Describes the main distribution activities of the clover root weevil biocontrol agent undertaken in the North Island 2007/2008 summer, and the reasons behind the methods employed. Source: National ...Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Pastures in southern Chile are composed of forage grasses and associated legumes. Apart from native grass species, in many areas perennial ryegrass (Lolium perenne L.) and white clover (Trifolium ...repens L.) have been introduced. It is thought that most of the N in these pastures is derived from the symbiosis between rhizobium bacteria and the clover. However, various factors can limit the biological nitrogen fixation (BNF) potential. Soils of Chiloé (southern Chile) are derived from volcanic ash (Andisols), and show high acidity and phosphorus (P) retention capacity and there is often a low availability of exchangeable cations and, sometimes, micronutrients, which together with high aluminium (Al) concentrations can inhibit BNF potential by nodulated legumes. An experiment was carried out on an Andisol of Chiloé, on a permanent pasture, to evaluate the influence of these fertility factors grass and legume productivity and on the BNF contribution to white clover. Treatments included two rates of lime (0 and 4 Mg ha-1) and eight fertilisation treatments: 1. Complete (macronutrients in kg ha-1: N-50, P2O5-180, K2O-100, MgO-70, S-50, and micronutrients); six other treatments with complete fertilisation but, respectively, without N, P, K, Mg, S and micronutrients, and a control without fertiliser application. The experiment was conducted over 2 years and soil fertility parameters, grass and clover biomass production were evaluated and the BNF contribution to the clover was estimated using 15N isotope dilution technique. Potassium was found to be the most limiting element for dry matter production, especially for the clover. Liming increased soil pH values and Ca and Mg contents, strongly reduced Al saturation and increased dry matter production. The proportional contribution of BNF to the white clover was high, reaching 80% of total N accumulated by the plants and not significantly affected by addition of lime or fertiliser. However, the accumulation of dry matter and total N, and the total N derived from BNF by the clover were over three times higher in the complete fertilisation treatments than in the control in both years and in the limed and unlimed treatments. The results of this study indicate that pasture productivity can be improved by liming and fertilisation which favour growth of the legume and ryegrass to the detriment of the native grasses. The increase in the proportion of ryegrass and clover should result in improved quality of the available forage, and in the case of the clover, stimulates an increase in the N contribution from BNF thus dispensing with the need for N fertiliser.
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BFBNIB, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Three digestion experiments involving cryptorchid weaned lambs were conducted for 14-day periods in the spring, summer and autumn to determine the in vivo digestibility of dry matter (DMD), gross ...energy (GE), organic matter (OMD), digestible organic matter in the dry matter (DOMD) and estimated metabolisable energy (ME) concentration of
Lotus corniculatus L. (birdsfoot trefoil; cv. Grasslands Goldie) at different stages of maturity. The experiments were carried out indoors at Massey University's Riverside farm, in the Wairarapa, North Island, New Zealand. In vivo digestibility samples were then used as standards to investigate if the enzymic in vitro system of Roughan, P.G., Holland, R., 1977. Predicting in vitro digestiblities of herbages by exhaustive enzymic hydrolysis of cell walls. J. Sci. Food Agric. 28, 1057–1064 could predict OMD and DOMD of condensed tannin (CT)-containing
L. corniculatus.
Digestibility of
L. corniculatus declined as it matured, but the rate of decline was much less than that which occurs for perennial ryegrass (
Lolium perenne)/white clover (
Trifolium repens) pasture. It was concluded that the in vitro enzymic system of Roughan, P.G., Holland, R., 1977. Predicting in vitro digestiblities of herbages by exhaustive enzymic hydrolysis of cell walls. J. Sci. Food Agric. 28, 1057–1064 can be used to predict OMD and DOMD of
L. corniculatus with a high degree of accuracy, provided a standard curve involving in vivo data generated with
L. corniculatus is used. Using a standard curve with in vivo data from perennial ryegrass/white clover pasture led to bias which increased at lower OMD values. Reasons for the differences between
L. corniculatus and pasture standard curves are discussed, including possible effects of bound CT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Root-infecting nematodes are a major cause of white clover, Trifolium repens, not reaching its potential in New Zealand pastures. Resistance and/or tolerance are the preferred control options. ...Greenhouse-based, recurrent selection programs have developed resistance to Meloidogyne trifoliophila and Heterodera trifolii, and a field-based program has developed tolerance. Lines from these programs were compared with commercial cultivars as controls in a series of field trials at four sites over 4 years. Resistant lines from the CCN program performed better than susceptible lines and as well as most cultivars, reflecting the high level of resistance developed in this greenhouse-based program. In stained root from Cambridge, numbers of CCN were lower in resistant lines than in cultivars; numbers in susceptible lines were intermediate. CCN resistance was also reflected to a lesser extent in the number of cysts counted in soil under resistant lines in Palmerston North. The root-knot nematode-resistant material performed better than the susceptible and as well as most cultivars. In one trial of CRKN-resistant lines, resistant and susceptible lines had similar numbers of CRKN which were both lower than the numbers in the cultivars; in the second trial, there were fewer CRKN in resistant than in susceptible lines or cultivars. The tolerant selections, developed under field conditions, performed as well as or better than the cultivars. The selections from the breeding programmes have exhibited strong agronomic potential across locations and years, and the best material has been crossed; progeny are being assessed in current field trials.
