Germination Of Clover Research Articles

Estimation of time to key phenological stages to guide management of subterranean clover (Trifolium subterraneum L.) in New Zealand

Coefficients that describe phenological development of subterranean (sub) clover (Trifolium subterraneaum L.) were derived from field and controlled environment experiments. These were combined with national scale historical climate data to estimate when key stages in the life cycle occur at different locations in New Zealand. Based on a 20 mm accumulated rainfall threshold in autumn, sub clover germination and emergence in eastern regions of the South and North Islands occurred between 10th and 24th March and later (~ 31st March) in the cooler southern areas of the South Island, after 36 ± 6.0°Cd and 115 ± 9.0°Cd, respectively. During this time the absolute photoperiod decreases from 13.7 h to 11.6 h (at latitude −34.3950) and from 14.4 h to 11.1 h (at latitude-47.2590). In spring, flowering was estimated to commence in August in North Island locations but from September onwards in South Island locations. The group of cultivars classified as ‘Late’ flowering by plant breeders were estimated to flower in the North Island starting by mid-August compared with mid-September to mid-October in southern (cooler) regions. The safe grazing period was estimated as 25% longer for ‘Late’ cultivars than the ‘Early’ cultivars. The quantification of these key phenophases can be extrapolated to different regions to enhance strategic management of weed control, grazing times and closing dates for seed set. This should enable increased species persistence of sub clover in pasture swards.

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.

Aqueous Extracts of Medicinal Mushrooms Ganoderma lucidum and Pleurotus eryngii (Agaricomycetes) Can Affect Seed Germination and Seedling Survival.

Rapid and complete seed germination results in the rapid initial growth of plants. In this study, aqueous extracts (boiling, maceration + filtration, and maceration + autoclave) of Ganoderma lucidum and Pleurotus eryngii were used to improve seed germination of three crops (maize, clover, and alfalfa). The results revealed that boiled water extractions of G. lucidum positively affected seed germination of clover and alfalfa. Moreover, P. eryngii boiling extract could increase the vigor index II in alfalfa. The results achieved are comparable with those gained by phytohormones and in some cases were even better. From these findings, it can be concluded that the existing metabolites in aqueous extracts of G. lucidum and P. eryngii can be used to enhance seed germination effectively and even increase the leaf area of crop plants.

Effect of seed treatment with cold plasma and electromagnetic field on red clover germination, growth and content of major isoflavones

Pre-sowing treatment of red clover seeds with cold plasma (CP) and electromagnetic field (EMF) was applied aiming to evaluate changes induced in germination and early seedling growth under controlled laboratory conditions, and to estimate treatment effects on plant growth, biomass production, nutritional value and the amounts of major leaf secondary metabolites under long-term field experimental conditions. The effects of seed treatment using radio-frequency EMF (5, 10, 15 min) and CP (2, 5, and 7 min) on seed germination kinetics, morphometric parameters of seedlings were assessed for two cultivars of red clover—‘Vyčiai’ and ‘Sadūnai’. Long-term observations revealed that the effects of seed treatments persist for the entire vegetation season, while the observed effects on germination (CP increased germination rate by 4%–20%) do not provide sufficient information to predict the impact on plants on a longer time scale. The effects on morphometric parameters were dependent on plant cultivar, and were much stronger (up to 24% for ‘Sadūnai’ and 49% for ‘Vyčiai’) after growing the plants in the field for 5 months in comparison to the effects (absent or below 10%) observed in the early growth stages. A minor improvement of nutritional value per biomass unit was observed for ‘Vyčiai’. Protein yield per plant increased substantially (up to 70%). Pre-sowing seed treatment with CP and EMF had an obvious impact on the amounts of major isoflavones in leaves, and the nature of these changes strongly depended on the vegetation stage of plants (before flowering or at flowering stage). CP treatment for 5 min was found to be the most effective in this respect in not flowering plants, inducing a strong increase in biochanin A/formononetin ratio in leaves of both cultivars. However, an opposite effect was observed in the flowering plants, where the CP and EMF treatments decreased biochanin A/formononetin ratio.

