Trifolium Dubium Research Articles

The effect of earthworms and snails in a simple plant community.

Snails and earthworms affected the dynamics of a simple, three-species plant community, in the Ecotron controlled environment facility. Earthworms enhanced the establishment, growth and cover of the legume Trifolium dubium, both via the soil and interactions with other plant species. Worms increased soil phosphates, increased root nodulation in T. dubium, and enabled T. dubium seedlings to establish in the presence of grass (Poa annua) litter, by increasing soil heterogeneity. Worms also buried the seeds of Poa annua and Senecio vulgaris, reducing the germination of new seedlings. Snails reduced nitrogen-fixing Trifolium dubium and increased cover of plant litter, thereby reducing ammonia-nitrogen concentrations in the soil. These effects and their interactions demonstrate that the detritivore food chain, and earthworms in particular, cannot be ignored if we are to understand the spatial and temporal dynamics of plant communities.

Morphology and Host Specialization ofSclerotinia trifoliorumfrom Small Hop Clover

Symptoms of a Sclerotinia disease were observed annually for 8 yr in volunteer stands of small hop clover (Trifolium dubium) near Starkville, Mississippi. Apothecia developed from sclerotia in November and December, and patches of dead plants with sclerotia present in and on tissue appeared from February through March. The pathogen was identified as Sclerotinia trifoliorum by ascospore morphology. Sclerotia formed by S. trifoliorum on small hop clover in the field and apothecia produced from them were smaller than those recovered from berseem and crimson clovers (.)

Uromyces Minor on Peas in Australia, With Notes on Other Rusts of Pisum.

Leaf and tendril rust of peas, caused by Uromyces minor, is reported for the first time in Australia, from northern Tasmania. This rust was first recorded in Australia on Trifolium dubium from King Island, Bass Strait, in 1979. The biology of the rust, its host range and relationship to other pea rusts are included. Information on all rust species reported from peas is summarised, brief notes on Australian reports of other pea rusts are provided and the quarantine significance of the finding of U. minor on peas in Australia is discussed.

Morphological and flowering variation ofTrifolium dubiumSibth

Abstract The morphology, flowering, survival to maturity, and re-establishment of 28 New Zealand and overseas lines of suckling clover (Trifolium dubium Sibth) were examined. Significant differences between lines were shown for leaf size, plant spread, leaf density, time of flowering, and survival at peak flowering in the first year. In the second year, there were no significant differences between lines for occurrence and leaf density. Forty lines of suckling clover derived from buried seed collected from three experimental farmlets of different fertiliser input and stocking management were also compared. Lines from the low fertiliser, rotationally grazed cattle farmlet had the greatest spread in November. Lines from the low fertiliser, rotationally grazed sheep farmlet were the densest in November. Peak flowering of most lines occurred in November, with no lines flowering in August and only three flowering in October. The earliest flowering lines included two from Portugal and one of unknown origin. The three latest flowering lines, with less than 30% of plants flowering in November, came from the United States, New Zealand, and France.

Root distribution in a low fertility hill country sward grazed by sheep

Abstract In a preliminary study, root distribution, biomass, length, and surface area were measured to a depth of 800 mm in mid summer on a sunny (north) and shady (south) aspect of a low fertility hill country sward grazed by sheep. The dominant grass species were browntop (Agrostis capillaris L.), crested dogstail (Cynosurus cristatus L.), and yorkshire fog (Holcus lanatus L.). White clover (Trifolium repens L.), suckling clover (T. dubium Sibth. L.)( and lotus (Lotus pedunculatus Cav.) were the dominant legume species. Calculated root biomass for the profile down to 800 mm was 14 410 kg dry matter (DM)/ha on the shady face and 21 470 kg DM/ha on the sunny face. This was 2.3–3.5 times more than above-ground biomass produced on an annual basis and 6–7 times the total above-ground pasture biomass at the times of sampling. The large root biomass, and consequently the large quantities of nutrients involved in the below-ground component of the nutrient cycle, highlight the need for further research to quantify and characterise the root dynamics of grazed swards.

