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Trifolium subterraneum L. subsp. yanninicum is a pasture legume that is widely grown in medium and high rainfall areas of southern Australia and shows waterlogging tolerance. This study investigated diversity within subsp. yanninicum corresponding to eco-geographic variables, which may help to identify adapted parents with new traits for genetic improvement. Diversity for 10 morphological traits, flowering time and leaf isoflavone content was investigated using 108 ecotypes derived from wild Mediterranean populations and 10 cultivars, grown as spaced plants. Among the ecotypes, the range of flowering time was 94–149 days after sowing, and contents of formononetin, genistein and biochanin A were 0.05–1.38%, 0.73–2.33% and 0.15–2.10% of dry matter, respectively. Leaf markings also varied considerably. Leaf size and petiole length were correlated at each growth stage. Later flowering genotypes had larger leaves, longer petioles, longer internodes and thicker stems at flowering, but smaller leaves and shorter petioles at both 63 and 88 days after sowing. Contents of genistein and biochanin A were unrelated, but both were negatively associated with formononetin. Flowering time had a weak positive influence on genistein and biochanin A, but a weak negative influence on formononetin. All traits among the ecotypes (except stem diameter and leaf mark crescent size) were significantly correlated with at least one of 22 eco-geographic variables from their collection sites. Precipitation and altitude were more influential than temperature. The study found sufficient diversity to broaden the narrow genetic base of current subsp. yanninicum cultivars; however, other agronomically important traits also need to be considered. Further diversity may result from targeted collection, particularly in areas not represented in annual legume genebanks.

[EN[ The introduction of well-adapted species, such as Trifolium subterraneum (subclover) and Poa pratensis (Kentucky bluegrass), might enhance the forage yield and quality of dehesa pastures for feeding livestock. However, the climatic hardness and poor soils in these agrosystems may limit plant establishment and development. Since fungal endophytes have been found to alleviate the environmental stresses of their host, the aim of this study was to assess the effect of five isolates on forage yield, nutritive value, and plant mineral uptake after their inoculation in the two abovementioned plant species. Two experiments were established (under greenhouse and field conditions) using plants inoculated with two isolates in 2012/2013 (Epicoccum nigrum, Sporormiella intermedia) and three isolates in 2013/2014 (Mucor hiemalis, Fusarium equiseti, Byssochlamys spectabilis). Fusarium equiseti (E346) increased the herbage yield of T. subterraneum under greenhouse conditions, and B. spectabilis improved the forage quality of T. subterraneum by reducing fiber content and of P. pratensis by increasing crude protein. S. intermedia increased the mineral uptake of Ca, Cu, Mn, Pb, Tl, and Zn in subclover, and M. hiemalis increased the uptake of K and Sr in Kentucky bluegrass. These results evidence the potential of the studied fungal endophytes to enhance herbage yield and nutritional value of forage, although further studies should include all of the target forage species as certain host specificity in the effect was observed., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This research was funded by Project AGL2011-27454, granted by the Ministry of Economy and Competitiveness of Spain (the former Ministry of Science and Innovation) and by the European Regional Development Fund (ERDF)., Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