High tannin (HT) white clover (Trifolium repens), bred for increased floral condensed tannin (CT) and flowering prolificacy, was assessed under dairy grazing in the Waikato region of New Zealand. HT ...and 'Grasslands Huia' white clover monocultures sown in April 2001 were monitored until November 2003. HT grew 1 t DM ha
-1
less than 'Huia' each year and both had similar CT concentrations in flower heads across sampling dates (13-80 g kg
-1
DM). HT had more flowers per plant and per node than 'Huia', but similar numbers of stolon branches per node. Higher flower densities in HT than 'Huia' swards from October 2001 to January 2003 resulted in higher clover CT concentrations, reaching 12 g kg
-1
clover DM, but contamination of HT swards by clover plants arising from the seedbank reduced treatment differences. Future attempts to increase CT concentration in white clover should involve CT expression in foliage rather than flowers to maintain agronomic performance.
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Successful winter survival of perennial plants, like white clover, is dependent on proper timing of both hardening and dehardening. The purpose of this study was to investigate the regulation of ...these processes in two cultivars (AberCrest and AberHerald) and two Norwegian ecotypes (Særheim collected at 58°46′N lat. and Bodø at 67°20′N lat.) of white clover (Trifolium repens L.). For hardening and dehardening, plants were exposed to controlled temperature conditions and frost hardiness of stolons was tested by programmed freezing at the rate of 3°C per hour. In addition, stolons were analysed for starch, soluble sugars and soluble amino acids. Cultivars AberCrest and AberHerald, selected for growth at low temperature and winter hardiness in the United Kingdom, were significantly less hardy than the Norwegian populations. After six weeks of hardening (2 weeks at 6°C and 4 weeks at 0.5°C), estimated LT50 values were −13.8, −13.0, −17.8 and −20.3°C for AberCrest, AberHerald, Saerheim and Bodø, respectively. The rate of dehardening increased with increasing temperature. At low temperature (6°C), the northern ecotype from Bodø was more resistant to dehardening than AberHerald. However, at 18°C the absolute rate of dehardening (°C day−1) was twice as high in Bodø as in AberHerald plants. Stolon elongation during dehardening was initiated at lower temperatures in AberHerald than in plants of the Bodø ecotype. The content of total soluble sugars, sucrose and the amino acids proline and arginine were significantly higher in hardy plants of Bodø than in those of AberHerald. Sucrose levels decreased during dehardening and correlations between sucrose content and LT50 during this process were statistically highly significant for both Bodø and AberHerald. The least hardy populations of white clover were characterized by thick stolons, long internodes and large leaves.
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The predominant root-knot nematode in New Zealand pastures is Meloidogyne trifoliophila, and a recurrent selection program in Trifolium repens has developed resistance to this species. No data are ...available, however, on the mechanisms of resistance in T. repens or resistant genotypes of T. semipilosum. The development of M. trifoliophila in roots of T. repens and T. semipilosum was examined weekly after a 2-day inoculation with eggs. More second-stage juveniles (J2) were found in two resistant genotypes of T. repens than in two susceptible ones 1 week after inoculation. J2 did not develop further in resistant genotypes, but in susceptible plants development proceeded to the adult stage, visible at 4 weeks after inoculation. The mode of action of resistance to M. trifoliophila in T. repens and in T. semipilosum was compared after a 24-hour inoculation with J2. Numbers of J2 per root tip ranged from 0 to 12 with a median of one for each species. At 24 hours after inoculation (HAI), similar numbers of J2 were seen in the cortex oriented toward the root tip in both resistant and susceptible genotypes of both plant species. At 48 HAI, accumulations of J2 were seen in the meristem in both resistant and susceptible genotypes of both plant species. At 72 HAI, differences in nematode responses were evident between resistant and susceptible genotypes of both plant species; in susceptible roots, J2 heads were embedded in the developing stele. At this time, a browning reaction in resistant genotypes of both plant species indicated a hypersensitive response, and differences in the reaction were recorded between T. repens and T. semipilosum. More study is needed to determine whether the resistance reaction in T. semipilosum is suitable for introgression or insertion into T. repens.
Parasitism by an ichneumonid wasp, Bathyplectes sp., on the clover leaf weevil, Hypera punctata, was investigated for over 10 years in the field of the white clover in Tsukuba, Ibaraki Prefecture. ...The rate of parasitism fluctuated annually, and sometimes reached more than 30%. High rate of parasitism was observed in third and fourth instar larvae of H. punctata; the maximum rate was 42.6%. The trend of annual fluctuation on parasitism since 1996 was similar at two experimental sites, although the maximum rate of parasitism was different between the two experimental sites. This suggests that such an annual trend of parasitism could be commonly observed through the relatively wide area around the study site.
Three replicate paddocks, each of 0·235 ha, containing adjacent monocultures of perennial ryegrass or white clover 50:50 by ground area, 6 cm sward surface height (SSH) at start of experiment were ...continuously stocked with three yearling and four mature non‐lactating, non‐pregnant Scottish halfbred ewes for 12 weeks. Herbage intake, grazing behaviour and dietary selection were measured on seven occasions. Clover SSH declined rapidly over the first 5 weeks then stabilized at 1·2–1·6 cm, whereas perennial ryegrass SSH rose slightly initially, then declined gradually. Animals initially included proportionately c. 0·6 white clover in their diet but, by the end of the experiment, this had fallen to 0·3. Total daily herbage intake declined over the 12 weeks from 1·8 kg dry matter (DM) day–1 at the start to 1·0 kg DM day–1. Total grazing time increased from 561 min day–1 to 649 min day–1 at the end of the experiment. The results suggest that, despite overall herbage depletion and a greater depletion of white clover than perennial ryegrass as a result of the initial partial preference for white clover, the animals traded‐off a reduced total intake and an increased grazing time in an attempt to maintain their initial preferred dietary composition.
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