Academic literature on the topic 'Fields of Research – 300000 Agricultural, Veterinary and Environmental Sciences – 300200 Crop and Pasture Production'

There is an extensive debate on the potential environmental impact of dairy farms and in particular the effect of dairy farms on the nitrogen cycle and the effect that this has on ecosystems. Within New Zealand and in particular in the South Island, the expansion of dairying and the adoption of new dairy systems has led to this becoming an increasingly important issue, locally through its effect on water quality and the environment and nationally and internationally through the production of green house gases. Increases in nitrogen usage at the expense of clover nitrogen fixation, irrigation, stocking rate and the introduction of dairy cows onto light free draining soils previously the preserve of arable or sheep farming has led to concern as to the effect intensive pastoral dairying may have on the nitrogen dynamics of the farm and the environment. This study is designed to assess how changes in grazing management in particular changes in pre-grazing and post-grazing residuals alter the clover/ryegrass balance on the farm and the effect that this has on the farm’s nitrogen dynamics. The effects of qualitative changes in grazing management on pasture composition are well established but little is known of the effect of quantitative changes in pasture management on composition, in particular the effect of grazing residuals. There are a number of detailed models of the physiological processes in the energy and nutrient cycling in plants, animals and the soil. There are a smaller number of whole farm models that through integration and simplification of component models attempt to represent the flux of nutrients though a dairy farm. None of these whole farm models is currently able to model the nitrogen flux through a dairy farm at a sufficient level of resolution to capture differences in pasture composition as these occur spatially, temporally and in response to grazing management. This project sought to better understand the nitrogen dynamics on a dairy farm by constructing and then linking component models – a pasture composition and growth model, a cow model, an excretal return model, a soil model and a water balance model – within a whole farm management schedule. The formal null hypothesis is that the mechanistic, mathematical model constructed for this PhD cannot capture and explain the full range of the changes in soil water content, soil nitrogen status, pasture production and composition and animal production, following the alteration in management of the dairy farm between 2002 and 2004. Individual component models were constructed by the author using the computer software package (Matlab) and validated against data extracted from the literature. The models were then converted into one simulation package using C-sharp as the source code language by Elizabeth Post, Senior Computer Scientist at Lincoln Ventures Ltd, Lincoln, New Zealand and the author. This model was then used to investigate the nitrogen dynamics of a dairy farm: the relationship with pasture composition and whether small changes in pasture residuals make a difference to pasture composition and nitrogen dynamics. Two different simulations were run based on the management practice of Lincoln University Dairy farm (LUDF) over two dairy seasons (2002-03 and 2003-04) and validated against the data recorded on this farm. In 2002-03, 50 cows were over wintered and 580 cows were subsequently milked on 200ha. Post grazing residuals where maintained at 1600-1750KgDM/ha. In 2003-04, 125 cows were overwintered and 635 cows were milked on 200ha with post grazing residuals maintained at 1400KgDm/ha. All models operate on a daily time step. Within the pasture model composition is described by 9 state variables describing different components of the pasture and pasture growth is modelled mechanistically from a calculation of component photosynthesis. A further 9 state variables describe the nitrogen composition of the pasture components. The soil model is a variable two layer, mechanistic representation, parametised for the shallow, stony soils of LUDF. Soil water status is an input for the pasture model while water uptake by the growing plants affects the soil water balance within the soil model. Animal intake and production are modelled mechanistically with model cows described in terms of their age, genetic merit, body weight, breed, pregnancy status, conception date and body condition score. Each cow type produces a different quantity of urinary and faecal excretion which varies with dry matter intake, milk yield and the sodium and potassium status of the pasture. Excretal nitrogen composition is predicted within a separate model which calculates daily nitrogen excretion in faeces, urine and milk. Excretions are deposited randomly over the grazed area and account is taken of overlapping excretions that are created on the same day and overlaps that occur with older excretal patches deposited in previous grazing rounds. Each excretal patch has its own associated pasture, water and soil model reflecting the differences in nitrogen status between patches. Grazing