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    Pollination patterns in safflower (Carthamus tinctorius L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University
    (Massey University, 1981) Woods, Peter William
    The influence of environmental conditions on safflower (Carthamus tinctorius L.) floret characters and insects were studied in relation to pollination in this species. Insect activity was studied in a field experiment using part of the world germplasm collection of safflower. Honey bees were the most likely cross-pollinators. Activity of honey bees did not vary between genotypes studied. Correlations between insect and weather data were mainly non-significant. A sample of 12 genotypes from the world collection were intensively studied in controlled environment rooms. Single plants were used as plots in a randomised complete block design, in each of four environments (day/night temperature treatments of 28/22°c and 24/l8°c in combination with vapour pressure deficit treatments of -1.0 and -0.4 kPa). Environments reflected New Zealand summer conditions. Coefficients of variation were acceptable for most characters. Considerable genotypic, environmental and genotype-environment interaction variances were observed for most characters. Standardised partial regression coefficients (path coefficients) and principal factors were utilized to determine the characters most important in self-pollination of safflower. These characters were: the length of the style-stigma; the rate of style-stigma growth; the rate of corolla tube growth and amounts of viable pollen present during floret expansion. Pollen viabilities remained high for the longest time in higher humidity environments. Large amounts of pollen were produced at the lower humidity. Floral parts were largest in the cool dry environment, however rates of style-stigma and corolla expansion were greater at lower temperatures. It was concluded that synchronization of the rates of style-stigma and corolla tube growth were important in maintaining the stigma in close proximity to viable pollen, and thus promoting the possibility of self-pollination. Self-pollination was greatest at the lower temperature and lower humidity. The basic self-pollination mechanism observed was in agreement with previous authors. A number of improvements for future controlled environment experiments involving safflower were suggested. The implications of pollination of safflower on germplasm collection and maintenance, artificial crossing and breeding plans were discussed.
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    Pollination of "Sundrop" apricot : an analysis of the effect of self incompatibility and bloom phenology on fruit set in Hawkes Bay : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University
    (Massey University, 1995) Austin, Paul Thomas
    A range of observational, experimental and simulated data are analysed to discover how self incompatibility, relative bloom phenology and dormancy alleviation affect fruit set on 'Sundrop' apricot in Hawkes Bay. The derivation of two mathematical models, one of cross pollination, the other of bud development, provides a unifying theme to the study. Controlled pollination experiments demonstrated that 'Sundrop' displays gametophytic self incompatibility. Pollen tubes from 'Sundrop' pollen generally fail to penetrate styles of 'Sundrop' flowers and this prevents fruit set under Hawkes Bay conditions. Study of apricot pollen tube growth at five constant temperatures between 5° and 25°C suggested that the penetration failure was not due to adverse temperature conditions since self pollen tube penetration was strongest at 10° and 15°C, temperatures typical of Hawkes Bay during apricot bloom. Field observations of honey bee foragers illustrated the strong influence that weather conditions have on honey bee foraging activity, but showed that activity on 'Sundrop' flowers is normally sufficient to achieve satisfactory cross pollination. Analysis of bloom records indicated that relative times of bloom of apricots in Hawkes Bay and other North Island sites vary considerably from year to year. A simple model of pollenizer pollen transfer was therefore derived to estimate the optimum pollenizer bloom divergence for 'Sundrop'. It indicated 'Sundrop' should bloom slightly before (1-2 days) a pollenizer. Optimum divergence was most sensitive to the durations of pollen release and floral receptivity. Delayed pollination experiments showed that the duration of receptivity of 'Sundrop' flowers was the same as petal lifespan. Significant opportunity for cross pollination was still predicted when the pollenizer bloomed as late as six days after 'Sundrop'. By this criteria, 'Trevatt' (the most commonly-used pollenizer) appeared satisfactory under most, though not all, conditions. The pollen transfer model indicated that relative bloom phenology needed consideration for selection of pollenizers for 'Sundrop'. However, the "Utah' chill unit index was a poor predictor of dormancy alleviation and bloom for apricots under Hawkes Bay conditions. Hence, a model of low temperature-mediated alleviation of dormancy incorporating a progressive shift in bud temperature response was established based on an analysis of dormancy as the depression of a 'thermal response window' and chilling as a twofold seasonal signal controlling window size. Initial evaluation confirmed that the resulting PHYSHIFT model was highly flexible and could reproduce many of the responses that dormant buds of Prunus species display to constant and cyclic temperature regimes. Hence, the results suggest that the PHYSHIFT model may offer more reliable prediction of relative bloom timing for the purpose of pollenizer selection than chill unit models.
