Staff Publications

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.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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On the induction of injury in tomato under continuous light : Circadian asynchrony as the main triggering factor
Velez-Ramirez, Aaron I. ; Dünner-Planella, Gabriela ; Vreugdenhil, Dick ; Millenaar, Frank F. ; Ieperen, Wim Van - \ 2017
Functional Plant Biology 44 (2017)6. - ISSN 1445-4408 - p. 597 - 611.
circadian regulation - light-induced signalling - photodamage - photoinhibition - photoperiod - quantum yield
Unlike other species, when tomato plants (Solanum lycopersicum L.) are deprived of at least 8h of darkness per day, they develop a potentially lethal injury. In an effort to understand why continuous light (CL) is injurious to tomato, we tested five factors, which potentially could be responsible for triggering the injury in CL-grown tomato: (i) differences in the light spectral distribution between sunlight and artificial light, (ii) continuous light signalling, (iii) continuous supply of light for photosynthesis, (iv) continuous photo-oxidative pressure and (v) circadian asynchrony- A mismatch between the internal circadian clock frequency and the external light/dark cycles. Our results strongly suggest that continuous-light-induced injury does not result from the unnatural spectral distribution of artificial light nor from the continuity of light per se. Instead, circadian asynchrony seems to be the main factor inducing the CL-induced injury, but the mechanism is not by the earlier hypothesised circadian pattern in sensitivity for photoinhibition. Here, however, we show for the first time diurnal fluctuations in sensitivity to photoinhibition during normal photoperiods. Similarly, we also report for the first time diurnal and circadian rhythms in the maximum quantum efficiency of PSII (Fv/Fm) and the parameter F0.
Plant reageert bij bloei op externe signalen als temperatuur en daglengte : vernalisatie zorgt voor het juiste bloeitijdstip
Heuvelink, E. ; Kierkels, T. - \ 2016
Onder Glas 13 (2016)12. - p. 40 - 41.
temperatuur - fotoperiode - planten - bloei - milieufactoren - temperature - photoperiod - plants - flowering - environmental factors
Een plant die op het punt staat te gaan bloeien, kan zich niet bedenken als de omstandigheden toch tegen blijken te vallen. De overgang naar de bloei is onomkeerbaar. Daarom is het van het grootste belang voor het voortbestaan van de soort dat de bloei precies op het juiste tijdstip valt. Om dat voor elkaar te krijgen, reageert de plant op externe signalen, vooral de temperatuur en de daglengte.
Light on phloem transport (an MRI approach)
Prusova, Alena - \ 2016
University. Promotor(en): Herbert van Amerongen, co-promotor(en): Henk van As. - Wageningen : Wageningen University - ISBN 9789462579156 - 130
solanum lycopersicum - phloem - light - flow - photoperiod - nuclear magnetic resonance - biophysics - magnetic resonance imaging - floëem - licht - stroming - fotoperiode - kernmagnetische resonantie - biofysica - kernspintomografie

This thesis (Light on phloem transport – an MRI approach) aims to answer the question whether phloem transport can be a limiting factor for photosynthesis efficiency (and ultimately causing a bottleneck towards achieving higher yields). To answer this key question, we manipulated the source: sink ratio within tomato (Solanum lycopersicum L.) while measuring phloem transport with magnetic resonance imaging (MRI) flowmetry. Additionally we compared phloem flow characteristics of two potato plants (Solanum tuberosum L.) which differed in source : sink ratio. In Chapter 2, the source strength was manipulated by varying the light intensity. An increase in phloem sap volume flow under higher light intensities was observed. However, under all light intensities applied, the phloem flow velocity was found to be constant (as has previously been suggested in other studies) although a clear diurnal pattern was observed. This finding does not fit in current models to describe the mechanism of phloem transport and a different mechanism must be at play. The results of this chapter demonstrate that increased levels of photo-assimilates are transported in sieve tubes, which are activated when needed by the plant. This is the first study which shows that plants activate individual sieve tubes when more photo-assimilates are available, yet maintain constant velocity. Those observations were in a tomato plant with pruned fruit trusses (i.e., in a simplified system). In Chapter 3, we investigated whether tomato plants still exhibit constant phloem flow velocity (with a diurnal pattern) under normal conditions, i.e., with strong sinks (tomato fruits) still attached. This was tested for both a long and short photoperiod by measuring flow characteristics with MRI flowmetry. We simultaneously monitored other plant processes like xylem flow rates with a heat balance sensor, net photosynthesis with gas exchange and stem diameter changes with a linear motion potentiometer. With this integrated approach, we revealed a correlation between night phloem volume flow, dark respiration and stem growth. We also conclusively showed that phloem volume flow performs a diurnal pattern under a variety of source-sink ratios which appears to be a normal behaviour for tomato plants growing under moderately-high light conditions. In chapters 2 and 3 we learned that under higher source strength a greater amount of phloem sap is transported, but the changes in flow were not accompanied by changes in velocity. To further our understanding of the mechanisms driving phloem transport, it is of interest to know how the sucrose concentration in phloem sap relates to phloem flow. In Chapter 4 we used an average T2 relaxation time in the phloem vascular tissue region to reveal the plant’s phloem carbon status under source manipulation. In this chapter we demonstrated that T2 relaxation time, when measured in parallel with phloem flow, can provide additional information about phloem region carbon status, i.e., changes in the T2 relaxation time are correlated with changes in sucrose concentration in the whole phloem region.