preference is expressed within the model between different classes of excretal patch and between excretal patches and the base pasture and between clover and grass. Supplementary silage is conserved and fed according to the management schedule of LUDF. Cows calve, become pregnant and are dried off within the model according to the relevant records from LUDF. Cows are deemed to arrive on the farm on the day of calving and to leave on the day that drying off is finished (a 5 day procedure within the model), except for those cows that are overwintering which remain on the farm. The soil model has multiple nitrogen/carbon pools and is dynamically linked to all the other models. External nitrogen losses from the system are modelled as volatilisation, leaching and denitrification, with pasture nitrogen uptake from the soil model and fixation by clover from the atmosphere. Both the individual component models and the final assembled composite model were successful in matching the available data in terms of pasture and animal production, pasture composition, soil water balance and nitrogen status and external losses. The model indicates that the low residual, high stocking rate farm returns more excreta to the soil. However, this is countered by a reduction in the amount of dead material returned to the paddock and this reduces the relative size of the pool of nitrogen in the dead organic matter. This produces a relative lack of substrate for the soil microbes which are thus unable to exploit all of the nitrogen in the available pool. Soil ammonium and nitrate pools are also increased from the increase in faecal and urinary return so precipitating an immobilising flux from these larger pools to the smaller pool of nitrogen available to the soil microbes. However, the relative inability of the soil bacteria to fully exploit this means that the production of soil organic live matter and the resulting mineralising flux from the dead organic matter pool through the available pool to the ammonium and nitrate pools is reduced. The larger ammonium and nitrate pools will also be associated with increased external losses from the system as denitrification, leaching and volatilisation are increased. The increase in the clover percentage within the sward in 2003-04 led to greater nitrogen fixation and the model suggests that some of the extra nitrogen is effectively captured by the animals in increased production. However, the reduction in the return of dead matter coupled with an increase in excretal return and the consequent increase in the mineral nitrogen pools within the soil lead to greater losses of nitrogen from the soil.

Variables for the accelerated ageing (AA) test, methods for reducing fungal contamination during the AA test, using the conductivity test as a vigour test, the effect of seed size on seed vigour and the relationship between laboratory test results and field perfonnance in selected Brassica spp were investigated. In the first experiment, three seed lots of turnip rape hybrid (B. rapa x campestris), turnip (B. campestris) and forage rape (B. napus); and seven seed lots of Asian rape (B. napus), six seed lots of Asian kale (B. oleraceae var. alboglabra L.) and five seed lots of choisum (B. rapa var. pekinensis) with germinations above 90% were aged at two different temperatures (41 and 42°C ± 0.3°C) and three ageing times (24, 48 and 72 ± 15 minutes). The second experiment was divided into three sections. In the first, the same seed lots and species were aged at one temperature (41°C) and time (72 h), but either 40 ml of saturated salts; KCl (83%RH), NaCl (76%RH), NaBr (55%RH); or distilled water (96%RH) were used as the ageing solutions. In the second, one turnip rape hyprid seed lot was aged at three temperatures (41, 42 and 45°C) and two times (72 and 96h), again using the three saturated salts and distilled water as ageing solutions. In the third, three turnip rape hybrid seed lots and three Asian kale seed lots were surface sterilised (1 % sodium hypochlorite) prior to ageing at one temperature (41°C) and time (72 h). In the third experiment, the same species and seed lots used in experiment one at their original seed moisture content (SMC) were tested for conductivity after soaking in deionised water for 4, 8, 12, 16, 20 and 24 h. They were then re-tested after the SMC had been adjusted to 8.5%. In the fourth experiment, three seed lots of forage rape and three seed lots of Asian kale were graded into three seed size categories; large (retained on a 2.0 mm screen), medium (retained on a 1.7 mm screen) and small (passed through a 1.7 mm screen). Graded seeds were then tested for standard germination, AA (41°C/48 h) and conductivity (measured at 16 and 24 h). In the final experiment, the relationships between laboratory tests for the six species (each consisting of three seed lots), field emergence from three sowings, and cold room emergence were evaluated. Both time and temperature influenced post-AA germination. Increasing the ageing period from 48 to 72 hours at 41°C, and 24 to 48 hours at 42°C resulted in decreased mean germination percentage for all species but not always clear separation of seed lots. While there were sometimes few differences