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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

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Cross-sectoral conflicts for water under climate change: the need to include water quality impacts
Vliet, M.T.H. van; Ludwig, F. ; Kabat, P. - \ 2013
planten - polyploïdie - hybriden - hybridisatie - genomica - evolutie - drosophila - plants - polyploidy - hybrids - hybridization - genomics - evolution
Climate change is expected to increase pressures on water use between different sectors (e.g. agriculture, energy, industry, domestic uses) and ecosystems. While climate change impacts on water availability have been studied widely, less work has been done to assess impacts on water quality. This study proposes a modelling framework to incorporate water quality in analyses of cross-sectoral conflicts for water between human uses and ecosystems under climate change and socio-economic changes. We illustrate this with an example that shows that increasing river temperatures and declines in summer low flow under climate change are likely to increase environmental restrictions on cooling water use, with substantial reductions in power plant capacities in Europe and the US. Hence, conflicts between environmental objectives and electricity supply are expected to increase due to both changes in water availability and water quality (water temperature) under climate change. A new impact modelling framework is proposed, which integrates relations between water availability, water quality and cross-sectoral water uses, including water requirements for ecosystems. This could provide improved understanding of how climate change and socioeconomic developments will affect the ‘water-energy-food-ecosystem nexus’. Index Terms—river flow, water temperature, water quality, climate change, socio-economic developments, human water use, ecosystems
A molecular cytogenetic analysis of chromosome behavior in Lilium hybrids
Xie, S.L. - \ 2012
University. Promotor(en): Richard Visser; Jaap van Tuyl, co-promotor(en): Paul Arens. - S.l. : s.n. - ISBN 9789461732248 - 115
lilium - cytogenetica - moleculaire genetica - genetische analyse - hybriden - chromosomen - recombinatie - soortkruising - meiose - cytogenetics - molecular genetics - genetic analysis - hybrids - chromosomes - recombination - interspecific hybridization - meiosis

Lily (Lilium) has become one of the top bulbous crops for the cut flower industry in the past two decades. The genus Lilium comprises of approximately 80 species, which have been classified into seven sections. Each section possesses distinctive phenotypic characters, such as flower color, flower shape and resistances to diseases and pests. Crosses between species in the same section are relatively easy and the resulting hybrids are in general fertile, while interspecific crosses between species from different sections are rather difficult and the resulting hybrids are in general sterile. As a result, different hybrid groups have been bred in the 20th century. Within these different hybrid groups, Longiflorum (L), Asiatic (A) and Oriental (O), which are derived from the section Leucolirion, Sinomartagon and Archelirion respectively, are of commercial importance and hence, are the most widely cultivated lilies worldwide.

Lily hybrids provide an ideal model for molecular cytogenetic research. With the development of techniques of overcoming pre- and post- crossing barriers of interspecific crosses, as well as the application of asexual and sexual polyploidization to restore the fertility of F1 lily hybrids, combining of desirable traits from different hybrid groups has become feasible. As a result, interspecific hybridization and polyploidization have been widely used in the breeding of new cultivars of lily. These cultivars, as well as other breeding materials from interspecific crosses, facilitate the application of molecular cytogenetic analysis due to three reasons: 1) the chromosomes of lily are large enough for cytological observations; 2) genomes of different hybrid groups are homoeologous; and 3) these homoeologous genomes can be simultaneously distinguished by DNA in situ hybridization. Using these lily hybrids combined with genomic in situ hybridization (GISH) and florescence in situ hybridization (FISH), the interaction of homoeologous genomes can be studied though meiotic observation of the F1 hybrids. Meanwhile, chromosome sequential variation with relevance to crossover and chromosome rearrangements can also be observed.

For this purpose, interspecific crosses between the Lilium longiflorum cultivar ‘White Fox’ and the Asiatic cultivar ‘Connecticut King’ were made, and some of these F1 hybrids, which show a relatively high fertility with the production of unreduced gametes, were backcrossed with an Asiatic cultivar . The meiosis of the interspecific hybrids, as well as the sexual polyploidized progenies, were analysed by GISH and FISH. In addition, one population of sexual polyploidized AOA hybrids was also analysed for the genome composition. Results showed that there was no evidence that lily allopolyploids possess any noticeable chromosome rearrangements. The equal segregation of reciprocal and non-reciprocal recombinant product showed that the intergenomic recombination in the sexual polyploidized progenies was indeed from a natural process-chiasmata formation and crossovers and hence, should not be considered as translocations as was suggested in literature for intergenomic recombination. This conclusion was further confirmed by meiotic observation of the interspecific F1 hybrids.

Detailed meiotic observations were carried out in interspecific hybrids between Longiflorum × Asiatic groups of lilies (Lilium) which were used as parents to generate sexual polyploids with intergenomic recombination. Bivalents involving two homoeologous chromosomes, as well as unpaired univalents were the main configurations at metaphase I. However, in two genotypes, multivalents and bivalents both involving non-homologous pairing of two Asiatic chromosomes were observed. This indicated the presence of a duplication which was common to two non-homologous chromosomes in the hybrids. It is deduced that there was a reciprocal translocation in the Asiatic parent cv. ‘Connecticut King’ and these two genotypes resulted from duplication-deficiency gametes. Results from Anaphase I showed that chiasma formation involving non-sister chromatids gave rise to two strand single, two strand double, three strand double, four strand double and multiple exchanges. It is also noticeable that there was a high frequency of multiple crossovers in the genotypes with duplication, indicating a reduced crossover interference in multivalents. Beside the normal crossovers, also chromosome bridges at anaphase I of meiosis were observed. GISH and FISH painting showed that these bridges involve not only non-sister chromatids but also sister-chromatids. The bridges, without any differentiation along their length, were always accompanied by fragments with a variable size. These results indicated that the bridges, together with the accompanying fragments, were derived from U-type exchanges. Other than homologous recombination (HR), nonhomologous end joining (NHEJ) probably led to the production of bridges when repairing the double strand breaks (DSBs) during meiosis.

