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    The biosynthesis of galactolipids in red clover (Trifolium pratense) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry
    (Massey University, 1972) Bycroft, Wesley
    Galactolipids occur in all cells capable of the photosynthetic evolution of oxygen. The main galactolipids are monogalactosyl diglyceride (MGDG), digalactosyldiglyceride (DGDG) and sulfolipid (SL), MGDG being the most abundant. These three together form the major nonpigment lipids in both leaves and green algae, accounting for about 40% of the total lipids. Nearly all of the cellular MGDG of plants is present in the chloroplasts and is concentrated in the lamellae. Galactolipids contain unusually high percentages of polyunsaturated acids (MGDG contains greater than 90% in some plants), the major one being α-linolenic acid (9,12,15-octadecatrienoic acid; 18:3). Thus in higher plants most of the MGDG is monogalactosyl dilinolenoyl glycerol. MGDG may be the actual substrate of the desaturation reactions of α-linolenic biosynthesis.
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    Effects of early grazing on the growth and development of red clover (Trifolium pratense L.) : a dissertation presented in partial fulfilment of the requirements for the degree of Master of AgriScience in Agriculture at Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Martin, Tyler John
    Developments in red clover cultivars have shown that persistency issues that have limited the inclusion of red clover in New Zealand pastures in the past are now less of a concern. The seasonality of current New Zealand pastures can lead to poor summer production. Red clover (Trifolium pratense L.) offers high drought tolerant pasture along with strong yields and high quality herbage. The objective of this research was to compare recent red clover cultivars with an industry standard red clover cultivar and lucerne (Medicago sativa L.), determining the effects of timing of first grazing and grazing frequency. Two experiments were conducted. The field experiment included two red clover cultivars, Grasslands Relish and Grasslands Sensation, and a lucerne cultivar, Grasslands Torlesse. Treatments consisted of a first grazing 10, 12 and 14 weeks after sowing and a final grazing at 28 weeks after sowing. The species were measured over the experiment for morphological development and production through the establishment period. The second experiment was conducted in a glasshouse which included three red clover cultivars Grasslands Relish, Grasslands Sensation and Grasslands Colenso. Defoliation treatments were applied at 1, 2 and 4 week frequencies while production and development were continuously measured including monthly destructive harvests to further measure total plant biomass content and allocation. The two recent red clover cultivars showed better production than lucerne and the older red clover cultivar, and especially notable production was seen by Grasslands Relish during the field experiment. Grasslands Relish was able to be grazed earlier than Sensation giving more flexibility, as well as maintaining a high plant population from autumn through to spring. Timing of first grazing showed that it substantially affected yield but had no effect on plant populations. High frequency defoliation resulted in less total herbage mass production and suppression of unique cultivar characteristics, such as growth habit, that was shown in red clover cultivars that were defoliated less frequently.
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    A study of the relationship between seed vigour and seed performance in Trifolium pratense L. cv. Grasslands pawera : a thesis presented in partial fulfilment of the requirement for the degree of Master of Agricultural Science in seed technology at Massey University
    (Massey University, 1989) Wang, Yan Rong
    Significant differences in seed vigour within lots of red clover cv. Pawera, white clover cv. Huia and lucerne cv. Wairau were recorded in a preliminary experiment. Subsequently, 7 high viability Pawera seed lots were used to explore the relationship between seed vigour, as measured in the laboratory, and seed performance, both in the field and in storage. Four vigour testing techniques i.e. conductivity, accelerated aging (AA), controlled deterioration (CD) and speed of germination were employed. Results for standard germination (SG) and each of the vigour tests were related to seed performance by correlation analysis. Field performance was monitored for 6 seed lots, sown at 8 dates through spring and autumn. Seed storability was determined by measuring the viability of 4 seed lots under 5 storage conditions (including ambient open storage and simulated temperate controlled storage: 20°C, 45% to 