Moist Vermiculite Research Articles

Seedling emergence and growth of ‘China Rose’ radish microgreens in response to radicle breakage following pre-sowing seed germination

ABSTRACT Germinating seeds in moist, fine-grade vermiculite followed by broadcasting the mix over the seedbed can reduce greenhouse production time for microgreens, but seedling radicles could be broken. The study was undertaken to determine if radicle breakage affected plant yield of radish (Raphanus sativus L) used for microgreens. During pre-sowing handling of germinated seed in moist vermiculite the percent of broken radicles increased as radicle length increased, and as mechanical force increased (resulting in 0%, 8%, or 22% with minimal, medium or high mechanical force, respectively). Imposition of these levels of radicle damage was achieved by cutting radicles half-way along their length after germination for 2 days in moist vermiculite (200% water, dry weight) at which time radicles were about 1.5 cm long. This treatment had no effect on numbers of shoots (as a percent of sown seed) or number of shoots∙m−2 at 7 days after sowing at 25% or 100% of a commercial rate (9,266 seed∙m−2). Yield as shoot fresh weight∙m−2, or per seedling was unaffected by percent of cut radicles sown. Removal of up to 12 mm of radicle from the tip increased numbers of roots per seedling but decreased total root length and decreased fresh weight per shoot. The higher seeding rate decreased fresh weight per shoot from raw (42%) or germinated (32%) seed. Sowing germinated seed in moist vermiculite, rather than raw seed, and sowing seed at the higher rate, increased shoot fresh weight∙m−2 and shoot fresh weight per seedling. Seedlings with broken radicles had lower shoot fresh weights but smaller shoots were counted in the final yield. Microgreen yield (shoot fresh weight∙m−2) was unaffected after sowing germinated seed that had been subjected to a high mechanical force (with up to 22% broken radicles) during broadcasting .

Photomorphogenesis of the root system in developing sunflower seedlings: a role for sucrose

The domestic sunflower (Helianthus annuus L. cv. 'Giganteus') has been used since the 19th century as a model plant for the study of seedling development in darkness and white light (WL) (scoto- versus photomorphogenesis). However, most pertinent studies have focused on the developmental patterns of the hypocotyl and cotyledons, whereas the root system has been largely ignored. In this study, we analysed entire sunflower seedlings (root and shoot) and quantified organ development in the above- and belowground parts of the organism under natural (non-sterile) conditions. We document that seedlings, raised in moist vermiculite, are covered with methylobacteria, microbes that are known to promote root development in Arabidopsis. Quantitative data revealed that during photomorphogenesis in WL, the root system expands by 90%, whereas stem elongation is inhibited, and hook opening/cotyledon expansion occurs. Root morphogenesis may be mediated via imported sucrose provided by the green, photosynthetically active cotyledons. This hypothesis is supported by the documented effect of sucrose on the induction of lateral root initials in sunflower cuttings. Under these experimental conditions, phytohormones (auxin, cytokinin, brassinolide) exerted little effect on root and cotyledon expansion, and no hormone-induced initiation of lateral roots was observed. It is concluded that sucrose not only acts as an energy source to fuel cell metabolism but is also a shoot-derived signalling molecule that triggers root morphogenesis.

Effect of temperature and inoculum density on disease intensity of Phytophthora parsiana

ABSTRACT- The effects of inoculum density and temperature on the disease intensity of Phytophthora parsiana on almond seedlings were investigated. Almond seeds (Rabie and Kaghazi cultivars) were placed in moist vermiculite at 4°C for 45 days. Germinated seeds were sown in a soil: sand mixture (2:1 v/v) and grown in greenhouse (18°C-25°C). One-month-old seedlings were transferred from the greenhouse to the growth chambers set at 15, 18, 20, 25,30 and 32°C. The seedlings were subsequently inoculated either with mycelium of P. parsiana grown for 4-6 weeks on vermiculite amended with hemp seed extract or with zoospore (103, 104, 105 and 106 ml-1) by root dip method. The effect of temperature, inoculum density and their interaction on seedling mortality was measured. The results indicated that all three factors had significant effects on seedling mortality. While the highest disease incidence (100% mortality in almond seedlings) occurred at 30°C and 32°C, no mortality was observed at 15°C and18°C. Increasing temperature from 20°C to 30°C and inoculum rate from 103 to 106 zoospores ml-1 increased disease incidence significantly. Higher temperatures and inoculum densities also caused significant increases in the colonization level of the crown, main and lateral roots as well as reductions in the fresh and dry root weights of the seedlings.