between ageing at 41°C and 42°C, the former is preferred because it is already the temperature used for other species. For Asian rape, choisum and turnip, the previously recommended testing conditions of 41°C/72 h provided good seed lot separation, but for Asian kale and turnip rape hybrid, AA testing at 41°C/48 h provided better results. Seed moisture content after ageing ranged from 29-37% depending on species. Fungal growth on seeds during the ageing period appeared to reduce post-ageing germination in some seed lots . Substituting saturated salts for distilled water did not stress seed lots in the AA test, due to the lowered RH%, the exception being seed lots 1210 and 1296. For forage and Asian species, seed lot germination mostly remained above 90% when aged for 72 h at lowered RH%. Increasing the ageing duration from 72 to 96 hours resulted in some decreases in post-AA germination but no clear separation of seed lots. Surface sterilising the seeds prior to the AA test resulted in a lower incidence of contaminant fungi which was associated with a lower percentage of abnormal seedlings. The conductivity test was mostly able to identify vigour differences among forage and Asian vegetable brassica seed lots. Differences in conductivity readings were observed among seed lots in all species. Increasing the period of imbibition resulted in increased conductivity from most seed lots but radicle emergence occurred after 16-20 h of imbibition. Variation was observed in the time to reach 95% maximum of the imbibition curve for most species. Conductivity readings at 16 h would avoid possible influences of radicle emergence on results. Adjusting the SMC to 8.5% resulted in reduced variation in conductivity among replicates of seed lots, due to a reduction in imbibition damage. Seed size had a significant effect on both post-AA germination and conductivity results. In forage rape, large size seeds had higher post-AA germination cf. medium cf. small size seeds. In Asian kale, large size seeds had higher post-AA germination compared with small size seeds. For both forage rape and Asian kale, large size seeds had lower conductivity readings cf. small size seeds. The correlation analyses demonstrated significant relationships between AA testing and field emergence parameters (percentage emergence, emergence index and emergence rate). Significant relationships were also observed between conductivity testing and these field emergence parameters. Based on the correlation analysis, AA testing at 41°C/48 hand/or 42°C/48 h could be recommended to be used as an AA test for turnip and Asian rape; and 41°C/48 hand/or 41°C/72 h for Asian kale and choisum. Based on the correlation analysis, conductivity testing at 16 h can be used to predict the field emergence potential of forage and Asian vegetable seed lots. Vigour tests were consistently able to provide better indicators of field perfonnance than the standard germination test, although these relationships did vary with the different field sowings.

This study was undertaken to research the principles and practices behind increased pasture productivity on Longslip Station, Omarama. A range of landscape - soil - climate - plant systems were identified, then analysed and the legume responses measured. By isolating cause and effect and appreciating the driving variables of each system, lessons learnt could be reliably and objectively transferred to the rest of the farm. Extrapolation to the balance of the property (15,150 ha) permitted immediate large-scale development and engendered confidence to lending institutions, Lands Department, catchment authorities and ourselves. Soil (land) cannot be well managed and conserved unless it is mapped reliably and its characteristics measured and interpreted by skilled observers (Cutler, 1977). Soil resource surveys, and their interpretation, are an essential ingredient of rational resource evaluation and planning. This thesis is a figurative and comparative survey and study of the soil catenary bodies, resident vegetation, legume establishment and pasture production characteristics of a 400 hectare catchment, in relation to, and as influenced by soil landscape unit, slope component, altitude, aspect and time. The inherent diversity in landform, soil properties and vegetation communities in a single catchment in the high country has not previously been fully studied or appreciated. This has lead to blanket recommendations for fertilizer, seed and management regimes both within and between properties and even regions. This study reports on the diversity of, yet predictable change in soil properties with slope position (upper, middle and lower) aspect and altitude in terms of both soil physical properties e.g. soil depth and water holding capacity and soil chemical properties such as pH, BS%, %P, %S, %N and %C. The composition of the resident vegetation and its differential response to oversowing and topdressing and subsequent change through time is reported and discussed. Finally an epilogue gives an insight into the problems and frustrations of farming practices in the high country from a motivation and personal perspective and political point of view that it is essential to come to terms with.