90% RH) over a total of 11 months. The effects of mechanical damage, thousand seed weight, imbibition rate and storage fungi on seed viability and vigour were also investigated and seed quality changes during storage were monitored. The vigour rankings found in the laboratory were consistent with those for field emergence, emergence rate over the 8 sowings and performance during storage. Low vigour lots also showed a significant reduction in seedling dry weight for the autumn sowings when soil temperatures were very low. Each of the four vigour techniques were able to provide more accurate parameters for predicting seed performances than the SG test. For predicting seed field emergence over all the sowings, the best result was provided by the CD test at either 16% or 18% seed moisture content (r = 0.933 and 0.911 resp.), followed by AA (2-day AA of surface sterilized seed) (r = 0.840) and conductivity (r = -0.602). For predicting seed storability, the best result was obtained from the CD test (at either 18% or 20% seed moisture content) for ambient storage conditions, and from both CD (either 18% or 20% seed moisture content) and AA (3-day aging) under controlled storage conditions. Correlation coefficients for vigour tests and storage performance tended to vary between storage periods. Seeds which imbibed water rapidly (within 4h) were low in viability and vigour, but this was generally related to the extent of mechanical damage to the seed coat. Seed weight was not related to seed vigour. Seed deterioration during storage was associated with increasing conductivity, abnormal seedlings and dead seed content, and decreasing germination rate, normal seedlings, and field emergence. Vigour was lost before viability. The deterioration rate was quicker at high RH (75 and 90% RH), since the seeds were quickly invaded by storage fungi. The present experimental results strongly suggest that standard germination was a poor predictor of seed performance, both in the field and during storage. Both accelerated aging and controlled deterioration seem promising techniques for determining vigour of red clover seed lots. The further development of these vigour tests is discussed.
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    Effect of herb-clover mixes on weaned lamb growth : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palerston North, New Zealand
    (Massey University, 2014) Somasiri, Sharini Carol
    The quality and production of ryegrass (Lolium perenne L.) /white clover (Trifolium repens) pastures are seasonal in New Zealand. Earlier research showed that a sward mix of plantain (Plantago lanceolata), chicory (Cichorium intybus L.), white- and red-clover (Trifolium pratense) resulted in greater lamb live weight gains in the late summer early autumn period. However, this has not been tested across all the seasons in New Zealand. Therefore, research was undertaken for two consecutive years (2011/2012 and 2012/2013) on three sward mixes; Pasture mix, Plantain mix and Chicory mix in early spring, late spring and early summer (late spring), summer and autumn. The Pasture mix consisted of perennial ryegrass and white clover. The Plantain mix consisted of plantain, white- and red-clover. The Chicory mix consisted of plantain, chicory, white- and red-clover. It was hypothesised that lamb performance (live weight, live weight gain (LWG) and carcass weight) and apparent carcass weight production per ha would be greatest in the Plantain and Chicory mixes in all four periods. Secondly it was hypothesised that Plantain and Chicory mixes would have lower feed conversion ratios (FCR) with higher herbage utilization efficiencies (EHU%) than the Pasture mix. In each period weaned lambs were reared in the three herbage treatments for a maximum of two months. Lambs were weighed fortnightly and they were slaughtered within 12 hours of being off the pasture at the end of the experiment. Carcass weights were obtained from the abattoir. The Plantain and Chicory mixes had a higher feeding value than the Pasture mix during early spring to autumn. Both Plantain and Chicory mixes produced heavier (P<0.05) lambs, higher (P<0.05) live weight gains (LWG) and carcass weights compared to the Pasture mix in all periods. Total apparent carcass weight production per ha were 407, 748 and 709 kg/ha in year one and 474, 607 and 642 kg/ha in year two in the Pasture mix, Plantain mix and Chicory mix, respectively. Both Plantain and Chicory mixes had lower (P<0.05) feed conversion ratios (FCR) and higher (P<0.05) herbage utilization efficiencies (EHU%) compared to the Pasture mix. This research has shown that sheep farmers in New Zealand can finish lambs at a faster rate for heavier carcasses using herb-clover mixes from spring to autumn than on ryegrass/white clover pastures.
