White Clover Varieties Research Articles

Optimization of Protocols for the Induction of Callus and Plant Regeneration in White Clover (Trifolium repens L.).

White clover is a widely grown temperate legume forage with high nutritional value. Research on the functional genomics of white clover requires a stable and efficient transformation system. In this study, we successfully induced calluses from the cotyledons and leaves of 10 different white clover varieties. The results showed that the callus formation rate in the cotyledons did not vary significantly among the varieties, but the highest callus formation rate was observed in 'Koala' leaves. Subsequently, different concentrations of antioxidants and hormones were tested on the browning rate and differentiation ability of the calluses, respectively. The results showed that the browning rate was the lowest on MS supplemented with 20 mg L-1 AgNO3 and 25 mg L-1 VC, respectively, and the differentiation rate was highest on MS supplemented with 1 mg L-1 6-BA, 1 mg L-1 KT and 0.5 mg L-1 NAA. In addition, the transformation system for Agrobacterium tumefaciens-mediated transformation of 4-day-old leaves was optimized to some extent and obtained a positive callus rate of 8.9% using green fluorescent protein (GFP) as a marker gene. According to our data, by following this optimized protocol, the transformation efficiency could reach 2.38%. The results of this study will provide the foundation for regenerating multiple transgenic white clover from a single genetic background.

White clover (Trifolium repens) population dynamics are partly dependent on timing of seminal taproot death

AbstractThe expanded usage of white clover has increased the importance of understanding white clover dynamics in pastures. It is assumed that clover plants have a higher tolerance for moisture and nutrient deficiencies when the taproot is still present. Therefore, the survival of the seminal taproot can influence the dynamics of clover. Past breeding efforts in countries like New Zealand have focussed on increasing the taproot longevity through hybridisation with a close relative of white clover. However, there is no direct evidence whether increased survival of the taproot results in increased performance of white clover. In this study, we aimed to (i) assess the relationship between taproot volume and taproot survival, and (ii) whether the timing of death of the seminal taproot influences the population dynamics of white clover varieties. In a two‐year field experiment with 18 white clover varieties grown in monoculture and in mixture with Lolium perenne L, the taproot characteristics and population dynamics were studied. It was shown that taproot volume was positively correlated to both leaf size and taproot presence during autumn 2017, 1 year after sowing. The combination of the timing of death of the seminal tap root and the development of stolons seems to play a more important role in increasing the persistence of white clover than the absolute survival of the seminal taproot. Future research should focus on understanding the transition from a taprooted white clover to a stolonous white clover plant in relation to specific weather events such as winter frost conditions.

Broadleaf weed control and white clover response to florpyrauxifen-benzyl + 2,4-D and common pasture herbicides

AbstractThe combination of florpyrauxifen-benzyl + 2,4-D is a new, pre-packaged herbicide mixture for use in pastures and hayfields in the United States. Unlike many other pasture herbicides, florpyrauxifen-benzyl + 2,4-D is reported to preserve white clover. However, limited research exists on the efficacy of florpyrauxifen-benzyl + 2,4-D on common weed species and on the level of tolerance of white clover to it. Field trials were conducted in Virginia in 2018 to 2020 to evaluate control of various broadleaf weeds with florpyrauxifen-benzyl + 2,4-D compared to other commonly used herbicides. Field and greenhouse studies were also carried out to assess white clover tolerance. Weed species evaluated included bulbous buttercup, Canada thistle, horsenettle, and broadleaf plantain. Florpyrauxifen-benzyl + 2,4-D provided 75% to 99% control of all weeds 90 d after application except for horsenettle (56%), while causing the least white clover injury of any herbicide treatment that was evaluated. Spring herbicide applications resulted in greater bulbous buttercup control compared to fall applications, but florpyrauxifen-benzyl + 2,4-D provided greater than 81% control from both application timings. There were no differences in aboveground biomass between white clover varieties; however, all herbicides reduced white clover biomass compared to a nontreated control. This research suggests that florpyrauxifen-benzyl + 2,4-D can improve overall forage quality by controlling broadleaf weeds in mixed grass-legume stands while preserving white clover.