Potential use of biochar, compost and iron grit associated with Trifolium repens to stabilize Pb and As on a multi-contaminated technosol

Vegetation cover can be used in the phytomanagement of polluted areas by adding value to abandoned sites and reducing the dispersion of pollutants by erosion. Appropriate amendments, that allow both efficient plant growth and the immobilization of contaminants in the soil must be chosen in order to optimize the efficiency of this process. We used a mining technosol mainly contaminated by arsenic (1068 mg kg−1) and lead (23387 mg kg−1) to study the effect of three amendments (biochar, compost and iron grit) on (i) physico-chemical properties of the soil and soil pore water, (ii) metal(loid) mobility, bioavailability and bioaccessibility (CaCl2 and Simple Bioaccessibility Extraction Test (SBET)), and (iii) the capability of Trifolium repens to germinate and grow. All the amendments used increased the pH and electrical conductivity of the SPW, resulting in a 90% decrease in the concentration of lead in the soil pore water (SPW). We also demonstrated a decrease in Pb phytoavailability. The amendments allowed the establishment of a plant cover, although the addition of iron grit alone did not allow any clover germination. For the Pontgibaud technosol, the combination of the three amendments resulted in a significant decrease in As and Pb concentrations in clover tissues, mainly in the aerial organs. The amendments also made it possible for some of them to halve the phytoavailable fraction of arsenic. However, for compost, both the As concentrations in the SPW, and the bioavailable fraction of As increased. All the amendments used had contrasting effects on the bioaccessible fractions of metal(loid)s. The most efficient amendment combination was the addition of 5% biochar and 5% compost.

Insights into oil recovery, soil rehabilitation and low temperature behaviors of microwave-assisted petroleum-contaminated soil remediation.

As an environmental contaminant, petroleum-contaminated soil will pollute water, stunt agricultural growth, and cause serious harms to human health if it wasn't safely disposed and remediated. Here, low-temperature microwave-assisted treatment of petroleum-contaminated soil was developed for simultaneous soil rehabilitation, oil recovery and revegetation. The results indicated the concentration of petroleum contaminant was decreased to regulatory standard after 20 min treatment at 250-300 °C. 91.6% of the oil was recovered, and it mainly consisted of C11-C30 hydrocarbons. Using the soil remediated at 250 °C for plant growth test, no adverse effect or fertility loss was observed and an optimal clover germination rate was reached. The results of microwave thermogravimetric analysis, dielectric property and EDX mapping revealed that the efficient remediation was attributed to the presence of hot spots, and the efficient heat /mass transfer during microwave heating. A three-stage petroleum removal mechanism was proposed, where the hydrocarbons were gradually removed via steam stripping, thermal desorption, and pyrolysis/carbonization as the temperature increased.

Dynamics of PCB removal and detoxification in historically contaminated soils amended with activated carbon

Activated carbon (AC) can help overcome toxicity of pollutants to microbes and facilitate soil bioremediation. We used this approach to treat a Histosol and an Alluvial soil historically contaminated with PCB (4190 and 1585 mg kg −1, respectively; primarily tri-, tetra- and pentachlorinated congeners). Results confirmed PCB persistence; reductions in PCB extractable from control and AC-amended soils were mostly due to a decrease in tri- and to some extent tetrachlorinated congeners as well as formation of a bound fraction. Mechanisms of PCB binding by soil and AC were different. In addition to microbial degradation of less chlorinated congeners, we postulate AC catalyzed dechlorination of higher chlorinated congeners. A large decrease in bioavailable PCB in AC-amended soils was demonstrated by greater clover germination and biomass. Phytotoxicity was low in treated soils but remained high in untreated soils for the duration of a 39-month experiment. These observations indicate the utility of AC for remediation of soils historically contaminated with PCB.

