Impact of Environmental Factors on Seed Germination and Seedling Emergence of White Clover (Trifolium repens L.)

White clover (Trifolium repens L.) is cultivated as a forage crop and planted in various landscapes for soil conservation. There are numerous reports of failed white clover stands each year. A good understanding of the seed germination biology of white clover in relation to environmental factors is essential to achieve successful stand establishment. A series of experiments were conducted to investigate the impacts of light, temperature, planting depth, drought, and salt stress on seed germination and the emergence of white clover. White clover is negatively photoblastic, and seed germination averaged 63 and 66% under light and complete dark conditions 4 weeks after planting (WAP), respectively. Temperature affected the seed germination speed and rate. At 1 WAP, seeds incubated at 15 to 25 °C demonstrated a significantly higher germination rate than the low temperatures at 5 and 10 °C; however, the germination rate did not differ among the temperature treatments at 4 WAP. The results suggest that white clover germination decreases with increasing sowing depths, and the seeds should be sown on the soil surface or shallowly buried at a depth ≤1 cm to achieve an optimal emergence. White clover seeds exhibited high sensitivity to drought and salinity stress. The osmotic potential and NaCl concentration required to inhibit 50% seed germination were −0.19 MPa and 62.4 mM, respectively. Overall, these findings provide quantifiable explanations for inconsistent establishment observed in field conditions. The results obtained in this research can be used to develop effective planting strategies and support the successful establishment of white clover stands.

Dynamics of the Species Composition of Phytocenoses of Floodplain Mountain Meadows of the Carpathians Subject to Superficial Improvement

The conducted research of various authors has developed a number of measures for surface improvement of meadowland in various soil and climatic conditions. However, studies on the influence of such surface improvement measures as the use of organic and mineral fertilizers and sowing of perennial grasses and legumes in the sod on the dynamics of the species composition of Floodplain Mountain meadows of the Carpathians have not yet been conducted, which confirms the relevance of this study. The article presents the results of three-year studies conducted during 2017-2019 in the peasant farm of V.F. Martyshchuk (the Verkhovinsky District of the Ivano-Frankivsk region) to study the features of transformation of the species composition of natural phytocenoses of floodplain Meadows of the Black Cheremosh river of the mountain and forest belt of the Carpathians under the influence of their surface improvement with the use of organic and mineral fertilizers and sowing of a cereal mixture for haymaking use and Tribolium repens L. for multipurpose use. It was found that floodplain Meadow phytocenoses were mainly cereals and mixed grasses with a share of wild cereals of 57-58% (up to 15 of them % Festuca rubra L. s. str. and 5-6% of low-value ones in feed terms Calamagrostis arundinaceae (L.) Roth and Deschampsia caespitosa (L.) Beauv.), mixed grasses – 35-38% and unseeded Fabaceae 5-7%. When applying a set of measures for surface improvement of cereals and mixed grasses, low productive (within 1.95-2.15 t/ha of dry weight) floodplain mountain meadowlands, their species composition improved. For making P30K60 the content of wild plants increased by 2-5% Fabaceae, and N60P30K60 – by 9-10% unseeded Poaceae. For haymaking use, Poaceae with Phleum pratense L. and Festuca pratensis Huds. against the background of making N60P30K60 for sowing a mixture in the sod in the spring, their share increased to 74%, and for multi-year use and sowing Trifolium repens L. against the background of making P30K60 the quantity of Fabaceae increased to 44% or by 32%. The highest floral saturation (43 species from 19 families and 93-98% from perennials) was observed in variants without fertilization and with the introduction of P30K60 for multi-year use, which is 4-14 species more compared to haymaking use, or with the introduction of N60P30K60 and or with sowing a mixture of cereals on the background of N60P30K60 for haymaking use, or sowing Trifolium repens L. against the background of P30K60 for multipurpose use

CREEPING CLOVER (Trifolium repens L.): BIOLOGICAL FEATURES, ECONOMIC SIGNIFICANCE, VARIETIES AND METHODS OF SEED PRODUCTION WHEN GROWN IN GRASS MIXTURES WITH A CEREAL COMPONENT

Creeping clover (Trifolium repens L.) is one of the best crops for creating meadow and pasture agrophytocenoses of long-term use. The biological features of this crop, such as durability, good yield, resistance to grazing, high leafiness, along with good feed quality indicators, its high protein nutritional value, make it indispensable when creating pastures not only in Russia, but also abroad. Creeping clover is one of the main components of grass mixtures for improving pastures and developing fallow lands; it is also an excellent phyto-meliorative crop that restores soil fertility. The most important problem of creeping clover seed production is harvesting due to the short stature of pasture varieties. Therefore, it is recommended to grow creeping clover for seeds in a mixture of grass together with cereal components such as perennial ryegrass, reed fescue, meadow fescue, etc. Due to the use of biological nitrogen of the legume component, energy consumption for the production of 1 kg of cereal grass seeds is reduced by 20–30% in comparison with uncoverless single-species crops. In addition to clover seeds, growing in grass mixtures allows you to get high yields of grass seeds in the second year of use without the use of nitrogen fertilizers.