Progenies from unilateral polyploidization of crosses between LA hybrids and Asiatic cultivars were predominant triploids. However, three exceptional plants, which possessed 35 normal chromosomes and a small aberrant chromosome instead of the expected normal number of 36, were observed. In all three cases the small aberrant chromosomes were isochromosomes which had obviously originated during the first backcross generation, and the length of the arms of these aberrant chromosomes were always related with the length of the short arm of the missing chromosome. Furthermore, one of these three chromosomes possessed 45S rDNA hybridization sites in the proximal positions, which resembles the short arm of the missing chromosome (chromosome 4 of L genome). Combined with the results of chromosome breakage during meiosis, centric breakage and fusion is a putative mechanism of the production of these isochromosomes. Meanwhile, two small, supernumerary or B chromosomes were detected as extra chromosomes in a tetraploid plant derived from chromosome doubling of an intersectional hybrid (2n=2x=24) between a cultivar of the Longiflorum (L) and the Trumpet (T) group. When this tetraploid LLTT hybrid was crossed with a triploid LLO hybrid (O=Oriental), the B chromosome was transmitted to 73.4% of the progenies. Based on GISH and FISH characterization it was shown that the B chromosome found consisted of two identical arms, with 5S rDNA hybridizing to the majority of it, which were flanked by normal telomeres, suggesting that this is an isochromosome.

The results of current investigations are of practical implication for a number of reasons. Firstly, the behavior of homoeologous chromosomes during meiotic processes in lily hybrids was studied in detail, and it can be used to explain the profound genetic changes in the early generations during hybrid speciation. Secondly, some problems that go unnoticed in genetic mapping can be predicted and well explained by the occurrence of chromosome rearrangements in the parents which are used to produce the segregation population and thirdly, the discovery of U-type exchanges during meiosis and de novo isochromosomes in the backcross progenies supplies an alternative mechanism for the origin of B chromosomes.

Buddleja davidii en hybriden : sortimentonderzoek en keuringsrapport
Hop, M.E.C.M. - \ 2011
Dendroflora 2011 (2011)48. - ISSN 0374-7247 - p. 34 - 67.
buddleja davidii - houtachtige planten als sierplanten - rassen (planten) - cultivars - hybriden - winterhardheid - gebruikswaarde - ornamental woody plants - varieties - hybrids - winter hardiness - use value
In Buddleja davidii zijn de afgelopen jaren veel ontwikkelingen geweest. Om het kaf van het koren te scheiden is eerst een proef in Boskoop gedaan, die later ook nog in Europees verband is opgepakt. De keuringsresultaten worden hier gepresenteerd. Tevens volgt een overzicht van wereldwijd beschikbare Buddleja's waaronder meerdere veelbelovende nieuwigheden.
Towards F1 Hybrid Seed Potato Breeding
Lindhout, P. ; Meijer, D.A. ; Schotte, T. ; Hutten, R.C.B. ; Visser, R.G.F. ; Eck, H.J. van - \ 2011
Potato Research 54 (2011)4. - ISSN 0014-3065 - p. 301 - 312.
plantenveredeling - plantenveredelingsmethoden - hybridisatie - hybriden - diploïdie - zelfincompatibiliteit - aardappelen - plant breeding - plant breeding methods - hybridization - hybrids - diploidy - self incompatibility - potatoes - species solanum-chacoense - inhibitor sli gene - self-compatibility - quantitative trait - diploid potatoes - yield - heterosis - sequence - markers - tomato
Compared to other major food crops, progress in potato yield as the result of breeding efforts is very slow. Genetic gains cannot be fixed in potato due to obligatory out-breeding. Overcoming inbreeding depression using diploid self-compatible clones should enable to replace the current method of out-breeding and clonal propagation into an F1 hybrid system with true seeds. This idea is not new, but has long been considered unrealistic. Severe inbreeding depression and self-incompatibility in diploid germplasm have hitherto blocked the development of inbred lines. Back-crossing with a homozygous progenitor with the Sli gene which inhibits gametophytic self-incompatibility gave self-compatible offspring from elite material from our diploid breeding programme. We demonstrate that homozygous fixation of donor alleles is possible, with simultaneous improvement of tuber shape and tuber size grading of the recipient inbred line. These results provide proof of principle for F1 hybrid potato breeding. The technical and economic perspectives are unprecedented as these will enable the development of new products with combinations of useful traits for all stakeholders in the potato chain. In addition, the hybrid’s seeds are produced by crossings, rendering the production and voluminous transport of potato seed tubers redundant as it can be replaced by direct sowing or the use of healthy mini-tubers, raised in greenhouses.
Invloed lagere nachttemperatuur tijdens opkweek Phalaenopsis
Kromwijk, J.A.M. ; Campen, J.B. - \ 2011
Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1115) - 80
phalaenopsis - hybriden - cultivars - luchttemperatuur - orchidaceae - bloei-inductie - teelt - energiebesparing - nederland - glastuinbouw - sierteelt - hybrids - air temperature - flower induction - cultivation - energy saving - netherlands - greenhouse horticulture - ornamental horticulture
In Amerika bleven twee Phalaenopsiscultivars geteeld bij een hoge dag- en lage nachttemperatuur (29/23 oC en 29/17 oC) volledig vegetatief. In Nederlands onderzoek, gefinancierd door het ministerie van EL&I en het Productschap Tuinbouw in het kader van het programma Kas als Energiebron, bleek dat het tegenhouden van de bloei door middel van een dagtemperatuur van 29°C en een lage nachttemperatuur sterk afhankelijk is van de cultivar. Bij de cultivars ‘Boston’, ‘Bristol’ en ‘Lennestadt’ werd de bloemtakvorming gedurende de eerste 23 weken van de opkweek wel voldoende tegen gehouden, maar bij de andere 5 cultivars (‘Chalk Dust’, ‘Fire Fly’, ‘Liverpool’, ‘Precious’ en ‘Vivaldi’) werden al meer of minder snel voortakken gevormd. Ondanks het achterblijven van de bladafsplitsing en de weggeknipte voortakken na een opkweek bij een hoge dag- en lage nachttemperatuur, was het percentage meertakkers (=planten met minimaal 2 bloemtakken) in het veilingrijpe stadium maar 5 tot 8% lager dan na een gangbare opkweek bij een constante temperatuur van 28 oC. Voor toepassing van een lagere nachttemperatuur onder gangbare praktijkomstandigheden is een energiebesparing berekend van 8%.