Established perennial grasses reduce the growth of emerging subterranean clover seedlings through competition for water, light, and nutrients

The effect of defoliating mature phalaris (Phalaris aquatica L.) plants on the growth and turgor of subterranean clover (Trifolium subterraneum L.) seedlings was examined at high and low rates of watering in tubs under a rain shelter with and without root competition. Clover germination was stimulated by applying 36 mm of water to seeds planted in the interspatial areas between phalaris plants, followed by either 12 mm (high) or 3 mm (low) of water every 2 days to simulate good or poor moisture conditions following emergence. The effect of 3 grasses (Phalaris aquatica, Dactylis glomerata L., and Danthonia richardsonii Cashm.) in drying the soil surface was confirmed in a field experiment following 41 mm of rainfall in early March. The percentage of light reaching the clover was twice as high (P < 0· 001) at seedling emergence in defoliated phalaris than undefoliated phalaris. The proportion of light reaching the clover increased from 40% to 70% during the experiment in the undefoliated low water treatment but remained low (33-48%) in the high water treatment. In the presence of root competition, defoliation under conditions of high water resulted in more water for the clover (>17%) in the top 5 cm of soil compared with undefoliated phalaris (13%). Defoliated phalaris with low water also maintained more favourable soil water conditions than undefoliated phalaris, but only for 5 days. Excluding root competition increased soil moisture levels from about 8% to 14% in treatments receiving low water. Defoliation increased (P < 0·05) clover seedling weight at 14 and 21 days after emergence in both the high and low water treatments, by a mean of 0·3 mg/day. In the absence of root competition and at low water, clover seedlings in the defoliated phalaris were twice as large (P < 0·001) 14 days after emergence and had a higher relative water content (RWC) (55% v. 40%) than seedlings in undefoliated swards. At low water, the RWC of clover was higher in the absence of root competition from phalaris than it was in its presence, but competition had no effect on RWC in the high water treatments. Available soil nitrate was significantly (P < 0·001) higher (160 µg N/g) in the absence of phalaris root competition than in its presence (3 µg N/g). The field experiment demonstrated that, in March, the 3 grasses dried the soil more rapidly (P < 0·01) (losing 9·8% of the remaining soil water/day) than pure subterranean clover (6·1%), which had little green biomass. Following later rains in May, when there was >400 kg/ha of green biomass (expressed as dry matter) in both the perennial and annual swards, the surface soil dried at the same rate regardless of whether the sward was perennial or annual. Scavenging for water by the perennial roots was an important factor in drying the surface soil in both March and May and there appeared to be no benefits from shading of the surface by the perennials. The results showed that early growth of clover seedlings in phalaris swards is reduced by a combination of competition for water, soil nitrate, and light. Defoliation of phalaris reduces the loss of water from the topsoil, increases clover seedling size, and, where water is limiting, increases seedling turgor.

Allelopathic activity in wheat-conventional and wheat-no-till soils: Development of soil extract bioassays