Optimization of germination and initial quality of seedlings of Prunus persica tree rootstocks

Abstract: The present study evaluated the germination potential of seeds from eight peach tree rootstocks under different stratification methods, aiming at the production of high quality seedlings. In the first experiment, seeds with endocarp from eight genotypes (‘Aldrighi’, ‘Capdeboscq’, ‘Flordaguard’, ‘Okinawa’, ‘Okinawa roxo’, ‘Tsukuba 1’, ‘Tsukuba 2’, ‘Tsukuba 3’) were stratified on sand and moist vermiculite, at 7 ºC for 60 days. In the second experiment, endocarpless seeds of the same genotypes were stratified on Petri dishes at 7 ºC. In the third experiment, the time at which at least 75% of the seedlings reached transplanting height (15 cm high) was verified. The endocarp was a limiting factor for seed germination of the eight rootstocks, since the highest germination percentages were 21% and 48.3% for ‘Aldrighi’ and ‘Capdeboscq’, respectively. Germination of ‘Okinawa’ was only 19.2% and 4.2%, in sand and vermiculite, respectively. Seeds stratified without the endocarp, showed 100% germination, except for ‘Flordaguard’ and ‘Tsukuba 2’ and 3’, with 93% germination. Seed mass presented a positive correlation with the germination speed index and the initial growth of the seedlings. ‘Aldrighi’ and ‘Capdeboscq’ presented more vigorous seedlings with greater growth in height, stem diameter, and Dickson quality index.

Standardization of priming treatments for enhancement of seed germination and field emergence in carrot

Carrot (Daucus carota L.) seeds were subjected to solid matrix priming with moist vermiculite at 15°C and 20°C for 12, 24, 36 and 48 h. Seeds were also osmoprimed at −0.5, -1.0 and -1.5 MPa potential for 2, 4 and 6 days. Solid matrix priming for 24 h registered significantly higher seed germination (85%) and speed of germination (14.45), while priming duration of 48 h gave minimum value for speed of germination. However, no significant differences in speed of germination were found at different temperatures. Solid matrix priming for 24 h at 20°C was optimum for obtaining maximum speed of germination (14.67) and vigour index I (821.5). With increase in priming duration from 2 to 6 days, there was significant decrease in germination. Osmopriming at −1.0 MPa PEG potential significantly improved speed of germination (7.07) and was at par to PEG priming at −0.5 MPa. Osmopriming for 2 days at −1.0 MPa PEG potential recorded maximum speed of germination (9.24) over all other treatment combinations. Osmopriming at −1.0 MPa and solid matrix priming for 24 h at 20°C improved germination and field emergence over control in carrot. Hence, osmopriming and solid matrix priming can be effectively employed for improved field performance in carrot.

Copulation and Oviposition in the Green-blotched Giant Anole, Anolis smallwoodi (Squamata: Dactyloidae), from southeastern Cuba


 
 
 
 Crown-giant anole ecomorphs have evolved independently across the Greater Antilles (Cuba, Hispaniola, Jamaica, and Puerto Rico), but only a few of these species have well documented life histories. Herein we report previously undocumented observations of copulation, oviposition, and hatchlings for the Green-blotched Giant Anole (Anolis smallwoodi) of southeastern Cuba. We observed eight mating events (three with A. s. smallwoodi and five with A. s. palardis) along the coastline between Santiago de Cuba and Guantánamo Province during June 2010 and September 2011. One female A. s. palardis mated with two males in the same territory. Females dig a hole with their snouts, oviposit single eggs, and cover them with substrate. We monitored eight eggs incubated in slightly moist vermiculite. The minimum incubation times were 54-69 days (varying with temperature). Juveniles usually are colored like adults, bright green with white spots on the body, pale postlabial bands, and suprascapular stripes.
 