ЛАБОРАТОРНЫЙ СКРИНИНГ СОРТОВ ДОННИКА БЕЛОГО ОДНОЛЕТНЕГО ПО УСТОЙЧИВОСТИ К СОЛЕВОМУ СТРЕССУ

The purpose of the research was to laboratory diagnostics of the resistance of released varieties of white sweet clover to chloride salinization in the juvenile stage of development based on the assessment of the variability of the morphometric parameters of seedlings. The object of the study was the varieties of annual white sweet clover, bred by the Samara Federal Research Center of the Russian Academy of Sciences: Povolzhsky, Srednevolzhsky and Zavolzhsky. To determine the salt tolerance of sweet clover varieties, the method of seed germination in sodium chloride solutions was used. It has been established that chloride salinization significantly reduces the germination of sweet clover seeds at a test solution concentration of 0.25 mol/l. With an increase in NaCl concentration to 0.30 mol/l in the studied varieties, the number of germinated seeds decreased by 80.2–85.9% relative to the control variant. In terms of seed germination under the influence of a stress factor, the Povolzhsky variety stood out, the Zavolzhsky variety was noted as the most resistant to the negative effects of a high degree of salinity. With chloride salinity of 0.10; 0.15 and 0.20 mol/l variety Povolzhsky provided the best morphometric parameters of seedlings. The level of growth processes at the maximum level of salinity (0.25 and 0.30 mol/l) in Zavolzhsky variety was the highest. The use of the method of laboratory assessment of salt tolerance by seed germination in saline solutions made it possible to differentiate the studied varieties of annual white sweet clover in terms of sensitivity to the impact of a stress factor at the initial stages of ontogenesis. Taking into account the high field productivity and ecological plasticity of the studied varieties, they can be recommended for use as a source material in breeding programs to create highly productive varieties resistant to chloride salinity.

Dwarf White Clover Supports Pollinators, Augments Nitrogen in Clover–Turfgrass Lawns, and Suppresses Root-Feeding Grubs in Monoculture but Not in Mixed Swards

The runoff or leaching of nitrogen fertilizers from monoculture turfgrass lawns contri-butes to water pollution, and such lawns are susceptible to insect pests and provide few resources for pollinators. One approach to creating more sustainable lawns is to incorporate white clover (Trifolium repens L.), a nitrogen-fixing legume, into grass seed mixtures or existing turfgrass swards. “Dutch” white clover (DWC), a ubiquitous landrace, forms non-uniform clumps when intermixed with turfgrasses, thus it is often considered to be a lawn weed. Recently, several dwarf varieties of white clover have been selected for their small leaf size and low growth habit, allowing them to tolerate low mowing heights and blend better with grasses. To date, there have been no studies published on the entomological aspects of dwarf clover in pure stands or intermixed with turfgrass. We established field plots with combinations of DWC, two cultivars of dwarf clover, and tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) in monoculture or mixed swards, and compared the invertebrate communities therein. Predatory arthropods and earthworm numbers were similar in all plot types. The clover monocultures were resistant to white grubs, but the grub densities in the clover–tall fescue dicultures were similar to those found in the pure tall fescue swards. Dwarf clovers and DWC were similarly attractive to bees and supported similar bee assemblages. The tall fescue foliar N content was elevated 17–27% in the dicultures with clovers.

