Grassland Science最新文献

The growth responses of alfalfa (Medicago sativa L.) to azomite, a natural composite earth mineral, were assessed in a greenhouse experiment at Virginia State University, Chesterfield, VA. Alfalfa plants were raised on lime-amended Bojac, Bourne, Emporia and Cullen soils that received 224 kg K/ha in 14 × 16 cm pots. Azomite, a natural composite micronutrients fertilizer, was applied at 0, 200, 400, 600 kg/ha and experiment replicated three times. Over 29 weeks, plant heights and forage biomass were recorded and growth rates calculated at four different cuts. The data were analyzed using the PROC GLIMMIX procedure in SAS 9.3 to test for effects of soil type and azomite rates on the performance of alfalfa. Results indicate that, compared to the control, azomite application increased plant heights, forage biomass and growth rates of alfalfa and more so on Bojac and Bourne than Emporia and Cullen soils. This was most likely due to good water permeability and high nutrient activity in the semi-active Bojac and Bourne compared to the sub-active Emporia and Cullen soils. Plant heights, biomass and growth rates were greatest for plants receiving 200 kg azomite/ha while those on the 600 kg/ha rate performed worse than the control. Alfalfa on lime-amended and K-sufficient soils responded positively to 200 kg azomite/ha, but was impacted negatively at the higher rates.

For revealing the effects of NaCl and NaHCO₃ stress at different pH levels on the absorption and accumulation of main ions in roots, stems and leaves, alfalfa (Medicago sativa L.) plants were cultivated in a nutrient solution system. After NaCl and Na₂HCO₃ imposition, the contents of main ions in roots, stems, leaves and xylem bleeding sap were determined. Under NaCl and Na₂HCO₃ stresses with the same Na⁺ concentration, Na₂HCO₃ stress showed severer inhibitory effects on alfalfa growth in contrast to NaCl stress at different pH levels. Under NaCl stresses at different pH levels, alfalfa plants showed much lower Na⁺ accumulation and Na⁺ delivery rate in root bleeding sap than that under NaHCO₃ stress. The plants of NaHCO₃ stress showed a severer inhibition in K⁺ accumulation, lower K⁺ delivery rate, but higher Na⁺/K⁺ ratios than the plants of NaCl stress. NaHCO₃ stress increased Ca²⁺ and Mg²⁺ accumulation in alfalfa roots, decreased Ca²⁺ and Mg²⁺ delivery rates and increased leaf Na⁺/Ca²⁺ ratio and Na⁺/Mg²⁺ ratio. Both NaCl and NaHCO₃ stresses decreased the contents of Fe³⁺ and Mn²⁺ in roots, but increased the contents of Cu²⁺ in roots, stems and leaves, the content of Mn²⁺ in stems and leaf Zn²⁺ content in alfalfa plants. However, the contents of Fe³⁺ and Mn²⁺ in roots and stem Mn²⁺ content in the NaHCO₃ treatments were much lower than those in the NaCl treatments. In conclusion, NaHCO₃ stress produced severer injury and induced severer Na⁺ toxicity to alfalfa plants than NaCl stress. The effects of NaHCO₃ stress and NaCl stress on the absorption and accumulation of trophic ions were different. Under NaCl stress, the increased pH did not alter Na⁺ absorption and accumulation in plants, but altered the distribution of some nutrient ions in roots, stems and leaves.

