Tropical Pasture Legumes Research Articles

Unveiling Microbial Dynamics and Gene Expression in Legume–Buffel Grass Coculture Systems for Sustainable Agriculture

Legumes enhance pasture health and soil productivity by fixing atmospheric nitrogen and boosting soil microbiota. We investigated the effects of tropical pasture legumes, including butterfly pea (Clitoria ternatea), seca stylo (Stylosanthes scabra), desmanthus (Desmanthus virgatus), lablab (Lablab purpureus), and Wynn cassia (Chamaecrista rotundifolia), on the soil microbial community and buffel grass (Cenchrus ciliaris) gene expression. Additionally, we explored the impact of a phytogenic bioactive product (PHY) in the coculture system. A pot trial using soil enriched with cow paunch compost included four treatments: monoculture of buffel grass and five legume species with and without PHY supplementation and coculture of buffel grass with each legume species with and without PHY supplementation. Actinobacteriota and Firmicutes were the dominant bacterial phyla. Regardless of PHY application, the coculture of buffel grass with legumes positively influenced microbial composition and diversity. Transcriptomic analysis revealed significant gene expression changes in buffel grass shoots and roots, with each legume uniquely affecting nitrogen metabolism. Lablab and Wynn cassia exhibited similarities in modulating metabolic processes, butterfly pea contributed to mycotoxin detoxification, and desmanthus balanced cell death and growth. Seca stylo enhanced root cell growth and regeneration. These findings offer insights for optimizing legume–grass coculture systems, enhancing soil activity and promoting sustainable agriculture.

Preferential Phosphorus Placement Improves the Productivity and Competitiveness of Tropical Pasture Legumes

ABSTRACTExtensive grazing systems often receive minimal fertiliser due to the risk associated with using relatively expensive inputs. Nevertheless, nutrient applications are known to improve pasture productivity, and the benefit of applying fertiliser is being more widely accepted. Two tropical pasture mixes (Digit/Desmanthus and Rhodes/Centro) were established in plastic boxes containing phosphorus (P) responsive soil to investigate shoot yield and P fertiliser recovery. The grasses and legumes were planted in separate rows, and three P treatments were applied along with the seed (‘BOTH low‐P’ had 2 kg P ha−1 banded below both components, ‘BOTH high‐P’ had 12 kg P ha−1 banded below both components and ‘LEGUME superhigh‐P’ had 12 kg P ha−1 banded below the legume only). The P applied below the legumes was labelled with 32P‐radioisotope tracer. When P fertiliser was applied below both components, the grasses consistently out‐yielded the legumes (avg. legume content = 29%). Preferential fertiliser application below the legumes increased the average legume content of the two pasture mixes to 66%. Legume tissue P derived from applied P fertiliser increased from 20% to 77% as the P application rate was increased. However, total recovery of applied P by the legumes was relatively low in each of the treatments (≤ 7% of applied P). These collective results demonstrate that a preferential application of P fertiliser can benefit legume productivity, with applied P being a significant proportion of plant tissue P. Although only a small proportion of applied P was recovered within the seven‐week growth period, it is expected that this fertiliser application at planting will remain beneficial for a large proportion of the growing season following pasture establishment.

Emergence and Early Growth of Four Desmanthus Species in Three Alkaline Clay Soils

Tropical pasture legumes such as Desmanthus are expected to improve pasture productivity in the extensive grazing systems of Northern Australia. However, the soils in these areas are often hostile (e.g., hard-setting and nutrient-deficient), which reduces legume emergence and establishment. Furthermore, these soils are often not ameliorated with amendments such as gypsum or starter fertilisers before planting. A pot trial was conducted to investigate differences in the emergence and early growth of four Desmanthus species. The legumes were grown in three alkaline clay soils that were unamended or amended with either gypsum (1 t CaSO4.2H2O ha−1 equivalent), a starter MAP fertiliser (12 kg P ha−1 equivalent), or both gypsum and the starter fertiliser. Seedling emergence was recorded daily and shoot yield was determined after six weeks’ growth. Final seedling emergence (as a percentage of viable seeds) varied among the Desmanthus species (c.f. D. leptophyllus = 63%, D. pernambucanus = 68%, D. bicornutus = 85%, and D. virgatus = 86%). On average, across the treatments, gypsum increased seedling emergence by 15%, whereas the starter fertiliser had no effect. The shoot yields and shoot phosphorus content of the Desmanthus species generally increased in response to the starter fertiliser. The collective results demonstrated that there were differences in emergence and early growth among the four Desmanthus species, which indicates that Desmanthus cultivar selection may be important in the relatively hostile soils of Northern Australia. Gypsum was an effective amendment for seedling emergence, whereas the starter fertiliser was an effective amendment to increase legume productivity.

