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Item Pollen-mediated gene flow from wild carrots (Daucus carota L. subsp. carota) affects the production of commercial carrot seeds (Daucus carota L. subsp. sativus) internationally and in New Zealand in the context of climate change: A systematic review(Elsevier BV, 2024-07-10) Godwin A; Pieralli S; Sofkova-Bobcheva S; Ward A; McGill C; Paoletti EClimate change will impact the carrot seed industry globally. One adaptation strategy to limit climatic impacts on the production of commercial carrot seeds is geographical shift. However, production must be shifted to climate-optimal places that are free from weeds such as wild carrots to avoid genetic contamination via hybridization. The process of gene flow between wild and cultivated carrots is critical to enable management of wild carrots in the face of climate change. This review systematically assesses the resilience of wild carrots to climate change and their impact on commercial carrot seed production globally with a focus on New Zealand as a major carrot seed producer. The literature was critically analyzed based on three specific components: i) resilience of wild carrots to climate change ii) genetic contamination between wild and cultivated carrots, and iii) management of wild carrots. The majority of the articles were published between 2013 and 2023 (64.71 %), and most of these studies were conducted in Europe (37.26 %) and North America (27.45 %). Country-wise analysis demonstrated that the majority of the studies were carried out in the United States (23.53 %) and the Netherlands (11.77 %). There was limited research conducted in other regions, especially in Oceania (1.96 %). Spatial distribution analysis revealed that the wild carrot was reported in around 100 countries. In New Zealand the North Island has a higher incidence of wild carrot invasion than the South Island. The findings indicated that the wild carrot is becoming more adaptable to climate change, compromising the genetic purity of cultivated carrots due to pollen flow from wild to cultivated carrots. Therefore, ongoing research will be helpful in developing sustainable weed management strategies and predicting potential geographical invasiveness. This study provides a guide for scientists, policymakers, industrialists, and farmers to control wild carrots and produce genetically pure commercial seeds amid climate change.Item Phenological phase affects carrot seed production sensitivity to climate change - A panel data analysis(Elsevier BV, 2023-09-20) Godwin A; McGill C; Ward A; Sofkova-Bobcheva S; Pieralli S; Paoletti ENew Zealand is a major producer of carrot seeds globally. Carrots are an important nutritional crop for human consumption. Since the growth and development of carrot seed crops mainly depend on climatic factors, seed yield is extremely susceptible to climate change. This modeling study was undertaken using a panel data approach to determine the impact of the atmospheric conditions (proxied by maximum and minimum temperature) and precipitation during the critical growth stages for seed production in carrot, viz., juvenile phase, vernalization phase, floral development phase, and flowering and seed development phase on carrot seed yield. The panel dataset was created using cross-sections from 28 locations within the Canterbury and Hawke's Bay regions of New Zealand that cultivate carrot seed crops and time series from 2005 to 2022. Pre-diagnostic tests were performed to test the model assumptions, and a fixed effect model was selected subsequently. There was significant (p < 0.01) variability in temperature and rainfall throughout different growing phases, except for precipitation at the vernalization phase. The highest rate of changes in maximum temperature, minimum temperature, and precipitation were recorded during the vernalization phase (+0.254 °C per year), floral development phase (+0.18 °C per year), and juvenile phase (-6.508 mm per year), respectively. Based on marginal effect analysis, the highest significant influence of minimum (187.724 kg/ha of seed yield decrease for each 1 °C increment) and maximum temperature (1 °C rise increases seed yield by 132.728 kg/ha), and precipitation (1 mm increment of rainfall decreases the seed yield by 1.745 kg/ha) on carrot seed yield were reported at vernalization, and flowering and seed development, respectively. The minimum and maximum temperatures have a higher marginal effect on carrot seed production. Analysis of the panel data demonstrates that the production of carrot seeds will be vulnerable to climatic change.Item Viability and dormancy of the Clematis vitalba aerial seed bank.