Influence of fertiliser and grazing management on North Island moist hill country 3. Performance of introduced and resident legumes

Abstract A grazing trial was conducted on 99 ha of steep, low fertility hill country in southern Hawke's Bay, during 1975–81. There were 2 fertiliser treatments: low (LF) and high (HF) superphosphate application (plus lime on HF), and 3 grazing managements — rotational grazing by sheep (RGS) or cattle (RGC), and set stocking by sheep (SSS). A white clover (Trifolium repens L.) similar to Kent wild white, and annual suckling clover (T. dubium Sibth.) were already present in the pastures in small amounts. ‘Grasslands Huia’ white clover, ‘Grasslands Turoa’ red clover (T. pratense L.), ‘Grasslands Maku’ lotus (Lotus pedunculatus Cav.), and Woogenellup subterranean clover (T. subterraneum L.) were oversown into the pasture in 1974. Huia, Turoa, and Grasslands 4703 lotus were oversown again in 1977. Woogenellup subterranean clover was found to be unsuited to the environment. Lotus plants established, but contributed little to total herbage accumulation. Red clover was most important in RGC pastures. Its contribution was short-lived in sheep-grazed pastures, but was significant in the year after oversowing where fertiliser application history was short. Suckling clover produced a significant amount of herbage on steep NW sites during spring. Huia white clover was the most productive of the oversown legumes. However, the resident white clover was more productive than Huia in sheep-grazed pastures but not in RGC pastures. Huia was more responsive to HF (compared with LF) application in RGC than in sheep-grazed pastures — the converse applied for the resident genotype.

LACK OF SPREAD OF ENDOMYCORRHIZAS OF CENTAURIUM (GENTIANACEAE)

Seedlings of Centaurium died in the absence of inoculum of vesicular-arbuscular (VA) mycorrhizal fungi in a soil low in nutrients. The morphology of endomycorhizas of Centaurium and Eustoma grandiflora (Raf.) Shim, differed from that of commonly studied VA mycorrhizal hosts in that coils, arbuscules and vesicles were formed but rapidly collapsed. Endomycorrhizal infection spread down the roots of Centaurium erythraeq Rafn. when it was grown with a companion plant, Trifolium dubium Sibth. but when grown alone infection was restricted to the vicinity of the inoculum. Several different VA mycorrhizal plants did not become mycorrhizal when inoculated with mycorrhizal roots of Centaurium.

Leaf phosphorus fractionation and growth responses to phosphorus of the forage legumes Trifolium repens, T. dubium and Lotus pedunculatus

‘Grasslands Huia’ white clover (Trifolium repens L.), ‘Grasslands Maku’ lotus (Lotus pedunculatus Cav.) and suckling clover (T. dubium Sibth) were grown in a controlled environment at various levels of P supply. Dry weights and the concentration of inorganic‐, lipid‐, ester‐ and residual‐P in trifoliate leaves were measured. Lotus grew better than white or suckling clover at low P. White clover and lotus responded steeply to increased P and had similar shoot dry weights at high P. Suckling clover had lower shoot weights than the other species at all P levels. The superior growth of lotus at low levels of p was probably due to better root growth and P uptake. Lotus had higher shoot P concentrations at low levels of P but lower concentrations than the others at high levels. White clover and suckling clover had similar shoot P concentrations at all levels of supply. In white and suckling clover total leaf P concentration rose with P supply. Of the P fractions, inorganic‐and residual‐P showed the largest rises in concentration. The increases in lipid‐ and ester‐P were smaller. Increases in lotus leaf P were small, primarily because of the relatively small rises in inorganic‐ and residual‐P. White clover is a vigorous species but requires high levels of P for best growth. Suckling clover has a relatively small response to improvements in P availability. The behaviour of the various P fractions is similar to that in white clover. Lotus grows well at low P but also shows rapid growth at high P supply. Whether efficiency is defined as the ability to extract P from the environment or to maintain low internal P concentration, lotus makes efficient use of P over the whole range of P supply.

