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    An evaluation of lupins (Lupinus spp.) for seed protein production : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand
    (Massey University, 1979) Withers, Neville John
    Since 1972 there has been interest in the greater use of seed protein in grain-based meals for stock. Lupins were one of the crops proposed to fill this requirement. This study was initiated to provide information on the agronomic requirements of Lupinus angustifolius, L. luteus and L. albus for seed production with emphasis on the southern North Island of New Zealand. In addition, some more basic studies on carbon and nitrogen translocation and the response of lupins to water stress were also carried out to provide a better understanding of the lupin plant and its response to its environment. Initially some field experiments were laid down to measure responses to sowing date, plant density, defoliation and cultivar. At wide spacing, L. angustifolius showed an approximately linear decrease in seed yield/plant as sowing date moved from April to October. At normal densities, however, sowing in late July gave the best see yield. Autumn sowings were affected by disease. It was concluded that, in the absence of disease, seed yield was largely determined by the length of the period of favourable environmental conditions between the start of flowering and the finish of reproductive development. This period determined the number of lateral inflorescences produced which, in turn, determined the number of pods producing seed. Pod number was the main component influencing seed yield. Thus, early sowing and reliable summer rainfall or irrigation seem to be the factors determining high lupin seed yields. Responses to density were variable. In one experiment there was no response in seed yield by four cultivars over these sowing times to densities ranging from 50-140 pl/m2. In a further experiment, increases in seed yield were obtained as plant density increased from 25-100 pl/m2. Removal of the main stem growing point early in growth briefly stimulated lateral stem growth but the effect on lateral stem seed yield was insufficient to compensate for the loss of the main stem seeds. There was little difference between the L. angustifolius cultivars Uniharvest, Uniwhite and Unicrop when sown early but, with late spring sowing, Unicrop flowered earlier which was an advantage under dry early summer conditions. In one experiment comparing a range of legume species, L. albus and Pisum sativum produced the highest seed yield but L. albus and L. luteus yielded the most protein per unit area. The peak rate of nitrogen accumulation in all species was similar and the main factor influencing protein yield appeared to be the duration of nitrogen accumulation. Provided each crop utilised similar durations of the growing period, the yield of seed protein/ha from various legume crops is likely to be similar; the main difference being the composition of the seed. It was suggested that, for maximum seed protein yield, indeterminate cultlvars may have some advantage over more determinate cultivars provided appropriate management procedures are adopted. Studies on water stress indicated that it plays an important role by influencing the distribution of assimilate between vegetative and reproductive growth. Mild water stress tended to stop vegetative growth and increase the rate of seed growth. When sufficiently severe, water stress appeared to initiate the senescence of the plant, the timing of which determined the potential seed yield for that situation. Water deficit had its main effect on seed yield by reducing pod number. Other yield components were relatively stable. Day temperatures of 28°C, when imposed early in growth, reduced vegetative and seed yield in L. albus. As the plant developed, however, the adverse effects of high temperature decreased until growth was stimulated during first order lateral flowering. No direct effect of high temperature on pod abscission was apparent and it was suggested that pod loss under high temperatures which have been reported occurred largely because of an associated water stress. A 14C translocation study indicated that most movement of photosynthate in L. albus was into the branch on which the labelled leaf was inserted, or into lower branch orders directly connected to it. Results suggest that, in L. albus cv. Ultra, lower order stems are a more important competitor with the inflorescence for photosynthate than the new, rapidly developing, higher order lateral branches. A possible strategy for growing lupin in a commercially viable situation in the Southern North Island is discussed.