Differences in phosphorus acquisition and critical phosphorus requirements among nine

The extensive grazing systems of northern Australia are dominated by C4 grasses and are established in N- and P-responsive soils that receive minimal nutrient input. Under these conditions, tropical pasture legumes are expected to improve the quality of grazing forage and fix atmospheric N2. However, legume persistence is relatively poor, which may be due to a presumed disparity in P requirements among tropical pasture species. This disparity suggests that P-efficient legumes may improve legume persistence, yet the P requirements of many tropical pasture legumes remain unquantified. Nine Desmanthus spp. genotypes were grown in pots to determine differences in shoot yield and root morphology in response to soil P supply (0–100 mg applied P kg–1 soil; 5–63 mg Colwell P kg–1 soil). The shoot yield of each genotype increased in response to increased P supply. When P supply was adequate for maximum plant growth, the shoot yield of the best genotype (3.5 g DM pot–1; JCU 9) was 1.7-fold larger than that of the next most productive genotype. There were also substantial differences in the critical external P requirements of the genotypes (29.4–64.0 mg P kg–1 soil), although these differences did not always reflect the efficiency of dry matter production per unit of applied P fertiliser. Differences in shoot yield and P acquisition were positively associated with differences in the development of root length. The results indicated that P-efficient genotypes of Desmanthus spp. can be identified for improved growth in the P-responsive pastures of northern Australia. These genotypes may compete more effectively with C4 grasses and form resilient pasture swards as climate patterns change.

Improvement of plant regeneration and <i>Agrobacterium</i>-mediated genetic transformation of <i>Stylosanthes guianensis</i>

As a pioneer tropical pasture legume, stylo (Stylosanthes guianensis) is well adapted to growth-limiting factors in acid soils. Considering the importance of stylo, there is a need to improve Agrobacterium-mediated genetic transformation to enable development of elite cultivars. In this study, S. guianensis cv. RY5 was used to systematically optimize Agrobacterium-mediated transformation based on its plant regeneration. Results showed that Murashige and Skoog (MS) medium containing 0.2 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 2 mg/L 6-benzylaminopurine (6-BA) was the optimal callus induction medium. MS medium supplemented with 2 mg/L 6-BA was suitable for shoot regeneration from cotyledon-derived calluses, and 0.5 mg/L indole-3-acetic acid (IAA) and 0.5 mg/L indole-3-butyric acid (IBA) applications were beneficial for rooting. The highest transformation efficiency (67%) was obtained at an Agrobacterium concentration of optical density = 0.6 combined with an infection time of 15 min and 3 days of co-cultivation. Furthermore, 200 mg/mL carbenicillin (Carb) and 0.6 mg/L Basta® supplements were effective in eliminating excess bacterial growth and selecting transgenic plants, respectively. Subsequent polymerase chain reaction (PCR) analysis confirmed that the β-glucuronidase (GUS) and BAR genes were successfully integrated into the stylo genome. Wider testing of this improved protocol as a means of enhancing genetic improvement and gene function analysis of stylo seems warranted.

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XI.国頭および島尻マージにおける暖地型マメ科およびイネ科牧草の燐施与に対する生育反応

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XI.国頭および島尻マージにおける暖地型マメ科およびイネ科牧草の燐施与に対する生育反応

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XII.国頭および島尻マージにおける有効態燐酸定量法の比較

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XII.国頭および島尻マージにおける有効態燐酸定量法の比較

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : VI.サイラトロと数種暖地型イネ科牧草との混播栽培における可消化乾物収量と乾物消化率

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : VI.サイラトロと数種暖地型イネ科牧草との混播栽培における可消化乾物収量と乾物消化率

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XIV.暖地型マメ科・イネ科18草種の生育におよぼす土壌pHの影響

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XIV.暖地型マメ科・イネ科18草種の生育におよぼす土壌pHの影響

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : VIII.暖地型マメ科牧草スタイロ(Stylosanthes spp.)とイネ科牧草との混播栽培における可消化乾物収量