Praktijkervaringen lelies koken met voor- en nawarmte
Kok, B.J. ; Aanholt, J.T.M. van - \ 2010
BloembollenVisie 2010 (2010)184. - ISSN 1571-5558 - p. 22 - 23.
bloembollen - lelies - cultivars - hybriden - heetwaterbehandeling - warmtebehandeling - steriliseren - mijten - dood - ornamental bulbs - lilies - hybrids - hot water treatment - heat treatment - sterilizing - mites - death
In 2009 hebben 10 lelietelers de nieuwe kookbehandeling bij 41°C in combinatie met voor- en nawarmte in 27 leliecultivars uit de groep van de Oriëntals en de LA-hybriden. De resultaten waren positief
Broei en afzet van biologische lelies
Kok, B.J. ; Kool, S.A.M. de - \ 2009
Lisse : Praktijkonderzoek Plant & Omgeving, Bloembollen (PPO 721) - 34
biologische landbouw - bloementeelt - forceren van planten - lelies - liliaceae - lilium longiflorum - hybriden - organic farming - floriculture - forcing - lilies - hybrids
Jaarrond levering van biologische bloemen is nog niet goed mogelijk. Vooral in het voorjaar en najaar is er een tekort aan bloemen die een substantieel deel kunnen uitmaken van biologische boeketten. In dit project werd onderzocht of het mogelijk is om in genoemde periodes biologische lelies te broeien. Het uitgangspunt daarbij is dat de lelies zonder of met minimale belichting in bloei worden getrokken. Uit een inventarisatie onder lelieveredelaars is naar voren gekomen dat lelies uit de groep van de LA-hybriden het meest geschikt zijn om zonder licht te broeien. Ook lelies uit de groep van de Longiflorums zouden geschikt zijn om zonder licht in bloei te trekken maar de verwachting is dat de trekduur erg lang zal zijn. Leliebollen uit de groep van de orientals zijn te duur als uitgangsmateriaal voor de biologische broeierij. Er werden 5 cultivars uit de groep van de LA-hybriden getest en 1 cultivar uit de groep van de Longiflorums. De roze bloeiende LA-hybride Brindisi en de rood bloeiende LA-hybride California bleken geschikt te zijn om in de winter zonder belichting in bloei te trekken. Met minimale belichting was ook Salmon Classic bij alle geteste plantdata in bloei te trekken
A molecular cytogenetic study of intergenomic recombination and introgression of chromosomal segments in lilies (Lilium)
Nadeem Khan, M. - \ 2009
University. Promotor(en): Richard Visser; Jaap van Tuyl. - [S.l. : S.n. - ISBN 9789085853800 - 121
lilium - cytogenetica - recombinatie - genomen - introgressie - hybridisatie - hybriden - genetische kartering - polyploïdie - koppelingskartering - cytogenetics - recombination - genomes - introgression - hybridization - hybrids - genetic mapping - polyploidy - linkage mapping
Lilies (Lilium L.) are one of the most important ornamental bulbous crops for cut flower industry
grown extensively in The Netherlands for last few decades. The genus Lilium consists of seven
different sections with about 80 species. The species within genus Lilium (2n = 2x = 24)
comprise a range of desirable and complementary characters. Besides being an important
horticultural crop, lily (Lilium) also serves as an interesting model plant for molecular
cytogenetic research and introgression breeding for several reasons like, i). Lily is a model crop
for interspecific hybridization and it includes plants of different taxonomic species each of which
possess valuable horticultural traits that need to be combined in the new cultivars. ii) Through
careful selection n and 2n gametes can be obtained in interspecific hybrids. iii) The genomes of
different species are so well differentiated genetically that the parental chromosomes can be
clearly identified in the F1 hybrids as well as in the progenies through DNA in situ hybridization
techniques. iv) The chromosomes are large enough and the number and position of
homoeologous recombination sites can be clearly detected. v) The large and easily identified
chromosomes in different lily species could be a potential source for the cytological mapping of
the Lilium genomes. Taking advantage of these favourable attributes of lily, a molecular
cytogenetic investigation was conducted to evaluate the amount of recombination and
introgression of characters between Longiflorum - Asiatic (LA) and Oriental - Asiatic (OA)
hybrids through the use of n and 2n gametes.
For this purpose different F1 Longiflorum × Asiatic (LA) and Oriental × Asiatic (OA)
hybrids were backcrossed with different Asiatic cultivars. Ovule and embryo rescue techniques
were employed to get backcross (BC) progenies. Most of the F1 LA appeared to be sterile but
some hybrids were able to produce only 2n gametes in considerable frequencies. However, in
rare occasions it was also found that normal meiosis took place in few of the LA hybrids which
resulted into the formation of normal n gametes. Ploidy level and intergenomic recombination
was studied in LA interspecific hybrids in order to assess the possibility of functional n gametes
and their potential use in introgression at diploid level in lily. A total of 104 BC1 LA
interspecific lily hybrids were obtained, 27 diploids (2n = 2x = 24), 73 triploids (2n = 2x = 36)
and 4 aneuploids (2x – 1, 2x + 2 or 2x + 3). Similarly, triploid BC1 (LAA) plants were
backcrossed to diploid Asiatic parents. As a result 14 diploid BC2 progenies were produced. The
intergenomic recombination and amount of introgression of respective genome (L and A) was
assessed in these diploid genotypes through GISH (Genomic in situ Hybridization). Extensive
intergenomic recombination was found among the chromosomes in LA hybrids. A large of
amount of L- genome was transmitted from F1 LA hybrids to their subsequent BC1 progenies.
However, very few segments of L- genome were introgressed from the BC1 diploid and triploid
(LAA) plants to the BC2 progenies (Chapter 2). GISH identifies a considerable amount of
recombination events amongst different interspecific lily hybrids (LA and OA) obtained from
functional 2n gametes. Based on recombination sites on different chromosomes identified by
GISH, cytological maps of three genomes of Lilium were constructed. For this purpose, BC
progenies of two diploid interspecific hybrids of lily, viz., Longiflorum × Asiatic (LA) and
Oriental × Asiatic (OA) were used. The BC progenies of LA hybrids consisted of both triploid
(2n = 3x = 36) and diploid (2n = 2x = 24) with some aneuploid genotypes and those of OA
hybrids mostly consisted of triploid (2n = 3x = 36) and some aneuploid genotypes. In LA
hybrids 248 recombination sites were cytologically localized on 12 different chromosomes of
each genomes (i.e., L and A). Similarly, 116 recombinant sites were marked on 12 chromosomes
each from the BC progenies of OA hybrids (O and A genomes). The distances of the
recombination sites from the centromeres are measured (in micrometres). Based on these
recombination sites four cytological maps were constructed. Since an Asiatic parent was
involved in both hybrids, viz., LA and OA, two maps were constructed for A genome which
were indicated as Asiatic (L) and Asiatic (O) and one each for Longiflorum (A) and Oriental (A)
genomes (Chapter 3).