The general goal of this research was to understand the agronomic and physiological changes of a lucerne crop in distinct physical radiation environments and to verify the potential of lucerne to grow under shaded conditions. To achieve this, the research was conducted in four main steps: (i) firstly, experimental data collection in the field using two artificial shade materials (shade cloth and wooden slats) under inigated and non-irrigated conditions; (ii) a second experiment with data collection in a typical temperate dryland agroforestry area under non-irrigated conditions; (iii) generation of a light interception sub-model suitable for shaded crops and (iv) a linkage between the light interception sub-model and a canopy photosynthesis model for agroforestry use. In experiments 1 and 2, lucerne crop was exposed to 6 different light regimes: full sunlight (FS), shade cloth (FS+CL), wooden slats (FS+SL), trees (T), trees+cloth (T +CL) and trees+slats (T+SL). The FS+SL structure produced a physical radiation environment (radiation transmission, radiation periodicity and spectral composition) that was similar to that observed in the agroforestry site (f). The mean annual photosynthetic photon flux density (PPFD) was 41 % under the FS+CL, 44% under FS+SL and 48% under T compared with FS in clear sky conditions. Plants were exposed to an intermittent (sun/shade) regime under both FS+SL and T, whereas under FS+CL the shaded light regime was continuous. The red to far-red (RIFR) ratio measured during the shade period under the slats was 0.74 and under the trees was 0.64. However, R/FR ratio increased to 1.26 and 1.23 during the illuminated period under FS+SL and T, respectively, and these were equivalent to the ratio of 1.28 observed under the FS+CL and 1.31 in FS. The radiation use efficiency (RUE) of shoots increased under the 5 shaded treatments compared with full sunlight. The pattern of radiation interception was unchanged by radiation flux, periodicity and spectral composition and all treatments had a mean extinction coefficient of 0.82. However, the magnitude of the decrease in canopy growth was less than those in PPFD transmissivity. The mean lucerne annual dry matter (DM) yield was 17.5 t ha⁻¹ in FS and 10 t ha⁻¹ under the FS+CL, FS+SL and T regimes. This declined to 3.4 t DM ha⁻¹ under T+CL (22% PPFD transmissvity) and 4.1 t DM ha⁻¹ under T+SL (23% transmissivity). A similar pattern of response was observed for leaf net photosynthesis (Pn) rates under the shade treatments compared with full sun. In addition, spectral changes observed under the trees and slats affected plant motphology by increasing the number of long stems, stem height and internode length compared with full sunlight. Thus, there were two main explanations for the increase in RUE under shade compared with full sun: (i) preferential partition of assimilates to shoot rather than root growth and/or (ii) leaves under shade were still operating at an efficient part of the photosynthetic light curve. The changes proposed for the canopy Pn model were appropriate to simulate the radiation environment of an agroforestry system. However, the model underestimated DM yields under the continuous and intermittent shade regimes. These were considered to be mainly associated with plant factors, such as overestimation in maintenance respiration and partitioning between shoots and roots in shade and the intermittency light effect on leaf Pn rates. Further investigation in these topics must be addressed to accurately predict crop yield in agroforestry areas. Overall, the lucerne crop responded typically as a sun-adapted plant under shade. It was concluded that lucerne yield potential to grow under intermediate shade was superior to most of C3 pastures previously promoted in the literature.