Including chicory and selecting white clover varieties as strategies to improve temporal stability of forage yield and quality in white-clover-based temporary grassland

Clover-based crop stands are gaining importance in temporary grasslands for intensive livestock production. However, knowledge of their optimal composition to achieve high temporal stability of forage provision is insufficient, particularly so for long cultivation periods. A five-year field trial was conducted to study the effect of adding a non-leguminous forb to clover-based crop stands and to evaluate the impact of the clover variety on inter- and intra-annual stability of forage yield and quality. At two contrasting sites, we cultivated eight white clover (Trifolium repens) populations in pure stands and in mixtures with perennial ryegrass (Lolium perenne) and/or chicory (Cichorium intybus) under a four-cut system without fertilization and determined the seasonal and annual forage yield and quality. Temporal stability of forage provision differed between crop stand types, with marked differences between years and cropping sites. In the study years with lower than long-term precipitation, adding chicory enhanced temporal stability of forage yield as compared to white clover pure stands or clover-grass mixtures at least at the site with deep soil, and maintained or enhanced that of forage quality as compared to clover-grass mixtures. This was often reversed in the study years with higher than long-term precipitation. The white clover populations only slightly varied in temporal stability of forage provision, and did so independently of the crop stand type. Our findings highlight the potential but also constraints of including a non-leguminous forb in unfertilized mown clover-based crop stands, as well as of decisions on the clover variety, to improve temporal stability of forage provision.

Выращивание клевера белого на семенные цели в Кировской области

The results of studies on the formation of seed herbage of white clover varieties Lugovik of the second year of life are presented, the productivity of herbage and seed yield in variants of experiment is given. The yield of green mass differs significantly over the years. This is due to the fact that in 2020 the herbage dried up on the root, it became possible to get good hay. Of all the variants, the highest yield of seeds was collected from plots where white clover grew in its pure form, the lowest yield was in a mixture of white clover with pasture ryegrass. Thus, the cultivation of white clover "Lu-govik" in the conditions of sod-podzolic soils of the Kirov region is more effective in its pure form.

Оценка взаимодействия видов многолетних мятликовых трав (Poaceae) с клевером ползучим (Trifolium repens L.) в смешанных агрофитоценозах в контексте биологизации семеноводства

Nitrogen consumption is one of the most important factors and necessary conditions for plant growth and development. The contribution from the biological fixation of N2 by legumes in grass mixtures can reduce or completely replace the need for industrial nitrogen fertilizers for perennial bluegrass grasses. When white clover is cultivated in grass mixtures, the net nitrogen gain to the ecosystem from the atmosphere during the growing season as a result of biological fixation can vary from 100 to 300 kg/ha or more. This is equivalent in effect to the application of mineral nitrogen fertilizers on grass in doses from 150 to 350 kg/ha. Types and varieties of perennial grasses have different competitiveness and complementarity when they are jointly cultivated in mixed crops. The use of grasses to create less lying grass stands allows you to increase the collection of white clover seeds. When cultivating white clover in grass mixtures, there was a decrease in the biological yield of seeds compared to mono-crop by 15–38% due to a decrease in the number of generative shoots. However, seed losses during harvesting decreased by up to 9–23% depending on the type of accompanying cereal crop and the method of harvesting. They were minimal in mixed crops of clover with pasture ryegrass or reed fescue and accounted for 9–11% and 12–13% of the biological yield of seeds, respectively. The highest seed collections were obtained from grass stands of the second year of use without the use of nitrogen fertilizers from crops of pasture ryegrass, reed fescue and meadow fescue: 761, 402 and 373 kg/ha, respectively. Along with the types of cereal components, the nature of plant interaction in grass mixtures and their response to anthropogenic stresses also depend on the genotypes of white clover varieties. A comparative assessment of the effectiveness of cultivating clover varieties mixed with reed fescue showed that the highest collection of legume seeds 188 kg/ha from grass stands of the first year of use was provided by the 'Lugovik' variety – 36–68% more than with grass mixtures of the cv. 'Volat' variety f. giganteum and cv. 'VIK 70' of the f. hollandicum variety.

