Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Filters

1990 - 199922020 - 20241

Settings

Subject: search.filters.subject.Medicago sativa

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Genome-Wide Analysis of BBX Gene Family in Three Medicago Species Provides Insights into Expression Patterns under Hormonal and Salt Stresses.
    (MDPI (Basel, Switzerland), 2024-05-26) Wang J; Meng Z; He H; Du P; Dijkwel PP; Shi S; Li H; Xie Q; Igamberdiev AU
    BBX protein is a class of zinc finger transcription factors that have B-box domains at the N-terminus, and some of these proteins contain a CCT domain at the C-terminus. It plays an important role in plant growth, development, and metabolism. However, the expression pattern of BBX genes in alfalfa under hormonal and salt stresses is still unclear. In this study, we identified a total of 125 BBX gene family members by the available Medicago reference genome in diploid alfalfa (Medicago sativa spp. Caerulea), a model plant (M. truncatula), and tetraploid alfalfa (M. sativa), and divided these members into five subfamilies. We found that the conserved motifs of BBXs of the same subfamily reveal similarities. We analyzed the collinearity relationship and duplication mode of these BBX genes and found that the expression pattern of BBX genes is specific in different tissues. Analysis of the available transcriptome data suggests that some members of the BBX gene family are involved in multiple abiotic stress responses, and the highly expressed genes are often clustered together. Furthermore, we identified different expression patterns of some BBX genes under salt, ethylene, salt and ethylene, salicylic acid, and salt and salicylic acid treatments, verified by qRT-PCR, and analyzed the subcellular localization of MsBBX2, MsBBX17, and MsBBX32 using transient expression in tobacco. The results showed that BBX genes were localized in the nucleus. This study systematically analyzed the BBX gene family in Medicago plants, which provides a basis for the study of BBX gene family tolerance to abiotic stresses.
  • Thumbnail Image
    Item
    A study of the germination and establishment of lucerne (Medicago sativa L.) oversown on an uncultivated grass sward : a thesis presented in partial fulfillment of the requirements for the degree of Master of Agricultural Science (M. Agr. Sci.) at Massey University
    (Massey University, 1977) Kusekwa, Martin Lawrence
    In this study on the oversowing of lucerne on an uncultivated sward at Massey, three trials were conducted, two in the field and one box trial under glasshouse conditions during the summer of 1975/76 and the autumn and early winter of 1976. The triars compared the effects of two lengths of ground cover, untreated, suppressed for a longer or shorter period with herbicides and burnt on the early establishment of lucerrne sown as bare or pelleted seed. It was found that small amounts of cover at sowing encouraged lucerne germination under high moisture conditions subsequent establishment and early survival was best on the burnt and chemically desiccated, plots. The cover was most useful where it was short (8 cm) and desiccated by long term paraquat or glyphosate treatments. Dense live cover was harmful to lucerne seedlings and smothered them within 5 weeks after sowing. Where recovery of the resident vegetation and weeds was rapid, as on the burnt and short term herbicide plots, lucerne establishnent and survivar was poor and surviviag plants were small and weak. Weed infestation was heavy both on burnt and herbicide treated plots, pointing to the need to introduce an early weed control programme with oversowing. Weeds were found to respond in a similar manner to lucerne to grass competition. In the autumn and early winter tria1s, slug damage was observed and this problem appeared to be of major importance under wet conditions. The effects of slugs were fourd to be most damaging during the first 4-5 weeks after sowing. Metaldehyde slug bait pellets were effective in reducing slug damage if applied at least twice during the establishment period of lucerne. The implications of these findings are reported and discussed with particular reference to the possibilities of oversowing under East African conditions
  • Thumbnail Image
    Item
    An investigation into the mechanisms involved in the depression of ovulation rates in ewes grazing oestrogenic lucerne : a thesis peresented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University
    (Massey University, 1978) McLeod, Bernard Joseph
    The reproductive performance of 123 Romney and Border Leicester x Romney ewes was compared after they grazed oestrogenic lucerne or non-oestrogenic ryegrass/clover pasture. To synchronize oestrus prior to the experimental treatment, progestagen-impregnated intravaginal sponges were inserted in all ewes for 14 days. In Experiment I, which involved 42 Romney and Border Leicester x Romney ewes, the animals grazed treatment pastures for one complete oestrous cycle. Blood samples were taken at intervals throughout the cycle and luteinizing hormone concentrations were determined. Ovulation rates and the numbers of follicles present on the surface of the ovaries were recorded at laparotomy, three days post-oestrus. In Experiment II, which involved 81 Romney ewes, oestrogenic lucerne or non-oestrogenic ryegrass/clover pasture was grazed for a complete oestrous cycle, or treatments were interchanged in mid-cycle. All ewes were slaughtered three days post-oestrus and their reproductive tracts were recovered and individually identified. Ovulation rates and the numbers of follicles on the surface of the ovaries were recorded. After sectioning the ovaries, all follicles of a diameter greater than 2.0mm were recorded. Sections of tissue from the vagina, cervix, uterus and fallopian tubes of each ewe were mounted, stained with haematoxylin and eosin, and the height of their epithelial cells measured. The ingestion of oestrogenic lucerne for one complete oestrous cycle depressed ovulation rates by 29 percent (0.67 ovulations per ewe) in Experiment I and by 22 percent (0.40 ovulations per ewe) in Experiment II. The ingestion of oestrogenic lucerne for part of the oestrous cycle, depressed ovulation rates only if it was consumed for the latter half of the cycle. Oestrogenic lucerne did not significantly influence the secretion of luteinizing hormone over the pre-ovulatory period, or at any other stage of the oestrous cycle. There were no significant differences in the total numbers of ovarian follicles present, in the numbers of follicles on the surface of the ovaries, or in the numbers of large follicles (with a diameter of greater than 3.5mm) present, between the treatment groups. The ingestion of oestrogenic lucerne did not increase significantly, the height of epithelial cells in genital tract tissue, when compared with that in ewes grazing non-oestrogenic ryegrass/clover pasture. Similarly, there was no significant difference in uterine weights. This is in contrast to published data where lucerne is fed to speyed ewes.
