Asparagus Seeds Research Articles

CHARACTERIZATION OF SUBSTRATES AND THEIR INFLUENCE ON GERMINATION AND GROWTH OF ASPARAGUS SEEDLINGS

The survival and performance of vegetables in the field production cycle depend on the seedling quality and, in turn, the substrate. Asparagus is not part of the vegetables cultivated in Boa Vista-RR, so basic studies, such as substrate preparation, are necessary. Thus, the present study aimed to evaluate the effect of six substrates on the initial development of asparagus seedlings in two growth phases. For this, an experiment was set up in an entirely randomized design, with treatments arranged in a factorial scheme (6 x 2). In the initial phase of the study, six compositions were evaluated with the following materials: (S - soil; M - goat manure; C - root and shoot of cassava) in two sowing seasons. The S40M30C30 substrate stands out by having better particle distribution, 79% ranging between 2 and 0.5 mm and 21% less than 0.5 mm, wet bulk density of 0.823 g cm-3 and dry of 0.726 g cm-3, relative humidity of 7.1% and particle density of 1.88 g cm-3. This substrate also provided higher growth variables than the others and is suitable for growing asparagus in its initial phase. Asparagus seeds should be sown in a substrate prepared with soil and organic waste (goat manure and residue from the shoot and roots of cassava) at least seven days before sowing.

Mineral analysis of dry extracts from the seeds of the plant Silybum marianum (L. Gaertner) introduced in Uzbekistan

Silybum marianum (L.) Gaerth. (Asteraceae) is a valuable medicinal plant In the domestic and foreign literature the following pharmacological properties of the medicinal forms from Silybum marianum are described: antioxidant, antitoxic, hemostatic, hepatoprotective, detoxification, choleretic, anti-inflammatory, wound healing, reparative, laxatives, tonic, improving digestion, cholekinetic, cholesecret [1,2]. In Uzbekistan, the development of products for functional and therapeutic-preventive purposes for preventing various diseases and strengthening protective functions body, reducing the risk of exposure to harmful substances, including for the population living In ecologically unfavorable zones [3]. Macro and microelement analyzes of dry extract from asparagus seeds were performed. It was found that the extract contained balanced macro and microelements. Based on the results of the experiments, the product was recommended for use in biologically active supplements.

Is the European red fox a vector of the invasive basket asparagus (Asparagus aethiopicus) in eastern Australia?

Basket asparagus (Asparagus aethiopicus) has become a naturalised invasive plant in some coastal areas of Australia since its introduction in the late 19th century. Its spread through garden waste dumping and avian seed dispersal has been well documented and both are considered to be the primary means of dispersal. While a small number of avian vectors have been identified, no Australian studies have investigated the potential of mammals to disperse basket asparagus seeds. We collected basket asparagus seeds from fox (Vulpes vulpes) scats collected in the field, confirmed the viability of these seeds in germination trials, and further documented the germination of basket asparagus seeds from an undisturbed fox scat in situ. These results demonstrate that foxes consume and disperse basket asparagus seeds, and that these seeds are viable and germinate under field conditions. Foxes not only use basket asparagus stands as harbour, but can also facilitate the plant’s dispersal in coastal ecosystems.

Seed Treatment Techniques to Improve Germination of Wild Asparagus (Asparagus acutifolius L.), a Potential New Crop

Pre-sowing seed treatment techniques of stratification and scarification were used in order to find the most appropriate method to overcome dormancy of wild asparagus (Asparagus acutifolius L.) seeds. An indoor and an outdoor experiment were carried out at the Agricultural University of Athens. For the indoor experiment, the pre-sowing treatments of stratification (fresh and stratified seeds) and scarification (non-scarified, mechanical scarification and chemical scarification with sulfuric acid) were used as the main treatments, and three different temperatures (15, 20 and 25 °C) as sub-treatments. For the outdoor experiment, there were only the treatments of stratification and scarification. The stratification of asparagus seeds was found to have a positive effect on germination and vigor indices compared to non-stratified (fresh) seeds. The highest germination percentage, vigor index I and II were recorded with the stratified seeds that had been mechanically scarified in both indoor and outdoor conditions. The results indicate that just the scarification cannot improve germination of fresh collected seeds of wild asparagus. Stratification increased the germination percentage from 2.7-6.6% to 45.1-75.3%. The mechanical and the chemical scarification had a positive effect on the root length compared to the non-scarified seeds that have been stratified. These pre-sowing treatments can increase the germination percentage and produce vigorous seedlings that can be used to establish plantations of this potential new crop.