Biodiversity in forage legumes adapted to semiarid-arid conditions is scarce. In the Pampa-Patagonia transitional region of Argentina (PTRA), the annual rainfall is 440 mm with annual evapotranspiration of 1690 mm. Only Vicia villosa Roth shows agronomic adaptation to such an environment. Dry matter production of 19 selected legume species was compared to V. villosa (cv. Patagonia INTA) in the first year of establishment during 2015-to-2019. Medicago truncatula Gaertn. and Trifolium subterraneum L. (cv. Goulburn) showed high winter dry matter production, similar to V. villosa, but poor biomass production in spring. Spring dry matter contributed ≈ 80% of the total biomass per year. Preliminary results showed that Onobrychis viciifolia Scop. overcame the rest of the accessions evaluated, except for V. villosa. O. viciifolia could be considered a complementary species to V. villosa, a candidate for initiating a process of breeding as a new pasture legume for semiarid-arid environments. This is the first record of the potential use as a pasture of O. viciifolia in the PTRA. La biodiversidad de leguminosas forrajeras adaptadas a condiciones semiáridas-áridas es escasa. En la región de transición Pampa-Patagonia de Argentina (PTRA), la precipitación anual es de 440 mm con una evapotranspiración anual de 1690 mm. Solo Vicia villosa Roth muestra adaptación agronómica a dicho ambiente. Se comparó la producción de materia seca de 19 especies de leguminosas seleccionadas con V. villosa (cv. Patagonia INTA) en el primer año de establecimiento durante 2015-2019. Medicago truncatula Gaertn. y Trifolium subterraneum L. (cv. Goulburn) mostraron una alta producción de materia seca invernal, similar a la de V. villosa, pero una pobre producción de biomasa en primavera. La materia seca de primavera aportó ≈ 80% de la biomasa total por año. Los resultados preliminares mostraron que Onobrychis viciifolia Scop. superó al resto de las accesiones evaluadas, excepto a V. villosa. O. viciifolia podría considerarse una especie complementaria a V. villosa, candidata a iniciar un proceso de mejoramiento como nueva leguminosa de pastoreo para ambientes semiáridos-áridos. Este es el primer registro del uso potencial como forrajera de O. viciifolia en la PTRA. EEA Hilario Ascasubi Fil: Renzi Pugni, Juan Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi; Argentina. Fil: Renzi Pugni, Juan Pablo. Universidad Nacional del Sur. Departamento de Agronomía; Argentina Fil: Chantre Balacca, Guillermo Ruben. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Fil: Chantre Balacca, Guillermo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentina Fil: Chantre Balacca, Guillermo Ruben. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentina Fil: Reinoso, Omar Juan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi; Argentina Fil: Quintana, Matias. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi; Argentina Fil: Grand, Andres Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi. Agencia De Extensión Rural Carmen de Patagones; Argentina Fil: Cantamutto, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Hilario Ascasubi; Argentina. Fil: Cantamutto, Miguel Angel. Universidad Nacional del Sur. Departamento de Agronomía; Argentina Fil: Cantamutto, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentina Fil: Cantamutto, Miguel Angel. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentina

Context The use of dual-purpose crops (for grazing and grain) has increased in the high-rainfall zone in southern Australia. Aim A systems experiment examined the impact on livestock production and supplementary feeding when dual-purpose crops were incorporated into a production system based on Merino ewes producing yearling lambs for sale. Methods The experimental site near Canberra, ACT, was subdivided into nine experimental units (‘farmlets’) with three replicate farmlets for each of three production-system treatments. Each farmlet was managed as a self-contained unit with six Merino ewes and their progeny during 2013–16 (4 years). Ewes were joined in February, lambed in July and shorn in spring; the original cohort of ewes (born 2009) was replaced by a new cohort (born 2012) at the midpoint of the experiment. Six weaners were retained after weaning in each farmlet and sold as yearlings. Control farmlets were sown to pasture based on phalaris (Phalaris aquatica L.) and subterranean clover (Trifolium subterraneum L.) and comprised sub-paddocks to allow rotational grazing. Farmlets in treatments that included dual-purpose crops comprised six sub-paddocks (0.231 ha), with two sown to permanent pasture, and four supporting a rotation of pasture–pasture–dual-purpose canola (Brassica napus L.)–dual-purpose wheat (Triticum aestivum L.). In one of the crop–pasture production system treatments, crop-grazing was prioritised for ewes (ECG treatment); in the other, crop-grazing was prioritised for their progeny weaners (WCG treatment). Key results Greasy fleece weight from ECG (5.3 kg) and WCG (5.1 kg) ewes was higher (P < 0.001) than from control ewes (4.7 kg) averaged over the 4 years. The final sale weight of yearling weaners from the WCG system (44.3 kg) was higher (P < 0.001) than from the control (39.2 kg) or ECG (39.1 kg) systems when averaged over the 4 years. The benefit was predominantly due to greater weight gain during the period when weaners grazed the crop during late autumn and winter. Sale weight of lamb per hectare was higher (P = 0.003) in the WCG treatment (216 kg) compared with the ECG treatment (186 kg) when averaged over the 4 years of the experiment but did not differ (P > 0.05) to the control (201 kg). Meat production over the 4 years was higher (P < 0.001) in the WCG system (226 kg/ha) than other treatments when weight gain from wethers in 2014 was included. The impact of including dual-purpose crops on supplementary feeding was variable and depended on seasonal conditions. Conclusions Incorporation of dual-purpose crops into the high-rainfall production system can increase meat and wool production, with the highest meat production being obtained when crop grazing was prioritised for young carry-over livestock. Implications Prioritising dual-purpose crops for young growing livestock can increase meat production from the system while allowing other livestock classes (wethers or ewes) to graze the crops in better seasons when there was excess forage that would otherwise have been under-utilised.