When studying phloem transport in plants with magnetic resonance imaging (MRI) flowmetry, plants which are relatively easy to manipulate (e.g. fruit pruning) like tomato have so far been used. However, tomato plants (used in all three previous chapters) have relatively low sink strength beneath the MRI measurement site. A potentially preferable approach is to work with plants with strong sinks beneath the measurement site. In Chapter 5 we studied potato as a potentially better test subject for MRI flowmetry as it possesses strong sink below the MRI measurement site (i.e., developing tubers). For that purpose we used two potato plants (cv. Desiree) both with several developing tubers. One of the plants overexpressed the StSWEET gene (35S:StSWEET) which appears to have altered its source : sink ratio. As a result, the 35S:StSWEET plant transported 60% more phloem sap than Desiree WT. Strikingly, the average phloem flow velocity in both plants was the same and the greater amount of transported phloem sap in the 35S:StSWEET plant was accommodated by more sieve tubes than in Desiree WT. This finding agrees with the hypothesis about the conserved nature of phloem flow velocity, where volume flow is regulated by the number of active sieve tubes (Chapter 2 and 3). In this chapter we also demonstrate that a potato plant with developing tubers represents a good subject to study phloem transport with MRI flowmetry. We concluded that under optimal conditions (which are commonly met in greenhouses) phloem transport is likely to reach its maximum capacity and therefore photosynthesis could be limited by the export and transport of photo-assimilates because of the finite number of sieve tubes and constant flow velocity.

Hemp for textiles : plant size matters
Westerhuis, W. - \ 2016
University. Promotor(en): Paul Struik, co-promotor(en): Tjeerd-Jan Stomph; Jan van Dam. - Wageningen : Wageningen University - ISBN 9789462577879 - 234 p.
cannabis sativa - fibre plants - textile fibres - textiles - photoperiod - hemp - plant fibres - plant density - harvesting date - sowing date - biobased materials - vezelgewassen - textielvezels - textiel - fotoperiode - hennep - plantenvezels - plantdichtheid - oogsttijdstip - zaaitijd - materialen uit biologische grondstoffen

Abstract

Key words: Cannabis sativa L., day length sensitivity, fibre hemp, genotype, harvest time, plant density, plant weight, primary fibres, secondary fibres, sowing date, textiles.

Westerhuis, W. (2016) Hemp for textiles: plant size matters, PhD thesis. Wageningen University, Wageningen, The Netherlands, 234 pp. With English and Dutch summaries.