Changes in sward structure, plant morphology and growth of perennial ryegrass–white clover swards over winter

White clover (Trifolium repens L.) is at a disadvantage to perennial ryegrass (Lolium perenne L.; PRG) due to its limited cold tolerance and low growth rates at colder temperatures, which can affect subsequent spring herbage dry matter (DM) availability. The effect of PRG ploidy on white clover morphology and growth over winter, and its subsequent recovery in spring and the following growing season, is poorly understood. The objective of this study was to compare the effect of white clover inclusion and PRG ploidy on sward structure, plant morphology and growth of PRG–white clover swards over winter. Four swards (diploid PRG only, tetraploid PRG only, diploid PRG–white clover and tetraploid PRG–white clover) were evaluated over a full winter period (November–February) at a farmlet scale. The PRG ploidy had no effect on herbage DM production, white clover content or tissue turnover (P > 0.05) over winter. However, white clover inclusion caused a significant decrease in herbage DM production (P < 0.001; −254 kg DM/ha) and tiller density (P < 0.001; −1,953 tillers/m2) over winter. Stolon mass was not affected by PRG ploidy (P > 0.05); however, stolon length and number of leaves per stolon were affected by PRG ploidy (P < 0.05). Including white clover in PRG swards can alter winter sward dynamics, potentially causing difficulties in subsequent spring management and performance due to the reduced over-winter growth rate when compared with PRG.

Assessing Competitiveness of Fine Fescues (Festuca L. spp.) and Tall Fescue (Schedonorus arundinaceous (Schreb.) Dumort) Established with White Clover (Trifolium repens L., WC), Daisy (Bellis perennis L.) and Yarrow (Achillea millefolium L.)

Regulatory restrictions on herbicide use for managing turfgrass weeds has prompted the search for alternative control strategies. Fescue (Festuca) species were identified for their potential to interfere with growth of annual and perennial weeds. In a study conducted in 2018 and 2019, six fescue cultivars were tested from five different species for interference with the growth of three common turfgrass weeds: white clover (Trifolium repens L., WC), daisy (Bellis perennis L.) and yarrow (Achillea millefolium L.). Fine (Festuca L. spp.) and tall fescues (Schedonorus arundinaceus (Schreb.) Dumort.) were sown and grown in a field trial for 14 days before overseeding with different weeds. vigor and visual quality of grasses, weed cover, and vegetation cover was recorded regularly for 84 days. Differences in mean temperatures and precipitation between the two years of the study resulted in differences in growth of grasses and weeds, as well as in the extent of weed interference of fescue cultivars. Cultivars Musica (F. rubra L. ssp. commutata Gaudin) and Barpearl (F. rubra L. ssp. littoralis) were least affected by weed growth during both years, but there was overlap with other cultivars for the measured parameters. Melyane (tall fescue) was deemed unsuitable for natural weed suppression because growth and vigor declined after first mowing, ultimately leading to unacceptable visual quality. Turfgrass visual scores were moderately negatively correlated to weed cover in both years. Future research should focus on F. rubra L. ssp. rubra Gaudin and F. rubra L. ssp. littoralis subspecies and identify the mechanisms used to interfere with weed growth.

Creation of a new breeding material for creeping clover (Trifolium repens L.) hay-pasture type using the hybridization method

The studies were carried out in the Moscow region in 2019-2021. In order to create a new breeding material for creeping hay-pasture clover, samples of the Lodian type (giganteum variety), characterized by high peduncles and longer leaf petioles, and a low content of hydrocyanic acid (0.3 mg%), were selected as parental forms. Reciprocal crossing was carried out. Hybrids F1 and F2 in the first year of life were assessed by the main economic and biological characteristics: the length of the peduncles, the number of inflorescences on the plant, fodder and seed productivity, early maturity, winter hardiness and other indicators. Based on the assessment results, the best hybrids and individual biotypes were identified.