The contamination of process pea (Pisum sativum L.) crops by the immature fruit of black nightshade (Solanum nigrum L.) and hairy nightshade (S. physalifolium Rusby var. nitidibaccatum (Bitter.) Edmonds) causes income losses to pea farmers in Canterbury, New Zealand. This thesis investigates the questions of whether seed dormancy, germination requirements, plant growth, reproductive phenology, or fruit growth of either nightshade species reveal specific management practices that could reduce the contamination of process peas by the fruit of these two weeds. The seed dormancy status of these weeds indicated that both species are capable of germinating to high levels (> 90%) throughout the pea sowing season when tested at an optimum germination temperature of 20/30 °C (16/8 h). However, light was required at this temperature regime to obtain maximum germination of S. nigrum. The levels of germination in the dark at 20/30 °C and at 5/20 °C, and in light at 5/20 °C, and day to 50 % germination analyses indicated that this species cycled from nondormancy to conditional dormancy throughout the period of investigation (July to December 2002). For S. physalifolium, light was not a germination requirement, and dormancy inhibited germination at 5/20 °C early in the pea sowing season (July and August). However, by October, 100% of the population was non-dormant at this test temperature. Two field trials showed that dark cultivation did not reduce the germination of either species. Growth trials with S. nigrum and S. physalifolium indicated that S. physalifolium, in a non-competitive environment, accumulated dry matter at a faster rate than S. nigrum. However, when the two species were grown with peas there was no difference in dry matter accumulation. Investigation of the flowering phenology and fruit growth of both species showed that S. physalifolium flowered (509 °Cd, base temperature (Tb) 6 °C) approximately 120 °Cd prior to S. nigrum (633 °Cd). The fruit growth rate of S. nigrum (0.62 mm/d) was significantly faster than the growth rate of S. physalifolium (0.36 mm/d). Because of the earlier flowering of S. physalifolium it was estimated that for seedlings of both species emerging on the same date that S. physalifolium could produce a fruit with a maximum diameter of 3 mm ~ 60 °Cd before S. nigrum. Overlaps in flowering between peas and nightshade were examined in four pea cultivars, of varying time to maturity, sown on six dates. Solanum physalifolium had the potential to contaminate more pea crops than S. nigrum. In particular, late sown peas were more prone to nightshade contamination, especially late sowings using mid to long duration pea cultivars (777-839 °Cd, Tb 4.5 °C). This comparison was supported by factory data, which indicated that contamination of crops sown in October and November was more common than in crops sown in August and September. Also, cultivars sown in the later two months had an ~ 100 °Cd greater maturity value than cultivars sown in August and September. Nightshade flowering and pea maturity comparisons indicated that the use of the thermal time values for the flowering of S. nigrum and S. physalifolium can be used to calculate the necessary weed free period required from pea sowing in order to prevent the flowering of these species. The earlier flowering of S. physalifolium indicates that this species is more likely to contaminate pea crops than is S. nigrum. Therefore, extra attention may be required where this species is present in process pea crops. The prevention of the flowering of both species, by the maintenance of the appropriate weed free period following pea sowing or crop emergence, was identified as potentially, the most useful means of reducing nightshade contamination in peas.

The association between individual plant performance and seed yield variability within and between field pea crops was investigated. In 1988/89 six F8 genotypes with morphologically distinct characteristics were selected from a yield evaluation trial. Analysis of the individual plant performance within these crops indicated an association between low seed yields and the location and dispersion of plant harvest index (PHI) and plant weight (PWT) distributions. The analyses also showed there was a strong linear relationship between the seed weight (SWT) and PWT of the individual plants within each crop, and that the smallest plants tended to have the lowest PHI values. A series of 20 simulations was used to formalize the relationships between SWT, PWT and PHI values within a crop into a principal axis model (PAM). The PAM was based on a principal axis which represented the linear relationship between SWT and PWT, and an ellipse which represented the scatter of data points around this line. When the principal axis passed through the origin, the PHI of a plant was independent of its PWT and the mean PHI was equal to the gradient of the axis. However, when the principal axis had a negative intercept then the PHI was dependent on PWT and a MPW was calculated. In 1989/90 four genotypes were sown at five plant populations, ranging from 9 to 400 plants m⁻². Significant seed and biological yield differences were detected among genotypes at 225 and 400 plants m⁻². The plasticity of yield components was highlighted, with significant genotype by environment interactions detected for each yield component. No relationship was found between results for yield components from spaced plants and those found at higher plant populations. The two highest yielding genotypes (CLU and SLU) showed either greater stability or higher genotypic means for PHI than genotypes CVN and SVU. Despite significant skewness and kurtosis in the SWT, PWT, and PHI distributions from the crops in this experiment, the assumptions of the PAM held. The lower seed yield and increased variability in PHI values for genotype CVN were explained by its higher MPW and the positioning of the ellipse closer to the PWT axis intercept than in other genotypes. For genotype SVU, the lower seed yield and mean PHI values were explained by a lower slope for the principal axis. Both low yielding genotypes were originally classified as having vigorous seedling growth and this characteristic may be detrimental to crop yields. A method for selection of field pea genotypes based on the PAM is proposed. This method enables the identification of weak competitors as single plants, which may have an advantage over vigorous plants when grown in a crop situation.