 
 

Aeroponic Propagation of VAMycorrhizal Spores for Soil Inoculation as a Biofertilizer

Onion (Allium cepa) and Barley (Hordeum vulgare) colonized by Glomus mosseae, G. fasiculatum, and G. intraradices were grown in aeroponic cultures. After 14 weeks, all roots were colonized by the inoculated vesicular-arbuscular mycorrhizal fungi. Abundant vesicles and arbuscules formed in the roots, and profuse sporulation was detected intra- and extra-radically. Within each fungal species, barley contained significantly more roots and spores per plant than onion did, although the percent root colonization was similar for both hosts. Mean percent root colonization and sporulation per centimetre of colonized root generally increased with time, although with some treatments colonization declined by week 14. Spore production ranged from 4 spores per cm of colonized root for G. fasiculatum to 51 spores per cm for G. intraradices. Infectivity trials with root inocula resulted in a mean ranged from 28.9 to 51.1% of onion roots colonized byG. mosseae, G. fasiculatum, and G. intraradices, respectively, while in aeroponic culture it ranged from 33.8 to 38. However, infectivity studies comparing G. fasiculatum spores from soil and aeroponic culture indicated no biological differences between the spore sources. Aeroponically produced G. mosseae and G. fasiculatum inocula retained their infectivity after cold storage (4°C) in either sterile water or moist vermiculite for at least 4 and 9 months, respectively.

First report of infestation of cassava fruit, Manihot esculenta, by Neosilba perezi (Romero & Ruppell) (Lonchaeidae) in Brazil

, were collected in the municipality of Ponte Nova, Minas Gerais, Brazil (20° 24’ 39” S and 42° 55’ 15” W; 456 m) in July, 2011. The fruit was counted, weighed and stored in screen-covered plastic trays containing vermiculite and kept at room temperature. The substrate was sifted daily and the obtained puparia were stored in flasks containing moist vermiculite. The emerged adults were preserved in 70% ethanol and identified using the identification keys published by Zucchi (2000), Canal and Zucchi (2000), and McAlpine and Steyskal (1982).

Comparison of the effects of flooding vs. low-oxygen gas on pea (Pisum sativum L. cv. 'Alaska') primary roots

Flooding reduces soil oxygen necessary for root growth. In some mesophytes low levels of oxygen are mitigated by the formation of aerenchyma or expansion of intercellular spaces. But root immersion in water may have effects on roots in addition to reducing oxygen levels. At temperatures >15°C Pisum sativum primary roots develop cavities in the centers of their vascular cylinders in response to saturated or flooded conditions. In the present study we compared the response of flooded pea roots to their response to hypoxia without flooding by using an innovative system that allows separation of the gas environment of a root system from that of its shoot system. Seedlings were flooded after 4 d growth and compared to seedlings in unflooded medium and to seedlings in the gas-manipulation experiment. At 25°C in slightly moist vermiculite, roots 4 d after planting were exposed to a gas mixture with 10.5% oxygen and shoots to 20.5% oxygen and compared to normoxic controls. Oxygen levels in all containers were monitored, root growth was measured, and frequency and size of vascular cavities were determined for all treatments. Under flooding and low-oxygen gas, root growth was suppressed and vascular cavity frequency was strongly enhanced compared to controls. Significant differences in root growth responses were not seen between these differing hypoxic conditions, but low-oxygen gas caused larger cavities than flooding, which suggests flooding with water may have subtle effects different than simple hypoxia.