With a view to generate genetic variation via homoeologous recombination in BC
progenies of LA and OA hybrids the most logical approach was the use of 2n gametes. 63 BC1
LA (LA × AA or AA × LA) and 53 OA (AA × OA) progeny plants were obtained after unilateral
sexual polyploidization. 16 genotypes from F2 LA populations were obtained after bilateral
sexual polyploidization through sib-mating of F1 LA hybrids. GISH was employed for the
identification of the parental genomes, mode of origin of these progenies and measurement of the
introgression in different interspecific lily hybrids. Most of the BC1 progeny plants (LA and OA)
had originated through 2n gametes by First Division Restitution (FDR) mechanism. However,
there were 12 genotypes in LA hybrids and four genotypes in OA hybrids that originated through
2n gametes formation as the result of Indeterminate Meiotic Restitution (IMR). A higher amount
of recombination was found in LA hybrids as compared to OA hybrids. Intergenomic
recombination was also determined in the sib-mated F2 LA population. In this case both parents
had contributed gametes with the somatic number of chromosomes (i.e., 2n-2n) thus confirming
the event of bilateral sexual polyploidization in interspecific LA hybrids. Based on these results,
the relevance of interspecific lily hybrids obtained from uni- and bilateral sexual
polyploidization leading to allotriploid and allotetraploid formation in interspecific lily hybrids is
discussed in the context of introgression and mapping (Chapter 4). Molecular markers are an important tool for the construction of genetic linkage maps, as the first step in the genetic
dissection of the required traits leading to crop improvement followed by the marker assisted
breeding in different plants. Lilium has one of the largest genome in plant kingdom and genetic
mapping in lilies is constrained by its large genome. DArT (Diversity Array Technology), a
molecular marker technique can detect and type DNA variation at several hundred genomic loci
in parallel without relying on genome sequence information. The DArT technique was developed
for Longiflorum × Asiatic (LA) lily hybrids to enable an efficient and effective genetic mapping
with the production of a large numbers of markers in microarrays-based assay. The restriction
enzyme PstI + TaqI combination generated the largest frequency of polymorphic genomic
representations for a genotyping array. Genomic representations from 88 F1 LA plants were used
to assemble a DArT genotyping microarray. A total of 687 DArT markers were developed and
382 polymorphic markers were mapped on 14 main linkage groups which is two more then the
haploid chromosome number (i.e. n = 12). The resulting linkage map with 382 DArT markers
spanned 1329 cM (3.5 cM/marker on average). The results highlighted the potential of DArT as
a genetic technique for genome profiling in the context of molecular breeding and genomics,
especially in crops with large genome sizes where other techniques proved to be less useful
(Chapter 5).
The results of the present investigation are of practical implication. These results show
the advantages of the n gametes and their subsequent progenies which opened a new approach of
lily breeding ‘the analytic breeding’ in the allopolyploids. It also shows the possibility of using
certain triploid hybrids for further breeding. A comparison has been made between different
types of interspecific crosses, the amount of intergenomic recombination and introgressions of
chromosomal segments obtained after unilateral sexual polyploidization. Furthermore, bilateral
sexually polyploidization via sib-mated F1 hybrids producing 2n gametes has been proven. The
use of allotetraploids obtained from bilateral sexual polyploidization could be a novel approach
in the breeding of LA-hybrids. These allotetraploid with recombinant chromosomal segment
may be a potential source to generate genetic variation in subsequent progenies. The molecular
cytogenetic GISH and FISH techniques proved to be a powerful tool useful for the construction
of cytogenetic maps in interspecific crosses in crops with large genomes sizes like lily. These
techniques are also used for the identification and integration of genetic maps with chromosome
maps. FISH also helps to monitor the introgressed chromosome segment or marker of interest in
the subsequent progenies. Application of the DArT technique proved to be an effective method
to construct genetic linkage maps especially crops (like Lilium) with large genome sizes where
other techniques might be less useful.

Hoever staat het met de OA-hybriden?
Tuyl, J.M. van; Silfhout, A.A. van - \ 2007
BloembollenVisie 1 (2007)107. - ISSN 1571-5558 - p. 24 - 25.
lilium - bloembollen - plantenveredeling - rassen (planten) - hybriden - laboratoriumproeven - ornamental bulbs - plant breeding - varieties - hybrids - laboratory tests
In de ontwikkeling van het leliesortiment spelen niet alleen veredelingsbedrijven zelf een belangrijke rol. Ook in Wageningen vormen allerlei lastige kruisingen onderwerp van studie. Al veertien jaar is de kruising tussen Oriëntal en Aziaat een project dat voor twaalf veredelingsbedrijven wordt uitgevoerd door PlantBreeding van WUR. In dit artikel de stand van zaken in dat project
Red de iep
Hiemstra, J.A. ; Kopinga, J. ; Buiteveld, J. - \ 2007
De Boomkwekerij 20 (2007)5. - ISSN 0923-2443 - p. 18 - 19.
ulmus - ulmaceae - ulmus laevis - ulmus glabra - ulmus minor - hybriden - rassen (planten) - ophiostoma ulmi - ziekteresistentie - hybrids - varieties - disease resistance
Het gebruik van de iep - ook resistente iepen - is in de afgelopen decennia dan ook sterk afgenomen. Hierdoor verdwijnt de iep steeds meer uit het Nederlandse landschap. De onvrede van groenbeheerders en boomkwekers leidde in de afgelopen jaren tot een aantal discussiebijeenkomsten over de toekomst van de iep. De conclusie hiervan was dat de iep in Nederland niet kan worden gegemist. Het nieuwe iepenproject van PPO en Alterra is onderzoek doen naar de groei- en gebruikseigenschappen van het huidige iepensortiment. Om de rassen onderling goed te kunnen vergelijken worden proefbeplantingen aangelegd waar rassen naast elkaar worden uitgeplant. De eerste twee grote beplantingen worden door de gemeente Amsterdam aangelegd in IJburg en het Westpoortgebied.
