Species concepts and relationships in wild and cultivated potatoes

Wild and cultivated potatoes (Solanum section Petota) present challenges to taxonomists arising from lack of clearly defined morphological character differences among many species, phenotypic plasticity, a range of ploidy levels from diploid to hexaploid, and hybrid speciation and introgression. Taxonomic treatments of the group have differed greatly regarding numbers of species and hypotheses of their interrelationships at the series level. Recent morphological phenetic studies and molecular studies have confirmed the general lack of clearly defined species, have shown the need to use a number of character states with overlapping ranges for species delimitation (polythetic support), and have suggested the need for the reduction of species in section Petota. Molecular studies have sometimes confirmed hypotheses of hybridization and sometimes have failed to support them. Molecular studies have suggested the need for a reconsideration of the traditionally held series concepts. Currently, section Petota contains 196 wild species and a single cultivated species, Solanum tuberosum, with eight landrace cultivar groups, exclusive of the modern cultivars that are not yet classified into cultivar groups. The number of wild species likely will decrease with future study. These points are here illustrated by (1) a discussion of published species level studies in Solanum series Longipedicellata, the Solanum brevicaule complex, and the cultivated landrace populations of potatoes; (2) reinvestigations of hybridization in S. chacoense, S. raphanifolium and S. xrechei; and (3) studies of ingroup and outgroup relationships of section Petota

Meclatis in Clematis: yellow flowering Clematis species : systematic studies in Clematis L. (Ranunculaceae), inclusive of cultonomic aspects

The general classification of the genus Clematis (Ranunculaceae) was subject of study in chapter 1. Based on species character scores, the infrageneric classification was analyzed by applying Hennig86 as phylogenetical analysis package. As result of this analysis Clematis was subdivided into 18 sections, one of them subdivided in 3 subsections.The world distribution of Clematis was also studied with Hennig86. It was not possible to postulate the area of origin of the genus Clematis with the available data set.A interspecific cross polygon was made and analyzed by seed set and pollen tube growth. Its systematic significance with regard to Clematis and in general was discussed. Dependent on the adopted species concept, these crosses are crucial or just academic. The adoption of the phylogenetic species concept made that this choice for Clematis is academic. Nevertheless, it is useful information for plant breeders.A general description of the genus Clematis was presented with some background information on certain characters, such as overall habitus, nectar leaves and the position of nectaries.Chapter 2 was devoted to Clematis sect. Meclatis . This particular section consists of the yellow-flowering Clematis spp., that are gaining popularity in gardening. Many efforts were directed to reveal the species delimitation. It appeared that the phenetic methodology is of restricted value in such a complex of quite similar species. Using a combination of methods, the phylogenetic analysis by Hennig86 finally revealed the species delimitation: Clematis orientalis , C. graveolens , C. intricata , C. ispahanica , and C. tibetana . C. tibetana was subdivided into three subspecies: subsp. tibetana , subsp. tangutica and subsp. vernayi . Well-known 'horticultural species' such as C. tangutica and C. vernayi were reduced in rank and others such as C. glauca and C. akebioides were reduced to synonymy. A summary of chromosome, pollen and isozyme data was presented.Chapter 3 was focusing on more fundamental aspects of systematics of cultivated plants. It has been shown that the cultivar group is of crucial importance in classifying cultivars, that the classification principle for cultivated plants is open instead of closed and consequently that the basal term in systematics of cultivated plants for an entity cannot be taxon, but should be a new term culton (plur. culta; cultonomy for culta vs. taxonomy for taxa).Clematis is one of the first genera for which a cultivar group classification was presented in a systematic way, as was outlined in chapter 4. A short survey was given of the introduction into cultivation of yellow-flowering Clematis spp., and a major part of the yellow-flowering Clematis cultivar assortment has been described. So far no cultivar groups are needed for these cultivars.</p

Phase toxicity of dodecane on the microalga Dunaliella salina

In the so-called milking process of Dunaliella salina carotenoids are extracted and simultaneously produced by the culture, whilst the biomass concentration remains constant. Different theories exist about the extraction mechanisms although none have been proven yet. In this research, direct contact between dodecane and cells during the extraction process was studied microscopically and effects of direct contact were determined during in situ extraction experiments. Our results showed that water– solvent interphase contact resulted in cell death. This cell death and consequent cell rupture resulted in the release and concomitant extraction of the carotenoids. Furthermore, it has been suggested to add a small amount of dichloromethane to the biocompatible dodecane to create an organic phase with more extraction capacity. Our results showed that the addition of dichloromethane resulted in increased cell death and consequently the extraction rate increased. The improved solubility of carotenoids in an organic phase with dichloromethane did not significantly increase the extraction rate

Asperge als gewas in Nederland

Aan de hand van schilderijen wordt de geschiedenis van de aspergeteelt in Nederland besproken. Het belang van gewasgeschiedenis voor de verdere ontwikkeling van de teelt wordt benadrukt

Plant growth under high salinity

Plants most suitable for growing under high saline or even seawater conditions are the ones naturally living under high saline circumstances. A series of tolerant or moderate salt tolerant plants are experimentally tested and described in literature. For many species of this group a threshold value has also been described

Plantentaxonomie in onderzoek en dagelijks gebruik

Over het belang van de taxonomie als onmisbare hulpwetenschap in het landbouwkundig onderzoe

Zilte landbouw Texel : een voorbeeld transitieproject 2006-2010 : eindrapport

Het project Zilte Landbouw Texel is in mei 2006 van start gegaan op het perceel nabij ‘De Petten’ op Texel. Er is gekozen om een Zilte Proeftuin aan te leggen op een nabij gelegen perceel waar gedurende twee jaar ongeveer twintig verschillende potentiële zilte gewassen zijn onderzocht op hun groei onder zoute condities en hun marktpotentie. De focus van de werkzaamheden op Texel van de Vrije Universiteit Amsterdam was gericht op Zeekool, Strandbiet, Hertshoornweegbree, Monniksbaard, Reukloze kamille en Wilde Rucola. Daarnaast heeft een langdurig onderzoek plaatsgevonden op de Afsluitdijk wat als referentie heeft gediend voor de natuurlijke groei van halofieten. In de kassen van VU zijn meerdere groei-experimenten onder gecontroleerde omstandigheden uitgevoerd, welke gebruikt zijn om de teelt van de verschillende gewassen op Texel verder te ontwikkelen. De teelt van vooral Zeekool, Zilte Rucola en Strandbiet is met succes opgeschaald en de producten zijn afgezet op de (lokale) markt. Door onder andere de promotie via verschillende kanalen en de unieke smaak van de zilte groenten is een vraag ontstaan naar de zilte gewassen die in veel gevallen het aanbod overtrof

An annotated history of the principles of cultivated plant classification.

Important episodes in the history of the classification of cultivated plants are highlighted and commented upon in the light of recent developments in the systematics of cultivated plants. It is shown that throughout history, a division between classifying cultivated plants and plants as found in nature has existed in the minds of most taxonomists, but the slow development of systematic thought in cultivated plant taxonomy has slowed down progress in this field and left ample opportunity for too strong an influence of the taxon concept. As a result, the nomenclature of cultivated plants has always leaned heavily on the International Code of Botanical Nomenclature