Glasshouse and field investigations of the phenotypic expressions of resistance of a 97-member World Core Collection of subterranean clover (Trifolium subterraneum) collected from its native Mediterranean habitat and representing approximately 80% of the total genetic diversity within the known 10,000 accessions of the species against the most important damping-off and root rot (Phytophthora clandestina, and Pythium irregulare) and foliar (Kabatiella caulivora, Uromyces trifolii-repentis, and Erysiphe trifoliorum) pathogens were performed. An additional 28 diverse cultivars were also included. Associations of these genotypes among 18 disease parameters and 17 morphological traits, and among these disease parameters and 24 climatic and eco-geographic variables from their collection sites, were examined. Many genotypes showed strong phenotypic expression of novel host disease resistance against one or more pathogens, enabling their potential deployment as disease-resistant parents in subterranean clover breeding programs. These new sources of resistance enable future “pyramiding” of different resistance genes to improve resistance against these pathogens. Of particular value were genotypes with multiple disease-resistance across soilborne and/or foliar diseases, because many of these pathogens co-occur. All diseases had some parameters significantly correlated with one or more morphological traits and with one or more sites of origin variables. In particular, there were significant negative correlations between damping-off (i.e., germination) and 8 of the 17 morphological characters. The outcomes of these studies provide crucial information to subterranean clover breeding programs, enabling them to simultaneously select genotypes with multiple resistance to co-occurring soilborne and foliar diseases and desirable traits to offer renewed hope for re-establishing a more productive subterranean clover livestock feedbase despite multiple diseases prevailing widely.

Tolerance to waterlogging and recovery ability was compared among the three subspecies of subterranean clover (Trifolium subterraneum L.) to identify tolerance mechanisms, in order to guide future subclover breeding activities. Three cultivars each of ssp. yanninicum, subterraneum and brachycalycinum were grown in a controlled environment glasshouse with T. michelianum as a waterlogging-tolerant control. After 28 days of growth two treatments were imposed for 35 days: free-draining (control) and waterlogged. A 21-day recovery period followed. After 35 days, waterlogging reduced shoot dry weight (DW) to 58–27% and root DW to 35–21% of respective controls in each subspecies. Shoot relative growth rate (RGR) of yanninicum was least affected (78–104% of control), compared to subterraneum (51–100%) and brachycalycinum (45–69%). The subterraneum cv. Denmark had a similar response to subspecies yanninicum. Shoot RGR of T. michelianum was 138% of its control. After recovery, all traits (except tap root length) recovered to control values. Up to 21 days, the main traits associated with waterlogging tolerance (shoot and root growth) were high petiole length, less petiole anthocyanin pigmentation and high leaf chlorophyll content, but by 35 days these were a high proportion of leaf biomass, high stomatal conductance and enhanced root porosity. Average root diameter and nodulation rates were unrelated to waterlogging tolerance. Subspecies yanninicum had superior waterlogging tolerance. Priority traits for easily-assessed indicators of waterlogging tolerance are less reduction of leaf size and high stomatal conductance.