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    Quantitative genetics of prostrateness and other related attributes in red clover (Trifolium pratense L.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Breeding and Genetics, Department of Plant Genetics, Massey University, New Zealand
    (Massey University, 1993) Mirzaie-Nodoushan, Hossein
    Three major experiments were conducted to investigate quantitative genetic aspects of prostrateness and related attributes in red clover (Trifolium pratense L.) during the years 1991-1993. These were done on several red clover genotypes with prostrate growth habit, nodal rooting ability, and early flowering characteristics, together with several other genotypes from semierect and erect types. Three types of experiments were carried out: 1)Since genotype environment interaction is believed to be ubiquitous in affecting the performance of plants, a series of experiments were carried out in order to get general information on a range of red clover germplasm representative of the three distinct types of red clover. Twelve genotypes (four per type) were studied in a randomized complete block design with three replications at two sites for two successive years. Several techniques of univariate and multivariate analysis were applied in order to quantify and qualify the magnitude and pattern of the possible genotype-environment interaction effects. Phenotypic and genotypic correlation values were estimated for each year and type separately as well as for the whole data set in genotype-environment interaction experiment. As a result of GE interaction analysis, a large amount of genetic variation was found in the genotypes examined. Several attributes presented significant first and second order interaction effects. Multivariate discriminant analysis based on these effects revealed discriminant scores by which the contribution and importance of each attribute in the response of genotypes examined in the environments was studied. Cluster analysis revealed that each of the three red clover types have their own particular responses to the environment effect. Phenotypic and genotypic correlation patterns were different from year to year and type to type. Prostrate growth habit reduced dry matter yield through significant negative correlation with yield components. 2) One accession from each of the two extreme types, erect and prostrate, were examined using a hierarchical mating design to investigate their genetic structure and to obtain more detailed genetic information on a narrower germplasm. Nine random plants from each type were cloned and used as male parent. Each male parent was crossed to six different random plants as female parents, three from the same population and three from opposite population. In other words four sets of crosses, two intra- and two inter-population sets, were made. To evaluate the 108 progeny families produced, male groups were divided into six sets, each containing three male groups from the same type. Each set was examined in a randomized complete block design with three replications. Various genetic parameters including genetic variance components and heritability of several morphological attributes were estimated. The two plant populations examined by the mating design, presented different patterns of genetic variation. Although the prostrate population did not have much genetic variation, its additive genetic variance components were of more importance than dominant components. However, in the erect population, dominance components of variance were more important than additive. In inter-population crosses, additive components were more important than dominance components. Stem length, number of internodes, number of branches, and plant diameter presented high level of heterosis. Number of stems, plant height, and stem thickness presented fairly high hybrid depression (negative heterosis). Heritability broad sense and narrow sense were estimated in genotype-environment interaction experiment and hierarchical mating design. Heritability values in GE interaction experiment were different from the heritability broad sense values in hierarchical mating design for most of the attributes, indicating the influence of GE interaction effect. This difference was not noticeable in prostrateness. Heritability narrow sense estimated in hierarchical mating design varied from intra- to inter-population crosses. 3) Three sets of generation mean analysis were carried out to obtain the most detailed genetic information including function of genes, and number of genes controlling the attributes. To achieve these, three pairs of parent plants were used (one erect and one prostrate in each pair) to produce F1, F2, Bc1, and Bc2. Several attributes which were distinct enough in the two types so that it could be assumed that parent populations were nearly homozygous in opposite directions, were studied in these crosses. Three, six, and the best parsimonious models were presented for the studied attributes. Prostrateness and stem thickness were partially to completely dominant over erectness and stem thinness. Small leaf size was over-dominant over large leaf size. There were strong evidences for additive x additive non-allelic interaction for stem thickness, additive x dominance interaction for leaf size, and dominance x dominance interaction for prostrateness and leaf size. Nodal rooting ability, prostrateness, and stem thickness seemed to be controlled by a low number of genes, whereas leaf size seemed to be controlled by several genes.