Вплив ширини міжрядь та доз азотних добрив на водоспоживання та урожайність насіння буркуну білого однорічного

The article presents the results of field studies with various varieties of white annual clover when growing them in the conditions of southern Ukraine. The solution to the problem of feed protein in modern economic conditions, when there is a very high cost of mineral and organic fertilizers, is possible largely due to the increase in acreage, expansion of the range and increase the yield of perennial and annual leguminous grasses. In the zone of risky farming, to which the south of Ukraine belongs, the choice of drought-resistant crops that are able to form stable yields with high quality of seeds under extreme conditions is of great importance. The white one-year white clover fully complies with these requirements - a universal-use culture with high and stable yields, drought-resistant, heat-resistant, relatively unpretentious to soils and technological. In the formation of high-yield crops of the white annual clover, a large role belongs to the variety. In turn, the full realization of the yield potential of a variety is possible only if favorable conditions for growing are created, all activities that fully comply with the requirements of this variety are carried out. Therefore, the development of new and improvement of the existing elements of the culture of cultivation, among which is the determination of the optimal row spacing and the dose of nitrogen fertilizer for the white one-year clover varieties, the South and the Donetsk one-year ones are relevant for agricultural production. The aim of the research was to establish the peculiarities of the formation of seed productivity of various varieties of culture by optimizing the width of the spacing and doses of nitrogen fertilizer in the conditions of the south of Ukraine. Field experience established by the method of split plots was carried out in quadruplicate with the placement of plots randomized in accordance with the method of conducting field research to improve the elements of agrotechnical methods of growing crops. In the experiment, we studied varieties of white clover of one-year-old South and Donetsk one-year (reproduction – super elite) width between rows – 15, 30, 45 and 60 cm; Nitrogen fertilization doses – without fertilizers, N 30 , N 60 , N 90 . The agrotechnical cultivation of the white one-year tributary cultivars was generally accepted for the south of Ukraine, except for the factors that were put to study. The studies used the following methods: general scientific (analysis, observation, comparison, measurement), special (field, laboratory), comparative analytical, regression, information-logical analysis and mathematical modeling. On average for 2016-2018 The maximum yield of white clover seeds of the annual one – 556 kg / ha – is established in the Yuzhny variety with a row spacing of 45 cm and a dose of nitrogen fertilizer N 60 . The analysis of variance revealed that the doses of nitrogen fertilizer had the greatest influence on the formation of the yield of white one-year white clover seeds – 71.1% and the row spacing–- 17.2%. Varieties showed the least impact on the seed productivity of the crop, the share of this factor was 6.3%.

Насіннєва продуктивність сортів буркуну білого однорічного на півдні України

Насіннєва продуктивність сортів буркуну білого однорічного на півдні України

Impact of various moisture regime on selected growth-production characteristics of Medicago sativa L. and Trifolium pratense L.