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : VIII.暖地型マメ科牧草スタイロ(Stylosanthes spp.)とイネ科牧草との混播栽培における可消化乾物収量

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : IV.永年生暖地型マメ科牧草8種とローズグラスとの混播栽培における乾物生産量の比較

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : IV.永年生暖地型マメ科牧草8種とローズグラスとの混播栽培における乾物生産量の比較

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XV.サイラトロと暖地型イネ科牧草との混播草地における乾物および可消化乾物収量におよぼす刈取り間隔の影響

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XV.サイラトロと暖地型イネ科牧草との混播草地における乾物および可消化乾物収量におよぼす刈取り間隔の影響

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XVI. 南西諸島北部における数種暖地型マメ科牧草及びローズグラスの単播及び混播栽培における乾物生産量と窒素収量

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XVI. 南西諸島北部における数種暖地型マメ科牧草及びローズグラスの単播及び混播栽培における乾物生産量と窒素収量

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : IX.暖地型マメ科牧草の追播によるマメ科イネ科混播草地の造成

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : IX.暖地型マメ科牧草の追播によるマメ科イネ科混播草地の造成

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XIII.島尻マージにおけるFeとZn,および国頭マージにおけるMoとMnの施与効果

南西諸島における暖地型マメ科牧草の実用栽培に関する研究 : XIII.島尻マージにおけるFeとZn,および国頭マージにおけるMoとMnの施与効果

Stylosanthes Production, Processing and Utilization Technologies for Animal Production-A Review

Stylosanthes popularly known as stylo, is among the most versatile, widely adapted, highly productive and fast growing tropical pasture legume commonly grown in a number of agricultural systems in many countries with a tropical or subtropical climate. Being a leguminous fodder, Stylosanthes is rich in nutrients and on an average, it contains 15–25% DM, 15–20% CP, 10–15% CF, 1–2% ether extract and 50–60% nitrogen free extract. In India, it is the most important tropical legume for semi-arid and arid regions, where it is mainly used as cut-and-carry fodder, a pasture and/or range crop, a cover crop to suppress weeds and control soil erosion, an inter-crop in agro-forestry and grass-legume mixture, a green manure to enhance soil fertility and nitrogen, protein banks, fallow crops, hay, a pioneering coloniser of problem soils and, more recently, a cash crop to produce dried leaf meal as an ingredient of animal feed formulations for poultry and fish. The surplus Stylosanthes can be processed as leaf meal and feed blocks and can be stored for lean period utilization. These can be sufficient for maintenance requirement of sheep and goats during scarcity period. The review provides a comprehensive account of Stylosanthes research for production, processing and utilization in India during last five decades.

Development and characterization of expressed sequence tag-derived simple sequence repeat markers in tropical forage legume Stylosanthes guianensis (Aubl.) Sw.

Most species of Stylosanthes (stylo) genus are important tropical pasture legumes with very versatile, widely adapted, and productive characteristics. These legumes are commercially used in various agricultural systems in many tropical and subtropical regions. However, the few molecular markers for the stylo species limit their genetic improvement. In this study, 36,558 expressed sequence tags (ESTs) have been de novo assembled using Illumina paired-end sequencing in Stylosanthes guianensis (Aubl.) Sw. to develop simple sequence repeat (SSR) markers. We searched these ESTs for SSRs and identified 4115 SSR loci from 3643 ESTs (9.96 %). Dinucleotide and trinucleotide repeat motifs were the most abundant types (30.50 and 50.33 %, respectively), whereas tetranucleotide, pentanucleotide, and hexanucleotide motifs represented <10 % of all SSRs. The motif AG/CT was the most abundant, accounting for 21.7 % of all SSRs. Moreover, 2008 SSR markers were developed using 1873 SSR-containing unigenes. A total of 115 EST-SSR markers located in the coding region were amplified using polymerase chain reaction to detect 29 S.guianensis accessions. Of these 115 markers, 96 produced reliable bands with expected sizes, and 81 markers were polymorphic, with 2–6 alleles among the 29 accessions. Analysis of the genetic diversity of all 29 accessions revealed similarity coefficients that ranged from 0.528 to 0.983. The EST-SSR markers developed in this study represent the first large-scale development of SSR markers for S.guianensis. These SSR markers will provide a valuable resource for genetic diversity studies, cultivar fingerprinting, construction of genetic maps, identification of quantitative trait loci for important traits, and molecular marker-assisted selection breeding in stylo species.