(John Wiley & Sons, Inc on behalf of German Society for Plant Sciences, Royal Botanical Society of the Netherlands., 2024-04-01) Jarvis-Lowry B; Harrington KC; Ghanizadeh H; Robertson AW; Bentsink LOld man's beard (Clematis vitalba L.) is a liana species that has become invasive in many areas of its introduced range. Seeds are produced in abundance and are both physiologically and morphologically dormant upon maturity. To understand the importance of seeds to its invasiveness, changes in viability and dormancy of the aerial seed bank were tracked throughout the after-ripening period and during storage. Seeds collected every second month for 2 years were subjected to germination tests. Other seeds stored in outdoor ambient conditions or in a dry, chilled state were dissected before, during, and after imbibition, as well as during incubation, to measure embryo size. Less than 72% of seeds on the mother plant were viable. Viable seeds remained completely morpho-physiologically dormant throughout autumn, even when treated with nitrate. Physiological dormancy declined in response to seasonal changes, yet morphological dormancy did not change until seeds had been exposed to appropriate germination conditions for several days. Fully dormant autumn seeds decayed at higher rates during incubation than partially or fully after-ripened seeds, which were also more germinable and less dormant. Furthermore, seeds incubated in complete darkness were more likely to decay or remain dormant than those exposed to light. This study demonstrates that fewer than three-quarters of seeds produced are viable and further decay occurs after dispersal, yet total fertility is still very high, with enormous propagule pressure from seeds alone. Viable seeds are protected with two forms of dormancy; morphological dormancy requires additional germination cues in order to break after seasonal changes break physiological dormancy.Item Comparison of seed traits of tropical (Indonesia) and temperate (New Zealand) orchid species to support orchid seed conservation : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Horticultural and Agricultural Science at Massey University, Palmerston North, New Zealand(Massey University, 2020) Diantina, SuryaMost orchid species are endangered, and a basic understanding of their seed biology is required to support conservation efforts. In particular, more knowledge of orchid seed characteristics would be useful for both in situ and ex situ conservation. This comparative study used morphological and biochemical approaches to characterise and compare orchid seed qualitative and quantitative traits, to explore biochemical changes during natural seed ageing and to investigate different asymbiotic in vitro seed germination media and cryopreservation techniques for ex situ conservation. This study included six orchid species with different growth habits and distribution ranges (Dendrobium strebloceras, D. lineale, D. cunninghamii (epiphytic), Gastrodia cunnninghamii, Pterostylis banksii and Thelymitra nervosa (terrestrial)) from temperate New Zealand and tropical Indonesia. Morphometric analyses revealed similarities in the qualitative traits of seeds and capsules at the genus level (Dendrobium). However, high variability in micro-morphological seed characteristics were observed in the orchid species in this study which were unrelated to their taxonomy, biogeographical origin, or growth habit, suggesting different ecological adaptations possibly reflecting different modes of dispersal. An investigation of the seed fatty acids showed that linoleic, oleic and palmitic acids (polyunsaturated, monounsaturated and saturated fatty acids, respectively) were the most abundant fatty acids in the seeds of all species and that rapid degradation of unsaturated acids occurred during ageing. Three epiphytic Dendrobium species had similar lipid composition but Gastrodia cunnninghamii, Pterostylis banksii and Thelymitra nervosa (terrestrial species) were characterised by the absence of erucic and palmitoleic acid. Changes in the proportion of oleic and linolenic acid were strongly correlated with seed viability loss. The ageing pattern was species-specific with D. strebloceras being more vulnerable to lipid degradation. Epiphytic Dendrobium orchids had a less stringent media formulation requirement for seed growth than terrestrial orchids, and similarly, seeds of tropical species D. lineale and D. strebloceras germinated more easily than those of temperate species in this study. Cryopreservation with direct immersion of dry orchid seeds in liquid nitrogen is suggested as the most effective and efficient method for orchid seed conservation.Item Persistency in crested dogstail : its relation to origin, flowering date, seed colour and germination capacity of New Zealand seed samples : thesis for M. Agr. Sc., by "Asteroid" [F. Sydenham](Massey University, 1932) AsteroidCrested dogstail is a valuable pasture grass, and is sown under a wide range of soil conditions. It is essentially a bottom grass. It is very palatable to sheep and thrives well under conditions of continous close grazing. It does not, however, feature to any large extent in dairying land. It shows very great powers of