A method for sex identification in asparagus using DNA from seeds

Asparagus (Asparagus officinalis L.) is a dioecious species, with both male and female individuals. Male plants are more desirable to cultivate than female plants because they have higher yields, and, unlike female plants, they do not have a weed problem resulting from fallen seeds. A male-specific DNA marker is currently available to identify the sex of asparagus individuals using total DNA extracted from cladodes and roots. However, no published method is currently available for DNA extraction and PCR amplification from asparagus seeds. In this study, we tested several heat-resistant DNA polymerases for PCR and several methods for extracting DNA from asparagus seeds and successfully established a method for identifying the sex of asparagus seeds using this male-specific DNA marker. We found that PCR amplification of DNA extracted from asparagus seeds using simple methods such as single-step DNA extraction requires the use of high efficiency DNA polymerase. By contrast, many types of heat-resistant DNA polymerases can be used for PCR amplification of high-quality DNA extracted from asparagus seeds using a commercially available DNA extraction kit. Our method for sex identification of asparagus seeds could facilitate quality checking of all-male asparagus seeds and accelerate the screening of super-male asparagus.

ANATOMICAL AND CHEMICAL INVESTIGATIONS ON ASPARAGUS OFFICINALIS L. (ASPARAGACEAE)

Although Asparagus (Asparagus officinalis L.) is chiefly known as a vegetable herb, little information about the botanical characteristics of such plant are available. Therefore, it is aimed in this study to bring light more information about the morphological, anatomical and some important chemical contents of vegetative and reproductive organs of the plant, throughout the consecutive stages of its entire life span under the local conditions. Seeds of Asparagus (cv. Mary Washington 500 W) were sown 2nd Feb. 2013. The field experiment was carried out at the Experimental and Research Station of Fac. of Agric., Cairo Univ., Giza, Egypt during the two successive growing seasons 2013 and 2014. Asparagus is a herbaceous, perennial plant that grows up to 1.5- 2 m height. The plant posses aerial stems (ferns) and much- branched feathery foliage. The leaves are triangular scales like, 3-7 mm in length. The cladodes (modified stems) arise in the axis of scale leaves . Cladodes are found in fascicles (3-6) on each node. The flowers are bell- shaped, greenish –white to yellowish, 4.5-6.5mm long, with 6- tepals,single or in clusters of 2-3. Anatomical studies were carried out for various organs of Asparagus plant including, apex of the aerial stem, visible internode below shoot apex, median portion of the aerial stem, the cladode , median portion of spear, scale - like leaf, rhizome, adventitious root. The major chemical metabolites contents of spear were determined.

Effects of after-ripening, stratification and GA 3 on dormancy release and on germination of wild asparagus ( Asparagus acutifolius L.) seeds

Seeds of wild asparagus ( Asparagus acutifolius L.) were treated and compared in this research to investigate seed dormancy class and level involved in this species. Four seed lots were compared: (i) freshly harvested seeds in 2007 (07Fr); (ii) freshly harvested seeds in 2008 (08Fr); (iii) after-ripened (AR) 2007 seeds dry stored in glass jars (AR g); (iv) AR 2007 seeds dry stored in paper bags (AR p). The 07Fr seeds were exposed to (1) chemical scarification combined with gibberellic acid (GA 3) levels (0, 200, 400, and 600 mg L −1) and to (2) 28-day moist stratification at 5 and 23 °C, and two sequences of 5/23 °C combined with 0 and 400 GA 3 mg L −1 levels, and (3) together to the 08Fr and AR seeds were exposed to 56-day moist stratification at 5, 23, or 5/23 °C. With the 08Fr and AR seed lots this last stratification treatment was combined with 0 or 800 GA 3 mg L −1 levels. The dormancy depth of 08Fr (32% germination) was less than 07Fr seeds (2%). The latter after-ripened during dry storage and when stored in glass germinated more (47.5%) than in paper (12%). Stratification for 4 weeks was ineffective in improving germination of 07Fr seeds; when chemically scarified they did not germinate at all. The highest (nearly 70%) and the most rapid and uniform germination were observed for all the lots when they were warm stratified for 56 days. Warm stratification improved germination more than alternate temperature stratification, while cold stratification inhibited germination especially for the 08Fr and ARg lots, thus seeds seem not to have a morphological component to their dormancy. GA 3 only improved germination of 07Fr seeds, at a low rate. A. acutifolius seeds fit the characteristics of a non-deep physiological dormancy.