The Dynamics of Seed Bank Size and Seed State of Medicago Lupulina

SUMMARY (1) The annual dynamics of seed bank size and seed state were recorded for Medicago lupulina (black medick) in an abandoned pasture in southern Ontario, Canada. (2) The seed bank density of Medicago lupulina was relatively small (600-2000 seeds m-2) compared with those reported for other pasture species (3700-55 000 m-2), but roughly the same as the density reported for another legume, Trifolium dubium (2500 m-2). (3) The seed bank was smallest following spring and summer germination and largest in late winter when most seeds had been detached from parent plants. (4) The lowest seed density (600-1100 m-2) was recorded in grass-filled hollows. It was 2-3 times greater on ridges. (5) In both ridge and hollow habitats the seeds, which have a hard seed coat, remained dormant throughout most of the year. The largest transition between dormancy states occurred during winter months when seed coats were scarified and innately dormant seeds entered a state of enforced dormancy. (6) Between 78 and 85% of some experimentally introduced seeds germinated within twelve months, mostly in the spring (April-May). It was estimated that normally only 30-40% of the natural seed bank would germinate in a single year. Medicago lupulina apparently has a persistent seed bank in the study area. (7) The regenerative strategy of Medicago lupulina was compared with that of Hieracium floribundum which dominated ridge habitats in the study area. While both species had flourishing populations on ridges in the pasture, most seeds of H.floribundum survive for no more than 1 year, and recruitment to the population is mainly vegetative. The strategy of Medicago lupulina appeared to be better suited to colonizing small patches of bare ground created by the activities of animals or by erosion.

Analysis of the response of pasture legumes to phosphorus in a controlled environment

Abstract White clover, red clover, suckling clover, and lotus were grown under a controlled environment in soil to which phosphorus had been added at levels of 50, 250, 600, and 2000 ppm w/w. Growth analysis was used to explain differences in yield in terms of attributes describing growth, P uptake, and assimilation. The yield of white clover, red clover, and lotus increased markedly with P supply. Suckling clover responded less to P and its yields were smaller than those of the other species except that of lotus at 50 ppm. In all species the rate of P uptake per unit root length increased with P supply. There were differences in uptake rate among species but these could not be consistently related to differences in yield. The efficiency with which absorbed P was used in the production of dry matter declined as the P supply increased in all species. Lotus used P with the greatest efficiency. Root/shoot ratios and root length/weight ratios were affected by an increase in P supply. Suckling clover had the h...

I. Buried seed populations

Abstract Numbers of buried legume seeds in the upper layers of soil were determined in a survey over an area of hill country pasture at the Grasslands Division research station, Ballantrae. Seeds of suckling clover (Trifolium dubium L.) and white clover (T. repens L.) were most numerous, mean numbers per m2 being average for this particular type of pasture (2541 and 291 repectively). White clover seed numbers were not significantly different between site types, whereas suckling clover seeds were highest on north aspects and stockcamps and lowest on south aspects and wet sites. These variations could be attributed largely to climatic and stock behaviour factors, and distribution of legume plants. Little of the buried legume seed germinated in tests, but scarification revealed that viability was high. The role of buried legume seed as a source of seed in pasture improvement is discussed.

Growth and nitrogen fixation of pure stands of three pasture legumes with high/low phosphate

Abstract The growth and N-fixation capacities of pure stands of white clover (Trifolium repens L.), suckling clover (T. dubium Sibth.), and Lotus pedunculatus Cav. were compared under high and low phosphate conditions in mown plots for 3 years. With high inputs of P, white clover yielded 10% more herbage DM and nitrogen than lotus, but with low P input lotus yielded 30% more than white clover. The main factor operating was the greater ability of lotus to take up P from the soil. Full development of an efficient N-fixing system took a year in lotus, much longer than for white clover. Suckling clover performed better than white clover at low P during its growing season. White clover and lotus accumulated twice as much soil N as suckling clover. Phosphate had no effect on soil N accumulation. The mean annual amount of N fixed (herbage + soil) at high P was 570, 590, and 265 kg/ha, and at low P was 400, 410, and 195 kg/ha for white clover, lotus, and suckling clover respectively.