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    Breeding systems and reproduction of indigenous shrubs in fragmented ecosystems : Breeding systems and reproduction of indigenous shrubs in fragmented ecosystems : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2006) Merrett, Merilyn F.
    Sixteen native shrub species with various breeding systems and pollination syndromes were investigated in geographically separated populations to determine breeding systems, reproductive success, population structure, and habitat characteristics. Of the sixteen species, seven are hermaphroditic, seven dioecious, and two gynodioecious. Two of the dioecious species are cryptically dioecious, producing what appear to be perfect, hermaphroditic flowers, but that function as either male or female. One of the study species, Raukaua anomalus, was thought to be dioecious, but proved to be hermaphroditic. Teucridium parvifolium, was thought to be hermaphroditic, but some populations are gynodioecious. There was variation in self-compatibility among the four Alseuosmia species; two are self-compatible and two are self-incompatible. Self-incompatibility was consistent amongst individuals only in A. quercifolia at both study sites, whereas individuals in A. macrophylla ranged from highly self-incompatible to self-compatible amongst four study sites. The remainder of the hermaphroditic study species are self-compatible. Five of the species appear to have dual pollination syndromes, e.g., bird-moth, wind-insect, wind-animal. High levels of pollen limitation were identified in three species at four of the 34 study sites. Moderate to high levels of pollen limitation were evident in 50% of the gender dimorphic populations compared with 31% of hermaphroditic populations. Melicope simplex populations were female-biased in 14 study plots and successful fruit set was influenced by combinations of male plant density, male flower numbers and distance to the nearest pollen. Natural fruit set in wind-pollinated species was generally higher than in animal-pollinated taxa. Populations of Coprosma spathulata were mostly malebiased, and male plant density and proximity influenced natural fruit set, with a correlation between low fruit set and low male density. Population recruitment was evident in 32 of the 34 sites. In Pimelea arenaria, recruitment failure was widespread in populations throughout the North Island despite high seed set. Gender ratios showed variation from north to south, with a lower proportion of females with increasing latitude. Many of the sixteen shrubs in this study show remarkable resilience to the effects of fragmentation of natural ecosystems, and many of the species have benefited from the creation of new edge habitat after perturbation - it may be that edges are important refugia for some native taxa, especially shrubs.
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    The effects of honeybees on the biodiversity of manuka patches : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology, Massey University, Palmerston North, New Zealand
    (Massey University, 2009) Bennik, Rebecca Marie
    Honeybees (Apis mellifera) are important pollinators of many plant species and are employed globally for crop and honey production. However, little is known about the effects of this species on native pollinator and plant species in areas to which they have been introduced; and previous research has not been able to reach a general consensus as to the type of impact honeybees have on pollination systems. In addition to the effects of exotic pollinators, the loss and fragmentation of natural habitats is also of major concern to the continuing diversity of pollinators and plant populations. Here, the impact of honeybee density on other pollinator guilds, and levels of remaining pollen and nectar standing crop among 18 patches of the New Zealand native shrub – manuka (Leptospermum scoparium) is examined at three different regions within the North Island. The same sites were also used to test the reproductive capabilities of manuka and subsequent pollen limitation among patches. A further 11 sites were utilised to examine biodiversity via intercept and pitfall traps within manuka patches, and the patch variables driving taxa composition. Large fly (Diptera = 5 mm) abundance was negatively correlated with honeybee abundance and instances of physical disturbance of large flies by honeybees were observed. There was no significant correlation between honeybee abundance and other pollinator guilds. Nectar was a limiting resource for both honeybees and large flies, whereas, pollen was not a limiting resource among any of the major pollinating insect guilds. Pollination treatments revealed that manuka is partially self-compatible, but relies more heavily on cross pollination for higher yields of capsule and seed set. Pollen limitation did not occur significantly at any of the sites. A total of 159 Coleoptera, 125 Diptera, 131 Hymenoptera morphospecies, and 50 other groups of taxa from various orders were collected among sites. Invertebrate richness was higher at lower altitudes and litter invertebrate richness was significantly higher with an increase in the proportion of manuka cover. There were distinct differences in taxa composition between the three regions, with plant community composition and altitude the most significant factors. Patch size also played a part, but a lack of overall variation in patch sizes may understate the effect this has on insect composition. Overall, honeybees are competing for nectar resources and displacing large flies as a consequence; however, capsule and seed set among manuka patches did not significantly suffer as a consequence. Regional variation in patch characteristics such as altitude, plant community composition, patch size, proportion manuka cover, and plant evenness appear to be influencing insect composition found within manuka patches to varying degrees. Further investigation into the impact of patch size and patch connectivity is also warranted.