The primary objective of this research was to determine if soil extracts could be used directly in bioassays for the detection of allelopathic activity. Here we describe: (1) a way to estimate levels of allelopathic compounds in soil; (2) how pH, solute potential, and/or ion content of extracts may modify the action of allelopathic compounds on germination and radicle and hypocotyl length of crimson clover (Trifolium incarnatum L.) and ivyleaved morning glory (Ipomoea hederacea L. Jacquin.); and (3) how biological activity of soil extracts may be determined. A water-autoclave extraction procedure was chosen over the immediate-water and 5-hr EDTA extraction procedures, because the autoclave procedure was effective in extracting solution and reversibly bound ferulic acid as well as phenolic acids from wheat debris. The resulting soil extracts were used directly in germination bioassays. A mixture of phenolic acids similar to that obtained from wheat-no-till soils did not affect germination of clover or morning glory and radicle and hypocotyl length of morning glory. The mixture did, however, reduce radicle and hypocotyl length of clover. Individual phenolic acids also did not inhibit germination, but did reduce radicle and hypocotyl length of both species. 6-MBOA (6-methoxy-2,3-benzoxazolinone), a conversion product of 2-o-glucosyl-7-methoxy-1,4-benzoxazin-3-one, a hydroxamic acid in living wheat plants, inhibited germination and radicle and hypocotyl length of clover and morning glory. 6-MBOA, however, was not detected in wheat debris, stubble, or soil extracts. Total phenolic acids (FC) in extracts were determined with Folin and Ciocalteu's phenol reagent. Levels of FC in wheat-conventionaltill soil extracts were not related to germination or radicle and hypocotyl length of either species. Levels of FC in wheat-no-till soil extracts were also not related to germination of clover or morning glory, but were inversely related to radicle and hypocotyl length of clover and morning glory. FC values, solute potential, and acidity of wheat-no-till soil extracts appeared to be independent (additive) in action on clover radicle and hypocotyl length. Radicle and hypocotyl length of clover was inversely related to increasing FC and solute potential and directly related to decreasing acidity. Biological activity of extracts was determined best from slopes of radicle and hypocotyl length obtained from bioassays of extract dilutions. Thus, data derived from the water-autoclave extraction procedure, FC analysis, and slope analysis for extract activity in conjunction with data on extract pH and solute potential can be used to estimate allelopathic activity of wheat-no-till soils.

Bermudagrass-Subterranean Clover Response to Nitrogen Application

Overseeding perennial warm-season grasses with annual clovers can extend the grazing season and improve available forage quality. Grass yield following annual clovers may be reduced however, compared with grass-N systems. Our objective was to determine the effect of rate and date of N application on the productivity and quality of hybrid bermudagrass [Cynodon dactylon (L.) Pers.] following subterranean clover (Trifolium subterraneum L.), and on subsequent clover establishment. On a Catalpa silty clay soil (fine, montmorillonitic, thermic Fluvaquentic Hapludoll), ‘Tifton 44’ bermudagrass previously overseeded with ‘Mt. Barker’ subterranean clover was fertilized with no N or with 60 lb N/acre in early June, July, or August in combinations of any one, two, or three months in each of 2 yr. After the final harvest (1 September), bermudagrass was clipped every 7 or 28 d through the fall, when rainfall sufficient for clover germination was received. Clover establishment and yield were determined beginning in early October. Results indicate that dry matter (DM) yield of bermudagrass was increased over that receiving no N by a split-application of 120 lb N/acre in July and August (mean of 371s5 vs. 4420 lb DM/acre). Applying 60 lb N/acre in early June did not increase total yield over no N. Application of N increased crude protein concentration of bermudagrass forage from a mean of 10.2 to 11.99% in only one of three harvests each year. Total N fertilizer uptake efficiency by the bermudagrass was low (range of 3 to 17%) and similar among all N rates. Although unaffected by date and rate of N application, establishment and yield of clover were improved when bermudagrass was clipped on 7- vs. 28-d intervals prior to, and during, emergence of clover seedlings in the fall.

Influence ofAcremonium loliiinfection in perennial ryegrass on germination, emergence, survival, and growth of white clover

Abstract Four glasshouse experiments and two field trials were conducted to determine the effects of perennial ryegrass (Lolium perenne L.) infected with Acremonium lolii Latch, Christensen & Samuels on white clover (Trifolium repens L.) germination, emergence, growth, and survival. Under controlled laboratory experiments, ryegrass leachates temporarily inhibited the rate of white clover germination, but did not affect white clover emergence or yield. In glasshouse experiments, the presence of A. lolii did not influence white clover emergence or growth. Emergence of indicator plant species grown in pumice sand substrate which previously grew ‘Ellett’ or ‘Grasslands Nui’ perennial ryegrass was not affected (‘Ellett’) or was enhanced (‘Grasslands Nui’) by the presence of A. lolii. In field trials, A. lolii infection did not significantly affect white clover survival, vigour, or leaves and stolons per plant, when ryegrass tiller densities were similar. Later, when tiller density of A. lolii-free plants decre...