Subterranean clover (Trifolium subterraneum L.) is Australia’s most widely sown annual pasture legume. Its widespread use as a pasture plant requires a well-functioning seed production industry, and Australia is the only significant producer of subterranean clover seed globally. However, the sustainability of this industry is under threat due to its reliance on ageing harvest equipment and the resultant environmental impacts. In order to evaluate seed harvesting practices, technology, and issues, we report on case studies, workshops, and a survey of seed producers across southern Australia. The Horwood Bagshaw Clover Harvester, designed in the 1950s, remains the most popular subterranean clover seed harvester. We discuss its use and modifications, and document several contemporary issues facing the seed production industry. Issues are primarily soil erosion and degradation; the expensive, slow and labour-intensive harvest process; and poor reliability and maintainability of harvesters that are now at least 30 years old. We conclude the root cause of these issues is the suction harvest technology utilised by the Horwood Bagshaw Clover Harvester. Analysis of the current harvest system is provided to support the development of new approaches to harvest subterranean clover seeds.

A field experiment was established in Lincoln, Canterbury in autumn 2018 to evaluate the effect of acetolactate synthase (ALS) inhibiting herbicides on subterraneun (sub) clover. Two herbicides, imazethapyr and flumetsulam, were applied to seven sub clover cultivars at the 4-5 trifoliate leaf stage during July 2018. By December 2018, both herbicides had reduced the broadleaf weed yield by 1000 kg DM/ha. Sub clover herbage yield in spring (3 Oct 2018) increased only for ‘Antas’ and ‘Napier’ cultivars but all cultivars had an increase in total annual herbage yield when herbicides were applied. Plots were managed for seed set so re-establishment was examined. Imazethapyr had a longer residual than flumetsulam with greater control of broad-leaved dock (Rumex obtusifolius) eight months after application. Herbicide application had no effect on subsequent sub clover emergence the following year. This experiment demonstrated the potential to establish a pure sward of sub clover with the use of ALS inhibiting herbicides, which could be used to create a high legume base in pasture before overdrilling grass the following year.

Context Biserrula (Biserrula pelecinus L.) is a relatively new legume species in Australia that has been shown to maintain higher quality forage late in the season than subterranean clover (Trifolium subterraneum L.). Aim This study investigated the suitability of lucerne (Medicago sativa L.), subterranean clover and biserrula, or a choice of both biserrula and subterranean clover, for finishing White Dorper and White Suffolk × Merino lambs during spring. Methods An experiment was established near Wagga Wagga, NSW, in 2013 in a randomised complete block design with three replicates and four pasture treatments grazed by lambs during late spring and early summer. Liveweight, carcass weight and GR fat depth of White Dorper and White Suffolk × Merino lambs grazing lucerne, subterranean clover, biserrula or a choice of subterranean clover plus biserrula were compared. Key results Lambs grazing lucerne had significantly (P < 0.05) higher final liveweight, carcass weight and GR fat depth than lambs grazing other pasture treatments. After 61 days of grazing, mean liveweight of lambs grazing lucerne, subterranean clover and subterranean clover plus biserrula was higher than of lambs grazing biserrula monoculture. In vitro digestible organic matter digestibility and crude protein content indicated that lambs grazing biserrula should have achieved growth rates at least as high as lambs grazing subterranean clover. Sheep genotype and pasture type affected final liveweight. Final liveweight was higher for White Dorper lambs when grazing the subterranean clover plus biserrula treatment than the subterranean clover monoculture (45.6 vs 44.5 kg; P < 0.05) but was similar for White Suffolk × Merino lambs grazing these treatments (47.3 vs 47.2 kg; P > 0.05). Conclusions Provision of a companion species or mixture of species when lambs graze biserrula during late spring to summer appears to offer benefits for lamb growth rate over this period.

