Further Observations on Physiological Breakdown In Stored Plums

Summary

Seeds of Fagus sylvatica, Prunus avium and Acer pseudoplatanus were sown on 10 May and covered with four materials: white polyethylene, white polypropylene, yellow net or green net for 90 d to study the effect of a temporary covering on soil and air temperature, increment in dry weight, and root cellular diameter of nursery tree seedlings in a northern climate. Root collar diameter, height and dry weight of covered seedlings were compared with those of uncovered control seedlings at the end of growing season. The increase in soil and air temperature under white polyethylene, white polypropylene and yellow net and the decrease in soil temperature under the green net influenced the growth of F. sylvatica and P. avium seedlings. Dry weight, as well as root collar diameter and height, was increased under the coverings increasing temperature. A. pseudoplatanus responded less to temperature, but increased dry weight and root collar diameter when cultivated under white polypropylene and green net. Hence temporary coverings can be used to improve the quality of seedlings grown in a northern climate.     

Biological control of the shoot disease of Amaranthus hybridus caused by Choanephora cucurbitarum with Bacillus subtilis

Summary

Isolates of Bacillus subtilis from soil and ogili (a local food condiment) controlled choanephora shoot disease of the vegetable crop plant, Amaranthus hybridus, in the greenhouse. Disease developed on plants inoculated simultaneously with the pathogen Choanephora cucurbitarum and the ‘ogili’ isolate, but not the soil isolate, of B. subtilis. Application of either bacterial strain to plants one day before a challenge with the pathogen prevented disease development. A single application of either strain prevented disease development from a subsequent challenge with the pathogen at any time over a thirty day period. Viable counts of the microflora on the shoot tips of the treated plants indicated strongly that the inoculated bacteria multiplied and colonized the extending shoot tip whether or not the shoots were covered with polythene bags. Both strains of Bacillus subtilis inhibited mycelial extension growth as well as conidial germination in vitro.     

Shoot zinc (Zn) concentration varies widely within Brassica oleracea L. and is affected by soil Zn and phosphorus (P) levels

Summary

The low availability of zinc (Zn) in soils and crops affects dietary Zn intake worldwide. This study sought to determine if the natural genetic variation in shoot Zn concentrations ([Zn]shoot) is sufficient to pursue a crop improvement breeding strategy in a leafy vegetable crop. The gene-pool of Brassica oleracea L. was sampled using a large (n = 376) diversity foundation set (DFS), representing almost all species-wide common allelic variation, and 74 commercial varieties (mostly F₁). The DFS genotypes were grown at low and high soil phosphorus (P) levels under glasshouse and field conditions, and also in a Zn-deficient soil, with or without Zn-fertilisation, in a glasshouse. Despite the large variation in [Zn]shoot among genotypes, environment had a profound effect on [Zn]shoot. The heritability of [Zn]shoot was significant, but relatively low, among 90 doubled-haploid (DH) lines from a mapping population. While several quantitative trait loci (QTL) associated with [Zn]shoot occurred on chromosomes C2, C3, C5, C7, and C9, these were generally weak and conditional upon growth conditions. Breeding for [Zn]shoot in B. oleracea is therefore likely to be challenging. Shoot P concentrations increased substantially in all genotypes under low soil Zn conditions. Conversely, only some genotypes had increased [Zn]shoot at low soil P levels. Sufficient natural genetic variation may therefore exist to study some of the interactions between Zn and P nutrition.     

The effect of irrigation and crop load on stem water potential and apple fruit size

Summary

The effect of irrigation rate under various crop loads on the fruit size of apple (Malus domestica Borkh cv. Golden Delicious) was investigated in three field experiments in 1993–1995. During the first two years the field experiments evaluated the effects of various crop loads on yield, fruit size and midday stem water potential under 40% deficit irrigation. In 1995, the effects of five irrigation levels (0.42–1.06 of USDA Class A evaporation pan) and four crop loads (100–450 fruits per tree) were studied in a factorial experiment. Midday stem water potential increased with irrigation level and decreased with crop load in 1993 and at the lowest irrigation level in 1995. Daily fruit growth rate decreased with midday stem water potential in 1993 and at the lowest irrigation level in 1993. The effect of crop load on fruit growth rate was associated with limited soil water availability. A reduction in yield and average fruit size were associated with midday stem water potentials lower than –1.3 MPa. Taking an additional 0.1 MPa as a safety factor, –1.2 MPa could serve as a reasonable threshold for irrigation control in the orchard.     