  • Thumbnail Image
    Item
    The effect of water stress on water relations, carbon isotype discrimination, and shoot and root growth of sainfoin (Onobrychis viciifolia Scop.) and lucerne (Medicago sativa L.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Department of Plant Science at Massey University
    (Massey University, 1994) Mir-Hosseini-Dehabadi, Seyed Reza
    Sainfoin (Onobrychis viciifolia Scop.) is a useful forage legume regarded as having drought resistant attributes. Also, it does not cause bloat in ruminants and is not sensitive to alfalfa weevil (Hypera postica. L). Although the physiological and morphological responses to water stress of lucerne (Medicago sativa L.) are well known the responses of sainfoin to water stress have not been fully studied. In this study the physiological and morphological responses of sainfoin to water stress were investigated, with lucerne used as a reference plant. The results of the indoor and outdoor studies showed sainfoin had useful characteristics for forage production in dry conditions. Relative to lucerne it had a lower yield, due to lower leaf area, lower stem number and poor regrowth. However, sainfoin responded to water stress at least as well as lucerne. Sainfoin had a higher root:shoot ratio and a lower specific leaf area ratio than lucerne, indicating a higher allocation of carbohydrate to the roots, and a lower leaf surface area for transpiration in sainfoin than for lucerne. Water stress decreased the yield of lucerne proportionally more than sainfoin mostly due to the greater reduction in the above ground dry weight of lucerne. The indoor study of root characteristics of sainfoin and lucerne in 1m tall tubes showed that in terms of root development sainfoin responded to water stress better than lucerne. Although sainfoin had equal root mass and root length to lucerne, the root distribution of sainfoin at below 0.6 m depths was greater than for lucerne. As water stress developed sainfoin roots grew below 0.6 m earlier than lucerne roots. Sainfoin had a higher root osmotic adjustment than lucerne and also maintained higher (less negative) leaf water potential than lucerne. The stomatal resistances (Rs) of sainfoin and lucerne were equal, but Rs was not distributed equally between adaxial and abaxial leaf surfaces. The Rs of the adaxial leaf surface of sainfoin was lower and more sensitive to water stress than the Rs of the abaxial leaf surface. The different Rs of the adaxial and abaxial leaf surfaces of sainfoin was partly due to the different stomatal frequencies of the respective surfaces. Comparison of sainfoin cultivars in a climate room showed that the water use efficiencies (WUE) of Remont, Fakir, Cotswold-Common, and Eski, were similar. Remont was more sensitive to water stress than the other three cultivars, and Eski produced a greater root length and mass than other cultivars. The growth of Eski was initially slower than that of the Remont in both the indoor and the outdoor studies. However, lucerne grew faster than all the sainfoin cultivars. Over three harvests in the field the yields of Eski and Remont were similar but lucerne out yielded both sainfoin cultivars. Sainfoin produced a greater proportion of its yield earlier than lucerne, whereas lucerne distributed its yield throughout the whole season, indicating that sainfoin is adapted to regions with precipitation in only winter and spring. The results of the carbon isotope discrimination (Δ) analysis for the indoor and outdoor studies showed Δ had a negative correlation with WUE, leaf water potential, osmotic potential, and stomatal resistance, but had a positive correlation with relative water content, turgor potential, transpiration rate, and photosynthetic rate. These correlations demonstrated the usefulness of this technique for evaluating the responses of plants to water stress. The stressed plants always had lower Δ than the control plants showing the higher WUE of stressed plants. The Δ of roots was higher than the Δ of the leaves suggesting that the growth of leaves occurred in conditions that were an average drier than for the growth of roots. This was supported by the lower (more negative) water potential of leaves than roots. The Δ of the roots below 0.6 m depth was higher than the Δ of roots above 0.1 m depth suggesting the roots above 0.1m grew under higher water stress than the roots below 0.6m depth. Over three harvests in the field the Δ of Eski and lucerne were similar and the Δ of Remont was higher than for Eski and lucerne. In conclusion, sainfoin was found to have several useful attributes for growth and survival in dry regions. Of the sainfoin cultivars examined Eski was the best adapted to water stress. Relative to lucerne, sainfoin yielded less, but had a similar water use efficiency, a shorter season of growth, a greater root: shoot ratio, deeper roots and better maintenance of leaf water potential under water stress.