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    A study of seed development, seed coat structure, and seed longevity in "Grasslands Pawera" red clover (Trifolium pratense L.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, New Zealand
    (Massey University, 1978) Pe, Win
    'Grasslands Pawera' tetraploid red clover is an important agricultural legume through its agronomic roles in soil enrichment by nitrogen fixation and the production of high yields of quality herbage. Since this cultivar was only recently released in New Zealand, many of its agronomic aspects, and particularly those relating to seed production are still not fully understood. The present study was conducted to investigate the pattern of seed development, attainment of seed quality components, time of harvesting, cell structure in the seed coat, hardseededness and related problems, and the longevity and germination characteristics of seeds buried in the soil. Peak flowering date varies with time of sowing and climatic conditions, a sufficiently large number of effective bee pollinators (Bombus species) being essential during the flowering period for successful seed production. The pattern of seed development in 'Pawera' red clover is similar to that of its diploid counterparts and may be divided into three distinct stages. The first stage lasts for 10 days after pollination. The second stage occupies a period of 16 days, and the third stage takes a further 10-14 days. Seed dry weight is maximal 26 days after pollination (physiological maturity). Maximum seed viability is attained 22 to 26 days after pollination. Therefore if seed is harvested during the third or ripening stage, seed quality components such as viability, seedling vigour, seed weight, and storage life will not be adversely affected. The correct time of harvesting can be decided by using seed coat colour and seed moisture content as seed maturity indices. Generally the sequences of both embryo and endosperm development in 'Pawera' red clover show close similarity to some other Trifolium species. The processes of cell degeneration and differentiation occur throughout the seed developmental period. Cell structure in the seed coat is also similar to corresponding structures in the testa of other small-seeded legumes. The present investigation highlights the relationship between individual seed coat structures and their respective role in affecting seedcoat permeability and impermeability mechanisms. The results fail to implicate the micropyle or hilum as permeable sites on the seed coat. In originally permeable seeds, water conduction occurs at random sites on the seed coat. However, when a hard seed is softened by mechanical impaction or under natural environmental conditions, the strophiole is the only initial permeable site on the testa. Observations in the present study have clearly implicated the cell structure of the strophiolar region as a unique and most sensitive area of the seed coat. The findings of the present study suggest that the rate of breakdown of hardseededness varies inversely with the depth of seed burial. Seed samples containing mature seeds maintain their viability in the soil longer than immature seeds. The rapid depletion of seed numbers in the soil is mainly due to germination in situ. Certain proportions of the seed population persist in the soil for extended periods due to the influence of different types of dormancy mechanisms. Of these, enforced dormancy plays a most important role in maintaining the viability of buried seeds, especially with increased burial depth. 'Pawera' red clover seeds show a distinct periodicity of germination at different times of the year. This is an effective genetically controlled and environmentally modified seed survival mechanism.
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    Effects of root-invading fungi on the growth of red clover (Trifolium pratense L.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Pathology at Massey University
    (Massey University, 1989) Nan, Zhi Biao
    Methods to monitor invasion of red clover roots by soilborne fungi, and assess effects on clover growth and persistence, were developed and tested using soil from a plant breeder's red clover evaluation block at DSIR Grasslands Division, Palmerston North, which was known to contain several fungal species pathogenic to red clover. A quantitative method employing tissue maceration and plating was used to determine the internal microflora of red clover roots from the evaluation block. Effects of environmental factors, and of application of fungicide drenches to the soil, on root invasion under controlled environment and field conditions were also studied using the root maceration method. Fungi isolated from roots of red clover from the evaluation block were tested for their effects on establishment, growth, and persistence of red clover in the glasshouse and in field microplots. Light microscopy and transmission electron microscopy were used to study invasion of red clover roots by Trichocladium basicola, and the effects of the fungicides benomyl and prochloraz