ALCEPAS,an onion growth model based on SUCROS87.I. Development of the model

Summary

A dynamic simulation model for onion crop growth is presented that is based on SUCROS87, a Simple and Universal Crop Growth Simulator. Onion specific values of parameters and relations of SUCROS87 were established using results from field experiments. The model simulates potential crop growth when weeds, pests, diseases and soil conditions are not limiting growth and there is ample supply of water and nutrients. The model accounts for the influence of sowing date and plant density. The combined influence of environmental factors on leaf growth, bulb initiation and maturity is incorporated. The potential use of the model is discussed.     

Land cover and climate changes drive regionally heterogeneous increases in US insecticide use

Context

Global environmental change is expected to dramatically affect agricultural crop production through a myriad of pathways. One important and thus far poorly understood impact is the effect of land cover and climate change on agricultural insect pests and insecticides.

Objectives

Here we address the following three questions: (1) how do landscape complexity and weather influence present-day insecticide use, (2) how will changing landscape characteristics and changing climate influence future insecticide use, and how do these effects manifest for different climate and land cover projections? and (3) what are the most important drivers of changing insecticide use?

Methods

We use panel models applied to county-level agriculture, land cover, and weather data in the US to understand how landscape composition and configuration, weather, and farm characteristics impact present-day insecticide use. We then leverage forecasted changes in land cover and climate under different future scenarios to predict insecticide use in 2050.

Results

We find different future scenarios—through modifications in both landscape and climate conditions—increase the amount of area treated by ~ 4–20% relative to 2017, with regionally heterogeneous impacts. Of note, we report large farms are more influential than large crop patches and increased winter minimum temperature is more influential than increased summer maximum temperature. However, our results suggest the most important determinants of future insecticide use are crop composition and farm size, variables for which future forecasts are sparse.

Conclusions

Both landscape and climate change are expected to increase future insecticide use. Yet, crop composition and farm size are highly influential, data-poor variables. Better understanding of future crop composition and farm economics is necessary to effectively predict and mitigate increases in pesticide use.

     

Influence of soil hydrothermal environment,irrigation regime,and different mulches on the growth and fruit quality of strawberry (Fragaria × ananassa L.) plants in a sub-temperate climate