Fibre hemp (Cannabis sativa L.) may be an alternative to cotton and synthetic fibres as a raw material for textile yarn production in the European Union. The agronomic options to manipulate plant development and crop growth with the aim to optimise hemp long fibre production were investigated. Field trials with factors sowing density, sowing date, harvest time and variety were conducted. Stems were traditionally processed by retting, drying, breaking, and scutching. Following standard protocols, almost 1500 hemp stem samples were analysed. Varieties differ widely in their fibre content, but this thesis shows that when variety and plant size are known, the amounts of fibres, wood, and retting losses are known. The dry weight of the stems at harvest, not the factors underlying this weight, are determinant. In retted stems the dry matter is split–up into fibres and wood in a fixed way. The options to manipulate this ratio by crop management, given variety, are very small and for practical reasons they can be neglected. In fibre hemp two bast fibre types occur. Primary or long fibres are valuable for yarn spinning. Secondary fibres are too short and their presence hampers the production of fine yarns. This thesis shows that the secondary fibre front height increases with plant weight. Although a causal relationship between secondary fibre formation and flowering does not exist, the secondary fibre front is found higher in flowering plants when compared to non–flowering plants of the same height. This is likely to be caused by the higher weight or momentum of flowering plants as compared with non–flowering plants of the same height. Consequently, a harvest before flowering is preferable. This was shown in a greenhouse experiment, in which the short–day response of hemp was used to create size ranges of flowering and non–flowering plants. To produce high–quality raw materials for textile production, short crops should be grown. The options to produce plants with the desired size are manifold. Since sowing density, sowing date, and harvest time do not have an additional effect on the primary fibre content besides the indirect effect through stem weight, any combination of these factors could be chosen to optimize plant size.

Winterrust kent drie fasen: voorrust, autonome rust en opgelegde rust : afnemende daglengte en koude stimuleren
Kierkels, T. ; Heuvelink, E. - \ 2015
Onder Glas 12 (2015)1. - p. 36 - 37.
glastuinbouw - sierteelt - winter - gewassen, groeifasen - plantenontwikkeling - rust - fotoperiode - cultuurmethoden - greenhouse horticulture - ornamental horticulture - crop growth stage - plant development - rest - photoperiod - cultural methods
Het merendeel van de glastuinbouwgewassen is bij voldoende licht zonder problemen jaarrond in productie te houden. Dat geldt echter niet voor gewassen die in winterrust gaan: bladverliezende boomkwekerijgewassen en zachtfruit onder glas. Ze zijn vaak wel te ‘forceren’, maar dan alleen op het juiste moment: als interne fysiologische processen een bepaalde cyclus hebben doorgemaakt.
Daglengtegevoeligheid stoelt op opbouw van eiwit in de cel : Inzicht groeit sterk door genetisch onderzoek
Ieperen, W. van; Heuvelink, E. ; Kierkels, T. - \ 2014
Onder Glas 11 (2014)11. - p. 22 - 23.
glastuinbouw - cultuurmethoden - fotoperiode - lichtrelaties - genetische factoren - bloei-inductie - daglicht - plantkunde - snijbloemen - greenhouse horticulture - cultural methods - photoperiod - light relations - genetic factors - flower induction - daylight - botany - cut flowers
Veel planten zijn van nature daglengtegevoelig. Ze gaan pas bloeien als de dag kort of juist lang genoeg is. Daarvoor hebben ze een klok nodig om de tijd te kunnen meten en een sensor om te kunnen zien of het licht is. De laatste jaren groeit het inzicht in de genetische aansturing sterk. Dat maakt de zaak ingewikkelder, maar geeft tevens aanknopingspunten voor mogelijke teeltmaatregelen in de toekomst.
A crop model-based approach for sunflower yields
Belo Leite, J.G. Dal; Nunes Vieira da Silva, J.V. ; Barbosa Justino, F. ; Ittersum, M.K. van - \ 2014
Scientia agricola 71 (2014)5. - ISSN 0103-9016 - p. 345 - 355.
water-stressed sunflower - radiation-use efficiency - phenological development - oilcrop-sun - growth - temperature - simulation - photoperiod - farmers - carbon
Pushed by the Brazilian biodiesel policy, sunflower (Helianthus annuus L.) production is becoming increasingly regarded as an option to boost farmers' income, particularly under semi-arid conditions. Biodiesel related opportunities increase the demand for decision-making information at different levels, which could be met by simulation models. This study aimed to evaluate the performance of the crop model OILCROP-SUN to simulate sunflower development and growth under Brazilian conditions and to explore sunflower water- and nitrogen-limited, water-limited and potential yield and yield variability over an array of sowing dates in the northern region of the state of Minas Gerais, Brazil. For model calibration, ani experiment was conducted in which two sunflower genotypes (H358 and E122) were cultivated in a clayey soil. Growth components (leaf area index, above ground biomass, grain yield) and development stages (crop phenology) were measured. A database composed of 27 sunflower experiments from five Brazilian regions was used for model evaluation. The spatial yield distribution of sunflower was mapped using ordinary kriging in ArcGIS. The model simulated sunflower grain productivity satisfactorily (Root Mean Square Error approximate to 13%). Simulated yields were relatively high (1,750 to 4,250 kg ha(-1)) and the sowing window was fairly wide (Oct to Feb) for northwestern locations, where sunflower could be cultivated as a second crop (double cropping) at the end of the rainy season. The hybrid H358 had higher yields for all simulated sowing dates, growth conditions and selected locations.
