reyan-4 and MT-1 had better fermentation quality of silage than Mott and Guimu-1; the latter might need additives to improve fermentation quality at ensiling.

The genetic diversity of the Vicia (Vicia L.) genus was analyzed using simple sequence repeat (SSR) markers. A total of 201 sampled individuals from 12 Vicia were assayed to study the genetic diversity and polymorphisms using 12 simple sequence repeat markers; 115 alleles were identified. The average observed heterozygosity (Ho) and the average expected heterozygosity (He) were 0.4283 and 0.6941, respectively. The polymorphic information content (PIC) varied from 0.8739 (V81) to 0.9579 (V97), with a mean of 0.9033, indicating that the markers were highly informative. Moreover, cluster and principal coordinate analysis (PCoA) divided the 12 species into three main clusters. Structure analysis and PCoA of Vicia narbonensis and Vicia tibetica agreed well with the cluster analysis results, and analysis of molecular variance (AMOVA) results revealed that 89% genetic variation was observed within the population and 11% was among the population. These results clarify the genetic diversity and population structure of the Vicia, providing useful information for understanding genetic variability and establishing a foundation for future breeding programs and genetic improvement.

We investigated the maize grain yield in response to nitrogen topdressing at different planting densities and planting patterns (twin row, TR; narrow row, NR; and conventional row, CR) over 3 years using early-maturing cultivars. The P8025 grain yield was higher with a nitrogen topdressing of 6 g/m² (N6) than without a nitrogen topdressing (N0) at all planting densities in 2017, 2018, and 2019. The difference between the nitrogen topdressing treatments was largest at a planting density close to 10 plants per square meter, which resulted in the highest grain yield in the N0 plot. The rank order for the grain yields among planting patterns was TR ≥ NR > CR in the three analyzed years. Changes in grain yield associated with planting densities followed significant negative quadratic regression curves for all planting patterns. In both the N0 and N6 plots, the grain yield response to planting density was more stable for TR cultivation than for CR and NR cultivation. The rank order for the nitrogen use efficiency (NUE) among planting patterns was TR ≥ NR ≥ CR. The differences in the NUE among planting patterns were higher at higher planting densities. The high NUE observed for TR and NR cultivation was due to the high topdressed nitrogen absorption rate (Nab) at a planting density less than 8.9 plants per square meter as well as the efficiency of the grain yield increase resulting from absorbed nitrogen (Ngy) at a planting density greater than 10.3 plants per square meter. The higher NUE for TR cultivation than for NR cultivation at 12.1 plants per square meter was because of a difference in Ngy and was unrelated to Nab. These results suggest that the improvement of planting pattern (TR, NR) can enhance the effect of topdressed nitrogen on grain yield in maize due to the increase of Nab or Ngy according to the planting density.

The ZjHSP18.9 gene was isolated from Zoysiagrass by homologous cloning based on publicly available transcriptome database. Sequence alignment analysis revealed that ZjHSP18.9 protein contains a classic Hsp23/ACD domain. Phylogenetic analysis and subcellular localization prediction suggested that ZjHSP18.9 belongs to cytosolic class VI subfamily. The expression profiles of ZjHSP18.9 in leaf and root after abiotic stress or Abscisic Acid (ABA) treatment was investigated using quantitative real-time polymerase chain reaction. The results showed that the expression level of ZjHSP18.9 in leaf was higher than that in root. The expression of ZjHSP18.9 was strongly induced by high temperature in leaf; the ZjHSP18.9 expression level was up-regulated in both leaf and root by the treatment of low temperature, salt and heavy metal, while down-regulated under the treatment of drought and ABA. The gene expression profiles indicated that ZjHSP18.9 may play an important role in Zoysiagrass response to environmental stress including extreme temperature, salinity, water deficiency and heavy metal through ABA dependent and/or independent pathway.