Changes in α- and β-amylase activities during seed germination of clover (Trifolium repens)

Changes in α- and β-amylase activities in the cotyledons of germinating clover were examined. The activity of α-amylase decreased during germination and growth of seedling, while β-amylase activity increased. These changes are different from those of germinating seeds of many other plants, but similar to the germinating seeds of alfalfa, which belongs to the same tribe (Trifolieae) as clover.

Seedling establishment characteristics of alternative legume species in tussock grassland environments

Four alternative legume species, Caucasian clover (Trifolium ambiguum), zigzag clover (T. medium), crown vetch (Coronilla varia), and birdsfoot trefoil (Lotus corniculatus), were compared with white clover (T. repens) on four tussock grassland sites. Seed was inoculated and pelleted, and then oversown at a rate equivalent to 5 kg/ha viable seed. Germination, nodulation and survival of white clover, Monaro Caucasian clover, and zigzag clover were similar on the two lowest sites (600 and 830 m). However, low rates of zigzag clover germination occurred on the two higher sites (1090 and 1100 m). Germination of crown vetch appeared to be prevented or delayed by the low temperatures, and no plants established on any site. Low nodulation occurred in Treeline Caucasian clover and birdsfoot trefoil. Further research is required to select more suitable strains of rhizobia for both these legumes. The results provide information for estimating likely plant densities of these new cultivars when oversown in tussock grassland environments. Keywords Coronifla varia, establishment, germination, inoculation, Lotus corniculatus, nodulation, Trifoliumambiguum, Trifolium medium, Trifolium repens

Germination of Cool Season Annual Clovers1

AbstractInformation on the effect of temperature on germination of the major cool season annual clover species adapted to the southeastern United States is limited. Such data would be useful in determining optimum planting dates and reveal differences between species. Seed of arrowleaf (Trifolium vesiculosum Savi.), crimson (Trifolium incarnatum L.), subterranean (Trifolium subterraneum L.), and Persian (Trifolium resupinatum L.) cultivars was placed on indented blotter pads in 90 ✕ 50 cm petri dishes. Petri dishes were placed in a low temperature incubator and subjected to day/night temperatures of 15/5, 20/10, 25/15, 30/20 and 35/25 C with 12‐hour light periods which simulate natural temperatures during clover establishment in the southern states bordering the Gulf of Mexico. Numbers of normal and abnormal seedlings were recorded every 2 days from the 3rd to the 13th day.Crimson and Persian clover had the fastest germination rate followed by subterranean and arrowleaf. Persian clover was the least responsive to temperature with only 11% difference in germination between treatments by day 13. Crimson clover reached maximum germination across all temperatures most rapidly with only 1 to 4% difference between day 9 and 13, but the number of abnormal seedlings was three to four times greater than the other clover species. Good germination of Persian and crimson clovers occurred at the highest temperature of 35/25 C. This could result in poor natural reseeding if hard seed content and dormancy decrease too quickly after seed maturation to prevent summer seed germination.Arrowleaf clover was affected most severely by the temperature treatments with maximum germination reaching only 17 and 9% under the 30/20 and 35/25 C treatments, respectively. Therefore, good arrowleaf seed germination occurs later in the fall than the other species which means less fall forage production and increases the risk of seedling damage by an early frost. Subterranean clover germination was depressed only at the 35/25 C treatment with the best germination rate at 30/20 C.

Effect of Various Aqueous Plant Extracts upon Seed Germination

Aqueous extracts of residues from 23 plant species inhibited the germination of clover, lettuce, radish, and wheat seeds. Extracts from potato, sugarbeet, sagebrush, green soybean, alfalfa, pea, and bean were extremely toxic to germinating seeds, while the extracts from Douglas-fir, peat moss, and sphagnum moss stimulated the growth of some germinating seeds. The degree of toxicity was dependent upon the maturity of the plant residue, the concentration of the extract, the species from which the extract was obtained, and the species of seed used in making the bioassays.