A two-step approach to quantify photothermal effects on pre-flowering rice phenology
Awan, M.I. ; Oort, P.A.J. van; Bastiaans, L. ; Putten, P.E.L. van der; Yin, X. ; Meinke, H.B. - \ 2014
Field Crops Research 155 (2014). - ISSN 0378-4290 - p. 14 - 22.
oryza-sativa l - climate-change - heading date - aerobic rice - water-use - model - temperature - performance - photoperiod - cultivars
Decreasing water availability for rice based systems resulted in the introduction of water saving produc-tion systems such as aerobic rice and alternate wetting–drying technology. To further improve resourceuse efficiency in these systems, water management should be attuned to critical growth stages, requiringaccurate prediction of crop phenology. Photoperiod-sensitivity of aerobic rice genotypes complicates theestimation of the parameters characterising phenological development and hence impairs predictions. Toovercome this complication, we followed a two-step approach: (1) the photoperiod response was deter-mined in growth chambers, through a reciprocal transfer experiment with variable day length, conductedat a fixed temperature, and consecutively, (2) the temperature response was studied by combining theobtained photoperiod parameters with data from field experiments. All four aerobic rice genotypes testedexhibited strong photoperiod-sensitivity. Durations of basic vegetative phase (BVP) i.e. when plants arestill insensitive to photoperiod, photoperiod-sensitive phase (PSP), and post-PSP (PPP) varied amonggenotypes. The temperature response of the genotypes was explored by combining phenological observa-tions in the reciprocal transfer experiment with observations in two field experiments. The temperaturerange in the field experiments was too narrow to obtain convergence to a unique set of temperatureresponse parameters, regardless whether a bilinear or a beta model was used. Sensitivity analysis how-ever provided clear arguments in support of the recent doubts on the validity of a commonly used set ofcardinal temperatures for rice phenology. Using standard cardinal temperatures, the rate of developmentat temperatures below 31¿C was overestimated. This finding stresses the need for experiments on ricephenology under a wider range of temperatures.
Responses of supplemental blue light on flowering and stem extension growth of cut chrysanthemum
Jeong, S.W. ; Hogewoning, S.W. ; Ieperen, W. van - \ 2014
Scientia Horticulturae 165 (2014). - ISSN 0304-4238 - p. 69 - 74.
plant-growth - spectral filters - red - morifolium - photosynthesis - gibberellins - phytochrome - end - photoperiod - inhibition
To determine the effects of blue (B) spectrum supplemental lighting on flower bud formation and stem elongation growth of cut chrysanthemum, plants of ‘Zembla’ cultivar were grown for 42 days under 4 different light treatments. Treatments comprised: RB (11 h of mixed red and blue [RB] light), RB + B (11 h of mixed RB light and then 4 h of supplemental B light), LRB + B (15 h of mixed RB light and then 4 h of supplemental B light) and RB + LB (11 h of mixed RB light and then 13 h of B light) by using light-emitting diodes. Diurnal patterns in the net assimilation rate were observed, depending on light-quality combinations. Under mixed RB light, the net assimilation rate increased rapidly, then slightly decreased under B light, and finally dropped to negative values during darkness. Final stem length was the highest in plants grown under RB + LB, followed by LRB + B, RB + B and then RB treatment. The stem lengths under RB + B, LRB + B and RB + LB were 1.3, 1.5 and 1.7 times longer than that of RB treatment, respectively. However, fully developed flower buds were formed under RB and RB + B treatments only. The extended final stem length of RB + B plants was determined by internode extension. Overall, our results indicate that supplemental B light, at least in part, may promote stem and internode elongation growth without any inhibitory effect on flower bud formation. The results of this study present a useful practical technique for optimizing cut chrysanthemum production in greenhouse horticulture.