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    A study of seed production in 'Grasslands Ruanui' perennial ryegrass(Lolium Perenne L.) 'Grasslands Kahu' Timothy (Pheleum Pratense L.) prairie grass (Bromus Unioloides H.B.K.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, New Zealand
    (Massey University, 1971) Hill, Murray John
    The place of grasslands in the economy of New Zealand is paramount. Consequently grassland seeds must and do play a vital role in the agricultural industry. Increasing land values and soaring costs make it imperative that our farms are sown with seed of the highest quality. On many farms seed production is only considered as secondary to the production of meat and milk. It is only in seasons when stock feed is abundant that many areas are closed for the production of seed. It would be to the advantage of the seed industry if grass seed production was viewed more as a primary consideration with stock grazing being employed to assist in the management of the seed crop rather than the present 'catch' crop system employed on many farms. This system would also help to reduce the large annual fluctuation in national seed production. Herbage seed production in this country amounts to about 18,000 tons annually although fluctuations in this figure do occur (1967 20,370 tons, 1968 17,430 tons, 1969 18,770 tons, 1970 14,880 tons). In 1970 seed exports represented a total value of over $7 million, of which approximately $0.7 million was obtained from the export of perennial ryegrass seed. In recent years a number of grassland workers have carried out studies on various aspects of seed development and production. Despite this, however, much work still remains to be done before the physiological processes underlying seed production are fully understood. Some of these workers have found it necessary to study the position and contribution of individual tillers to seed production. In comparison, studies of the factors influencing anthesis, fertilisation and seed maturation have been somewhat neglected. The production of a large number of head-producing tillers, each bearing large numbers of florets is obviously not enough. A high percentage of these florets must undergo anthesis, be effectively fertilised and ultimately develop to maximum seed weight and germination capacity if the potential yield of the crop is to be fully realised. This suggests that seed yield might be considerably increased if the conditions required at each of these stages were more fully understood. During the late summer, autumn and winter tillers grow vegetatively and it is not until the spring that those tillers destined to produce heads actually begin reproductive development. It is at this time that the first contribution to total seed yield occurs, viz. the number of reproductive tillers per unit area. Ear development continues until shortly before ear emergence at which point the number of florets per head is fixed. Subsequently, anthesis, pollination and fertilisation follow to determine the seed-set component of total yield. Finally the seeds develop and mature to determine the final yield component-seed weight.
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    Seed production in birdsfoot trefoil (Lotus corniculatus L.) : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Seed Technology at Massey University, Palmerston North, New Zealand
    (Massey University, 1989) Li, Qingfeng
    This thesis reports the results of three years' research on seed production of birdsfoot trefoil (Lotus corniculatus L.). Previous work by other researchers has suggested that a protracted flowering period is a major factor limiting seed production in this legume. The research programme was begun in 1986 with an investigation of the cause(s) of this protracted flowering period. By carefully examining the growth and flowering behaviour of tagged shoots formed at different times of the year, it was identified that the protracted flowering pattern in this plant is caused by the continuous production of shoots with the capacity to flower. The continuous development of new shoots replacing older flowering shoots was the main cause of the long flowering period. Results of the first year's research also showed that seed yield is primarily determined by the number of inflorescences produced. In turn, inflorescence numbers are primarily dependent on the number of shoots available at the time of flowering. It was suggested by the results that manipulation of the number and branching of shoots should be an important management strategy for improving seed production in this plant. The second stage of the study involved a number of hand removal and cutting treatments designed to investigate the possible effects of shoot removal on plant growth and seed production. Hand removal of crown shoots affected branching behaviour in this plant. Removal of young crown shoots at different growth stages resulted in a range of plant structural forms which influenced seed production potential. Cutting treatments, the major effect of which was to remove a section of shoot from the top, showed no obvious beneficial effects on seed yield in birdsfoot trefoil. In the third stage studies were extended to investigate a more practical situation in which plant growth regulating chemicals (paclobutrazol (PP333), ethofumesate (Nortron) and fatty alcohols (Fatol Super)) were used to manipulate shoot growth and development. Research at this stage involved both widely spaced individual plants and plants grown in a sward to simulate commercially practised situations. Results showed that PP333 is a promising pre-peak flowering shoot manipulator which acts by promoting branching. Nearly a 40% increase in seed yield was consistently obtainedin two years' experiments when this chemical were applied during the time from the pre-bud stage to the early flowering stage. Nortron showed its value in sward situations when applied at early plant development stage. However, Nortron was of limited value when it was used as a post-peak flowering shoot manipulator because of its injurious effect on plant growth and flowering. Fatol Super showed some potential as a post-peak flowering shoot manipulator, particularly when applied to spaced plants, but was less effective in sward situations. This reduces its value for use in the narrow row or sward seed production systems currently practiced in New Zealand for birdsfoot trefoil.