Article Details: Received: 2019-04-08 | Accepted: 2019-06-03 | Available online: 2019-06-30 https://doi.org/10.15414/afz.2019.22.02.52-57 The aim of the experiment was to find out the impact of different moisture regime on selected indicators of the growth and production process of Medicago sativa L. cv. Zuzana and Trifolium pratense L. cv. Poľana. The pot experiment was carried out at the Department of Grassland Ecosystems and Forage Crops, FAFR SUA in Nitra in 2015. There were evaluated two variants of irrigation: 1 st – irrigation once a week and 2 nd – irrigation twice a week with a single dose of 300 ml of water per pot. The results of the experiment showed a positive effect on the height of Medicago sativa L. and Trifolium pratense L. plants (p = 0.006 and p = 0.316), the number of stems (p = 0.001 and p = 0.002), dry phytomass production (p = 0.001 and p = 0.044) and the quantity of harvest residues of evaluated legume forages (p = 0.100 and p = 0.146) with a general more visible effect under irrigation twice a week. By comparison of both species, irrigation twice a week was more effective for Medicago sativa L. on plant height, number of stems and weight of above-ground phytomass, whereas for Trifolium pratense L. only on the weight of harvest residues compared to irrigation once a week. References ABBERTON, M. T. and MARSHALL, A. H. (2005) Progress in breeding perennial clovers for temperate agriculture: centenary review. In Journal of Agricultural Science. vol. 143, no. 2–3, pp. 117–135. https://doi.org/10.1017/S0021859605005101 BIRO, D., MICHALKOVA, J. and JURACEK, M. (2006) Changes in amino acid composition of Medicago sativa during the preservation process. Animal nutrition 2006: Proteins. Brno: MZLU, pp. 22–26 (in Slovak). BLAHA, L. et al. (2003) Plant and stress. Praha: VURV, p. 156 (in Czech). BRESTIC, M. and OLSOVSKA, K. (2001) Water stress of plants: causes, consequences, perspectives. Nitra: SPU (in Slovak). FARISSI, M. et al. (2014) Water deficit effect on yield and forage quality of Medicago sativa populations under field conditions in Marrakesh area. In Annals of West University of Timisoara, ser. Biology, vol. 17, no. 1, pp. 1–8. GALIK, B. et al. (2011) Nutritional characteristics of feeds. Nitra: SPU (in Slovak). GEJGUS, J. et al. (1998) Impact of climatic factors on phenophases in Medicago sativa and Trifolium pratense in the East Slovak lowlands. In: Proceedings of scientific works 14. Michalovce: OVUA, pp. 179–185 (in Slovak). HOLUBEK, R. et al. (2007) Fodder crops production – management of the cultivation and use of forage. Nitra: SUA (in Slovak). KRIVOSUDSKA, E. and FILOVA, A. (2016) Physiological responses of genotypes soybean to simulated drought stress. In Acta fytotechn zootechn, vol. 19, no. 4, pp. 157–162. https:// doi.org/10.15414/afz.2016.19.04.157-162 LICHNER S. et al. (1990) Instructions for exercises from forage crops production. Bratislava: Priroda (in Slovak). LICHNER, S. et al. (1983) Fodder crops production. Nitra: VSP (in Slovak). McKENNA, P. et al. (2018) The use of red clover (Trifolium pratense) in soil fertility-building: A Review. Field Crops Research. vol. 221, pp. 38–49. https://doi.org/10.1016/j.fcr.2018.02.006 MIKA, V. et al. (1997) Fodders quality. Praha: Ustav zemědělských a potravinařských informaci (in Czech). PORVAZ, P. (2001) The production potential of the Medicago sativa L. in the different systems of founding. Doctoral thesis. Michalovce: OVUA (in Slovak). PROCHAZKA, S. (2003) Botany. Morphology a physiology of plants. Brno: Mendel University (in Czech). RADOVIC, J. et al. (2009) Alfalfa-most important perennial forage legume in animal husbandry. Biotechnology in Animal Husbandry, vol. 25, no. 5–6, pp. 465–475. Retrieved 2019-01-25 from http://www.doiserbia.nb.rs/img/doi/1450-9156/2009/1450-91560906465R.pdf ŘIHA, P. (2009) Recommended varieties of alfalfa, white clover and perennial ryegrass. Picninařske listy, vol. 16, pp. 5–8 (in Czech). SAFARNEJAD, A. (2008) Morphological and biochemical response to osmotic stress in alfalfa (Medicago sativa L.). Pak. J. Bot., vol. 40, no. 2, pp. 735–746. Retrieved 2019-02-12 from http://www.pakbs.org/pjbot/PDFs/40(2)/PJB40(2)735.pdf SKLADANKA, J. et al. (2014) Fodder crops production. Brno: Mendel University (in Czech). SLOVAK HYDROMETEOROLOGICAL INSTITUTE (2015) Bulletin Meteorology and Climatology. Retrieved 2019-01-10 from http://www.shmu.sk/sk/?page=1613 (in Slovak). Stat Soft, Inc. (2005). STATISTICA Cz [Software system for data analysis], version 7.1. www.StatSoft.Cz