Algeria is a country rich in phytogenetic resources, especially those of pastoral and forage interest. Unfortunately, few studies have been conducted to characterize Algerian local ecotypes. Recently, advances in next-generation sequencing technologies have allowed for robust genotyping by sequencing (GBS) for single nucleotide polymorphism (SNP) discovery, making the characterization of plant relationships with complex and unsequenced genomes more feasible. In the present study, we investigate the genetic diversity of cocksfoot and tall fescue ecotypes from different regions in Algeria, using the SNP variation supplied by a GBS analysis. We compared ecotypes to two common cultivars of both species. A total of 787 SNP markers for cocksfoot and 743 for tall fescue were obtained, and the diversity analysis revealed that 88% and 86% of overall variation in cocksfoot and tall fescue, respectively, were within populations rather than among them. Genetic structure analysis revealed a moderate genetic differentiation among accessions with a mean F_st value of 0.127 for cocksfoot and 0.140 for tall fescue, with high gene flow (Nm_Orchardgrass = 1.723, Nm_{Tall fescue} = 1.535) and no significant isolation-by-distance pattern. A unweighted pair group method with arithmetic mean tree (UPGMA) and principal component analysis revealed the genetic distinctness of populations from cultivars for each species. The flow cytometry analysis confirmed the tetraploid level of cocksfoot and the hexaploid level of all tall fescue entries but one. Although the cocksfoot populations were distinct from the cultivars, the Ruines de djemila population had the broadest base and showed the closest relative relationship to the two cultivars. Similarly, the FE5729 tall fescue population showed the closest relationship to the two tall fescue cultivars.

This paper demonstrates a non-destructive method for measuring the moisture content of silage in wrapped round bales (WRBs) via microwave signals using a microstrip transmission line (MSTL) sensor and vector network analyzer under outdoor conditions. We analyzed the relationships between the amplitude changes (Δα) and phase shifts (Δφ) of the microwave-transmitted signals from the WRB surfaces without tearing their films. The press MSTL method was strongly suggested over the touch MSTL method for the non-destructive measurement of WRB qualities. We also obtained strongly negative and significant correlations between the slopes of the linear regression lines (Δφ–Δα ratios) and moisture contents for frequencies in the range of 3.6–6.2 GHz. Thus, in this frequency zone, the press MSTL method can be effectively used to determine the moisture content of silage in WRBs.

In southwestern Japan, palisadegrass (Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster) is used as annual summer grass with fertilizer application. In this system, the risk of a poisonous nitrate nitrogen concentration in grass is high. Nevertheless, no report describes a study of nitrate nitrogen in palisadegrass as annual summer grass. Therefore, we clarified the effects of chemical fertilizer to nitrate nitrogen concentration in palisadegrass cultivated as annual summer grass for two years. Treatments were factorial combinations of three basal fertilizer applications (0, 100 or 200 kg N, P₂O₅, K₂O/ha) and two additional fertilizer applications (0 or 100 kg N, P₂O₅, K₂O/ha) in a randomized complete block design with five replicates. Results well demonstrated that nitrate nitrogen concentrations in palisadegrass increase with fertilizer application, especially with fertilizer added after decreased growth of palisadegrass caused by lower temperatures. Harvest of palisadegrass after additional fertilizer application requires awareness of its nitrate nitrogen content.

Forage dry matter (DM) yield and its nutrient content are important in livestock nutrition; however, they have distinct, even opposite responses to mowing regimes. To optimize forage resources, two independent field experiments were conducted to determine effects of initial mowing time (15-day intervals from May 15 to September 1) and mowing frequency (one to five times per year) on DM yield and nutritive value of Leymus chinensis (Trin.) Tzvel. The greatest cumulative DM yield (cDMY), pre-mowing crude protein yield (pCPY) and cumulative crude protein yield (cCPY) were attained when initial mowing occurred from July 15 to August 15. The crude protein (CP) concentration of pDMY was higher, whereas fiber concentrations were lower, when initial mowing was from May 15 to June 15, with opposite results when the initial mowing was delayed (July 1 to September 30). When mowing three times annually, cDMY and cCPY of L. chinensis were higher (p < .05) than with less frequent mowing. With more than three mowings, accumulated CP yield of L. chinensis was not significantly affected. With four or five yearly mowings, accumulated DM yield of L. chinensis decreased significantly compared to mowing one to three times. In conclusion, based on DM yield and nutritive value, the optimal initial mowing date ranged from July 15 to August 15, whereas optimal mowing frequency was three times yearly.