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    Chemical manipulation of white clover (Trifolium repens L.) grown for seed production : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Seed Technology in the Plant Science Department of Massey University, Palmerston North, New Zealand
    (Massey University, 1992) Budhianto, Bambang
    The effects of chemical manipulation through the use of plant growth regulators on white clover (Trifolium repens L.) cv. Grasslands Pitau grown for seed were investigated in this study, using both sward and individual plant trials. A white clover seed crop was established in autumn 1988, certified breeders seed of cv. Grasslands Pitau being sown at 3 kg/ha in 45 cm rows. Three plant growth regulators, chlormequat chloride (1.5 and 3.0 kg a.i./ha), paclobutrazol (0.5 and 1.0 kg a.i./ha) and triapenthenol (0.5 and 1.0 kg a.i./ha) were applied at two growth stages; during reproductive initiation (11 October) or at the appearance of the first visible bud (8 November). A further plant growth regulator, daminozide (2.0 and 4.0 kg a.i./ha) was applied only in November. Chlormequat chloride, daminozide and triapenthenol did not significantly affect node production, inflorescence production or seed yield, although thousand seed weight (TSW) was reduced. Paclobutrazol significantly reduced petiole length and increased the number of nodes/m2, but did not affect dry matter production. The October application of paclobutrazol at 1.0 kg a.i./ha significantly increased potential harvestable seed yield by 71 % through increasing the number of inflorescences produced, but the 57 % increase following the November application at the same rate did not differ significantly from the control. Actual seed yield differences (+25 and 26 %) were also not significant. In the following season (1989/1990), three of the plant growth regulators (chlormequat chloride at 3.0 kg a.i./ha, paclobutrazol at 1.0 kg a.i./ha, triapenthenol at 1.0 kg a.i./ha) were applied using the same site as for the 1988/1989 trial (i.e. a second year crop), but avoiding plots previously sprayed with paclobutrazol to eliminate possible soil residual effects. Applications were either during early reproductive initiation (September), during peak reproductive initiation (October) or when reproductive buds/early flowers were first visible (November). Chlormequat chloride did not affect either vegetative or reproductive growth and development. Triapenthenol initially retarded growth (e.g. by reducing petiole length), but this effect was only transiatory, and was no longer evident 3 weeks after application. Although triapenthenol applied in November increased inflorescence number at peak flowering, seed yield was not increased. Triapenthenol applied in October did not affect inflorescence number at peak flowering, but reduced TSW. Paclobutrazol applied in September, October and November reduced petiole length and leaf size, but only application in November increased both node and stolon production. Application in October and November increased inflorescence numbers at peak flowering and harvest respectively, but seed yield was not increased. Data recorded from plots sprayed with paclobutrazol the previous season (1988/1989) provided no evidence of growth retardation through soil residual activity. In an attempt to clarify the effects of paclobutrazol on white clover growth and development, individual plants grown from seeds selected at random from a lot of certified breeders seed were established as spaced plants (80 x 80 cm) in the field in spring of 1990. Paclobutrazol was applied at 1.0 kg a.i./ha on 6 November 1990 (when more than 75 % of the plants were initiating reproductive buds at their terminal buds) or 23 November 1990 (when more than 50 % of the plant population had reproductive buds visible on their stolons). Petiole length and leaf size were initially reduced, but beginning two months after application, vigorous regrowth occurred, to the extent that paclobutrazol treated plants became as tall as the control plants. However, retardation effects occurred again at harvest. Total plant dry matter and root:shoot ratios were not affected by paclobutrazol. Chlorophyll content/unit leaf area and leaf thickness increased following paclobutrazol application, but increases were not correlated. Seed yield and yield components did not differ from that of the control plants, mainly because plant to plant variation was