Factors Affecting the Growth of Microgreen Table Beet

There are very few reports on the production of microgreens, a new category of salad crops, the shoots of which are harvested at the seedling stage. A series of cultural studies was conducted with the objective of lessening greenhouse production time and lowering production costs of microgreen table beet (Beta vulgaris L.). Sowing seed balls at a commercially recommended rate (201 g·m−2; 11,256·seed balls·m−2) resulted in greater shoot fresh weight·m−2 at 15 days after planting than sowing seed balls at lower rates, although individual shoots were lighter. Sowing seed balls that were germinated before sowing (pregerminated) in fine-grade exfoliated vermiculite moistened with 150% water (wt. per vermiculite dry wt.) for 5 days at 20°C resulted in 26% greater shoot fresh weight·m−2 at 15 days after planting than sowing nontreated seed balls. Combining preplanting fertilization of the peat-lite with calcium nitrate at 2000 mg·L−1 of N (150 mL·L−1of medium) with daily postplanting solution fertilization with 150 mg·L−1 of N led to a further increase in shoot fresh weight·m−2 of 21% (nontreated seed balls) and 22% (pregerminated seed balls) compared to other fertilization regimes (excluding the check). Germinating, and extruding, seed balls in hydrophilic polymer (hydroxyethyl cellulose gel) advanced microgreen growth but not to the extent achieved with vermiculite as the pregermination medium. Irrespective of seed ball treatment, producing microgreens in troughs using the hydroponic nutrient film technique, compared to production in trays containing peat-lite, increased shoot fresh weight·m−2. Depending on seed ball treatment, economic yield was increased 33% to 98% by 7 days after planting and 75% to 144% by 15 days after planting. The greatest shoot fresh weight·m−2 at 15 days after planting (10.14 kg·m−2) was achieved using seed balls pregerminated in moist vermiculite and subsequent growth using the nutrient film technique.

Slender Wheatgrass is Susceptible to Smut Caused by Ustilago phrygica from Turkey.

Slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners subsp. trachycaulus), family Poaceae, tribe Triticeae, is a native North American grass that is used as a livestock forage. Ustilago phrygica, a systemic ovary-smut fungus, is native to Turkey and West Asia and is pathogenic on Aegilops spp. and Taeniatherum caput-medusae (L.) Nevski subsp. asperum (Simonk.) Melderis (medusahead), an invasive weed in the western United States that is targeted for biological control. An isolate of the fungus (U.S. National Fungus Collections, BPI 871725; GenBank Accession No. DQ139961) was collected from medusahead in Turkey and screened for possible use in classical biological control of this weed. Screening was done in quarantine in a BSL-3 facility of the Foreign Disease-Weed Science Research Unit, USDA, ARS, Ft. Detrick, MD. The focus of screening was determination of host range of the fungus among related native and agriculturally important grasses in North America. A procedure was developed to consistently and quickly produce disease on medusahead and other grasses. Without vernalization, plants inoculated with U. phrygica will not produce smutted spikes (seedheads). Teliospores of the fungus were vacuum inoculated (1) onto caryopses (seeds) of medusahead and slender wheatgrass, which were then placed on moist germination paper in a petri dish or on moist vermiculite in plastic boxes. The dishes, sealed with Parafilm, and the boxes, covered with lids, were placed in a dark refrigerator at 3°C. After 8 weeks, all seedlings were transplanted into pots on a greenhouse bench at 22 to 25°C and 14 h light (photosynthetic photon flux density [PPFD] 620 μmol·s-1·m-2). The plants began to flower and produce smutted spikes 40 days later. These tests were repeated once. Fourteen of sixty medusahead plants from inoculated caryopses incubated on germination paper and nine of twenty-four plants from caryopses incubated on vermiculite became smutted and produced numerous smutted spikes per plant. Partial systemic infection was the norm, and all diseased plants had some spikes that were not diseased. One slender wheatgrass plant of nine plants grown from inoculated caryopses incubated on germination paper was also smutted and produced three diseased spikes. Nielsen (2) indicated susceptibility of slender wheatgrass to U. phrygica, but only as a single entry in a table under the synonym Agropyron trachycaulum (Link) Malte ex H. F. Lewis in a report on susceptibility of Aegilops spp. to U. phrygica. Because this is an obscure mention of the susceptibility of slender wheatgrass to U. phrygica, the fungus-host association does not explicitly appear in literature and is absent from relevant databases. Our tests with the fungus confirm that slender wheatgrass is susceptible to U. phrygica and lead us to conclude that the fungus would not be a good candidate for classical biological control of medusahead in North America. This formal report should establish this fungus-host association in literature and ensure reference in plant disease databases.

White Mold of Houndstongue (Cynoglossum officinale) Caused by Sclerotinia sclerotiorum in Canada.