Bradyrhizobium tropiciagri sp. nov. and Bradyrhizobium embrapense sp. nov., nitrogen-fixing symbionts of tropical forage legumes.

Biological nitrogen fixation is a key process for agricultural production and environmental sustainability, but there are comparatively few studies of symbionts of tropical pasture legumes, as well as few described species of the genus Bradyrhizobium, although it is the predominant rhizobial genus in the tropics. A detailed polyphasic study was conducted with two strains of the genus Bradyrhizobium used in commercial inoculants for tropical pastures in Brazil, CNPSo 1112T, isolated from perennial soybean (Neonotonia wightii), and CNPSo 2833T, from desmodium (Desmodium heterocarpon). Based on 16S-rRNA gene phylogeny, both strains were grouped in the Bradyrhizobium elkanii superclade, but were not clearly clustered with any known species. Multilocus sequence analysis of three (glnII, gyrB and recA) and five (plus atpD and dnaK) housekeeping genes confirmed that the strains are positioned in two distinct clades. Comparison with intergenic transcribed spacer sequences of type strains of described species of the genus Bradyrhizobium showed similarity lower than 93.1 %, and differences were confirmed by BOX-PCR analysis. Nucleotide identity of three housekeeping genes with type strains of described species ranged from 88.1 to 96.2 %. Average nucleotide identity of genome sequences showed values below the threshold for distinct species of the genus Bradyrhizobium ( < 90.6 %), and the value between the two strains was also below this threshold (91.2 %). Analysis of nifH and nodC gene sequences positioned the two strains in a clade distinct from other species of the genus Bradyrhizobium. Morphophysiological, genotypic and genomic data supported the description of two novel species in the genus Bradyrhizobium, Bradyrhizobium tropiciagri sp. nov. (type strain CNPSo 1112T = SMS 303T = BR 1009T = SEMIA 6148T = LMG 28867T) and Bradyrhizobium embrapense sp. nov. (type strain CNPSo 2833T = CIAT 2372T = BR 2212T = SEMIA 6208T = U674T = LMG 2987).

Sustainable, low‐input, warm‐season, grass–legume grassland mixtures: mission (nearly) impossible?

AbstractGrazing lands in warm‐temperate and subtropical North America have become less diverse. Pastures are typically grass monocultures, while rangelands are generally managed for the grass components. Overstocking, selective herbicides, fire exclusion and heavy rates of nitrogen fertilizer have contributed to near exclusion of native, warm‐season legumes. The simplicity of managing grass monocultures, pasture production responses to nitrogen fertilizer and profitability of grass‐only systems have limited interest in legume‐based approaches. Changing economics and ecological concerns with ecosystem accumulation of industrial inputs contribute to an increasing interest in legumes. Unlike the development of temperate pasture legumes and recent research in the tropics, legumes tolerant of both freezing temperatures and hot weather have received less attention. Poor establishment, limited persistence and potential invasiveness limit currently available introduced species. Native, herbaceous, warm‐season legume species occur throughout warm‐temperate North America, but little attention has been directed to these plants as potential forage species. Some success with a few native legume species, primarily in the genus Desmanthus, suggests potential for expanded assessment of forage value of the many species available. Current assessments of native legumes, primarily for conservation purposes, provide an opportunity to expand evaluations of these species for pasture and rangeland potential while economics of livestock production and public interest in ecosystem health are supportive. Experiences with legumes of warm‐temperate origin in North America, along with results with temperate and tropical pasture legumes globally, provide a starting point for future efforts at incorporating greater legume diversity in pastures and rangelands of subtropical and warm‐temperate regions around the world.

Isolation and characterization of microsatellite loci in the tropical forage legume Stylosanthes guianensis (Aubl.) Sw.

Stylosanthes guianensis is an important tropical pasture legume. Knowledge of genetic diversity and structure of S. guianensis populations is of great importance for the conservation and germplasm management of this species. Thus, 20 microsatellite markers were developed from a S. guianensis enriched library. The microsatellites were characterized in 20 accessions from the germplasm collection of the Empresa Brasileira de Pesquisa Agropecuaria (Embrapa). The average number of alleles per locus varied from 2 to 7, with an average of 4 alleles per locus. The observed and expected heterozygosities ranged from 0 to 0.60 and 0.10 to 0.85, respectively. This new set of microsatellites will contribute towards studies of genetic diversity and conservation of S. guianensis.