Enhancing the Sustainability of Temperate Pasture Systems through More Diverse Swards

Temperate grasslands can be highly productive. However, those that are productive are generally heavily dependent on high inputs of nitrogen (N) fertilizer. Including legumes such as white clover (Trifolium repens L.) in the sward can reduce reliance on N fertilizer. Recent investigations have evaluated the potential of multispecies swards, which are defined as agronomically improved grasslands that include multiple plant functional groups, e.g., grasses, legumes, and forage forbs. Several of the benefits and challenges of multispecies swards are summarized in this review. To date, the most prominent forb species included in multispecies swards are chicory (Cichorum intybus L.) and ribgrass/ribwort plantain (Plantago lanceolata L.). Multispecies swards grown under reduced N fertilizer input conditions can produce as much biomass as N-fertilized monocultures. The nutritive value of multispecies swards may potentially be greater than grass-only swards, especially since forbs may contribute additional micro and macro minerals to livestock diet. While challenges associated with multispecies swards may include weed management and facilitating persistence of the forb species in particular, the overall evidence suggests that well-managed multispecies swards can enhance the productivity as well as environmental sustainability of grazing systems.

Phytoaccumulation of heavy metals in native plants growing on soils in the Spreča river valley, Bosnia and Herzegovina

This study evaluated the phytoremediation potential of eight native plant species on heavy metal polluted soils along the Spreča river valley (the northeast region of Bosnia and Herzegovina). Plants selected for screening were: ryegrass (Lolium perenne L.), common nettle (Urtica dioica L.), mugwort (Artemisia vulgaris L.), wild mint (Mentha arvensis L.), white clover (Trifolium repens L.), alfalfa (Medicago sativa L.), dwarf nettle (Urtica urens L.) and yarrow (Achillea millefolium L.). All aboveground parts of selected native plants and their associated soil samples were collected and analysed for total concentration of Ni, Cr, Cd, Pb, Zn and Cu. The bioaccumulation factor for each element was also calculated. The levels of Cr (90.9–171.1 mg/kg) and Ni (80.1–390.5 mg/kg) in the studied soil plots were generally higher than limits prescribed by European standards, indicating that the soils in the Spreča river valley are polluted by Cr and Ni. Among the eight screened plant species, no hyperaccumulators for toxic heavy metals Ni, Cr, Cd and Pb were identified. However, the concentrations of toxic heavy metals in the above-ground parts of Artemisia vulgaris L. and Trifolium repens L. were significantly higher than in the other studied plants, indicating that both plant species are useful for heavy metal removal.

Study of the intrapopulation polymorphism of Trifolium repens L. from Lanivtsi under the anthropogenic load of various intensity

Aim. To study the phenotypic polymorphism of Trifolium repens L. populations growing under various anthropogenic load. Methods. The quantitative calculation of the leaves of the white clover by the presence or absence of the white leaf mark; the identification of the phenotype and genotype of the plant according to the pattern of the white leaf mark; the analysis of the phenotypic diversity and the study of the percentage of rare phenotypes; the calculation of the index of the phenotypes ratio. Results. 4 phenotypes were identified in the pasture area. The most common of them were the plants without the white mark with a frequency of 56.2 %. The plants with a full spot accounted for 27.5 %, with a spot with a gap – 15.4 %, with a central spot – 2.2 %. Heterozygous plants were absent. In the central part of the city, 7 genotypes were identified. Among these genotypes there were the significant decrease of the recessive homozygotes (by 43.6 %) and the increase of the frequency of VV (by 15.2 %) and VHVH (by 21.2 %) genotypes. Heterozygotes accounted for 1.3–3.0 %. The intrapopulation diversity in this territory was the highest (5.1) among the studied areas. In the population growing near Ternopil-Lanivtsi road, we identified 6 genotypes. The plants without spot (vv) and with the full spot (VV) were found with identical frequency of 34–35 %. The plants with a full high spot (VHVH) were about 20.4 %. Other phenotypes amounted to 10 %. Conclusions. In the populations located in ecologically polluted and anthropogenically loaded areas, the sets of alleles expand and the specific phenotypes appear under the influence of the mutation processes and natural selection. In the population without the anthropogenic load the decrease of the polymorphism and the increase of the frequency of individual genotypes (vv, VV) were observed. Keywords: Trifolium repens L., leaf phenotype, intrapopulation polymorphism, multiple allelism, bioindication, anthropogenic load.