  • Thumbnail Image
    Item
    Seed production studies in lucerne (Medicago sativa L.) cv. Grasslands Oranga : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science (Seed Technology) at Massey University, New Zealand
    (Massey University, 1993) Askarian, Mohsen
    Two years of field trials with lucerne (Medicago sativa L.), cv. Grasslands Oranga, were used to determine plant vegetative and reproductive responses to the effects of row spacing and sowing rate, application of two plant growth regulating chemicals, and weed control. For an autumn (March 15) sowing, seedling number per metre of row increased as sowing rate (1 to 12 kg/ha) and row spacing (15 to 60 cm) increased. However the number of seedlings was not directly proportional to the number of seeds sown, and percentage establishment six months after sowing was highest (73%) at the lowest sowing rate of 1 kg/ha. Overall mean establishment for all treatments was 57, 46, and 34% for 1, 6, and 18 months after sowing respectively. Dry matter production at 6 months after sowing was greatest at the 15 and 30 cm row spacings and 12 kg/ha sowing rate, but there were no significant differences in dry matter among treatments at later assessments. In the first year seed yield from the 15 cm row spacing was significantly lower than from the 30, 45 and 60 cm row spacings, while sowing rate had no effect on seed yield. In the second year, row spacings did not significantly affect seed yield, but the seed yield from the 1.0 kg sowing rate was significantly increased because harvestable racemes/m2 and thousand seed weight were significantly increased. Seed yield over the two years of the experiment was highest at the 1 kg/ha sowing rate and for the 30 and 45 cm row spacings. The average seed yield for all treatments was 127.2 and 186.9 kg/ha for the first and second year respectively. Neither row spacing nor sowing rate had any effect on the quality of harvested seed. There were no interactions between row spacing and sowing rate for plant establishment, dry matter production, or seed production. In the 1991/1992 season, the effect of two plant growth regulators, paclobutrazol at 1.0 kg a.i/ha (applied on 1 November or 1 December), and cycocel at 3.0 kg a.i/ha (applied on 1 December, 23 December, 1991 or 1 January 1992), on vegetative and reproductive growth was examined. Paclobutrazol applied during active vegetative growth (1 November) significantly altered vegetative shoot development by inhibiting apical dominance, thus inducing lateral branches which subsequently increased reproductive sites, and increased seed yield by 37%. This seed yield increase was due to an increased number of racemes/m2 (+36%) and pods per raceme (+72%). Paclobutrazol applied at first flower bud appearance (1 December) had no effect on seed yield or seed yield components because it did not alter shoot production or the number of racemes. Cycocel application did not retard plant height or increase racemes per unit area. However while application on 23 December (at first flowering) had no significant effect on seed yield, cycocel applied in early December (first flower bud appearance) or early January (at peak flowering) significantly decreased seed yield, because of a reduction in the number of flowers/m2 and/or harvestable racemes/m2. In the following season (1992/93), paclobutrazol at 0.5 kg a.i/ha and 1.0 kg a.i/ha was applied during active vegetative growth on 25 October 1992. Both rates significantly reduced plant height by 8 weeks after application, but this effect had disappeared by final harvest. As in the previous year, paclobutrazol at 1.0 kg a.i/ha significantly increased seed yield, but the increase (+153%) was much greater than in the previous year. This increase in seed yield was associated with an increase in the number of harvestable racemes/m2 (+126%), pods per raceme (+36%) and thousand seed weight (+11%). Paclobutrazol at 0.5 kg a.i/ha had no significant effect on seed yield. In 1992/1993 the effect of hand weeding and the application of three herbicides (hexazinone 1.0 kg a.i/ha, simazine 2.25 kg a.i/ha plus paraquat 0.6 kg a.i/ha) on seed yield in a second year crop was investigated. Hand removal of weeds, predominantly white clover but also Poa annua L. and broad leaved species increased seed yield from 0.7 to 21.3 g/m2, mainly because racemes increased from 89 to 1230/m2. Increases in pods per raceme and seeds per pod were also recorded. Hexazinone applied during active vegetative growth in early spring eliminated white clover from lucerne plots and increased seed yield to 14.3 g/m2. However this treatment did not control Rumex obtusifolius L. Simazine plus paraquat applied in winter before active spring growth controlled many annual weeds but, although initially checking white clover, did not control it. As a consequence, seed yield did not differ from that of the untreated control. Although hexazinone effectively removed white clover from a second year lucerne seed crop, it is recommended for use only on mature stands. Harvested lucerne seed viability did not differ among treatments, but hand weeding and herbicide treatments significantly reduced the percentage of hard seed.