To examine the legacy of pasture drill rows sown to various configurations of subterranean clover (Trifolium subterraneum L.), lucerne (Medicago sativa L.) and phalaris (Phalaris aquatica L.), on soil chemical characteristics and wheat (Triticum aestivum L.) production in the year following pasture removal. A field experiment comparing 10 pasture species combination treatments conducted on a Red Kandosol soil in a semi-arid environment in south-eastern Australia was monitored from the end of the pasture phase until harvest of the first wheat crop. Quadrats were fixed to the soil surface to mark previous pasture drill rows. Soil within and between rows was sampled to 0.6 m at three times and analysed for mineral nitrogen (N), pH, total carbon (C) and available macro-nutrients, and related to wheat growth rate and yield. Significantly higher total C, mineral N and plant-available potassium (K), and lower sulphur (S) concentrations, were still evident in the original pasture drill row after grain harvest compared to the inter-row area, four years after pastures were sown. Grain yield was 11% greater in wheat growing on the original pasture drill row compared to between rows. Pure lucerne swards had less mineralised N than mixed lucerne swards associated with reduced water in the soil profile. This study establishes the enduring legacy of pasture drill rows observed up to 14 months post-removal and highlights the opportunity to improve soil fertility through manipulation of pasture sowing configurations in a cropping field in south-eastern Australia.

Changed spatial configurations at sowing have been investigated as a strategy to minimize interspecific competition and improve the establishment and persistence of multi-species plantings in pastures, but the impact of this practice on the soil microbiome has received almost no previous research attention. Differences in populations of bacteria and fungi in the surface 10 cm of soil in the third year following pasture establishment were quantified using quantitative polymerase chain reaction and terminal restriction fragment length polymorphism methods. Populations were compared on, and between, drill rows sown to either the perennial grass phalaris (Phalaris aquatica L.), perennial legume lucerne (alfalfa; Medicago sativa L.) or the annual legume subterranean clover (Trifolium subterraneum L.). Results showed that soil microbial abundance and diversity were related to plant distribution across the field at the time of sampling and to soil chemical parameters including total carbon (C), mineral nitrogen (N), pH, and available phosphorus (P), potassium (K) and sulfur (S). Despite the 27-month lag since sowing, pasture species remained concentrated around the original drill row with very little colonization of the inter-row area. The abundance and diversity of bacterial and fungal populations were consistently greater under drill rows associated with higher total C concentrations in the surface soil compared with the inter-row areas. Our results showed that the pH and available nutrients were similar between the subterranean clover drill row and the inter-row, suggesting that soil microbial populations were not impacted directly by these soil fertility parameters, but rather were related to the presence or absence of plants. The abundance of bacteria and fungi were numerically lower under phalaris rows compared to rows sown to legumes. The richness and diversity of fungal populations were lowest between rows where lucerne was planted. Possible explanations for this observation include a lower C:N ratio of lucerne roots and/or a lack of fibrous roots at the soil surface compared to the other species, illustrating the influence of contrasting plant types on the soil microflora community. This study highlights the enduring legacy of the drill row on the spatial distribution of plants well into the pasture phase of a cropping rotation and discusses the opportunity to enhance the microbiome of cropping soils on a large scale during the pasture phase by increasing plant distribution across the landscape.