Field evaluation of asparagus crowns and germinating seeds inoculated with plant growth-promoting rhizobacteria

Plant growth-promoting rhizobacteria (PGPR) have the ability to enhance growth and establishment by reducing stress ethylene, or providing exogenous indol-3-acetic acid (IAA), nitrogen, iron, or phosphorus. In previous greenhouse studies, PGPR inoculation of asparagus seeds or seedlings enhanced growth under optimal and water stress conditions. Experiments were conducted in this study to determine if PGPR could provide benefits to transplanted crowns and germinating seeds in the field. Plant growth-promoting rhizobacteria did not positively affect shoot height, count, or diameter of inoculated crowns, or percent germination and seedling dry weight of inoculated seeds. The limitations of using PGPR in the field and potential for future success are discussed.Key words: Asparagus officinalis, Pseudomonas , water stress, drought, irrigation

Cowpeat as a Substitute for Peat in Container Substrates for Foliage Plant Propagation

This study evaluated the potential for using cowpeat, a composted dairy manure, as a component of container substrates for foliage plant propagation. Using a commercial formulation (20% perlite and 20% vermiculite with 60% Canadian or Florida peat based on volume) as controls, peat was replaced by cowpeat at 10% increments up to 60%, which resulted in a total of 14 substrates. Physical and chemical properties such as air space, bulk density, container capacity, total porosity, pH, carbon-to-nitrogen ratio, and cation exchange capacity of the cowpeat-substituted substrates were largely similar to those of the respective control. However, the electrical conductivity (EC) increased with the increased volume of cowpeat. The 14 substrates were used for rooting single-node cuttings of golden pothos (Epipremnum aureum) and heartleaf philodendron (Philodendron scandens ssp. oxycardium) and three-node cuttings of ‘Florida Spire’ fig (Ficus benjamina) and germinating seeds of sprenger asparagus (Asparagus densiflorus) in a shaded greenhouse. All cuttings rooted in the 14 substrates, and the resultant shoot and root dry weights of golden pothos and ‘Florida Spire’ fig 2 months after rooting did not significantly vary across seven Canadian peat- or Florida peat-based substrates. Shoot dry weights of heartleaf philodendron were also similar across substrates, but the root dry weight produced in the Canadian peat-based control substrate was much greater than that produced in the substrate containing 60% cowpeat. Root dry weight and root length produced in the Florida peat-based control substrate were also significantly greater than those produced in substrates substituted by 60% cowpeat. These results may indicate that cuttings of golden pothos and ‘Florida Spire’ fig are more tolerant of higher EC than those of heartleaf philodendron, as the substrate with 60% cowpeat had EC ≥ 4.16 dS·m−1. Seed germination rates of sprenger asparagus from cowpeat-substituted Canadian peat-based substrates were greater than or comparable to those of the control substrate. Seed germination rates were similar across the seven Florida peat-based substrates. The root-to-shoot ratios of seedlings germinated from both control substrates were significantly greater than those germinated from substrates substituted by cowpeat. This difference could be partially explained by the higher nutrient content in cowpeat-substituted substrates where shoot growth was favored over root growth. Propagation is a critical stage in commercial production of containerized plants. The success in using up to 60% cowpeat in rooting and seed germination substrates may suggest that cowpeat could be an alternative to peat for foliage plant propagation.