Селекция бобовых трав в Центральном Черноземье

Using the methods of recurrent breeding and using wild-growing forms as source material, new varieties of perennial legumes adapted to the soil and climatic conditions of the region were created. These are forage varieties of alfalfa (Krasnoyaruzhskaya 1, Krasnoyaruzhskaya 2, Alekseevskaya 1), of white clover (Varvarovsky), of red clover (Kazackij), which possesses a set of economically valuable traits: the high fodder value, the yield of green mass and the stable seed productivity. New varieties exceed standards for the crop of green mass by 15.8-21.0%, of hay by 16.7- 21.8%, of seeds by 12.9-52.4% The white clover variety Krasnoyaruzhsky is recommended to cultivation on the territory of the Russian Federation in different soil and climatic conditions for lawns creation and at reclamation of technogenic-disturbed landscapes. Selections from new varieties with different characteristics are included in further schemes of recurrent breeding in order to obtain new higher yielding forms. Currently, a scheme of primary and industrial seed production of new varieties has been developed in the Belgorod region based on the СJSC «Krasnoyaruzhskaya Grain Company » and СJSC «Novooskolskaya Grain Company» together with scientists from the Belgorod State National Research University.

Preplant Cultivation Techniques and Planting Date Effects on White Clover Establishment into an Existing Cool-season Turfgrass Sward

Managed turfgrass species require frequent inputs to maintain an acceptable level of density and appearance. Among these inputs, the N supply is often the most limiting input in terms of growth and development of the turfgrass stand. However, N fertilization has been linked to nonpoint source (NPS) pollution of groundwater and natural water bodies. White clover (WC), which would provide N in mixed turfgrass swards, could help reduce NPS pollution from N fertilization of turf. To test the feasibility of introducing WC into existing turf, a field study was designed to determine the best method of incorporating WC in mature stands of two cool-season grasses. Two varieties of WC, ‘Dutch White’ (DW), and ‘Microclover’ (MC), were sown (24.4 kg·ha−1) into existing stands of kentucky bluegrass (KBG) (Poa pratensis L.) and tall fescue (TF) (Festuca arundinacea Schreb.). Establishment techniques tested included core aeration (CA), scalping (SC), and vertical mowing (VM) compared with direct sowing into the turfgrass stand. Establishment treatments were performed in April, July, and October of 2012–13 to examine for any seasonal timing effect on establishment. No significant difference in plant numbers (individual clover plants per square meter) was found between WC varieties among planting dates and techniques. The SC treatment resulted in the highest individual clover plant numbers. However, turfgrass recovery was significantly slower from the SC treatment than all other treatments. The summer planting date yielded the highest WC plant numbers. Recovery of the turfgrass from all preplanting treatments was also highest at the spring and summer planting dates.

Trifolium interspecific hybridisation: widening the white clover gene pool

White clover (Trifolium repens) is adapted to moist, fertile soils in temperate zones. Despite its heterozygous allotetraploid nature, it lacks useful genetic variation for survival and growth in semi-arid, infertile soils. Although white clover is apparently genetically isolated in nature, 11 other taxa have so far been found that can be artificially hybridised into the wider gene pool. These species range from annuals to long-lived, hardy perennials with adaptations to stress environments, and they potentially provide new traits for the breeding of more resilient varieties of white clover. The delineation of the secondary, tertiary and quaternary gene pools is described, along with a review of interspecific hybrids achieved to date. The results of large breeding programs to integrate traits from T. nigrescens and 4x T. ambiguum are reviewed, and schemes introduced for the use of T. uniflorum, T. occidentale, T. pallescens, 2x T. ambiguum and 6x T. ambiguum. Interspecific hybrid breeding of white clover has the potential to enable the development of resilient perennial clovers for seasonally dry, infertile grassland environments in many parts of the world.