on this fungus in vitro and in vivo. The root maceration method detected a similar range of fungi to that found by plating 1 - 2 mm long segments, but yielded more colonies and showed less variation. Using standardised amounts of tissue and blending times (2 g and 60 or 120 sec.) differences in fungal populations in roots subjected to different treatments were readily detected. Verticillium dahliae, Trichocladium basicola, and Cylindrocladium scoparium were the major components of the root-invading mycoflora of red clover in the evaluation block, which consisted of 40 fungal species. Other major invaders were Fusarium solani, F. oxysporum, Cylindrocarpon destructans, and Gliocladium roseum, which are the fungi most commonly isolated from roots of red clover and other forage legumes worldwide. Fungal invasion of red clover roots was affected by plant age, soil temperature and moisture. Generally, numbers of fungal colonies isolated progressively increased from the seedling stage onwards and more colonies were isolated from roots of plants grown at 20 and 25°C than at 10 and 15°C, and from 60 and 80% WHC than at 40% WHC. Prochloraz was the most suitable of 11 fungicides tested for use as a soil drench to study effects of root-invading fungi on red clover growth in the field. It showed a broad spectrum of antifungal activity, controlled the major root-invading fungi encountered in the experimental soil, was not toxic to Rhizobium trifolii, and was least retardant to red clover growth. The numbers of fungal colonies recovered per gram of roots was 60 - 80% lower from plants from field plots receiving a single application of prochloraz drench at 3.46 g/m2 than from plants from untreated plots. Yields from treated plots harvested 4 times over a period of 45 weeks were 28 - 95% higher than those from untreated plots. The major root-invading fungi isolated from red clover plants grown in the plant breeder's evaluation block, Cy. scoparium, T. basicola, F. solani, and F. oxysporum, reduced survival of red clover plants in field plots and microplots by 20-75%, and dry matter yield by 20-60%, over a periods of 62 and 76 weeks. V. dahliae, C. destructans, and G. roseum, also reduced plant growth in field plots but to a lesser extent. Seedling establishment, and nitrogen fixation and nodulation, were affected adversely by some fungal isolates. T. basicola was found to penetrate roots of red clover directly and colonise tissue by means of "beaded hyphae" (intracellular hyphae which were constricted at their septa) then "straight hyphae" (unconstricted hyphae growing parallel to the root axis). The fungus is hemibiotrophic. Invaded host cells in the epidermis and cortex of the root are apparently unaffected at first then degenerate and die. Papillae are often found at sites of penetration through cell walls but these rarely obstruct fungal development. Pre-treatment of seedlings with benomyl or prochloraz reduced fungal penetration and growth within tissues. Changes in fungal ultrastructure resulting from benomyl treatment were an increased frequency of lomasome production and occasionally a disorganisation of cell contents. Changes resulting from prochloraz treatment included thickening and fragmentation of cell walls, and necrosis of hyphal cells.
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    Formononetin content in selected red clover strains and its effects on reproduction in ewes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University
    (Massey University, 1994) Anwar, Muhammad
    A series of trials were conducted to investigate the oestrogenicity of a low formononetin selection of red clover, 'G27', as compared to the original Pawera red clover. Formononetin concentration was measured in the plants at various stages of their growth. In ewes which grazed Pawera, G27, or Ryegrass-white clover (Control) pastures, comparisons were made of the incidence of ovulation, ovulation rate, and fertility. As the individual isoflavone level for any one strain may vary with growth stage, a study was conducted to characterize formononetin concentration in various components of G27 red clover and Pawera red clover during different stages of plant growth under field conditions. Mean formononetin concentration (percent dry weight) of leaflets and petioles was lower for G27 than for Pawera (P<0.05) at various stages of vegetative leaf development. G27 leaflet concentrations (0.29 ± 0.02) changed little during development compared to Pawera leaflets which declined from 2.16 ± 0.10 in the youngest leaflets to 0.75 ± 0.08 by the end of vegetative leaf development. Formononetin concentration in G27 leaves (leaflet + petiole) at the pre-flowering stage was 0.35% compared to 0.97% in Pawera leaves (P<0.05). At early and late-flowering stages, the formononetin concentration in G27 red clover, on a whole plant basis, was 50% of that in Pawera red clover because the formononetin concentration in petioles and stem of G27 did not decline to the same extent as that in the leaflets. When calculated only for the upper parts of the plant, which are usually ingested by