very large, irrespective of treatment. To attempt to reduce this source of variation, a further spaced plant trial was established in 1991/1992 using plants produced by clonal propagation from three distinct genotypes from within cv. Grasslands Pitau. Paclobutrazol was applied at the same rate and time as in the previous season, and while not affecting the number of nodes developed along stolons or inflorescence initiation at the stolon apices, it did significantly increase stolon production in all three genotypes through increasing secondary, tertiary and to a lesser extent quaternary branch numbers. However, not all these extra stolons were able to produce inflorescences, and this ability varied significantly with genotype. As a consequence, inflorescence number and potential harvestable seed yield were significandy increased only in one genotype following paclobutrazol application. However, paclobutrazol reduced seed abortion and increased seed weight in all three genotypes. In individual plants, inflorescence growth and development from emergence to the seed ripening stage occurred more quickly in paclobutrazol treated plants than untreated plants. A simulated sward trial was used in 1990/1991 to determine whether the previous failures to significantly increase actual seed yield were because paclobutrazol treated plots had ripened earlier than control plots, and as a consequence more seed had been shed by the time of harvest. However, no significant paclobutrazolXharvest time interactions for seed yield or seed yield components were recorded. These results suggest that paclobutrazol did not affect seed maturity in a sward situation. Irrespective of treatment, greatest seed yield came from harvesting 25 days after peak flowering, but this did not differ significantly from harvesting 35 days after peak flowering. Delaying harvest to 40 and 45 days after peak flowering significantly reduced seed yield. As in previous sward trials, paclobutrazol application significantly increased inflorescence numbers, but large (+56 %) differences in potential harvestable and actual seed yield were statistically not significant. In each case, high data variation (CV > 30 %) was recorded. Factors responsible for the failure of apparent biological increases to be statistically real are briefly discussed.
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    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.
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    Seed production in China aster (Callistephus chinensis (L.) Nees) : a thesis presented in partial fulfilment for the degree of Doctor of Philosophy in Seed Technology at Massey University
    (Massey University, 1992) Phetpradap, Luckana
    Seed production of two cultivars (Powderpuff and Kurenai) of China aster (Callistephus chinensis (L.) Nees.), grown under field conditions, was assessed to determine plant responses to the effects of plant density, crop manipulation by hand pinching and the application of three plant growth regulating chemicals, and some selected herbicides. Plant density effects on vegetative plant growth, flowering pattern, seed development, seed yield and yield components were investigated in 1987/1988 using a radial spacing design which provided plant densities ranging from 4.2 to 44.7 plants m-2. Increasing plant densities increased branch numbers m-2 which led to increased leaf numbers, leaf area, plant dry matter and flowers and resulted in an increased number of potential seed production sites. The number of flower heads m-2 was the most important component determining final seed yield in both cultivars and was identified as an important plant characteristic to be manipulated for improving seed yield. A period of 18 days was required to complete flowering within each individual flower head, since florets opened sequentially from the outside ring through to the centre. The flowering period lasted for 8 weeks. Each seedhead needed 30 or 39 days from first opening for seed to reach physiological maturity and seeds could remain on the seedhead for a further 9 or 12 days (cv. Kurenai and cv. Powderpuff respectively) before seed shedding started. Kurenai produced maximum seed yield at 27.8 plants m-2 (140 g m-2) and cv. Powderpuff at 17.4 plants m-2 (42 g m-2) but these yields did not differ significantly from those over a wide range of densities (between 12.7 to 44.7 plants m-2 in cv. Kurenai and 4.9 to 44.7 plants m-2 in