The effect of fertilizer seed coating on the germinating capacity and initial development of some turf grass species and white clover

The effect of the iSeed method treatment on germination dynamics, total germinating capacity and the length of above-ground and root parts was studied in laboratory conditions for the Red fescue varieties Darwin and Moccasin, Kentucky bluegrass varieties Yvette and Miracle, Perennial ryegrass varieties Beatrice and Milan, and White clover varieties Pirouette and Pipolina. In the Perennial ryegrass, the iSeed treatment adversely affected the energy of germination in the first days of study. The germinating capacity gradually equalized during the experiment. Red fescue and Kentucky bluegrass did not show any response to the treatment. Similarly as the Perennial ryegrass, the two varieties of White clover exhibited higher energy of germination on the third day from the establishment. A demonstrably positive effect of the iSeed treatment was recorded on the number of germinated individuals. Particularly the variety Pirouette showed significantly higher germinating capacity until the tenth day of monitoring the treated seeds. The iSeed method had no statistically significant influence on the values of total germinating capacity in all tested species and varieties. The effect of the iSeed method treatment on the length of shoot and root parts was not statistically demonstrated. Some varieties showed a positive effect and some showed a negative effect. A significant difference was observed only in the untreated variety Moccasin whose above-ground part was by 14 mm longer as compared with the treated variant.

Dry‐matter yield of Lotus varieties in grass–white clover mixtures in a low‐fertility soil

AbstractLotus corniculatus (bird's‐foot trefoil) and L. pedunculatus (greater bird's‐foot trefoil) have the potential to contribute nutritional benefits to grass–legume swards in temperate regions, but there is a lack of information on their competitive ability in such mixtures. This experiment compared the sward contribution and condensed tannin (CT) content of nine Lotus varieties established in plots on a low‐fertility upland site in Wales, UK, containing mixtures of meadow fescue (Festuca pratensis) and white clover (Trifolium repens) varieties of different leaf size, or without white clover (control). Total dry‐matter (DM) yields and Lotus DM were evaluated in two cuts in each of three harvest years, with CT content of Lotus measured at Cut 1 in each year. Lotus corniculatus varieties were significantly higher yielding than those of L. pedunculatus, except in Year 3. In all cuts, except Cut 1 in Year 1 and Year 3, the presence of white clover increased total DM yield compared with the zero‐clover treatment. Total DM yields were higher with large‐leaved cv. Katrina than with small‐leaved cv. AberAce except for Cut 1 in Year 1. Annual Lotus DM yields were significantly higher in the presence of white clover, except in Year 3, but were not significantly affected by white clover leaf size. The highest concentration of sward CT (17 mg g−1 of sward DM) was insufficient to bring about measurable environmental benefits. A Lotus breeding programme aimed at increasing the leaf/stem ratio within persistent germplasm could be pursued to ensure delivery of appropriate levels of sward CT.

Protein changes and proteolytic degradation in red and white clover plants subjected to waterlogging

Red (Trifolium pratense L., cv. “Start”) and white clover varieties (Trifolium repens L., cv. “Debut” and cv. “Haifa”) were waterlogged for 14 days and subsequently recovered for the period of 21 days. Physiological and biochemical responses of the clover varieties were distinctive, which suggested different sensitivity toward flooding. The comparative study of morphological and biochemical parameters such as stem length, leaflet area, dry weight, protein content, protein pattern and proteolytic degradation revealed prominent changes under waterlogging conditions. Protease activity in the stressed plants increased significantly, especially in red clover cv. “Start”, which exhibited eightfold higher azocaseinolytic activity compared to the control. Changes in the protein profiles were detected by SDS-PAGE electrophoresis. The specific response of some proteins (Rubisco, Rubisco-binding protein, Rubisco activase, ClpA and ClpP protease subunits) toward the applied stress was assessed by immunoblotting. The results characterized the red clover cultivar “Start” as the most sensitive toward waterlogging, expressing reduced levels of Rubisco large and small subunits, high content of ClpP protease subunits and increased activity of protease isoforms.