sheep, G27 and Pawera red clover contained 0.27% and 0.99% formononetin, respectively, at the early-flowering stage, and 0.19% and 0.53% formononetin, respectively, at the late-flowering stage. In ewes grazed on various red clover and Control pastures, the main effects studied were ovulation rate and fertility. An investigation was made of the development and the number of follicles in the ovaries and plasma FSH concentrations in ewes grazing either G27 red clover, Pawera red clover, or Control pasture, close to oestrus. A prostaglandin F2α (PGF) injection was used on day 13 of a synchronized cycle to enhance the synchrony of oestrus in ewes. Mean level of blood equol, which is the main oestrogenic metabolite of formononetin in ewes, was significantly lower on G27 red clover (1.81 ± 0.28 μg/ml) than on Pawera red clover (7.25 ± 1.70 μg/ml) (P<0.01). Total number of ovarian surface follicles in Pawera ewes (9.40 ± 1.13) was lower than that in G27 (15.36 ± 1.87) or Control ewes (16.18 ± 2.32) 24 h after PGF injection (P<0.05). Histological examination of the left ovaries conducted 72 h after PGF injection showed that the number of healthy follicles with diameter (D) 1mm4mm) in Pawera ewes but not in any of the ewes in the other two treatments. No differences were observed in the mean plasma FSH concentrations between ewes from the three treatments at various sampling times. Two trials were conducted to compare sperm transport in ewes mated after grazing on Pawera red clover, G27 red clover, or Control pastures. In the first experiment 84 ewes were inseminated each with 500 million spermatozoa at oestrus, after grazing for two oestrous cycles. Mean numbers of spermatozoa in the cranial part of the cervix were not different between various treatments 2 h after insemination. No spermatozoa were recovered from the Fallopian tubes and uteri of many ewes, but this was considered to be due to technical problems. In a second experiment 30 Romney ewes (10 per treatment) were mated to rams after 28 days of grazing either on Pawera red clover, G27 red clover, or Control pastures. The ewes were killed 24 h after service and sperm were recovered from the tract and counted using an improved technique. The number of spermatozoa recovered from different parts of the tract did not differ significantly between treatments, although there was a trend for the low formononetin (G27) ewes to have higher mean sperm numbers than Pawera and Control ewes. In another two trials, ewes (n = 16 per group), that were potential recipients for embryo transfer, grazed on the high oestrogenic red clover (Pawera), low oestrogenic red clover (G27), and Ryegrass-white clover (Control) pastures for 5 weeks around oestrus. In both the trials, the number of ovular ewes and ovulation rate were lower (P<0.05) in Pawera ewes. The ovulation rate in Pawera, G27, and Control ewes in trial 1 was 0.62 ± 0.15, 1.62 ± 0.18 and 1.93 ± 0.27, in trial 2 it was 0.31 ± 0.18, 1.17 ± 0.27 and 1.54 ± 0.14 for the three groups respectively. Following the transfer into suitable recipients of two embryos per ewe, post-mortem examination at 35 days showed a survival rate in Pawera, G27 and Control groups of 50%, 90% and 85% in trial 1, and 50%, 50% and 69% in trial 2. Fertility, and litter size in ewes when fed on the two types of clovers close to the time of mating were studied in another experiment. The treatment groups (n = 25) and grazing lengths prior to mating were: (1) Pawera, 6 weeks; (2) G27, 6 weeks; (3) G27, 12 weeks; (4) G27 / Ryegrass-white clover (Rg-wc), 6 weeks / 6 weeks; (5) Rg-wc (Control 1), 6 weeks, and (6) White clover (Control 2), 6 weeks. Ewes were mated on non-oestrogenic pasture. Ovulation rates in ewes after the first service were not different for all treatment groups (P>0.05). The incidence of returns to service was significantly higher in Pawera ewes (72.7%) than in any of the other groups (P<0.01). The return rates for the other groups were 33.3% (G27/6 weeks), 25.0% (G27/12 weeks), 4.8% (G27/Rg-wc), 9.5% (Rg-wc) and 14.3% (white clover). Most ewes which were mated at the next two cycles became pregnant. The litter size was not significantly different between various treatment groups after 3 cycles of matings. It is concluded that G27 red clover has significantly lower formononetin concentrations than Pawera red clover at different stages of plant growth and development. Follicle growth and ovulation rate in ewes on G27 red clover were not different from those in ewes on non-oestrogenic pasture, and were better than those in ewes on Pawera red clover. The performance of ewes after grazing the low formononetin, G27, red clover was better than that of the ewes that grazed the high formononetin Pawera red clover, because of fewer returns to service and thus earlier mean lambing date. Sperm transport in the reproductive tract, and embryo survival in ewes after transfer of fertilized eggs were also not different in G27 and Control ewes. The study showed that the oestrogenicity of G27 red clover was significantly reduced compared to that of Pawera red clover from which the selection was made.