The objective was to investigate effects of feeding lambs fresh versus dried Puccinellia. tenuiflora (Griesb.) Scribn. & Merr. on nutrient and water intake and apparent digestibility. Twenty-four lambs were offered fresh or dried (48 hr) grass. The dry matter (DM) content of fresh grass was 65% of dried grass and the neutral detergent fiber exclude ash (aNDFom) content of fresh grass was 87% of dried grass, whereas the metabolizable energy concentration of two forages was similar. Lambs eating fresh grass had higher (p < .05) DM intake (944 versus 837 g DM day⁻¹ sheep⁻¹), metabolizable energy intake (9.1 versus 7.9 MJ day^-1sheep⁻¹), and crude protein intake (86 versus 75 g day^-1 sheep⁻¹) than those eating dried grass. However, there was no significant difference between treatments in drinking water intake, fecal nutrient output or nutrient digestibility. In conclusion, feeding lambs fresh P. tenuiflora improved voluntary feed intake without depressing nutrient digestibility.

Integrated crop-livestock systems (ICLS) are diversified agroecosystems characterized by the rotation, succession or mixtures of agricultural, livestock or forestry activities, in no-tillage systems. In ICLS with trees, the tree modifies the light and water availability, and might generate root competition for nutrients, like potassium (K). The study aims to evaluate dry matter (DM) and macronutrients accumulation in white oat, DM and grain yield of maize, and the K use efficiency (KUE) by these crops cultivated in an ICLS with eucalyptus. The experimental design was a randomized block in a split-plot design with three replications. Plots consisted of four cultivation positions (CP) between the tree rows, where CP1 (0 to 4 m distance) refers to a position close to the trees; CP2 (4 to 8 m distance) and CP4 (12 to 16 m distance) corresponds to two intermediate positions between rows; and CP3 (8 to 12 m distance) corresponds to a central position between rows. In subplots, four potassium oxide (K₂O) annual doses were assigned, with potassium chloride being applied on the surface, where each rate was half the rate applied at sowing of each crop. DM and macronutrients accumulation in white oat shoot decreased due to eucalyptus shadow (64.5% light restriction). Responses of maize DM and grain yield to K₂O addition were different among CPs, possibly owing to different light patterns. No changes in the maize yield were observed with K₂O application in CP1 and CP2. However, for other positions, quadratic responses in grain yield were observed. In ICLS with eucalyptus in a subtropical region of Brazil, the reduction of K fertilization led to lower yields in white oat and maize. As KUE was high in plots with low K rate, the production cost in ICLS with trees may be decreased if massive production is not required.

Compensatory growth of forage grass can determine its optimal biomass, which is beneficial for increasing its production. The effect of rhizosphere soil nitrification on Italian ryegrass (Lolium multiflorum Lam) regrowth was investigated on the basis of root-produced cytokinin concentration in leaves to reveal the forage grass compensatory growth mechanism. The nitrification inhibitor 3,4-dimethylpyrazole phosphate was added to inhibit soil nitrification. Without soil nitrification being inhibited, compared with no clipping one defoliation cycle increased the leaf photosynthetic rate by 43.82%–53.79%, increased the leaf cytokinin content by 33.48%–34.73%, and increased the cytokinin transport from roots to leaves by 28.88%–39.47%. Nitrification inhibitor decreased soil nitrification rates by 23.33%–84.17% in the rhizosphere and by 42.71%–68.29% in the bulk soil during regrowth. In the rhizosphere micro-environment, nitrification increased soil nitrate concentration that played an important role in the transport of cytokinin from roots to leaves during regrowth, increasing the leaf cytokinin concentration. However, bulk soil nitrification rate and nitrate content had little influence on leaf cytokinin concentration during regrowth. An increase in leaf cytokinin improved the photosynthesis and the regrowth. Without soil nitrification being inhibited, total biomass at the end of regrowth period was 1.09 times higher in plants that were defoliated once than in non-clipped plants. However, soil nitrification inhibitor and two defoliation cycles decreased Italian ryegrass regrowth. Super compensatory growth occurred in the one defoliation cycle Italian ryegrasses without adding soil nitrification inhibitor. Compensatory growth occurred in once-defoliated Italian ryegrass with adding soil nitrification inhibitor and in twice-defoliated Italian ryegrass without adding soil nitrification inhibitor. In conclusion, rhizosphere soil nitrification is the key factor that regulates the compensatory growth of Italian ryegrass.