Comparative effects of summer and winter conditions on the growth of six species of pasture legumes subjected to various nutrient levels

The results of a series of water culture experiments is reported in which the comparative effects of summer or winter conditions respectively on the growth of subterranean clover (Trifolium subterraneum L. var. Dwalganup), red clover (T. pratense L. certified), white clover (T. repens L. 'mother strain' certified), cluster clover (T. glomeratum L.), suckling clover (T. dubium Sibth.), and barrel medio (Medicago tribuloides Desr. strain 173), in a complete nutrient solution and in solutions deficient in either potassium, phosphorus, or magnesium were studied. In the complete nutrient solution, the mean daily increment in dry weight (T+R) for each species was less in winter than in summer. Rates of growth (T+R) of red clover, white clover, cluster clover, and suckling clover were each reduced more by winter as compared with summer conditions than was that of barrel medic, while a similar comparison also showed that white clover and suckling clover were more affected than subterranean clover. For subterranean clover and barrel medic (T+R) differed little as between the summer and winter tests respectively, but (T+R) for red clover, white clover, cluster clover, and suckling clover was significantly depressed under winter conditions. Significant season X species interactions occurred. Differences in seasonal conditions had no effect on the percentage top of five of the species when grown in the complete nutrient solution, but in the sixth species (barrel medic) winter conditions when compared with summer conditions favoured top growth at the expense of root growth (i.e. increased percentage top). Within any species there was no significant seasonal effect on the depression in (T+R) caused by a deficiency of either potassium, phosphorus, or magnesium. Between species certain significant effects were unrelated to seasonal conditions for potassium or phosphorus deficiencies, but with magnesium deficiency significant species x season interactions occurred for (T+R). Within species, the mean effect of potassium deficiency in reducing percentage top in all tests was significant for white clover, barrel medic, and suckling clover, but the season x potassium level interaction was significant for cluster clover only. There were no significant differences between species. Phosphorus deficiency caused a significant reduction in percentage top within all species under both summer and winter conditions, but no significant season x phosphate level interaction occurred. The percentage top of white clover was reduced more than that of subterranean clover in summer, but not in winter. Magnesium deficiency produced a significant reduction in the percentage top of white clover and barrel medic in winter, but not in summer. The season x magnesium level interaction effect was significant for white clover. Several significant species x magnesium level interactions for percentage top were also recorded.

PASTURE SPECIES AND MIXTURES FOR THE AUCKLAND PROVINCE

The Auckland Province can be divided into two main climatic regions : ( 1) The, Central Plateau (2) The Lower and Coastal Regions The central plateau is characterised by fairly cold winters with severe frost at times, while the lower-lying and coastal regions lying to the north almost fall into the sub-tropical zone. This region, which includes the Waikato Basin, is reasonably suited to the growing of paspalum species and the frost-free areas suit kikuyu, a tropical grass. In parts of the central plateau the soils are so coarse in texture that in some seasons there is not sufficient moisture to support a high-producing sward of grasses and clovers. Here lucerne can, with advantage, replace much of the pasture for hay and for grazing. Apart from such small exceptions, the region is very well suited to the growth of red and white clover, cocksfoot, and ryegrass, provided the fertility is increased to the extent needed to support these pasture plants. Other grasses and clover may grow in association or in place of those generally desirable pasture plants. These include Yorkshire fog, Poa pratensis, Poa trivialis, Poa annua, browntop, sweet vernal among the grasses and Lotus major (pedunculatus), subterranean clover, and suckling clover among the clovers.