The use of 2n gametes for introgression breeding in Oriental x Asiatic lilies
Barba Gonzalez, R. - \ 2005
University. Promotor(en): Richard Visser, co-promotor(en): Jaap van Tuyl. - Wageningen : S.n. - ISBN 9085042682 - 111
lilium - plantenveredeling - introgressie - gameten - hybriden - ploïdie - genetische variatie - chromosoomtransmissie - plant breeding - introgression - gametes - hybrids - ploidy - genetic variation - chromosome transmission
Is bastaardering tussen zomer- en wintereik een gevaar voor de vitaliteit van eiken
Dam, B.C. van; Bovenschen, J. ; Kranenborg, K.G. ; Das, C. - \ 2001
Nederlands Bosbouwtijdschrift 2001 (2001)73. - ISSN 0028-2057 - p. 6 - 10.
quercus - quercus robur - quercus petraea - hybriden - hybridisatie - soortkruising - hybride rassen - plantenmorfologie - bladeren - genetische analyse - hybrids - hybridization - interspecific hybridization - hybrid varieties - plant morphology - leaves - genetic analysis
Over het begrip soort bij zomereik en wintereik (twee soorten of één soot met twee ecotypen), de morfologische verschillen, het voorkomen van soorten met intermediaire morfologische kenmerken in gemengde eikenbossen, en de vraag of hierbij sprake is van echte hybriden of niet. Kruisingsexperimenten en internationaal onderzoek naar de genetische diversiteit met behulp van bladkenmerken lossen het probleem van de bastaardisering tussen zomer- en wintereiken in Europa niet op; ouderschapsanalyse met behulp van DNA-technologie moet uitkomst brengen
Vergelijkend onderzoek naar de gebruikswaarde van twaalf Nederlandse en veertien Belgische klonen van populier. Comparative research on characteristics of twelve Dutch and fourteen Belgian poplar clones
Kranenborg, K.G. ; Vries, S.M.G. de - \ 1998
Wageningen : IBN-DLO (IBN-rapport 359) - 28
forestry - trials - hybrids - tree breeding - trees - plant breeding - clones - silviculture - forestry practices - growth - environmental factors - netherlands - belgium - bosbouw - proeven - hybriden - boomveredeling - bomen - plantenveredeling - klonen - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - nederland - belgië
A cytological characterization of genomes of Alstroemeria, the production of interspecific hybrids, and their performance during micropropagation
Buitendijk, J.H. - \ 1998
Agricultural University. Promotor(en): Evert Jacobsen; M.S. Ramanna. - S.l. : Buitendijk - ISBN 9789054858645 - 131
chromosomen - sierplanten - amaryllidaceae - somatische hybridisatie - soortkruising - hybriden - genen - weefselkweek - embryokweek - chromosomes - ornamental plants - somatic hybridization - interspecific hybridization - hybrids - genes - tissue culture - embryo culture
<p>The vegetatively propagated ornamental <em>Alstroemeria</em> has become highly popular in a relatively short period. During the last 40-50 years botanists and breeders realized that the genus <em>Alstroemeria</em> has tremendous potential as a cut flower crop, a bedding plant and a potted plant. They also became aware of the limited knowledge regarding the species and the interspecific hybrids that in several cases occurred spontaneously in their nurseries. There was a growing need for species descriptions and background information on their natural habitats. During the last 25 years, and especially during the last ten years, much information became available on the cultivation methods, tissue culture techniques and on the application of mutation breeding. Biosystematic studies and cytological investigations on chromosomes were, however, scarce in comparison to other major cut flowers.</p><p>In the biosystematic work on <em>Alstroemeria</em> frequent use was made of characteristics of the flowers. The underground organs, i.e. the rhizome and the root system, have not been described extensively. With the assumption that the morphological features of the rhizomes may affect micropropagation, the underground organs of several species and hybrids were studied. This investigation resulted in descriptions and illustrations of the general morphological structure of the rhizome, and of the underground organs of nine species and three hybrids in particular. The rhizomes varied considerably in length, diameter, internodal length, and the number of lateral rhizomes and visible axillary buds, giving more substance to the idea that the different species and hybrids respond differently when propagated <em>in vitro</em> .</p><p>A large part of the research that is described in this thesis concerned the chromosomes and genomes of <em>Alstroemeria</em> species and hybrids. The chromosomes of eight species were analysed after staining with Feulgen's reagent. The morphology of the chromosomes, i.e. the length, arm length ratio and the secondary constrictions, was clearly visible and chromosome arms could be measured. The application of Giemsa C-banding displayed unique banding patterns on the chromosomes of each of the eight species that were investigated. These banding patterns have cytotaxonomic value, and, once a larger number of species and species accessions has been studied, can throw light on the evolutionary events that occurred within the genus. The length of the chromosome complement already indicated that the species of <em>Alstroemeria</em> possess large genomes.</p><p>This finding was confirmed through flow cytometric analysis of nuclear DNA amounts. The amount of nuclear DNA in the diploid cells (2C-values), as determined through flow cytometric measurement of the relative fluorescence of isolated nuclei that were stained with propidium iodide (PI), ranged from 36.5 to 78.9 pg among the accessions of 12 species. When nuclei were stained with DAPI, a fluorescent dye with different staining properties, different values were obtained. The ratio of PI and DAPI fluorescence varied from 1.60 to 1.88. The Brazilian species had lower PI/DAPI ratios (1.60-1.67) than the Chilean species (1.68-1.88). The 2C-values together with the PI/DAPI ratio of the twelve species enabled the separation of species into four groups. These groups were (1) <em>A. magnifica</em> ssp. <em>magnifica</em> , <em>A. pelegrina</em> , <em>A. philippii</em> and <em>A. pulchra</em> ssp. <em>pulchra</em> , (2) <em>A. angustifolia</em> ssp. <em>angustifolia</em> , <em>A. aurea</em> and <em>A. hookeri</em> ssp. <em>hookeri</em> , (3) <em>A. ligtu</em> ssp. <em>ligtu</em> and <em>A. ligtu</em> ssp. <em>simsii</em> , and (4) <em>A. brasiliensis</em> , <em>A. caryophyllaea</em> , <em>A. inodora</em> and <em>A. psittacina</em> .</p><p>There were remarkable karyotype similarities within each of these groups, with regard to total chromosome length and C-banding pattern. A survey of the extent of intraspecific variation in genome size of three Chilean species revealed up to 1.21 fold variation in <em>A. ligtu</em> . The variation in genome size could be attributed to C-band and chromosome length polymorphism. The intraspecific variation in <em>A. magnifica</em> ssp. <em>magnifica</em> was discontinuous, and might be due to a broad taxonomic species concept of this particular taxon [as, according to Bayer (1987), the taxa <em>A. gayana</em> and <em>A. sierrae</em> are conspecific with <em>A. magnifica</em> ssp. <em>magnifica</em> ]. Giemsa C-banding and flow cytometry could both be used to check the hybrid nature of the plants that were produced in the interspecific hybridization programmes. Individual chromosomes of the parental species could be recognized in the C-banded karyotypes of most hybrids, and 2C-values as determined through flow cytometry were intermediate between those of the two parents. With the technique of flow cytometry it was possible to distinguish between aneuploid (2n=4x+1=33) and euploid (2n=4x=32) plants.