Phosphorus (P) is usually stratified in the topsoil layer under pasture, due to the broadcast application of fertiliser, excreta and leaf-litter deposition on the soil surface, and minimal soil disturbance. The objective of this study was to investigate root proliferation and P acquisition in response to P stratification by comparing two Trifolium subterraneum cultivars with contrasting root morphologies. Clover micro-swards were grown with deficient, constrained and sufficient P supplied in a topsoil layer overlying a P-deficient subsoil that mimicked the stratification of P that occurs under pasture. Phosphorus labelled with 33P- and 32P-radioisotope tracer was mixed throughout the topsoil and subsoil layers, respectively. The shoot yield and total plant P uptake of the cultivars increased in response to increased topsoil P supply. The length of roots produced by the cultivars was equivalent in each of the P treatments, although the specific root length achieved by the cultivars was substantially different. In the P-constrained and P-sufficient treatments, ~91% and ~ 99% of total plant P was acquired by topsoil roots, respectively. In contrast, subsoil roots acquired 60–74% of total plant P in the P-deficient treatment. Topsoil roots were most important for P acquisition when P was highly stratified, whereas subsoil roots contributed to P acquisition when P was uniformly distributed throughout the P-deficient soil profile. Selection for prolific nutrient-foraging roots, in conjunction with plasticity for subsoil exploration, may improve the P-acquisition efficiency of T. subterraneum genotypes and confer adaptability across a range of soil-P environments.

The experiment was conducted to understand how root morphological traits contributed to the contrasting P-acquisition efficiencies of two Trifolium subterraneum cultivars. Phosphorus acquisition, root length proliferation and root acclimation to P deficiency were investigated by varying the P supply (20–300 mg P kg−1) and planting density (1–12 plants pot−1) of clover micro-swards. The shoot yield of both cultivars increased in response to increased P supply and increased planting density. Higher planting densities increased shoot yield by reducing the time to leaf canopy closure. In P-deficient soil, the ‘less P-efficient’ cultivar acquired less P and yielded relatively poorly compared with the ‘more P-efficient’ cultivar when planting density was low (

Under changing climate, plants need combined ability to cope with co‐occurring biotic/abiotic stresses. Understanding simultaneous plant responses to multiple stresses offers unique insights towards developing effective strategies to mitigate effects of such stresses in plants. Quantitative reverse transcription PCR was used to determine and compare relative gene expression ratios (RGERs) of three disease resistance‐related genes, chalcone synthase, GA protein, and phenylalanine ammonia lyase (PAL), and three abiotic stress‐related genes, a LRR receptor‐like protein kinase (RPK), heat shock protein 81, and Trifolium repens cold responsive protein, across seven durations of infection by the root pathogen Pythium irregulare under three temperature regimes in three Trifolium subterraneum varieties of varying resistance. Temperature and genotype drove biotic and abiotic stress‐related gene expression in Pythium‐infected plants. RGERs of tested genes and their relationships differed across varieties, temperatures, and infection duration (ID). These are the first studies to report expression of defence‐related genes in relation to either biotic or abiotic stress in subterranean clover. The current study not only demonstrates how RGERs of tested genes and their relationships differ across varieties, temperatures, and ID, but also highlights as yet unexploited opportunities to use these biotic/abiotic‐related genes together to develop new varieties with combined biotic/abiotic stress resistances in forage legumes that are suitable for changing climate scenarios. Examples could include RGERs of PAL to identify “temperature‐stable” disease‐resistant varieties, and RGERs of RPK to eliminate susceptible and temperature‐sensitive genotypes.

Subterranean clover (Trifolium subterraneum L.) is an important legume in dryland hill pastures in New Zealand. In this environment plants adapt to low temperatures (