re-establishment by seeding even under adverse seed-bed conditions, and it is this re-establishment which enables it to persist in a pasture for a number of years. Such re-establishment should not occur each Autumn after the plants have seeded and died or are so low in vitality that they remain only as worthless vestiges. This is a weakness of crested dogstail which it is desirable to eliminate. What it requires is a vigorous turf which will, on the advent of Autumn rains, spring into a highly productive sward vigorous enough to check any inferior grasses or weeds which may attempt to gain a footing. [From Introduction]Item A study of the cause of germination injury following contact placement of dried blood fertilizer with seeds : a thesis presented in partial fulfilment of the reqiuirements for the degree of Master of Agricultural Science (Horticulture) at Massey University, New Zealand(Massey University, 1958) Baigent, Nancy LynnThe use of organic fertilizers has suffered a decline since the initiation of large scale production of soluble inorganic salts. Nevertheless, a demand for natural organic forms of nitrogen persists, especially in regions of high rainfall and sandy soils, and in connection with the production of crops of high acre value. In recent years knowledge of the principles and practice of fertilizer application also has expanded rapidly. Localized or contact placement of fertilizer has been found to favour rapid early growth, and to lessen "fixation'' of fertilizer nutrients by the soil. Difficulties in the forms of impaired germination and damage to young seedlings have arisen from contact placement of organic fertilizers. Many mechanisms have been put forth to explain the basis of fertilizer toxicity; viz. plasmolysis of root tissues by the high solute concentrations, production of excessive local acidity or alkalinity from fertilizer materials, direct toxic effects on the young plant by free ammonia or cyanide formed by chemical or microbial breakdown of fertilizer materials. Accordingly, it was decided to evaluate the hypothesis that germination injury to seeds results from the production of injurious quantities of free ammmonia during mineralization of dried blood fertilizer placed in contact with the seeds. [From Introduction]Item Bio-prospecting for endophytes of Brassica : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand(Massey University, 2019) Roodi, DavoodDisease and insect pests are major limiting factors for crop production worldwide. Farmers are often heavily reliant on synthetic biochemicals and fertilisers to mitigate the negative impact of pests and disease and to increase crop yield. However, the extensive use of chemicals has led to environmental concerns due to contamination of soil and water, human health issues, disturbance of macro and microorganisms balance and the development of resistance by both insects and fungal pathogens. Use of biological control agents including endophytic microorganisms is an alternative control option to combat these problems. Many endophytes are able to provide their host with beneficial traits such as resistance against insect-pests and pathogens and enhance crop performance under abiotic stresses. Although beneficial microorganisms of brassica crops have been discovered, endophytes of wild brassica’s, particularly those associated with the seed, have been ignored. In this study, we screened seed of various brassica species with a worldwide distribution and isolated 131 bacterial and two fungal species. Molecular identification of bacterial isolates indicates that most seed accessions harboured endophytic bacteria belonging to 17 species. Among these isolates, two species, identified as Methylobacterium fujisawaense and Me. phyllosphaerae were dominant and widespread across the majority of accessions sampled, and originated from different species and locations. The inoculation of oilseed rape (Brassica napus) root with these endophytic bacteria significantly increased the fresh weight of the seedlings. The fungal endophyte species identified were Beauveria bassiana and Geomyces pannorum, isolated from two different accession of a wild brassica species (B. rapa). Inoculation of the seeds of three brassica species, B. napus, B. rapa and B. oleracea with these fungal endophytes resulted in infection of below and above ground tissues of inoculated seedlings but colonisation of the next generation seeds/seedlings did not occur. Seed inoculation, foliar application and soil drenching when the plants were grown on non-sterile soil also did not result in plant colonisation. A dual culture test was performed to study the antagonistic effect of these bacterial and fungal endophytes against Leptosphaeria maculans, the causal agent of phoma stem canker in brassica crops. The highest inhibition rate was recorded for Stenotrophomonas rhizophila, Novosphingobium resinovorum, Pseudomonas azotoformans, Plantibacter flavus, Me. fujisawaense