A field experiment was conducted to examine the responses in growth, total dry matter (TDM), seed yield and nitrogen (N) accumulation of Kabuli chickpea cv. Principe and narrow-leafed lupin cv. Fest to different irrigation levels and N fertilizer on a Templeton silt loam soil at Lincoln University, Canterbury, New Zealand in 2007/08. The irrigation and fertilizer treatments were double full irrigation, full irrigation, half irrigation and nil irrigation and a control, full irrigation plus 150 kg N ha⁻¹. There was a 51 % increase in the weighed mean absolute growth rate (WMAGR) by full irrigation over no irrigation. The maximum growth rates (MGR) followed a similar response. The growth rates were not significantly decreased by double irrigation. Further, N fertilizer did not significantly improve crop growth rates. With full irrigation MGRs were 27.6 and 34.1 g m⁻² day⁻¹ for Kabuli chickpea and narrow-leafed lupin, respectively. Seed yields of fully-irrigated crops were trebled over the nil irrigation treatment. With full irrigation, seed yield of chickpea was 326 and that of lupin was 581 g m⁻². Seed yield of the two legumes was reduced by 45 % with double irrigation compared with full irrigation. Nitrogen fertilizer did not increase seed yields in either legume. Increased seed yield with full irrigation was related to increased DM, and crop growth rates, seeds pod⁻¹ and seeds m⁻². Crop harvest index (CHI) was significantly (P < 0.05) increased by irrigation and was related to seed yield only in narrow-leafed lupin. With full irrigation, the crops intercepted more than 95 % of incoming incident radiation at leaf area indices (LAIs), 2.9 and 3 or greater in Kabuli chickpea and narrow-leafed lupin, respectively. In contrast, without irrigation the two legumes achieved a maximum fraction of radiation intercepted of less than 90 %. With full irrigation, total intercepted photosynthetically active radiation (PAR) was increased by 28 % and 33 % over no irrigation for Kabuli chickpea and narrow-leafed lupin, respectively. Fully-irrigated Kabuli chickpea intercepted a total amount of PAR of 807 MJ m⁻² and fully-irrigated narrow-leafed lupin intercepted 1,042 MJ m⁻². Accumulated DM was strongly related to accumulated intercepted PAR (R² ≥ 0.96**). The final RUE was significantly (P < 0.001) increased by irrigation. With full irrigation the final RUE of Kabuli chickpea was 1.49 g DM MJ⁻¹ PAR and that of narrow-leafed lupin was 2.17 g DM MJ⁻¹ PAR. Total N accumulation of Kabuli chickpea was not significantly affected by irrigation level. Kabuli chickpea total N was increased by 90 % by N fertilizer compared to fully-irrigated Kabuli chickpea which produced 17.7 g N m⁻². In contrast, total N accumulated in narrow-leafed lupin was not increased by N fertilizer but was decreased by 75 % with no irrigation and by 25 % with double irrigation (water logging) compared to full irrigation with a total N of 45.9 g m⁻². Total N was highly significantly related to TDM (R² = 0.78** for Kabuli chickpea and R² = 0.99** for narrow-leafed lupin). Nitrogen accumulation efficiency (NAE) of narrow-leafed lupin was not affected by irrigation or by N fertilizer. However, the NAE of Kabuli chickpea ranged from 0.013 (full irrigation) to 0.020 (no irrigation) and 0.017 g N g⁻¹ DM (full irrigation with N fertilizer). The N harvest index (NHI) was not affected by irrigation, N fertilizer or legume species. The NHI of Kabuli chickpea was 0.50 and that of narrow-leafed lupin was 0.51. The NHI was significantly (r ≥ 0.95 **) related to CHI.