</p><p>In order to obtain well defined plant material, species were collected from breeders, botanical gardens and research institutes, and interspecific crosses were made between five species, that are often used in the development of cultivars. These were the Chilean species <em>A. aurea</em> , <em>A. pelegrina</em> and <em>A. magnifica</em> ssp. <em>magnifica</em> and the Brazilian species <em>A. inodora</em> and <em>A. psittacina</em> . Seed set in interspecific crosses, however, was poor. Histological observations of the fertilized ovules revealed a poor development of the endosperm, and a reasonable to good development of the embryo during the first two to three weeks after pollination. Through <em>in vitro</em> culture of dissected ovules, it was possible to produce more than 250 hybrids.</p><p>Conventionally, <em>Alstroemeria</em> plants are vegetatively propagated by division of greenhouse grown rhizomes, usually once a year. The multiplication rate with this practice of propagation is rather low (about two to six new plants), because it is restricted by the number of lateral rhizomes that are present on the mother plant. The development of micropropagation methods, using in vitro grown rhizomes, has enabled the mass propagation of plant material. However, the rhizome multiplication rate of hybrids is mostly unpredictable, and for groups of cultivars it is extremely low. An analysis of the rhizome multiplication rate of defined plant material, consisting of species and their interspecific hybrids, demonstrated that there is a genetic base for the performance during micropropagation. Thus, it is worthwhile to incorporate rhizome multiplication rate as a selection criterion in <em>Alstroemeria</em> breeding programmes. The choice of parental species and genotypes, to be used in interspecific crosses, is crucial. Because of the high degree of heterozygosity of the parental genotypes, selection among full sibs can be profitable. Morphological features of the rhizomes, such as the number of rhizome nodes, the degree of branching, and internodal length, may serve as criteria for indirect selection. It is suspected that the complementation of these morphological traits in the parental genotypes might lead to a superior micropropagation performance of the hybrid.</p><p>The research that is described in this thesis has contributed by providing defined plant material and basic information on species and hybrids of <em>Alstroemeria</em> . The results are beneficial for the breeding of new cultivars, and for further applied and fundamental research in the genus <em>Alstroemeria</em> .</p>
Regeneration and interspecific somatic hybridization in Allium for transfer of cytoplasmic male sterility to leek
Buiteveld, J. - \ 1998
Agricultural University. Promotor(en): Evert Jacobsen; J. Creemers-Molenaar. - S.l. : Buiteveld - ISBN 9789054858133 - 127
somatische hybridisatie - soortkruising - hybriden - verjonging - allium - hybridisatie - mannelijke steriliteit - somatic hybridization - interspecific hybridization - hybrids - regeneration - hybridization - male sterility
<p>The vast majority of the present day leek cultivars is of poor quality. The genetic constitution of leek makes it a difficult crop to breed and consequently mass, or family selection methods, both of which have a low efficiency, are mainly used. F <sub>1</sub> hybrid breeding seems the appropriate strategy for improvement of leek. With such a breeding system a higher uniformity of the crop, better fixation of desirable traits, such as pest and disease resistance and a better exploitation of heterosis effects can be achieved. Large-scale seed production of hybrid cultivars requires a hybridization system based on cytoplasmic male sterility (CMS), because of the considerable advantage of this system in maintaining the male sterile parent line. Since no source of CMS has yet been found in leek or related forms of <em>A. ampeloprasum</em> , several researchers are focused on introducing cytoplasmic male sterility into leek. In the present thesis the possibility of introducing CMS into leek via somatic hybridization with <em>A. cepa</em> as CMS donor was investigated. Successful application of such a technique requires an efficient system for regeneration of plants from protoplasts. At the beginning of the research project in 1990 such a protoplast-to-plant system for leek was not available. Therefore, substantial effort was directed towards the development of efficient plant regeneration methods from embryogenic callus cultures, suspension cultures and protoplasts.</p><p>Initially, much attention was focused on development of regenerative callus cultures from different explants and cultivars. The highest compact callus response was obtained when mature, zygotic embryos were cultured on MS medium, containing 30 g/l sucrose and 1 mg/l 2,4-D. Significant differences were found between the cultivars and accessions for shoot formation frequency. In addition, a genotype-dependent response of leek embryo explants for the formation of shoots was evident.</p><p>In contrast to plant regeneration from compact embryogenic callus of leek, which is efficient and easy to achieve, the establishment of suspension cultures from this type of callus was less successful. Although compact callus cultures in liquid medium retain their ability to form somatic embryos and shoots for a long period, they do not become a finely-dispersed suspension culture. For this purpose, a new friable embryogenic type of callus was induced on immature embryos instead of mature embryos. This friable callus comprised numerous globular embryoids, embedded in mucilage and is highly regenerative when plated on a cytokinin containing medium. It was found that the developmental stage of the immature embryo and the genotype of the donor plant significantly influenced the callus response. Characterization of the two callus types by a histological examination revealed striking differences and supported the suggestion that friable callus is more suitable for initiating suspension cultures than compact callus. A stringent selection within these friable callus cultures was necessary to obtain highly-embryogenic suspension cultures.</p><p>A procedure was described for the isolation, culture and regeneration of plants from protoplasts derived from these embryogenic suspension cells. Imbedding in alginate was an important factor in increasing the plating efficiency. The regeneration frequency of the protoplast-derived calli was primarily affected by the type of callus that developed. The protoplast-to-plant system described was reproducible for at least three genotypes. Plants were regenerated within 6 months after protoplast isolation.</p><p>Utilising this regeneration procedure for protoplasts, a method for symmetric hybridization between leek and onion as a CMS donor was set up. The fusion experiments yielded large numbers of hybrid calli and plants. The aneuploid status of the hybrid plants could be explained by the use of leek protoplasts, derived from an aneuploid suspension culture. This also implied that using cell suspensions as a protoplast source for fusion remains a restrictive factor in the establishment of a successful hybridization system for leek. The leaf morphology of the hybrids was intermediate between the two parents. It appeared that most of the hybrids possessed leek chloroplasts and a rearranged mitochondrial genome of both parents, but with a predominance of mtDNA fragments from leek.</p><p>With the methods described in this thesis the first steps to transfer CMS to leek have been realized. The results described here show that a cytoplasm of onion can be successfully transferred to leek via somatic hybridization. Future research should focus on further improvement of the system. For this, optimization of some aspects of the regeneration process and developing an efficient selection system for the desired hybrids, containing the onion specific CMS mtDNA sequences should be accomplished. The research has shown that somatic hybridization has a high potential to obtain CMS leek plants.</p>