Lichtspectrum bij stuur- en groeilicht in Freesia: Effect van stuurlicht met LED- en groeilicht met plasmalampen
Helm, F.P.M. van der; Dueck, T.A. ; Pronk, H. ; Penning, P. ; Kromwijk, J.A.M. - \ 2012
glastuinbouw - proeven - freesia - plantenontwikkeling - belichting - lampen - lichtrelaties - groei - blauw licht - lichtgevende dioden - verrood licht - fotoperiode - led lampen - greenhouse horticulture - trials - plant development - illumination - lamps - light relations - growth - blue light - light emitting diodes - far red light - photoperiod - led lamps
Meten meerwaarde nieuwe lampen (LED - en plasmalampen ) voor teelt van Freesia met als doel : • Beperken overmatige lengtegroei in najaarsteelt • Bepalen i nvloed op uitgroei en kwaliteit van haken
Teeltsturing moet voorbloei in bouvardia kunnen verminderen
Slootweg, G. - \ 2012
Vakblad voor de Bloemisterij 67 (2012)3. - ISSN 0042-2223 - p. 34 - 35.
bouvardia - cultuurmethoden - bloeidatum - vroegheid - landbouwkundig onderzoek - fotoperiode - lichtrelaties - glastuinbouw - cultural methods - flowering date - earliness - agricultural research - photoperiod - light relations - greenhouse horticulture
Teeltsturing moet voorbloei in bouvardia kunnen verminderen. Voorbloei in bouvardia veroorzaakt veel extra werk. Wageningen UR Glastuinbouw vermoedt dat de oplossing ligt in teeltmaatregelen. Te denken valt aan belichting of aanpassing van de EC.
Bloei-inductie bij Chrysant onder lange dag : toepassing van LED-licht technologie
Ieperen, W. van; Hogewoning, S.W. ; Dam, E. ten - \ 2011
Wageningen : Wageningen Universiteit, Leerstoelgroep Tuinbouwketens - 23
tuinbouw - glastuinbouw - chrysanthemum - led lampen - klimaatkamerproeven - fotoperiode - bloei-inductie - assimilatie - potplanten - snijbloemen - teeltsystemen - lichtregiem - horticulture - greenhouse horticulture - led lamps - growth chamber experiments - photoperiod - flower induction - assimilation - pot plants - cut flowers - cropping systems - light regime
Deze publicatie beschrijft een onderzoek naar daglengte verlenging tijdens de korte dag bij chrysant met behoud van bloei door sturing met speciale LED belichting. In klimaatkamerproeven met LEDs (zonder natuurlijk licht) kon bij Chrysant bloemknopaanleg worden geïnduceerd onder een lange dag (LD), door de laatste paar uur van de lichtperiode alleen blauw LED-licht te geven. De rest van de lichtperiode werd een combinatie van rood en blauw LED-licht gegeven. Omdat blauw licht fotosynthetisch actief is leverde dit aanzienlijke extra groei op. Echter, wanneer overdag natuurlijk zonlicht of kunstlicht met een zonlichtspectrum werd gegeven, bleek het doorbelichten met blauw LED-licht niet te resulteren in bloei. Langdurig blauw LED-licht kan dus niet zondermeer worden toegepast in de commerciële teelt van pot- en snijchrysant in kassen. Voor toekomstige meerlagen- en andere teeltsystemen zonder natuurlijk licht is het wel een optie. Deze experimenten laten voor het eerst zien dat ook de spectrale samenstelling van het licht overdag invloed heeft op de bloei-inductie bij chrysant.
Determinants of barley grain yield in a wide range of Mediterranean environments
Francia, E. ; Tondelli, A. ; Rizza, F. ; Badeck, F.W. ; Li Destri Nicosia, O. ; Akar, T. ; Grando, S. ; Al-Yassin, A. ; Benkelkacim, A. ; Thomas, W.T.B. ; Eeuwijk, F.A. van; Romagosa, I. ; Stanca, A.M. ; Pechionni, N. - \ 2011
Field Crops Research 120 (2011)1. - ISSN 0378-4290 - p. 169 - 178.