Houndstongue (Cynoglossum officinale L.) is a rangeland weed introduced into Canada from Eurasia, and it can be highly toxic to livestock feeding in pastures (3). During 2004, houndstongue plants near Creston, BC, Canada developed water-soaked lesions with white mycelia and black sclerotia on leaves and crowns. Isolations from diseased leaf tissues and sclerotia on potato dextrose agar (PDA) at 20°C for 5 to 7 days produced fungal colonies with formation of black sclerotia 5 to 10 mm in diameter. A single hyphal tip isolate from houndstongue. Ss-HT-C. was compared with a sunflower isolate of S. sclerotiorum, sun-87 (1), for morphology and pathogenicity. For apothecial production, Ss-HT-C and sun-87 were grown on PDA in petri dishes at 10°C for 10 weeks, and sclerotia produced were harvested, placed on moist vermiculite in petri dishes, and incubated at 20°C under light for 3 weeks. Mature apothecia were excised, stained with acid fuchsin, mounted on slides, and examined for asci and ascospores with a microscope. There were no morphological differences between Ss-HT-C and sun-87, each producing an ascus with eight binucleate, elliptical ascospores, measuring 4 × 10 μm (width × length), supporting the identity of Ss-HT-C as S. sclerotiorum (2,4). For pathogenicity tests of Ss-HT-C and sun-87, mycelial plugs (8 mm in diameter) were removed from the margin of colonies grown on PDA for 5 days at 20°C, and placed on leaves of C. officinale plants that were grown in a greenhouse (20 ± 4°C) to the rosette stage. Inoculated plants were covered with clear plastic bags, kept in the same greenhouse for 3 days, and the diameters of the leaf lesions developed at inoculation sites were measured. The experiment was run twice with 30 plants per isolate and five leaves per plant. Uninoculated plants covered with plastic bags were used as controls. Experiments used a completely randomized design. Results of leaf inoculations showed that Ss-HT-C and sun-87 were pathogenic to hound-stongue. There was no statistical difference between isolates or trials. The frequency of leaves with lesions was 90% for Ss-HT-C and 93% for sun-87. The mean leaf lesion diameters were 32 and 35 mm for Ss-HT-C and sun-87, respectively. Leaves of control plants remained healthy. S. sclerotiorum was reisolated from leaves with lesions, but not from controls. After 14 to 21 days, new sclerotia, 5 to 10 mm in diameter, were formed on leaves of inoculated plants. The plants eventually died. This study confirms that S. sclerotiorum is the causal agent for the disease of hound-stongue in Canada, and to our knowledge, this is the first world record of infection of this weed by S. sclerotiorum.

Partial vacuum extends the longevity of primed bitter gourd seeds by enhancing their anti-oxidative activities during storage

This study evaluates the effects of partial vacuum storage on longevity and anti-oxidative responses of primed bitter gourd ( Momordica charantia L.) seeds. Priming was achieved by mixing the seeds with moist vermiculite 25 °C for 36 h, followed by air-drying to the original moisture level. Primed seeds were vacuum-packed and stored at 25 °C for up to 12 months. Priming improved seed germination, reduced lipid peroxidation and enhanced anti-oxidative activity prior to storage. However, primed seeds accumulated more total peroxide than non-primed control after 12 months non-vacuum storage, and this led to a marked decrease in seed longevity. Increased total peroxide levels were associated with decreased percentage of 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical inhibition. Partial vacuum storage proved useful in extending the longevity of primed seeds for up to 12 months. Improved longevity was related to enhanced anti-oxidative activity that minimized the accumulation of total peroxide during long-term storage.

Partial vacuum storage improves the longevity of primed sh-2 sweet corn seeds

Priming offers an effective means to raise seed performance in fresh seeds of sweet corn ( Zea mays L.) hybrid carrying mutated shrunken-2 ( sh-2) genes. However, primed sh-2 seeds generally have poorer longevity than non-primed seeds. The effects and mechanisms of priming on sh-2 seed longevity remain unclear. This study evaluates the effects of partial vacuum storage on longevity and free radical processing systems of primed sh-2 seeds. Priming was achieved by mixing the seeds with moist vermiculite and incubation at 15 or 20 °C for 36 h, followed by air-drying to the original moisture level. Primed seeds were vacuum-packed and stored at 25 °C for up to 12 months. Priming improved seedling emergence, reduced lipid peroxidation and enhanced antioxidative systems prior to storage. The longevity of 20 °C-primed seeds was decreased considerably in comparison with non-primed seeds when they were stored under non-vacuum conditions for 12 months. In contrast, 15 °C-primed seeds showed higher viability and vigor than non-primed control seeds when they were stored under non-vacuum conditions. Partial vacuum storage proved useful in extending the longevity of 15 °C-primed seeds for up to 12 months. The improved longevity was related to the decreased free radicals-mediated peroxidative responses. Partial vacuum improved seed vigor (e.g., the emergence percentage, the shortened mean emergence time and the increased seedling growth) were related to the reduced free radical-mediated peroxidation.