Characterisation of alien chromosomes in monosomic additions of Beta
Mesbah, M. - \ 1997
Agricultural University. Promotor(en): Evert Jacobsen; W. Lange. - S.l. : Mesbah - ISBN 9789054857020 - 106
chromosomen - plantenveredeling - ziekteresistentie - plaagresistentie - beta vulgaris - suikerbieten - nucleïnezuren - moleculaire genetica - heterosis - inteelt - hybridisatie - hybriden - chromosomes - plant breeding - disease resistance - pest resistance - sugarbeet - nucleic acids - molecular genetics - inbreeding - hybridization - hybrids
<p>Wild <em>Beta</em> species of the section <em>Procumbentes</em> carry genes for several valuable agronomical traits, and are considered to be of interest for the breeding of cultivated beet <em>(B. vulgaris</em> subsp. <em>vulgaris).</em> In spite of several barriers, it was shown that gene transfer from <em>B</em> . <em>procumbens</em> into sugar beet is possible. In such studies monosomic additions (2n=19) in <em>B. vulgaris,</em> harbouring different individual chromosomes of the wild species, play a very important role. To select the monosomic addition plants, an extensive number of different <em>B.</em><em>procumbens</em> or <em>B. patellaris</em> derived monosomic addition families were screened, using repetitive DNA sequences and a squash-blot hybridisation procedure. The extra chromosomes of the monosomic additions were identified with the aid of DNA fingerprinting. In <em>B</em> . <em>procumbens</em> derived monosomic additions, the chromosome numbers of two additions had to be renamed. Seventyfive anonymous <em>B.</em><em>patellaris</em> derived monosomic additions were grouped in nine different groups, many of them with two sub-groups. The. morphological characteristics of the plants of the nine different groups of monosomic additions of <em>B. patellaris</em> were described and comparisons were made between these groups and the monosomic additions of <em>B.</em><em>procumbens.</em> Chromosome characterisation also was studied using fluorescence <em>in situ</em> hybridisation on mitotic chromosomes and extended DNA fibres of a series of monosomic additions of <em>B. procumbens.</em> The monosomic additions were evaluated in greenhouse tests for resistance to the beet cyst nematode <em>(Heterodera schachtii), Cercospora beticola, Polymyxa betae</em> and BNYVV. These experiments permitted the localisation of major genes for resistance on specific chromosomes, and the study of some quantitative effects.
Interspecific hybridization in the genus Tulipa L.
Creij, M.G.M. van - \ 1997
Agricultural University. Promotor(en): J.L. van Went; J.M. van Tuyl. - S.l. : Van Creij - ISBN 9789054856344 - 163
somatische hybridisatie - soortkruising - hybriden - bestuiving - in vitro - experimenten - bloembollen - tulipa - somatic hybridization - interspecific hybridization - hybrids - pollination - experiments - ornamental bulbs
<p>The genus <em>Tulipa L.</em> comprises about 55 species. The tulip species are classified in two subgenera, <em>Tulipa</em> and <em>Eriostemones,</em> which are subdivided into five and three sections respectively. Commercial tulips are mainly cultivars of <em>T. gesneriana</em> L <em>.</em> and of Darwin hybrids, the latter of which are obtained by interspecific hybridization between <em>T. gesneriana</em> and <em>T. fostefiana</em> Hoog ex . Irving. The present-day tulip assortment could be improved considerably by introducing traits from other tulip species, such as resistance for diseases and short forcing period. With conventional breeding methods, hybrids can only be obtained from a limited number of interspecific crosses. Most interspecific crosses are hampered by crossing barriers. The main goal of the research on crossing barriers in tulip was to bypass crossing barriers between cultivars of the present-day assortment and the other tulip species.<br/>This main goal was divided into two subgoals: (1) the identification of crossing barriers in crosses between T. <em>gesneriana</em> and a number of representative tulip species and (2) the development of techniques to bypass these barriers.<p>Pre-fertilization development and post-fertilization development have both been studied in a number of crosses to identify crossing barriers. Pre-fertilization development was analyzed in crosses between cultivars of <em>T.</em><em>gesneriana</em> and 13 tulip species from all eight sections of the genus <em>Tulipa</em> (Chapter 2). Pollen tube growth in the pistil and pollen tube penetration in the ovules showed much variation between the crosses in progamic development. Depending on the cross, pollen tubes grew as far as the stigma or the style or continued growing down into the ovary. This resulted in percentages of ovules with pollen tube penetration varying between 0%-79%. The percentages ovules with pollen tube penetration differed between the flowers of a specific cross, between the different years and between the maternal genotypes used.<p>The progamic phase and embryo and endosperm. development were studied in the incongruent cross <em>T.</em><em>gesneriana x T. agenensis DC.</em> (former name T. oculus-solis St. Amans) (Chapter 3) and in a compatible <em>T. gesneriana</em> cross. Less pollen tubes penetrated the ovules in the interspecific cross in comparison with the compatible cross. In the interspecific cross, the embryo development was more often retarded and higher percentages of ovules with aberrant embryogenesis (from 32 days after pollination) were found than in the compatible cross. In most ovules with aberrations in embryo development, also the endosperm showed abnormalities. Endosperm degeneration seems to be the major cause of starvation of the embryo before seed maturity in the cross <em>T. gesneriana x T. agenensis.</em><p>Several techniques have been studied for bypassing pre-fertilization barriers in interspecific tulip crosses: the cut-style method, the grafted-ovary method and placental pollination (Chapter 4). The application of the cut-style method or the grafted-ovary method in the interspecific crosses did not improve the pollen tube growth and pollen tube penetration in the ovules as compared to ordinary stigmatic pollination. The percentage of ovules with pollen tube penetration was also not increased after placental pollination. However, the pollination procedure applied for placental pollination might still be optimized to improve the percentage of ovules penetrated by pollen tubes.