carbon-isotope discrimination - drought tolerance - stress tolerance - number - genes - wheat - improvement - adaptation - temperature - photoperiod
Barley grain yield in rainfed Mediterranean regions can be largely influenced by terminal drought events. In this study the ecophysiological performance of the ‘Nure’ (winter) × ‘Tremois’ (spring) barley mapping population (118 Doubled Haploids, DHs) was evaluated in a multi-environment trial of eighteen site–year combinations across the Mediterranean Basin during two consecutive harvest years (2004 and 2005). Mean grain yield of sites ranged from 0.07 to 5.43 t ha-1, clearly dependent upon both the total water input (rainfall plus irrigation) and the water stress index (WSI) accumulated during the growing season. All DHs were characterized for possessing molecular marker alleles tagging four genes that regulate barley cycle, i.e. Vrn-H1, Vrn-H2, Ppd-H2 and Eam6. Grain yield differences were initially interpreted in terms of mean differences between genotypes (G), environments (E), and for each combination of genotype and environment (GE) through a “full interaction” ANOVA model. Variance components estimates clearly showed the greater importance of GE over G, although both were much lower than E. Alternative linear and bilinear models of increasing complexity were used to describe GE. A linear model fitting allelic variation at the four genes explained genotype main effect and genotype × environment interaction much better than growth habit itself. Adaptation was primarily driven by the allelic constitution at three out of the four segregating major genes, i.e. Vrn-H1, Ppd-H2 and Eam6. In fact, the three genes together explained 47.2% of G and 26.3% of GE sum of squares. Grain yield performance was more determined by the number of grains per unit area than by the grain weight (phenotypic correlation across all genotypic values: r = 0.948 and 0.559, respectively). The inter-relationships among a series of characters defining grain yield and its components were also explored as a function of the length of the different barley developmental phases, i.e. vegetative, reproductive, and grain filling stages. In most environments, the best performing (adapted) genotypes were those with faster development until early occurrence of anthesis. This confirmed the crucial role of the period defining the number of grains per unit area in grain yield determination under Mediterranean environments
Onderzoek daglengte in de teelt van Freesia
Heij, G. ; Mourik, N.M. van; Leeuwen, A.G.J. van; Labrie, C.W. - \ 2008
Wageningen : Wageningen UR Glastuinbouw (Rapport / Wageningen UR, Glastuinbouw 171) - 24
freesia - bloementeelt - cultivars - rassen (planten) - plantdichtheid - fotoperiode - teelt onder bescherming - groeifactoren - rassenproeven - glastuinbouw - floriculture - varieties - plant density - photoperiod - protected cultivation - growth factors - variety trials - greenhouse horticulture
Onderzocht is de invloed van de teeltstrategie op freesia met als doel de najaarskwaliteit en daarnaast de productie en teeltduur te verbeteren. Proeffactoren zijn daglengte, plantdichtheid en wel of geen voorbehandeling. Gebruikte cultivars zijn Summer Beach, Ambassador, Dukaat en Gold River
Food intake, growth, and reproduction as affected by day length and food availability in the pond snail Lymnaea stagnalis
Maat, A. ter; Zonneveld, C. ; Visser, J.A.G.M. de; Jansen, R.F. ; Montagne-Wajer, K. ; Koene, J.M. - \ 2007
American Malacological Bulletin 23 (2007)1-2. - ISSN 0740-2783 - p. 113 - 120.
caudo-dorsal cells - egg-laying behavior - freshwater snail - ovulation hormone - energy budgets - trade-off - neurohormone - photoperiod - precursor - peptides
With the aim of integrating the physiology and evolutionary ecology of Lymnaea stagnalis (Linnaeus, 1758), we studied the effects of day length and food availability on the energy budget. Snails were assigned to two different photoperiods and three levels of food availability. The snails were kept individually, and food consumption, growth, and egg production were measured for about 2 months. Snails could nearly compensate for a one-day starvation period by increasing the rate of food-intake. However, food-intake rates did not increase further after a starvation period of 2 days. Growth was well described by the Von Bertalanffy growth equation. The ultimate size of snails kept under medium-day conditions (MD; light:dark = 12:12 h) was not affected by food availability. By contrast, the ultimate size of snails kept under long-day conditions (LD; light:dark = 16:8 h) depended on food availability; those fed the lowest quantities grow the least. Dry-weight densities (dry weight/wet weight) of MD snails were considerably above those of LD snails. In MD snails, food availability did not appreciably affect dry-weight density. By contrast, in LD snails, dry-weight density decreased with decreasing food availability. The reproductive output of LD snails declined with declining food availability, but was 2 to 4 times that of MD snails. The difference in reproductive output was largely accounted for by the difference in stored energy, i.e. dry-weight density. To gauge the extent to which the conclusions from our laboratory work applied to free-living snails, a field study was conducted. The wild-caught snails' dry-weight density was also lowest in long-day conditions when most eggs were laid. However, the dry-weight densities during medium and short days were lower than the dry-weight densities of laboratory animals under LD conditions. Thus, in the field, snails stored less energy than in the laboratory.