Accelerated aging-enhanced lipid peroxidation in bitter gourd seeds and effects of priming and hot water soaking treatments

Both priming (mixing seeds with moist vermiculite for 36 h at 20 °C) and hot water soaking (soaking seeds for 4 h in water at 40 °C) improved the percentage and mean emergence time (MET) of bitter gourd seeds at sub-optimal temperature of 20 °C. The amounts of MDA and total peroxide in imbibing primed and hot water-soaked seeds were reduced and the activities of several free radical and peroxide scavenging enzymes were increased in comparison with imbibing untreated seeds. Thus, the improved emergence performance might be partly contributable to decreased lipid peroxidation during imbibition and peroxide scavenging activities. The percentage of emergence was decreased and MET was increased by accelerated aging. Accelerated aging not only resulted in increased lipid peroxidation, but also in decreased activities of several free radical and peroxide scavenging enzymes. Both percentage and speed of emergence after accelerated aging were decreased to a greater extent in primed and particularly in hot water-soaked seeds than in control seeds. Moreover, lipid peroxidation was increased to a larger extent in pretreated than in untreated seeds after accelerated aging. Therefore, as in the case of pretreated seeds, the increased peroxide accumulation and the reduced enzyme activities appeared to be linked to the reduced emergence performance of aged seeds.

In vitro field collection techniques for Eucalyptus micropropagation

A simple method was established for the collection and short-term storage of shoot material from field-grown Eucalyptus grandis and E. grandis hybrids for micropropagation. Initial studies were undertaken with plants grown outside a greenhouse, which were neither fertilised nor treated with fungicides. The method was then tested and adapted for field-grown clones. It involved collecting 35–50 mm long stems with three nodes and no leaves, spraying them with 70% (v/v) ethanol and storing them in glass bottles containing moist sterile vermiculite for 48 h. Addition of 1 g l−1 calcium hypochlorite to the first culture medium (bud break) inhibited endogenous contamination. Multiplication yields after storage of field-grown explants were 160–264 shoots/100 explants, depending on clone. This offers an alternative, improved means for explant collection over present standard procedures of maintaining parent plants in hedges or transporting shoots to the micropropagation laboratory in buckets.

The gravitropic setpoint angle of dark-grown rye seedlings and the role of ethylene.

The orientation growth of coleoptiles of dark-grown seedlings of rye (Secale cereale L. cv. Marder II), when grown under various conditions, was analysed with respect to the gravivector ('gravitropic setpoint angle', GSA). Coleoptiles growing through moist vermiculite attain and maintain a GSA with an average of about 180 degrees, i.e. a vertical orientation. Seedlings growing uncovered either on the surface of vermiculite or positionally fixed on filter paper attain and maintain a GSA of 140-150 degrees (i.e. deviating from the vertical by an average of 30-40 degrees ). Changing the position of the embryo relative to the horizontally fixed seed kernel or of the angle of the seed with respect to gravity during germination (+/-40 degrees relative to the horizontal) had no significant effect on the subsequent GSA of both covered and uncovered seedlings. The GSA of uncovered coleoptiles could be restored close to 180 degrees by treatment of the seedlings with ethylene, either applied via ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC) as well as by fruit-released ethylene. The results are discussed with respect to the mechanism of the regulation of gravitropic growth of grass seedlings.