cv. Powderpuff). Both cultivars exhibited a high ability for compensatory reproductive growth. Lodging and weeds were identified as constraints for seed production at this site and were studied in subsequent years. A series of experiments were conducted in 1987/1988 and 1988/1989 to evaluate herbicides which would provide good weed control without seed yield reduction, and which would not be phytotoxic to aster plants grown either as transplanted seedlings or when direct sown. For transplanted aster, a single application of oryzalin (3.75 kg a.i. ha-1 at 4 days after transplanting) provided excellent weed control and a tenfold increase in seed yield (to 568 kg ha-1). For direct sown aster, only trifluralin (2 kg a.i. ha-1) applied pre-sowing did not significantly reduce aster emergence, while oryzalin (4.5 kg a.i. ha-1 applied 10 days after sowing) provided the best aster seedling survival. However weed control from both chemicals was only partial and further work is required. In 1988/1989, hand pinching and the application of two different rates of three growth retardants, paclobutrazol (0.5 and 1.0 kg a.i. ha-1), daminozide (2.5 and 5.0 kg a.i. ha-1) and chlormequat chloride (1.5 and 3.0 kg a.i. ha-1) were carried out at two different growth stages (visible terminal bud and stem elongation stages) on cv. Powderpuff to investigate their retardation ability, any alterations in the partitioning of assimilate, and subsequent effects on seed yield and yield components. Powderpuff plant structure was altered by hand pinching only at the visible terminal bud stage. Neither pinching treatment increased seed yield, because, particularly for the earlier pinching time, fewer branches were produced from limited node numbers. The growth retarding effect of the three chemicals was transient and the differences in efficacy and the effective duration of each growth retardant treatment was recorded. The longevity of chlormequat activity in treated plants was short compared to paclobutrazol. Although paclobutrazol and daminozide decreased plant height at seed harvest, lodging was not prevented. None of the three chemicals increased flower head numbers or shortened the duration of flowering, and subsequently failed to increase seed yield. However, paclobutrazol showed enough promise for plant height reduction and seed yield improvement to warrant further investigation. Two experiments with paclobutrazol were conducted in 1989/1990. The first was on cv. Powderpuff, where two rates of paclobutrazol (0.5 and 1.0 kg a.i. ha-1) were applied at three growth stages (vegetative, terminal flower bud initiation and first visible terminal flower bud stages) to assess their effects on seed yield. The second was an investigation of cultivar/density responses, where the same two paclobutrazol rates were applied to two aster cultivars grown at two different plant densitites (16 and 36 plants m-2 for cv. Powderpuff and 25 and 49 plants m-2 for cv. Kurenai) at the terminal flower bud initiation stage. Paclobutrazol effects on China aster plant height were cultivar dependent. Both paclobutrazol rates effectively controlled plant height of cv. Kurenai but the results in cv. Powderpuff were inconsistent and the plant height reduction was insufficient to prevent lodging. Results from all the experiments showed that flowering was strongly influenced by environment (daylength and temperature), and since no growth retardant treatments shortened the duration of flowering, a high variation in seed maturity caused by sequential flowering and subsequent high losses of immature seeds during cleaning resulted in no significant seed yield increases. However, paclobutrazol significantly increased potential harvestable seed yield through increasing the number of seeds per plant when applied (i) at the vegetative stage at 1.0 kg a.i. ha-1 to cv. Powderpuff grown at 16 plants m-2 (56 % seed yield increase from 83.8 to 130 g m-2). (ii) at the terminal flower bud initiation stage at 0.5 kg a.i. ha-1 to late sown plants of cv. Powderpuff grown at 36 plants m-2 (48 % increase from 136 to 202 g m-2). and (iii) during flower bud initiation and early stem elongation at 0.5 and 1.0 kg a.i. ha-1 in cv. Kurenai grown at 49 plants m-2 (32 and 42 % increase from 178 to 236 and 253 g m-2 for the low and high rate respectively). Seed production problems and possibilities for the production of China aster seed under New Zealand and Thailand conditions are also discussed.