Phalaenopsis is an important ornamental pot plant for the global horticultural market. The inflorescences of Phalaenopsis horticultural hybrids require support from a stick during plant... Show morePhalaenopsis is an important ornamental pot plant for the global horticultural market. The inflorescences of Phalaenopsis horticultural hybrids require support from a stick during plant cultivation because of the weight of multiple large flowers. Developing a horticultural hybrid with a sufficiently lignified inflorescence stem that does not require additional support could be a way to reduce the costs of production. This study aimed to (i) determine the orientation and degree of lignification in the inflorescence stem of different species and horticultural hybrids of Phalaenopsis and investigate whether these lignification patterns follow any (ii) topological or (iii) phylogenetic pattern of interest to further explore in genetic precision breeding. Inflorescences of comparable devel- opmental stages of six species and 17 horticultural hybrids of flowering Phalaenopsis orchids were sampled. The orientation of the inflorescence varied from erect, sub-erect, arching, to pendant. The degree of lignification was measured with ImageJ using stained microscopic tissue sections and statistically analyzed. A molecular phylogeny of the species of Phalaenopsis was reconstructed based on plastid and nuclear ribosomal DNA sequences to analyze phylogenetic patterns. Our results show a significant difference in the degree of lignification between the different Phalaenopsis species and hybrids, between peduncle and rachis, and among the six different inflorescence positions analyzed. We found a positive correlation between inflorescence orientation and the proportion of lignified area per total stem area and the proportional thickness of the lignified fiber walls in the peduncle. We conclude that the degree of lignification is heritable, as we observed among our sample size a higher positive correlation between stem lignification variables among closely related taxa compared to more distantly related ones. However, a larger species sampling is needed to further validate our results. Show less
Plants and soils from natural ecosystems harbor great diversity of soil microorganisms, which could potentially contribute to the sustainability of horticulture. The knowledge about using wild... Show morePlants and soils from natural ecosystems harbor great diversity of soil microorganisms, which could potentially contribute to the sustainability of horticulture. The knowledge about using wild plant species and soil from natural ecosystem to improve the crop health will advance the application of ecological knowledge in horticulture. In this thesis, I evaluate the possibilities of using wild plant species and grassland soil to enhance the growth and reduce the disease susceptibility of chrysanthemum through plant-soil feedback principles. Grass-conditioned inocula contributed more to chrysanthemum growth than forb- or legume-conditioned inocula, this also lead to better chrysanthemum performance under Pythium treatment. Moreover, by mixing two plant-conditioned inocula, they interacted synergistically in terms of plant health but antagonistically in terms of plant growth. The influence of plant-conditioned inocula on chrysanthemum were still significant after two successive growth cycles, but their effects tended to converge because of the overriding effect of chrysanthemum growth. Inoculating greenhouse soil conditioned by wild plant species or grassland soil to greenhouse soil did not significantly improve the negative effects of greenhouse soil on chrysanthemum growth. Olpidium brassicae was identified as a main fungal pathogen of chrysanthemum when growing in greenhouse soil. Show less
This study focuses on the life and work of the sixteenth-century botanist Carolus Clusius in the context of court culture. Before accepting a position at the university in Leiden at the age of 67,... Show moreThis study focuses on the life and work of the sixteenth-century botanist Carolus Clusius in the context of court culture. Before accepting a position at the university in Leiden at the age of 67, Clusius spent a large part of his career at the courts of emperors, princes and aristocrats in Middle-Europe. There he met a wealthy and well-educated elite, who shared his passion for plants, gardens and travelling. But he also encountered a rich diversity of interests and approaches regarding the study of plants. These differences were used by Clusius to establish his authority as a professional botanist and to determine the standards for the proper scientific study of plants. Show less