Mestrado de dupla diplomação com a UTFPR, Universidade Tecnológica Federal do Paraná Na agricultura atual, o manejo integrado e uso eficiente de insumos agrícolas são exemplos de estratégias para maior otimização e produção de alimentos. No contexto global, além da disponibilidade de água, o nitrogênio (N) é o elemento nutricional que mais limita o crescimento e desenvolvimento das plantas. As leguminosas têm um papel relevante nos ecossistemas agrícolas, pois proporcionam uma maior quantidade de massa vegetal quando cultivadas em solos pobres, devido a associações simbióticas que formam com microrganismos fixadores de N. Desse mutualismo resulta uma maior disponibilidade de N para as leguminosas e para outras culturas não leguminosas cultivadas em consórcio ou que lhes sucedam na rotação. Assim, as leguminosas são cultivadas por todo o mundo com o objetivo de reduzir o uso de fertilizantes sintéticos, contribuindo para a manutenção e aumento da fertilidade do solo. Neste trabalho, estudou-se o potencial de produção de biomassa e de acumulação de nitrogênio e outros nutrientes nos tecidos de seis espécies de leguminosas anuais cultivadas para promoção da adubação verde em uma área de olival de sequeiro com solo ácido. O experimento a campo foi instalado na freguesia de Pinelo, no município de Vimioso, nordeste de Portugal. O ensaio consistiu em sete parcelas com uma área de 300 m2, onde se semearam aveia (Avena sativa L., cv. Boa Fé), como testemunha, trevo subterrâneo (Trifolium subterraneum, cv. Campeda), duas tremocilhas (Lupinus luteus, cvs. Nacional e Mister), duas favas (Vicia faba, cvs. Vesúvio e Favel) e tremoceiro azul (L. angustifolius, cv. Karo). O experimento a campo conduziu a resultados difíceis de interpretar, em que algumas plantas devido ao frio e/ou à excessiva acidez do solo originaram uma produção de biomassa muito baixa e não compatível com uma nodulação adequada. Para tentar isolar a causa do insucesso foi instalado um experimento em vasos usando o solo do olival e o trevo subterrâneo, cv. Campeda, como planta teste. Este ensaio decorreu nas estufas do Instituto Politécnico de Bragança. O ensaio consistiu em cinco tratamentos, correspondentes à aplicação de calcário, fósforo, boro, calcário + fósforo + boro (controlo+) e testemunha (controlo-), e quatro repetições. As plantas foram coletadas e levadas para estufa de secagem regulada a 70 oC até atingirem peso constante, sendo posteriormente pesadas, moídas e analisadas para a composição elementar dos seus tecidos. As tremocilhas, cvs. Nacional e Mister e o tremoceiro azul, cv. Karo, apresentaram os maiores valores de matéria seca, assim como o maior acúmulo de nitrogênio, se revelando as mais promissoras para adubação verde, constituindo-se como uma importante fonte de nitrogênio para a cultura principal e para a melhoria da fertilidade do solo. No experimento em vasos, o tratamento com fósforo originou maior produção de biomassa e boa nodulação. A aplicação de calcário também se mostrou efetiva na nodulação, mas não estimulou a produção de biomassa como a aplicação de fósforo. Este resultado parece indicar que o principal problema do solo do olival para o crescimento das leguminosas pode não ter sido o pH, mas talvez a reduzida disponibilidade em fósforo. In current agriculture, the integrated management and efficient use of agricultural inputs are examples of strategies for greater optimization and food production. In the global context, in addition to water availability, nitrogen (N) is the nutritional element that most limits plant growth and yield. Legumes play an important role in agricultural ecosystems, as they provide a greater amount of plant mass when grown in poor soils, due to symbiotic associations they form with N-fixing microorganisms. This mutualism results in a greater availability of N for legumes and others non-leguminous crops grown in intercropping or succeeding them in rotation. Thus, legumes are grown all over the world with the aim of reducing the use of synthetic fertilizers, contributing to the maintenance and increase of soil fertility. In this work, we studied the potential for biomass production and accumulation of nitrogen and other nutrients in the tissues of six species of annual legumes grown to promote green manure in a rainfed olive grove with acidic soil. The field experiment was installed in the parish of Pinelo, in the municipality of Vimioso, northeast of Portugal. The experiment consisted of seven plots with an area of 300 m2, where oat (Avena sativa L., cv. Boa Fé), as a control, subterranean clover (Trifolium subterraneum, cv. Campeda), two yellow-lupines (Lupinus luteus, cvs. Nacional and Mister), two fava beans (Vicia faba, cvs. Vesúvio and Favel) and blue lupine (L. angustifolius, cv. Karo). The field experiment led to difficult to interpret results, in which some plants, due to the cold and/or excessive soil acidity, resulted in a very low biomass production that was not compatible with adequate nodulation. To try to isolate the cause of failure, an experiment was installed in pots using olive grove soil and subterranean clover, cv. Campeda, as a test plant. This study took place in a greenhouse of the Instituto Politécnico de Bragança. The experiment consisted of five treatments, corresponding to the application of limestone, phosphorus, boron, limestone + phosphorus + boron (control+) and control (control-), and four replicates. The plants were collected and taken to a drying oven regulated at 70 oC until they reached constant weight, being later weighed, ground and analyzed for the elemental composition of their tissues. The yellow-lupines, cvs. Nacional and Mister, and the blue lupine, cv. Karo, presented the highest dry matter values, as well as the highest nitrogen accumulation, proving to be the most promising for green manure, constituting an important source of nitrogen for the main crop and for the improvement of soil fertility. In the pot experiment, the phosphorus treatment resulted in higher biomass production and good nodulation. Limestone application was also effective in nodulation but did not stimulate biomass production as did phosphorus application. This result seems to indicate that the main problem of the olive grove soil for the growth of legumes may not have been the pH but perhaps the reduced availability of phosphorus.