Kiwifruit are of huge economic importance for New Zealand representing 29 percent of total horticultural exports. Fruit size is the biggest determinant of what consumers are willing to pay, and there is also a positive relationship between consumer preference for flavour and percentage dry matter. The two main cultivars exported from New Zealand are Actinidia chinensis ‘Hort 16A’ (gold kiwifruit) and A. deliciosa ‘Hayward’ (green kiwifruit). Under current commercial practice the only product allowed for use on kiwifruit to increase fruit size in New Zealand is Benefit®. Benefit® has been shown to induce different results when applied to A. chinensis and A. deliciosa, whereas synthetic plant growth regulators such as the cytokinin-like substance N-(2- chloro-4-pyridyl)-N’-phenylurea (CPPU) have been found to promote similar increases in fresh weight of fruit in both cultivars. Final fruit size is determined by both cell division and cell enlargement. It was been shown that fresh weight can be increased in both of the major Actinidia cultivars even though their physiology differs. Hormonal control of fruit size in relation to cell division and cell enlargement phases of fruit growth was studied in both A. chinensis and A. deliciosa. CPPU was applied to both cultivars in a growth response experiment where fruit were collected throughout the growing season. The objective of this experiment was to create growth curves, to compare and contrast the effect on A. chinensis and A. deliciosa, and to provide material for hormone analysis. Application of CPPU was found to significantly increase the fresh weight of both A. chinensis and A. deliciosa fruit (46.98 and 31.34 g increases respectively), and alter the ratio of inner and outer pericarps of A. chinensis fruit. CPPU and Benefit® were applied individually and together to both cultivars. It was found that only A. chinesis fruit were affected by the application of Benefit®; fresh weight was increased by 26.38 g, and percentage dry matter was significantly reduced. There was a statistically significant (p < 0.05) interaction between CPPU and Benefit® when applied to A. chinensis. 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) was applied to A. deliciosa on two application dates at three concentrations and was found to decrease fresh weight of fruit, but significantly increase percentage dry matter regardless of application date or concentration. Lastly CPPU and 1-naphthalene acetic acid (NAA) were applied to A. deliciosa at two application dates and in all combinations. Application date affected the response to both a low concentration of CPPU and NAA. A synergistic interaction was observed when CPPU was applied early plus NAA late (CPPU early (4.53 g increase) plus NAA late (13.29 g) < CPPU early plus NAA late (33.85 g). Finally endogenous hormone content was studied. Methods were developed and tested for the simultaneous analysis of both indole-3-acetic acid (IAA) and cytokinins. Freeze dried fruit were purified using Waters Sep-pak® cartridges and Oasis® columns then IAA was quantified by high pressure liquid chromatography. Preliminary results indicate a correlation between application of CPPU and endogenous IAA, high concentrations of IAA correlated well with periods of rapid fruit growth particularly for CPPU treated fruit.

The annual and seasonal water use efficiency of six pasture combinations were calculated from the ‘MaxClover’ Grazing Experiment at Lincoln University. Pastures have been established for six years and are grazed by best management practices for each combination. Measurements for this study are from individual plots of four replicates of ryegrass (RG)/white clover (Wc), cocksfoot (CF)/Wc; CF/balansa (Bal) clover; CF/Caucasian (Cc) clover; CF/subterranean (Sub) clover or lucerne. Water extraction measurements showed soils for all dryland pastures had a similar plant available water content of 280±19.8 mm. Dry matter measurements of yield, botanical composition and herbage quality were assessed from 1 July 2008 until 30 June 2009. Lucerne had the highest annual yield of 14260 kg DM/ha/y followed by the CF/Sub at 9390 kg DM/ha/y and the other grass based pastures at ≤ 6900 kg DM/ha/y. All pastures used about 670±24.4 mm/y of water for growth. Lucerne had the highest annual water use efficiency (WUE) of 21 kg DM/ha/mm/y of water used (total yield/total WU). The WUE of CF/Sub was the second highest at 15 kg DM/ha/mm/y, and the lowest was CF/Wc at 9 kg DM/ha/mm/y. The CF/Sub pastures had the highest total legume content of all grass