and Me. phyllosphaerae which produced a significant inhibition zone indicating the antagonistic ability of these species. The fungal endophytes also suppressed the growth of the pathogen and created an inhibition zone. In planta tests in which the fungal endophytes were inoculated on to seed of a susceptible oilseed rape cultivar were also undertaken. At the cotyledon leaf stage, the leaf was punctured and spore suspension of L. maculans was placed on the wound site. Inoculated seedlings particularly B. bassiana, significantly decreased phoma stem canker disease symptoms on the cotyledon. To our knowledge, this is the first study that screen the fungal and bacterial endophytes of wild brassica species associated with the seeds and demonstrate their beneficial characteristic when inoculated to brassica crops.Item Effects of high temperature on pea (Pisum sativum) seed quality and attributed traits : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science, in Plant Breeding at Massey University, Manawatu, New Zealand(Massey University, 2018) Atung, Cyril KoleseThe experiment was set up in a randomised complete block design with four replicates and two pea cultivars (Greenfeast vs. Snow pea), at two different temperature regimes (25/15-35/25°C and 25/15°C). The objective of this study is to investigate the effect of high temperature on seed quality, germination and evaluates the changes in the protein and total soluble sugar content of pea seeds in response to high temperature. The high temperature had significantly reduced flower number, flower accumulation number, pod number and pod accumulation number. The pod number of Greenfeast was highest at day 104.10 at 15/15°C than Greenfeast at 15/25-35/25°C whereas Snow pea pod number was significantly higher at day 91.97 at 25/15°C than at 25/15-35/25°C and the rate of increase was higher for the Greenfeast at 25/15°C, followed by Snow pea t 25/15-35/25°C with the highest correlation (R2=0.73). The pod accumulation rate (K) for Greenfeast was lower than other treatments, with maximum peak at day 98.73. The highest correlations are detected between pod accumulation rate (k) Snow pea at 25/15°C and Greenfeast at 25/15-35/25°C (R2=0.96). There were more Snow pea seeds germinated at 25/15ºC in the first 5 days while the final germination rate was not significant between combination treatments (F3,28=0.92, P=0.4421). High temperature reduced Snow pea dry shoot weight at 25/15-35/25°C compared to Greenfeast which had a low significant dry shoot weight at 25/15°C. Root dry weight of both cultivars was reduced with high temperature (25/15-35/25°C) compared to the low temperature (25/15°C). In terms of protein and sugar content, Greenfeast had the highest protein content and higher sugar content than Snow pea at 25/15°C temperature regime.Item A study of vegetative and reproductive development in Caucasian clover (Trifolium ambiguum, M. Bieb.) cv. Monaro : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Seed Technology at Massey University, Palmerston North, New Zealand(Massey University, 1993) Efendi, FahamA four year established stand of Caucasian clover (Trifolium ambiguum,M.Bieb) cv. Monaro grown on Fine Sandy Loam with moderate fertility was studied to assess the vegetative and reproductive development and the effect of defoliation on seed yield and yield components from September 1991 to June 1992. As in many other traditional herbage legumes, an indeterminate growth habit and a protracted flowering period can be a factor limiting seed production in this clover. From the examination of the vegetative growth and flowering behaviour, it was found that the protracted flowering pattern in this clover is mainly caused by continuous production of reproductive shoots from the crowns rather than continuing inflorescence emergence in one stem as results indicated that inflorescences produced were mainly associated with the number of reproductive shoots available at the time of inflorescence emergence. Reproductive growth commenced at the beginning of October when most visible . Inflorescence buds were formed and subsequent flowering occurred about 8 weeks later. This reproductive growth was found to be the most concentrated on reproductive shoots/stems formed in November to December 1991. These reproductive shoots contributed the majority (70%) of proportion to total inflorescences. Inter-row cultivation decreased the number of reproductive shoots produced as well as decreasing the number of inflorescences at harvest. Inflorescences originating from main crowns produced a higher number of floret buds and seeds per inflorescence than those originating from secondary crowns as the main crowns have their own strong taproot system and are more mature. Throughout the flowering season, T. ambiguum consistently abort about 10 % flower buds before the flowers open. On average of 60% of the open florets developed into live pods at maturity, but only one from two