Tuber induction and initiation during production and early field growth of transplants from in vitro-derived potato plants
Lommen, W.J.M. ; Struik, P.C. - \ 2006
Annals of Applied Biology 149 (2006)3. - ISSN 0003-4746 - p. 281 - 290.
solanum-tuberosum - l cuttings - tuberization - temperature - photoperiod - yield - pretreatment
In transplants from in vitro-derived plantlets from very early potato (Solanum tuberosum) cultivars, a lower degree of tuber induction at the time of field planting is thought to increase tuber production. Leaf-bud cuttings were used to assess the progress to tuber induction in in vitro-derived potato plantlets during the transplant production phase and after subsequent transplanting into the field. Induction and initiation of tubers on the same plants were assessed to study the effects of the duration of transplant production and conditions during transplant production for cv. Gloria (very early) and cv. Bintje (mid-early). In vitro-produced plantlets were not induced by the time of planting but rapidly progressed to the induced state thereafter. The progress in induction with time and the change in percentage of plants showing tubers fitted typical sigmoid curves. Plantlets achieved 50% induction ca 15 days after planting into in vivo conditions, and 50% tuber initiation usually occurred 10 days later. Shorter transplant production periods reduced the degree of induction of the transplants at field planting. Transplant production for more than 2 weeks was required to allow conditions during that period to affect induction or initiation. Long-term non-inducing conditions delayed the progress to tuber induction in cv. Gloria and delayed tuber initiation in both cultivars. Cv. Gloria showed no faster progress to induction than cv. Bintje but initiated tubers earlier. The results suggest that the relation between progress to induction and tuber initiation is cultivar dependent and that leaf-bud cuttings can be used successfully in very young in vitro-derived plants for assessing the progress to tuber induction
Daglengte behandelingen bij Celosia : verbetering oogstpercentage bij Celosia cristata door variabele KorteDag behandelingen
Telgen, H.J. van; Janse, J. ; Eijk, J. van der; Wiskerke, A. - \ 2005
Aalsmeer : Praktijkonderzoek Plant & Omgeving, Business Unit Glastuinbouw - 21
celosia argentea var. cristata - kruidachtige planten als sierplanten - fotoperiode - relatie tussen groei en oogst - glastuinbouw - ornamental herbaceous plants - photoperiod - growth yield relationship - greenhouse horticulture
Om instrumenten in handen te krijgen voor een beter beheersbaar product en een hoger oogstpercentage in de zomerperiode is de reactie van Celosia cristata planten op de daglengte onderzocht. Bij Celosia cristata wordt bij sommige rassen in de zomermaanden namelijk de bloemknop vaak (te) laat aangelegd, waardoor onder de bloemknop veel bladeren worden gevormd. Tenzij tijdens de teelt zwaar geremd wordt, worden de stengels extra lang en kunnen ze elkaar daardoor snel gaan overgroeien en onderdrukken. Voor de proef is gekozen voor twee rassen die sterk verschillen in hun bladvorming: de ‘Bombay Fire’ die veel blad aanlegt en de ‘Bombay Pink’ die duidelijk minder aanleg heeft.
Are cuttings suitable for assessing maturity type in potato (Solanum tuberosum)?
Struik, P.C. ; Visker, M.H.P.W. ; Pauwels, J.P. ; Colon, L.T. - \ 2005
Annals of Applied Biology 147 (2005)1. - ISSN 0003-4746 - p. 27 - 34.
photoperiod - growth - shoot - l.