<p>The effect of hormone treatments and embryo rescue techniques on the ability of bypassing post-fertilization barriers was studied. Ovaries were treated with the cytokinin BAP (0. 1 % or I %) or the auxin NAA (1 %) at 12 days after pollination (Chapter 4). Seeds of the cross <em>T</em> . <em>gesneriana x T. agenensis</em> were obtained on the plant after treating ovaries with 0. 1 % BAR Seed production on the plant from this cross has not been reported previously. Additional research is needed before definite conclusions can be drawn about the effect of hormone treatments for bypassing crossing barriers in a wider range of interspecific tulip crosses.<p>Two embryo rescue techniques were studied: ovary-slice culture and ovule culture. Compatible <em>T. gesneriana</em> crosses were used as model system. The efficiency of direct ovule culture and ovary-slice culture followed by ovule culture was compared for cultures started at 2-9 weeks after pollination (Chapter 5). The influence of media composition on the percentage of ovules showing germination was also studied (Chapter 6). In most cases, the percentage of embryos that germinated increased significantly with a more advanced developmental stage of the embryos at the start of the culture. The lower efficiency at early culture dates is due to embryo abortion and retarded embryo development. The germination percentages for ovary- slice culture followed by ovule culture, started at various dates, were for some culture dates comparable to direct ovule culture, but for other culture dates significantly higher. The length of the period of ovary-slice culture prior to ovule culture mostly did not affect the germination percentage.<p>Media composition influenced the percentage of ovules showing germination after embryo rescue. The germination percentage was influenced by the sucrose concentration used for ovary-slice culture. 9% Sucrose resulted in higher germination percentages as compared to 5 % sucrose. The sucrose concentrations in media used for subsequent ovule culture (3 %, 5%) or in media used for direct ovule culture (3%, 6%, 9%) did not influence the germination percentages. Analysis of the carbohydrates concentrations revealed that the total concentration of carbohydrates decreased with 22%-50% in media for ovary-slice culture (9% sucrose), whereas the total concentration of carbohydrates remained rather constant in ovule culture (3% sucrose) applied after ovary-slice culture. Comparable germination percentages were obtained by using media with the full or half of the concentrations micronutrients and macronutrients of the MS-medium during ovary-slice culture and subsequent ovule culture. For direct ovule culture, started at 4, 6 and 8 weeks after pollination, the germination was not improved by the addition of the cytokinin BAP (0.01 and 0. 1 mg/1), nor by the use of liquid shaken culture.<p>An in vitro pollination procedure has been developed in order to perform an integrated system of pollination, fertilization and embryo rescue techniques under optimal controlled environmental conditions. Once an in vitro pollination procedure has been developed, it can also be used for the post-fertilization culture of whole ovaries. By using compatible intraspecific T. <em>gesneriana</em> crosses as model, the effect of the following media components on seed set and seed germination could be studied (Chapter 7): concentration of macronutrients and micronutrients of MS-medium, concentration sucrose, fructose and glucose, the auxin NAA, the cytokinin BAP, the gibberellin GA <sub>3</sub> , spermine, casein hydrolysate, the buffer MES and the use and type of agar. The application of MS-medium at full strength, with 5%-7% sucrose and 1 mg/l NAA proved to be suitable. Analysis of carbohydrate uptake revealed that on liquid media significantly more carbohydrates were absorbed by the ovaries than on agar solidified media. However, the numbers of seeds produced were higher on media with agar than on liquid media. The A of Daichin agar improved the seed set as compared to bacteriological agar. The addition of the buffer MES to liquid media, to control the pH, affected the seed set positively. The effect of the use of casein hydrolysate needs additional research. Other components tested had no or negative effects on the seed set and/or seed germination.<p>Unique hybrids have been obtained from the crosses <em>T. gesneriana x T. praestans</em> Hoog and <em>T.</em><em>gesneriana x T. agenensis</em> by using hormone treatments and/or ovary-slice culture and ovule culture. These techniques proved to be suitable for rescuing embryos of incongruent interspecific tulip crosses. Improvement of culture conditions and culture media can still increase the efficiency, especially at early culture dates. Bulblet formation in vitro after embryo germination and the transfer of the bulblets grown in vitro into the soil were not the subject of our research, but proved to be problematic. For hybrid plant production, it is therefore of great importance to improve the methods of hybrid plant recovery after embryo germination in vitro. For the introduction of genes for resistance in the cultivar assortment of tulip by means of the in this study developed methods, it is of importance to locate possible resistance genitors in the tulip species. Bypassing F1-sterility due to the formation of triploids and sterile diploids in interspecific tulip hybridization, also needs additional research. Traits from a number of tulip species such as forcing time, flower colours, flower shapes and other morphological characteristics can already be introduced in the present-day assortment with the aid of the described embryo rescue techniques. This can give a new impulse to e breeding of tulips
Microprotoplast fusion technology : stable transfer of traits between sexually incongruent plant species and transmission to the progeny
Toussaint, H.A.J.M. - \ 1996
Wageningen : CPRO-DLO
hybriden - soortkruising - protoplastenfusie - somatische hybridisatie - technieken - hybrids - interspecific hybridization - protoplast fusion - somatic hybridization - techniques
Protoplastregeneratie en somatische hybridisatie bij lelie en tulp : eindverslag van het project Protoplastregeneratie en somatische hybridisatie bij lelie en tulp
Famelaer, I.D.H. ; Ennik, E. ; Creemers - Molenaar, J. - \ 1996
Wageningen : CPRO-DLO (Urgentieprogramma bollenziekte- en veredelingsonderzoek ) - 30
hybriden - soortkruising - liliaceae - sierplanten - onderzoek - somatische hybridisatie - verwijderde hybridisatie - lilium - tulipa - protoplasten - hybrids - interspecific hybridization - ornamental plants - research - somatic hybridization - wide hybridization - protoplasts
Hybride lariks uit de zaadgaard Vaals
Kranenborg, K.G. ; Vries, S.M.G. de - \ 1995
Wageningen : IBN-DLO - 30
kruisbestuiving - cytogenetica - bosbouw - het enten (grafting) - hybridisatie - hybriden - plantenveredeling - herkomstproeven - zaadtuinen - zaadproductie - zelfbestuiving - boomveredeling - proeven - rassenproeven - larix marschlinsii - larix decidua - nederland - larix kaempferi - limburg - cross pollination - cytogenetics - forestry - grafting - hybridization - hybrids - plant breeding - provenance trials - seed orchards - seed production - self pollination - tree breeding - trials - variety trials - netherlands
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