ovules in an ovary usually developed into seeds. On average of about 72% of pods had one seed, 11% of pods with two seeds and 16% were without seed. Both in early and middle flowers, seed development studies revealed that maximum yield of high quality seed was obtained only when seeds attained their maximum dry weight at 30 days after pollination, at the time when seed moisture content had fallen to 30 to 40%. At this time the pods were yellowish brown in colour. To ensure the production of good quality seed with high yield in T. ambiguum it is necessary, therefore to wait crop until at least 34 days after pollination for harvesting the seeds. Seeds harvested early at day 14 to 22 did not retain their viability suggesting that these seeds was still immature and could not withstand desiccation. It was found that pod shattering begun at about 8 days after maximum dry weight (mass maturity) was reached. Heavy rainfall and strong dry wind was found to enhance the rate of shattering. Hardseededness was observed firstly in freshly harvested seeds when seed moisture contents were close to 20%. The levels of hardseededness was higher after drying. Inflorescences set later in the season produced more hard seeds due to higher temperatures and increased humidity during maturation stage. The results of this experiment have confirmed the high seeding potential of T. ambiguum (cv. Monaro) and this should facilitate the production of adequate seed supplies of this cultivars. The average seed yield potential, potential harvestable seed yield and actual seed yield was 893 kg/ha, 707 kg/ha and 427 kg/ha respectively. This might be attributed to the facts that the crop examined in this study was a four year established sward which was mature enough to produced a high yield. Another study was done involving late defoliation treatments designed to investigate their possible effects on plant growth and seed production. Cutting the plant to the ground level showed an obvious harmful effects on seed yield in T. ambiguum. The results show that October and November cutting resulted a 67 and 72% decrease in actual seed yield compared to uncut control. This results support Steiner's view (in press) that the plant morphology of T. ambiguum limits its ability to recover from defoliation.Item Seed production in garden nasturtium (Tropaeolum majus Linn.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture Science in Seed Technology at Massey University, Palmerston North, New Zealand(Massey University, 1992) Fakavā, Viliami TisileliThis thesis reports the results of research on seed production of garden nasturtium (Tropaeolum majus). The research programme was begun in late 1991 with an investigation on the effects of plant density on Tropaeolum majus cv. Choice Mixed grown under field conditions. The plant responses to changing plant density in terms of the vegetative growth and morphology, flowering pattern, seed yield and yield component were investigated using four different densities ranging from 3 to 45 plants per m2• The results of this research showed that increasing plant density decreased branch number, dry weight, leaf number and area, and flower number per plant. It was also shown that seed yield is primarily determined by the number of flowers produced per m2 and this character was identified as an important aspect to be manipulated for improving seed yield. Although increasing plant density resulted in decreased seed yield per plant, seed yield per unit area was similar at all densities. Nasturtium flower and seed development studies showed that irrespective of density it takes about 12 days for the green floral bud stage to complete flowering and each flower needed 40-50 days from pollination to reach physiological seed maturity. Seed started shedding at 40 DAP at a moisture content of 78-80% and a maximum seed weight of 0.18 grams. Seed ripening occurs after 50 days from pollination after seed shedding on the ground surface. Maximum seed yield was achieved at 40 days after peak flowering at all densities. The second stage of the study involved an assessment of the tolerance of nasturtium to various selective herbicides. This experiment was conducted in January-June 1992 in the glasshouse and was designed to provide information on the phytotoxicity of herbicides to nasturtium seedlings and plants. A wide range of soil and foliar applied herbicides were evaluated for their phytotoxicity to nasturtium. Four pre-emergence chemicals, chlorpropham (3.2 kg ai/ha), alachlor (2 kg ai/ha), oryzalin (3 kg ai/ha) and trifluralin (0.8 kg ai/ha) were considered to be the most selective and are recommended for direct sown nasturtium crops. Post-emergence applications of asulam (1.6 kg ai/ha), haloxyfop (0.3 kg ai/ha), methabenzthiazuron (1.4 kg ai/ha) were also well tolerated by nasturtium seedlings. Seed production possibilities for the production of garden nasturtium seed under New Zealand conditions are also discussed.