Changes in Carbohydrate Concentrations in Basal Leaf Sheaths of Allium × wakegi Araki in Relation to Bulb Development and Dormancy

Changes in carbohydrate concentrations in basal leaf sheaths (this part corresponds to a bulb after bulb development) of two Allium × wakegi Araki cultivars, 'Kiharabansei No.1'(dormant type) and 'Ginoza'(nondormant type) during bulb development and postharvest storage were investigated. There was little difference in the fructose, glucose, sucrose, and fructans concentrations throughout the experimental period between 'Kiharabansei No.1' and 'Ginoza'. Hence, only changes in the former are discussed. During bulb development, when plants of 'Kiharabansei No.1' became dormant, the concentrations of fructose and glucose decreased, while those of fructans and total carbohydrates increased ; there were no significant changes in sucrose concentrations. During postharvest storage of 'Kiharabansei No.1' bulbs, they were gradually released from dormancy and the concentrations of all the components remained constant. The percentage of fructans to total carbohydrates after bulb development exceeded 90% (w/w). This accumulation of fructans was specific to basal leaf sheaths. When bulbs of 'Kiharabansei No.1' planted in moist vermiculite began to sprout, the concentrations of fructose and glucose in the bulbs increased, while those of fructans and total carbohydrates decreased.

Soaking in Cold Water Replaces the Stratification Requirement of True Cedar Seeds

There is an increasing demand from growers for seeds to be of the highest vigor possible, with the ability to emerge rapidly, uniformly, and to a high level. Seed priming (soaking in salt, osmoticum, or water solutions) can accelerate germination and seedling establishment. This technique is a well-established practice for some horticultural crops (Parera and Cantliffe, 1994) and forest trees (Struve et al., 1991). True cedars (Cedrus sp.) are common forest trees in the Mediterranean basin and are also widely used as ornamental trees in Europe, the United States, and other countries. Seeds of true cedars usually require stratification for 2 weeks to improve germination (Heit, 1968). Since the stratification period must be accompanied by adequate water uptake (Bonner et al., 1989), we examined whether soaking true cedar seeds in cold water could reduce or replace their stratification requirement. Fresh seeds (one lot) of Cedrus deodara (D. Don.) were obtained from Setropa Ltd., Bussum, The Netherlands. Seeds were stored dry at 4 °C and used for the experiments within 4 months after collection. Seeds were soaked in aerated water solutions in 9-L polystyrene containers; an airstone placed on the bottom of the containers supplied air at a rate of 1.5 L·min. The rate of airflow was controlled by flowmeters. One hundred seeds were placed in a net bag floating in the water and were soaked in the dark for 2 d at 4 or 19 °C. Additional seeds were stratified in moist vermiculite at 4 °C for 2 weeks. To determine emergence, seeds were sown in vermiculite in germination trays placed in a growth chamber under the following conmainly improved the uniformity of seedling emergence. Uniform emergence is necessary to reduce the period of susceptibility to certain diseases, improve crop uniformity, and increase seedling size. Cold soaking increased the final emergence percentage only slightly above that of stratified seeds. However, this effect was consistent in all the experiments performed (Fig. 1 and two additional experiments not presented), and may also be beneficial due to the low germination rates (≈50%) of true cedars, primarily because of low viability (Bonner et al., 1989). Cold soaking also stimulates germination of C. atlantica seeds (Siaki, 1999). Results in this and previous studies suggest that cold soaking can replace stratification completely in seeds that require a short period of stratification, but only partly in seeds with longer stratification periods (Janerette, 1979).

Evaluation of a technique to obtain development-stage-synchronised earthworms ( Eisenia fetida )

The aim of this experiment was to investigate whether Eisenia fetida hatchlings of different ages, kept initially without food, could be used to obtain worms of a comparable development stage (measured as growth) with similar maturation properties (measured as clitellum development). Seven groups of hatchlings, each differing in age by 7 days (range: 0–42 days) were collected as follows. Cocoons were kept in water in multicell containers and individuals that hatched during a 24-h period were placed on moist vermiculite with no food, at weekly intervals. The longest period that hatchlings were fasted was 42 days, after which food was added and growth monitored for 50 days. No differences in weight gain between the different batches were observed. Analysis of the growth curves and attainment of sexual maturity (clitellum development) indicated no effect of age or stage of development at the onset of feeding. It was concluded that this technique allows the production of cohorts of E. fetida, synchronised with respect to development stage, for use in toxicological and biological investigations that require control of factors such as development stage, age and size, and in particular for use in toxicological experiments complying with OECD regulatory procedures.