Cowpeat as a Substitute for Peat in Container Substrates for Foliage Plant Propagation

This study evaluated the potential for using cowpeat, a composted dairy manure, as a component of container substrates for foliage plant propagation. Using a commercial formulation (20% perlite and 20% vermiculite with 60% Canadian or Florida peat based on volume) as controls, peat was replaced by cowpeat at 10% increments up to 60%, which resulted in a total of 14 substrates. Physical and chemical properties such as air space, bulk density, container capacity, total porosity, pH, carbon-to-nitrogen ratio, and cation exchange capacity of the cowpeat-substituted substrates were largely similar to those of the respective control. However, the electrical conductivity (EC) increased with the increased volume of cowpeat. The 14 substrates were used for rooting single-node cuttings of golden pothos (Epipremnum aureum) and heartleaf philodendron (Philodendron scandens ssp. oxycardium) and three-node cuttings of ‘Florida Spire’ fig (Ficus benjamina) and germinating seeds of sprenger asparagus (Asparagus densiflorus) in a shaded greenhouse. All cuttings rooted in the 14 substrates, and the resultant shoot and root dry weights of golden pothos and ‘Florida Spire’ fig 2 months after rooting did not significantly vary across seven Canadian peat- or Florida peat-based substrates. Shoot dry weights of heartleaf philodendron were also similar across substrates, but the root dry weight produced in the Canadian peat-based control substrate was much greater than that produced in the substrate containing 60% cowpeat. Root dry weight and root length produced in the Florida peat-based control substrate were also significantly greater than those produced in substrates substituted by 60% cowpeat. These results may indicate that cuttings of golden pothos and ‘Florida Spire’ fig are more tolerant of higher EC than those of heartleaf philodendron, as the substrate with 60% cowpeat had EC ≥ 4.16 dS·m−1. Seed germination rates of sprenger asparagus from cowpeat-substituted Canadian peat-based substrates were greater than or comparable to those of the control substrate. Seed germination rates were similar across the seven Florida peat-based substrates. The root-to-shoot ratios of seedlings germinated from both control substrates were significantly greater than those germinated from substrates substituted by cowpeat. This difference could be partially explained by the higher nutrient content in cowpeat-substituted substrates where shoot growth was favored over root growth. Propagation is a critical stage in commercial production of containerized plants. The success in using up to 60% cowpeat in rooting and seed germination substrates may suggest that cowpeat could be an alternative to peat for foliage plant propagation.

Germination and vigour of primed asparagus seeds

The osmotic conditioning or priming is considered a promising technique to speed up germination and to improve seed performance. Four seed lots of asparagus, Mary Washington cultivar, were primed at 25°C for seven or 14 days using PEG 6000 at -1.0 or -1.2 MPa, or sea water at -3.3 MPa; or for three days in distilled water. The physiological quality of the seeds was evaluated by standard germination, first count germination, speed of seedling emergence, and germination percentage and seedling fresh and dry weights after controlled deterioration test. Primed seeds presented higher germination speed, independently of their initial physiological quality. Beneficial effects of priming on germination and vigour were more expressive in the seed lot of low physiological quality. Priming in PEG 6000 at -1.0 MPa for 14 days was the most beneficial treatment to improve asparagus seeds performance.

Fusarium moniliforme and F. proliferatum Isolated from Crown and Root Rot of Asparagus and Their Association with Asparagus Decline in Argentina.