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    Quantitative genetics of sheep preference in red clover (Trifolium pratense L.) under spaced plant and sward conditions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph.D.) in Pasture Breeding, Department of Plant Science, Massey University, Palmerston North, New Zealand
    (Massey University, 1997) Real-Ferreiro, Daniel
    Nine populations of diploid Red clover (Trifolium pratense L.) (Erect: Turkish, Hamua and Quiñiquelli; Semi-erect: Colenso, Kenland and E116; Prostrate: F.2419, Astred and Turoa) representing material from the main temperate regions of the world were used in experiments conducted at Massey University (New Zealand) and INIA-La Estanzuela (Uruguay). Population seedlings were sampled under glasshouse conditions (one at each site) to raise representative samples for cloning for two field studies. Principal components were used to ensure representativeness of the sample. Field designs and statistical models were developed specifically to meet the requirements for genotype evaluation under grazing conditions, and to estimate genotypic parameters of plant characteristics influencing selective grazing behaviour. A preliminary grazing management experiment was conducted at Massey University with spaced plants (9 populations x 80 plants), where four stocking densities (2, 3, 5 and 9 sheep/18m2 for one hour) at two times of grazing (morning or evening) were imposed on the nursery, in order to determine optimum measurement of sheep grazing preference. It was found that the preferred grazing management was to graze until an average of 40% leaf remained in the residual plant material (equivalent to a stocking density of 5 sheep/18m2) for one hour, at either morning or evening. This achieved a 94% sampling intensity. This regime was used subsequently in the further three grazing experiments. Two spaced-planted experiments (one at each site) were conducted in three blocks of 324 plants each (9 populations x 12 genets x 3 ramets) which were completely randomised in a 0.75m grid in each block, using the optimum grazing management. Pre-grazing plant measurements were taken on some characters (habit, leaf size, flowering and density); while pre- and post-grazing measures were taken on others (height, spread and leafiness). Subsequently to the experimental defoliation, all plants were defoliated to a uniform 20% leaf residual, by mob stocking. The statistical design was a diffuse randomised complete block with plants nested inside populations at the whole plot level, with a split-plot in time and pooled across sites. The results demonstrated that grazing animals were grazing selectively, rather than grazing at random: the four most grazed populations were Quiñiquelli, E116, Kenland and Turoa and the least grazed were Astred and Turkish. The preferred populations had the highest levels of crude protein and digestibility, and the least grazed populations had the lowest values. Post-grazing leafiness was considered the most suitable morphological character to determine grazing preference because it was highly significant in the analyses of variance for the Population and Plant effects, and demonstrated heritability values > 0.2, allowing modest genetic progress. A sward experiment was conducted at INIA-La Estanzuela with a subset of six populations sown in three blocks, each with three internal replicates of 12.25 m2 each and four internal sub-samples. The same random principle was applied to give a random offer to the grazing animals, but at a plot level. The efficacy of selecting for swards in spaced plant nurseries was examined through the ratio of the correlated genetic advance in swards of selecting under spaced conditions to the direct genetic advance of selecting in sward conditions. Plant density, post-grazing leafiness, difference between pre- and post-grazing leafiness, and index of intake achieved greater genetic advance when selection was done as spaced plants: while for pre- and post-grazing height the opposite result was found. For all other characters, the best conditions to select in depended on the selection intensity achievable. It is concluded that the breeding of Red clover to improve its grazing preference should not be based on simple morphological characters. Rather, it should be based on a measurement of forage removal such as post-grazing leafiness, and under spaced plant conditions, even considering that the final use is under sward conditions.