based pastures at 21% and as a consequence had the highest annual nitrogen yield of 190 kg N/ha. This was lower than the monoculture of lucerne (470 kg N/ha). Ryegrass/white clover had the highest total weed component in all pastures of 61%. For dryland farmers spring is vital for animal production when soil temperatures are rising and moisture levels are high. The water use efficiency at this time is important to maximize pasture production. In spring lucerne produced 8730 kg DM/ha, which was the highest dry matter yield of all pastures. The CF/Sub produced the second highest yield of 6100 kg/DM/ha. When calculated against thermal time, CF/Sub grew 5.9 kg DM/ºCd compared with lucerne at 4.9 kg DM/ºCd. The higher DM yield from lucerne was from an extra 400 ºCd of growth. The highest seasonal WUE of all pastures occurred in the spring growing period. Linear regressions forced through the origin, showed lucerne (1/7/08-4/12/08) had a WUE of 30 kg DM/ha/mm (R2=0.98). Of the grass based pastures, CF/Sub produced 18 kg DM/ha/mm (R2=0.98) from 1/7 to 10/11/08 from 270 mm of water used. The lowest spring WUE was 13.5 kg DM/ha/mm by CF/Bal pastures which was comparable to the 14.3±1.42 kg DM/ha/mm WUE of CF/Wc, CF/Cc and RG/Wc pastures. During the spring, CF/Sub clover had the highest spring legume component of the grass based pastures at 42% and produced 120 kg N/ha. This was lower than the 288 kg N/ha from the monoculture of lucerne. Sub clover was the most successful clover which persisted with the cocksfoot. Based on the results from this study dryland farmers should be encouraged to maximize the potential of lucerne on farm, use cocksfoot as the main grass species for persistence, rather than perennial ryegrass, and use subterranean clover as the main legume species in cocksfoot based pastures. By increasing the proportion of legume grown the water use efficiency of a pasture can be improved. When pastures are nitrogen deficient the use of inorganic nitrogen may also improve pasture yields particularly in spring.

The vegetative and reproductive development of balansa clover (Trifolium michelianum Savi.) were quantified in relation to the environmental drivers of each phenophase in field and controlled environments. In a grazed experiment over 6 years, balansa clover sown with cocksfoot (Dactylis glomerata) contributed 1.6 t DM/ha/year, or ~20% of the total DM production. However, grazing management for increased seed production during flowering in the establishment year strongly influenced balansa clover regeneration. The earliest closed plot (September) averaged between 2.2 and 4.3 t DM/ha/year of balansa clover across all six years. In an incubator, balansa clover required 29°Cd for germination with an optimum temperature of 14°C and a maximum of 40°C. The base temperature for germination was 0°C. A field experiment determined that 38°Cd were required for emergence with an optimum soil temperature (Topt) of 8.5°C. The time from emergence until the first leaf appeared, the phyllochron and timing of axillary leaf appearance were compared with perennial ryegrass (Lolium perenne) and white clover (Trifolium repens L.). The rate of each was found to increase linearly with temperature. The balansa clover cultivar ‘Frontier’ required 97°Cd from sowing for the first leaf to appear, had a phyllochron of 47°Cd and secondary leaves appeared after 490°Cd. For each vegetative stage, the base temperature was 2.5°C. The timing of flower appearance depended on the quantity and direction of change of the photoperiod at emergence. A balansa clover plant, cv. ‘Bolta’, which emerged on 1 December into an increasing photoperiod of 15.6 hours flowered after 574°Cd (Tbase = 2.5°Cd) or 58 days after emergence. In contrast, if the plant emerged on 16 January into a similar but decreasing photoperiod it took 1503°Cd or 227 days to flower. This length of time became progressively shorter until remaining constant after the shortest day. In contrast, ‘Frontier’ took a constant 390 and 690 °Cd in increasing and decreasing photoperiods, respectively. The time which an individual inflorescence took from pollination until seeds were physiologically mature was 250 °Cd for both ‘Bolta’ and ‘Frontier’. The re-establishment of balansa clover each year relied on a large seed set (>1000 kg/ha) in the establishment year. The continued survival of balansa clover would then depend on a similar seeding event within a 4-5 year period to maintain the seed bank. Management considerations for balansa clover persistence and survival are discussed.