During the summer of 1995-1996, an 80-ha field of 6-year-old asparagus plants (cv. UC 72) in Saladillo (Province of Buenos Aires) was affected by a decline syndrome (1). The plants showed a decline in vigor and approximately 60 to 70% of the plants died. The symptomatic plants were chlorotic, stunted, with stem lesions and crown and root rot. Fusarium moniliforme and F. proliferatum were isolated from vascular and epidermal tissues of roots, crowns, and stems. Identification of Fusarium to species was made by examining conidiogenous cells from colonies cultured on KCl medium (2). Microconidia were born in long and short chains and false heads. The isolates were identified based on the the presence of polyphialides in F. proliferatum and their absence in F. moniliforme, which produces monophialides only (2). In two separate trials, asparagus seeds (cv. UC 72) were surface sterilized and placed in steamed soil infested with a conidial suspension of each species. The viable propagules in the soil (CFU per g) were estimated by soil plate dilutions on Nash & Snyder-PCNB (pentachloronitrobenzene) medium. The F. moniliforme and F. proliferatum soil densities were 19.2 × 103 and 23 × 103 CFU per g of soil, respectively. The pots were placed in the greenhouse on different benches to avoid cross-contamination. After 4 months, inoculated plants showed root and crown discoloration. F. moniliforme and F. proliferatum were reisolated (64 and 75%, respectively) from discolored portions of internal and external root and crown tissues. Although the stems did not show symptoms, F. moniliforme and F. proliferatum were also recovered (27 and 38%, respectively) from asymptomatic tissues. Six months after inoculation the plants developed chlorotic symptoms with crown and root rot, and then wilted. F. moniliforme and F. proliferatum were reisolated from root systems, crowns, and stems of all inoculated plants. F. moniliforme and F. proliferatum are involved in corn stalk and ear rot in Argentina. Corn and asparagus are frequently grown in close proximity and often follow one another at a particular site. Airborne and soil debris carrying F. moniliforme and F proliferatum from corn may be an additional source of inoculum for asparagus in Argentina. The results indicate that the presence of F. moniliforme and F. proliferatum is a factor that contributes to asparagus decline in Argentina.

Germination of Osmotically Primed Asparagus and Tomato Seeds after Storage up to Three Months

The influence of two drying regimes and two storage temperatures of primed asparagus (Asparagus officinalis L.) and tomato (Lycopersicon esculentum Mill.) seeds on germination after storage up to 3 months was examined. Seeds of `Mary Washington' asparagus and `Ace 55' tomato primed in synthetic seawater (-1.0 MPa, 20C, 1 week, dark) were surface-dried at 20C and 50% relative humidity (RH) for 2 h (42% to 49% moisture) or dried-back at 20C and 32.5% RH for 48 h (moisture = 13% tomato and 22% asparagus). These and nonprimed seeds were stored in tight-lidded metal cans and heat-sealed plastic pouches at 4 or 20C for up to 3 months before germination at 20C. After 3-month storage, primed surface-dried asparagus seeds stored at 4C had greater germination percentage and rate than nonprimed seeds, surface-dried seeds stored at 20C, or primed dried-back seeds. Dried-back primed tomato seeds had higher germination percentage than surface-dried primed seeds after 2 or 3 months of storage, with storage temperature having no effect on germination perecentage or rate. In a further study, primed surface-dried and primed dried-back seeds stored at 4 or 20C for 1.5 months in sealed containers were germinated at 15, 25, or 35C under low (-0.05 MPa) or high osmotic stress (-0.4 MPa). Primed surface-dried asparagus seeds stored at 4C, compared to nonprimed seeds, surface-dried seed stored at 20C, or primed dried-back seeds, had greater germination percentage at 15 and 35C and low osmotic stress, and higher germination rate at 15 or 25C. Primed tomato seeds had greater germination percentage than nonprimed seeds only at 35C and low osmotic stress, and higher germination rate at 15 or 25C. Storage of primed tomato seeds at 4C rather than 20C increased germination rate at 15 or 25C, and increased germination percentage at 35C and low osmotic stress. For maximal seed viability and germination rate after 1.5 to 3 months of storage, primed asparagus and tomato seeds should be stored at 4C rather than 20C; however, asparagus seeds should be surface-dried, and tomato seeds should be dried-back.

Asparagus Emergence in Fusarium-treated and Sterile Media following Exposure of Seeds or Radicles to One or More Cinnamic Acids

Several cinnamic acids have been identified as principal toxic components of asparagus (Asparagus officinalis L.) root autotoxin and have been shown to synergize Fusarium infection of asparagus. The basis for this synergism was studied by exposing asparagus seeds and radicles from pregerminated seeds to ferulic (FA), caffeic (CA), or methylenedioxycinnamic (MDA) acids alone and in combinations of two or three of these acids. After treatment, seeds were placed in pots of peat-lite mix, and, depending on the experiment, all or half were inoculated with F. oxysporum (Schlecht) f. sp. asparagi (Cohen). Seedling emergence from each pot was used as a measure of toxicity. All cinnamic acids at 1% suppressed emergence compared with the control. Solutions combining FA and CA (0.5%/0.5%, v/v) were substantially more toxic than 1% solutions of either alone. Exposure of radicles (early postgermination) for 10 minutes to combined FA/CA before planting decreased emergence from pots, whereas emergence following a 10-minute exposure to 1% CA or FA alone did not differ from the controls. The 2-hour exposure to FA or to FA/CA and the 24-hour exposure to CA, FA, or FA/CA decreased emergence, with toxicity progressing as follows: CA < FA < FA/CA. Root tip squashes showed fewer mitotic figures in treated than in untreated radicles, and scanning electron microscopic (SEM) examination of the radicle epidermis revealed damage to the surface of epidermal cells and precocious root hair development, the extent of which paralleled treatment toxicity.