The in vitro rumen methane output of perennial grass species and white clover varieties, and associative effects for their binary mixtures, evaluated using a batch-culture technique

Grassland swards containing white clover varieties (WCV) may result in lower enteric methane (CH4) output from grazing ruminants than swards of only perennial grass species (PGS) due to differences in their chemical composition and rumen fermentation dynamics. The objectives of the present study were to compare the chemical composition, in vitro rumen fermentation variables and CH4 output per unit of feed for a range of common PGS and WCV harvested in May from simulated grazing regimes, and to determine the effects of binary mixtures of the PGS and WCV on in vitro rumen fermentation variables and CH4 output, using a batch-culture technique. Four PGS (perennial ryegrass, cocksfoot, meadow fescue and timothy) and three WCV (Aran, Chieftain and Crusader) were incubated as sole substrates or as part of binary mixtures (PGS : WCV ratios of 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25 and 1 : 0) for 24 h at 39°C with buffered rumen fluid. All WCV had lower (P < 0.001) CH4 output per unit of apparent DM disappeared (aDMD; mean value across WCV (s.e.m.) of 27.0 (1.35) mL/g aDMD v. 36.1 (0.90) mL/g aDMD across PGS) during the in vitro rumen incubation than did all PGS. The WCV also had lower CH4 output per unit of total volatile fatty acids (corresponding values of 0.147 (0.0090) v. 0.199 (0.0073) mmol/mmol total volatile fatty acid output) and per unit of total gas produced (0.118 (0.0022) v. 0.153 (0.0024) mmol/mmol total gas produced) than did the PGS. In addition, Aran and Crusader had lower (P < 0.001) CH4 output per unit of feed DM incubated than did all PGS. There were synergistic associative effects (i.e. where the response was greater for the mixtures than the arithmetic calculation using the responses for PGS and WCV alone; P < 0.05) of mixing the PGS and WCV in binary combinations on all CH4 output variables.

White clover selected for enhanced competitive ability widens the compatibility with grasses and favours the optimization of legume content and forage yield in mown clover‐grass mixtures

AbstractWhite clover‐grass mixtures should provide swards with a high dry matter (DM) yield with a clover proportion of at least 0·30. This study assessed the compatibility of one white clover variety selected for competitive ability (Giga) and four other large‐leaved clover varieties (Aran, Espanso, Fantastico and Regal) in mown binary mixtures with each of four grass companions (cocksfoot cv. Padania, hybrid ryegrass cv. AberExcel, Italian ryegrass cv. Crema, and tall fescue cv. Magno) over 3 years in northern Italy. On average, the mixtures including Giga had at least a two‐fold greater clover proportion in the total harvested DM (P < 0·01) and contained fewer weeds (P < 0·10) than those with other clover varieties, and also tended to have the highest total DM yields. On average, mixtures containing AberExcel had clover proportions of >0·25 but gave the lowest total DM yields, whereas those of Magno maximized total DM and had a higher proportion of clover than Padania or Crema. No clover × grass interaction was detected (P > 0·05). The association with Giga allowed the tall fescue‐based mixture to attain a clover proportion 0·331 along with a top‐yielding total DM. This mixture, compared with the only one without Giga that displayed a near‐sufficient clover proportion (Espanso with AberExcel), exhibited a 21·7% higher total DM (P < 0·05) and had far fewer weeds.

Consequences of including adapted white clover in northern European grassland: transfer and deposition of nitrogen

The interspecific transfer of nitrogen (N) between white clover (Trifolium repens) and smooth meadow grass (Poa pratensis) in legume-based grasslands was assessed under North European field conditions using 15N individual plant leaf labelling. On average 50% of N in the grass was transferred from the white clover and about 6% of N in white clover was transferred from the grass. This corresponds to 2.5 and 0.3 g N m−2 being transferred over the growing season between the two species, respectively, and demonstrates that a significant part of the total N of the grass is coming through interspecific transfer. The majority of the 15N transferred was within a period of 20 days at relatively low soil temperatures. This implies that there is a need for a new focus on direct transfer pathways or exudation and transfer of organic N sources. Rhizodeposition in the top 10 cm of the soil was found to be 2.98 g N m−2 on average over the growing season for the grass and white clover mixture. Inclusion of adapted white clover varieties in the low-input grassland systems of northern Europe will lead to a substantial contribution of N.