Seed retention has not been evaluated for subterranean clover (Trifolium subterraneumL.), because its geocarpic seed-bearing burrs are currently harvested by suction systems. Development of improved harvest methods requires knowledge of subterranean clover seed retention characteristics and their changes with plant development. This study evaluates burr attachment and peduncle tensile strength during burr maturity until plant senescence across the three subspecies:subterraneum(cv. Dalkeith),yanninicum(cv. Monti) andbrachycalycinum(cv. Mawson). Peduncle tensile strength was greater than burr-to-peduncle attachment strength for each subspecies, with peak mean peduncle strength 30–130% greater than peak mean burr-to-peduncle attachment strength. Both strength measurements decreased significantly (greater than 50% for each subspecies) as the plant senesced, which was associated with reductions in burr moisture content, and burr and peduncle diameters. Microscopy indicated a ductile to brittle transition as peduncles senesced, reducing energy absorption and increasing the likelihood of failure at defects. These results are important for the commercial production of subterranean clover seed and suggest it may be possible to harvest seed before plant senescence with dig-invert machinery, similar to that used for peanut harvesting. However, this approach would require harvesting prior to maximum seed development and the implications for seed viability and yield need to be further evaluated.

Background and AimsIn the annual pasture legume Trifolium subterraneum, ssp. yanninicum exhibits higher waterlogging tolerance than ssp. brachycalycinum and ssp. subterraneum. This study investigates waterlogging tolerance within ssp. yanninicum ecotypes and explores correlations with seedling phenotypic traits and site of origin eco-geographic variables.MethodsTwenty eight diverse ssp. yanninicum ecotypes collected from the Mediterranean region and four cultivars were grown in a controlled environment glasshouse. After 14 days of growth seedling traits were measured. After 21 days of growth, free-drained (control) and waterlogged treatments were imposed for 28 days. Eco-geographic variables were generated from ‘WorldClim’ using collection site locations.ResultsUnder waterlogging, shoot relative growth rate (RGR) ranged from 87–108% and root RGR ranged from 80–116% of controls. Waterlogging reduced shoot dry weight (DW) in four of 32 genotypes, while root DW was reduced in 13 genotypes. Leaf size was maintained, or even increased, under waterlogging in 31 genotypes. However, petiole length was more affected by waterlogging and has value as a waterlogging tolerance indicator. Waterlogging tolerance was not significantly correlated with seedling DW, flowering time or precipitation at the site of origin, while shoot growth under waterlogging had a positive correlation with summer temperatures at origin.ConclusionsGenotypes of ssp. yanninicum tolerated transient waterlogging and greater tolerance was observed among ecotypes, rather than cultivars. An easy-to-measure indicator of tolerance was found in petiole length reduction. This study highlights untapped genotypic variability for breeders to improve the productivity and persistence of ssp. yanninicum under waterlogging.