Caffeic Acid Identified as an Inhibitory Compound in Asparagus Root Filtrate

A potential allelochemical was isolated and identified from methanol extracts of asparagus (Asparagus officinalis L.) fresh root tissue. Fractions were collected by cellulose column chromatography and tested for inhibition by an asparagus seed germination bioassay. The fraction showing the greatest inhibition contained caffeic acid, as identified by melting point, thin-layer chromatography, and infrared spectrum analysis. Seed germination bioassays and greenhouse pot tests showed depression of seedling emergence when asparagus seeds were exposed to various dosages of crude filtrate, a methanol extract from crude filtrate, and caffeic acid.

A Comparison of Priming Agents for Tomato and Asparagus Seeds

Tomato (Lycopersicon esculentum Mill.) and asparagus (Asparagus officinalis L.) seeds were primed for 1 week in –0.8 MPa (20C, dark) polyethylene glycol 8000 (PEG), synthetic seawater (INO), or combinations of Ca+2, K+, or Na+ with Cl–, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{H}_{2}\mathrm{PO}_{4}^{-}\) \end{document}, or \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{SO}_{4}^{-2}\) \end{document}) and then were placed in 0.5-fold Hoagland solution at 20C for germination. Priming did not affect percentage germination of tomato seeds; but asparagus germination increased from 85% in untreated seeds to 90% due to priming. All priming treatments reduced the time to 50% germination (G50) of both species but reduced the time between 10% and 90% germination (G10-90) of only tomato seeds. Salt solutions gave lower G50 values than PEG for tomato seeds but did not provide this advantage for asparagus seeds. The G50 and G10-90 of tomato seeds were lower after priming with nitrate salts than with other salts, but the reductions were greatest with sodium nitrate. The G50 of asparagus seeds was lowered with nitrate salts, but the G10-90 was unaffected.

Germination and Seedling Emergence of Primed Tomato and Asparagus Seeds under Adverse Conditions

Seeds of `Ace 55' tomato (Lycopersicon esculentum Mill.) and `Mary Washington' asparagus (Asparagus officinalis L.) were primed in -0.8 MPa (20C, 1 week, dark) polyethylene glycol 8000 (PEG), synthetic seawater (INO), or NaNO3. Primed seeds of both species had a higher percentage of germination than untreated seeds only at 10C in nonsaline (– 0.05 MPa) medium, while in saline medium (– 0.6 MPa) priming increased the percentage of germination of tomato seeds at 10 and 30C, and of primed asparagus seeds at 10 and 20C. Sodium nitrate was superior to PEG or IN0 for priming tomato seeds since it resulted in fewer days to 50% germination and higher final germination percentage in saline media at all temperatures. IN0 was a satisfactory alternative to PEG or NaNO3 for priming asparagus seeds since priming agent had little or no effect on germination. Seedling emergence from NaNO3-primed seeds of both species sown in a seedbed provided saline (– 0.39 MPa) irrigation was faster than from untreated dry-sown seeds. In the saline seedbed, priming increased final emergence percentage (FEP) from asparagus seeds, provided they were not subsequently dried, but had no effect on the percentage emergence of tomato seeds. Fluid-drilling primed or germinated seeds of either species enhanced seedling establishment in the saline seedbed by reducing time to 50% emergence and/or increasing FEP relative to primed, dried-b&k or untreated seeds.