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    Evaluation of vegetatively reproductive red clovers (Trifolium pratense L.) for use in pastoral systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, New Zealand
    (Massey University, 1999) Hyslop, Mark Graham
    The persistency of red clover (Trifolium pratense L.) can be poor when grazed in mixed and pure stands, but it is still regarded as a valuable source of high quality summer feed in some farming systems. Vegetatively reproductive red clover selections offer promise to solve this persistency problem. The objectives of this research were to study the growth, perennation, reproductive ability and productivity of vegetatively reproductive red clover selections. A series of nine spaced plant and mixed and pure sward experiments were conducted at Hastings, Dannevirke, AgResearch Grasslands and Massey University, Palmerston North, New Zealand (latitude 40°23'S) from 1995 to 1998. The vegetatively reproductive red clovers evaluated were cv. Astred, F2419 and cv. Gualdo with Grasslands Pawera and Turoa used as controls. Preliminary investigations into the incidence of rooted plantlet production by prostrate red clover selections under grazing found 37, 16 and 5 rooted plantlets per parent plant for Astred, F2419 and Turoa, respectively. Astred produced larger rooted plantlets which survived better than F2419 and Turoa. Astred produced 57% of its plantlets on primary stems, or branches off these stems, that grew from the parent plant crown in September, whereas F2419 plantlets developed on a wider spread of stem ages. The majority of plantlets formed on quaternary branches at a range of distances (4cm - 55cm) from the parent plant crown. Astred produced less rooted plantlets per parent plant, had longer, wider leaves, thicker stems and was taller at 10 months of age than Gualdo. More rooted plantlets were established per Astred parent plant under wet surface soil conditions than dry conditions (22.2% and 3.7% gravimetric soil surface water content, respectively), but when the dry soil surface was watered, there was a compensatory increase in the number of rooted plantlets. Removal or retention of flowers did not affect rooted plantlet formation. There was no difference in the total herbage accumulated between Astred and Pawera in the first growing season, under 4, 6 and 8 week grazing frequencies, and lax and hard grazing intensities, but Astred produced more (P<0.001) herbage at the first spring grazing. Astred swards had significantly higher percentages of parent plants than Pawera in all treatments after two seasons grazing. Grazing intensity and frequency affected the number of rooted plantlets produced which ranged from 29 to 66 per m2. The recommended grazing management for pure swards of Astred red clover is to graze every 4 to 6 weeks, or when pre grazing height reaches 30cm, whichever is later, with a minimum post grazing residual of 10 cm over the whole grazing season for effective plantlet production. Pawera and Astred had contrasting total percentages of leaf and stem from 20/9/96 to 6/1/97 (P<0.001) with Pawera having thicker stems compared with Astred in all corresponding grazing treatments (P<0.001). The total percentage of regrowth for Astred or Pawera was not significantly different. The persistence of tagged parent plants of Astred and Pawera in the 6 weeks hard grazed treatment was similar until after 2.5 years of age when (P<0.001) more Astred parent plants survived. Grazing intensity and frequency affected the number of all plantlets (plantlets with no roots, aerially rooted or rooted) produced, which ranged from 0 to 11 per m2 for rooted plantlets after each grazing. In mixed swards on three farm trials at Hastings, Dannevirke and Palmerston North, Astred parent plant persistence decreased with increasing grazing pressure, but significantly more parent plants survived than for Pawera. The vegetatively reproductive red clover selections performed at productive levels that could make a significant contribution to New Zealand agriculture as truly perennial, taprooted forage legumes capable of increasing or maintaining their parent plant population over time under grazing.