Two experiments were carried out to evaluate the potential of single-node cuttings of potato (Solanum tuberosum) as a tool to assess genotypic differences in maturity type. Plants were exposed to different photoperiodic treatments (different photoperiods, different numbers of photoperiodic cycles), and cuttings were taken at different plant ages. Cuttings from early (and to a lesser extent also late) maturing varieties exposed to short photoperiods showed strong induction to tuberise, irrespective of plant age; the induction increased with an increase in the number of short photoperiodic cycles. The response of cuttings taken from early-maturing varieties exposed to long photoperiods depended on plant age: cuttings showed stronger induction when mother plants were older; cuttings from late-maturing varieties hardly tuberised after exposure to long photoperiods. The tuberisation of the cuttings did not depend on the length of the long photoperiod (18 or 24 h) or on the number of cycles of a photoperiod of 18 h. Tuberisation on cuttings did not properly reflect the tuber formation on the mother plants, although within varieties, significant correlations between tuberisation on cuttings and tuber yield per plant 9 weeks after planting were found with different numbers of photoperiodic cycles of 12 h. Our experiments show that the cutting technique cannot be used on older plants to assess the maturity type of potato varieties, as there are interactions between photoperiod, genotype, plant age and number of photoperiodic cycles, in the reflection of the degree of induction to tuberise on single-node cuttings.
Tuber on a chip: differential gene expression during potato tuber development
Kloosterman, B.A. ; Vorst, O.F.J. ; Hall, R.D. ; Visser, R.G.F. ; Bachem, C.W.B. - \ 2005
Plant Biotechnology Journal 3 (2005). - ISSN 1467-7644 - p. 505 - 519.
solanum-tuberosum - phytochrome-b - gibberellin 2-oxidases - sucrose - starch - tuberization - plants - fructokinase - photoperiod - conversion
Potato tuber development has proven to be a valuable model system for studying underground sink organ formation. Research on this topic has led to the identification of many genes involved in this complex process and has aided in the unravelling of the mechanisms underlying starch synthesis. However, less attention has been paid to the biochemical pathways of other important metabolites or to the changing metabolic fluxes occurring during potato tuber development. In this paper, we describe the construction of a potato complementary DNA (cDNA) microarray specifically designed for genes involved in processes related to tuber development and tuber quality traits. We present expression profiles of 1315 cDNAs during tuber development where the predominant profiles were strong up- and down-regulation. Gene expression profiles showing transient increases or decreases were less abundantly represented and followed more moderate changes, mainly during tuber initiation. In addition to the confirmation of gene expression patterns during tuber development, many novel differentially expressed genes were identified and are considered as candidate genes for direct involvement in potato tuber development. A detailed analysis of starch metabolism genes provided a unique overview of expression changes during tuber development. Characteristic expression profiles were often clearly different between gene family members. A link between differential gene expression during tuber development and potato tissue specificity is described. This dataset provides a firm basis for the identification of key regulatory genes in a number of metabolic pathways that may provide researchers with new tools to achieve breeding goals for use in industrial applications.
The interaction of plant growth regulators and vernalization on the growth and flowering of cauliflower (Brassica oleracea var. botrytis)
Guo, D.P. ; Shah, G.A. ; Zeng, G.W. ; Zheng, S.J. - \ 2004
Plant Growth Regulation 43 (2004)2. - ISSN 0167-6903 - p. 163 - 171.
stem elongation - endogenous gibberellins - arabidopsis-thaliana - curd - photoperiod - pisum - ga(3) - napus
The growth and flowering response of a cold-requiring cauliflower (Brassica oleracea var. botrytis cv. '60 day') to a range of temperatures under 10 h photoperiod and to growth regulator application were investigated. Endogenous gibberellin A1 (GA1) concentrations were also assessed under these treatments. Flowering and growth of the inflorescence stalk were correlated with plant developmental stage at the time of a vernalizing cold treatment. Temperature and its duration also affected flowering and inflorescence development. The most effective temperature for inflorescence induction was 10 °C. Flowering did not occur in non-vernalized plants (25 °C) even though they had been treated with GA3. Application of GA3 promoted inflorescence stalk elongation greatly in vernalized plants (10 °C), but less so in partially vernalized plants (15 °C or 20 °C). Paclobutrazol (PP333) sprayed at the 8-9 leaf stage significantly suppressed inflorescence stalk length and slightly delayed flower bud formation and anthesis. Vernalization at 10 °C increased endogenous GA1 content in both leaves and the inflorescence stalk irrespective of GA3 or PP333 treatment. Application of GA3 tended to increase GA1 levels, while PP333 significantly reduce GA1, both irrespective of vernalization. Vernalization is an important factor for flowering, but not curd formation in this cauliflower cv. '60 day' and GA1 is likely a causal factor in inflorescence stalk elongation.
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