Effect of phenolic compounds on asparagus mycorrhiza

Asparagus (Aspurugus o@iic~nulis L.) produces several cinnamic acid derivatives known to be allelochemicals (Young. 1984: Young and Chou. 1985; Hartung ef ul.. 1990). It has been suggested that these allelochemicals may either be directly involved in asparagus decline by affecting plant vigor (Young. 1984; Young and Chou, 198s) or indirectly through chemical-mediated changes in the microbial community (iiartung and Stephens. lYX3). which in turn aflcct plant growth. Wacker CI cl/. (199Ob) have shown that ferulic acid, an allclochcmical found in asparagus roots, decreases root colonization by vesicular arbuscular mycorrhirae (VAM) and the growth ol’ mycorrhiznl asparagus. Wackcr (*I ul. (IYYOc) I‘ound a change in the composition of the VAM fungal community in asparagus fields with increasing age up IO 20 yr. Root colonization by VAM fungi and spore density in the soil also c Wackcr cr ul.. IYYOa) plant health may be adversely alTected if the nutritional contribution to asparagus by native VAM fungal species decreases with plant age. Because available P decreased with increasing number of years cropped in asparagus, soil P may not be the factor responsible for the reduction in root colonization by VAM fungi and the change in the composition of the VAM fungal community observed by Wacker (1990~). Accumulation of phcnolic allclochcmicals produced by asparagus could be a mechanism by which asparagus monocropping alters the species composition of the VAM fungal community. WC report the etfrcts of’ fcrulic. catTcic and methylencdioxycinnamic (MDC) acids and also those of soil extracts from an asparagus field soil and an adjacent non-cultivated soil on VAM formation and growth of asparagus. To examine the etTccts of three phenolic acids on VAM formation in asparagus. asparagus seeds (cv. “Mary Washington”) were surface-sterilized (Elmer and Stephens, 1988). germinated and sown into plastic cell-pack units (2 x 2) with 8Og of washed sand per cell. A 9.0cm dia Petri dish base was used under each J-cell unit to avoid chemical cross-contamination. A VAM fungus resembling G/r~nlus/ct.vcicu/urunr (Thaxtcr) Gerd. and Trappc emend. Walker and Koske was multiplied in pot cultures with sorghum (.Sorlral seedlings. Alier transplanting, plants were watcrcd weekly with IO ml of 0.1 strength

GERMINATION RESPONSES OF OSMOTICALLY PRIMED ASPARAGUS AND TOMATO SEEDS

Seeds of `Ace 55VF' tomato were soaked in solutions of -1.0 MPa Instant Ocean™ (inorganic salt mixture) or -0.6 MPa polyethylene glycol 8000 (P.E.G.) at 25 C for 1 week. `Mary Washington' asparagus seeds were soaked in the same solutions for 2 weeks. In solutions of decreasing matric or osmotic potentials, primed seeds germinated faster than untreated seeds. Germination percentages of primed seeds generally were greater than those of untreated seeds when water stress exceeded -0.5 MPa. All primed seeds, whether dried to a low moisture content or not, germinated faster than untreated seeds after storage for up to 3 months at 4 C or 20 C. Primed asparagus seeds germinated most rapidly and synchronously after storage at 4 C and high moisture content. Storage temperature and seed moisture content had no effect on subsequent germination of primed tomato seeds.

Emergence and seedling growth from osmotically primed or pregerminated seeds of asparagus (Asparagus officinalisL.)

SummaryThe optimum priming treatment for seeds of ‘UC 157’ asparagus was one week in –0.6 MPa polyethylene glycol 8000 at 20°C following three days in water at 20°C. This treatment advanced the time to 50% germination by 5.3 days but did not improve the synchrony or percentage of germination relative to those of untreated seeds. The emergence and plant growth responses from primed or water-soaked seeds that were sown dry or fluid-drilled were compared with those from either 100% germinated seeds that were fluid-drilled or untreated seeds. The relative responses to these treatments were similar under both glasshouse and field conditions. Seedling emergence was more rapid from primed seeds than from water-soaked ones but increased drying of both before planting led to slower emergence. Whilst the most rapid emergence occurred with primed seeds that were fluid-drilled (without drying), emergence was even earlier when 100% germinated seeds were fluid-drilled. Crown fresh weights of plants from primed or germi...