Summary

The present study was undertaken over two consecutive years under sub-temperate climatic conditions in the mid-hill region of Himachal Pradesh (30°52'N, 77°11'E; 1,175 m asl) on loamy sand Inceptisols. The aim was to investigate the effects of irrigation and mulch material on the growth, flowering, fruiting behaviour, relative leaf water content (RLWC), yield, and quality of strawberry (Fragaria × ananassa L. ‘Chandler’). The drip irrigation treatments included irrigation with 100, 80, or 60% (coded 1.0, 0.8, and 0.6 V) of the total water requirement. Both mulches increased the minimum soil temperature to a depth of 5 cm. The drip and surface irrigation treatments raised the minimum soil temperature by 3.0º – 5.4ºC, and lowered the maximum temperature by 2.2º – 5.8ºC compared to the rainfed control. Hay mulch was more effective in raising the minimum temperature and lowering the maximum soil temperature than black polyethylene mulch. Moisture conservation increased by 2.8 – 12.8% under the black polyethylene mulch compared to the no-mulch treatment. Drip and surface irrigation methods, as well as mulching, were found to be effective for enhancing the growth, irrigation water use efficiency (IWUE), fruit yield, and quality of strawberry plants. However, the number of crowns per plant, the percentage berry set, the RLWC, root length density (RLD), and fruit yield were highest under treatment M3I3 [i.e., black polyethylene mulch plus drip irrigation (1.0 V)] by 565.5%, 94.5%, 32.8%, 394.5%, and 549.6%,respectively, compared to the no mulch plus rainfed control. The maximum IWUE values for plant biomass [1.39 metric tonnes (MT) ha^–1 m^–1] and fruit yield (2.79 MT ha^–1 m^–1) were recorded under treatment M3I5 [i.e., black polyethylene mulch plus drip irrigation (0.6 V)]; whereas, the lowest values (0.39 and 0.68 MT ha^–1 m^–1, respectively) were observed using treatment M1I2 (i.e., without mulch, plus surface irrigation). Fruit size, weight, sugar content, and anthocyanin content increased significantly under treatment M2I3 [i.e., hay mulch, plus drip irrigation (1.0 V)] compared with all other treatments. Total soluble solids (TSS) contents and total acidity (TA) were highest under treatment M1I1 (i.e., no mulch, plus rainfed). A linear regression model could describe the variations in quality parameters of strawberry plants grown under sub-temperate climatic conditions. Root density was found to be the best indicator with which estimate fruit quality.     

Prediction of optimal harvest date for processing tomato based on the accumulation of daily heat units over the fruit ripening period

Summary

For maximum yield of processing tomato by once-over mechanical harvesting, an optimum date for harvest has to be selected at the time when the factory-graded fruit yield is at its maximum. By recording the proportion of green, ripe (i.e. turning and red) and rotten (i.e. over-ripe and damaged) fruit over a period of about 20 d, the optimal harvest date can be identified. Based on observations taken from crops at four sites in the Mediterranean region over three years (1997-1999), the proportional change of fruit types (i.e. percentage total fruit weight) has been found closely related to the accumulation of daily maximum temperature (x, °Cd) during crop maturation. The change of percentage green fruit was y = 6172 l0^–8 x² – 768 l0^–4 x + 25 (R² = 0.882). Over the same period, the change in percentage ripe fruit was described less satisfactorily by y = – 12588 l0^–8 x² + 867 l0^–4 x + 65.7 (R² = 0.568). When heat units were calculated based on the daily maximum and minimum temperatures by six well-known methods, it was found that the reduction in percentage green fruit was significantly related to the sum of heat units calculated by all methods. The maximum percentage ripe fruit, about 80% of the total fruit weight, occurred soon after the percentage green fruit was equal to the percentage rotten fruit, both around 10% of total fruit weight.Therefore, the heat units required to reduce the green fruit from 25% to 10% of total fruit weight, calculated by different methods, can be used to predict accurately the optimal harvest date based on the accumulation of ambient temperature. In a range of likely temperature regimes, 7–9 days prediction for optimal harvest date can be made. However, the simplest method based on daily maximum temperature alone is as accurate as all the more complex methods and is likely to find wider application in the processing tomato industry.     

Development of micropropagated plants from different clones of Senecio x hybridus in relation to BAP concentration and temperature in vitro

Summary

Selected mature seedling plants were used as stock plants and about half of them were successfully micropropagated. There was no correlation between the ability of petiole expiants to form adventitious shoots and the capacity of these shoots to multiply. Growth and development varied between the micropropagated clones, originating from one seedling each. The colour of the flowers was always constant within a clone. Developmental time, foliage height and the numbers of shoots, leaves and flowers were influenced by the BAP concentration used in vitro. The temperature during the in vitro phase affected the development time and the height of foliage and inflorescences. Increased BAP concentration (from 0 or 0.1 mg l^?1 to 1 mg H) resulted in plants with a longer development time to anthesis and more shoots, leaves and flowers. Plants raised on 5 mg l^?1 BAP developed slowly, resulting in stunted growth, low foliage height, few leaves and flowers. Consequently, it is possible to use the BAP concentration in vitro to regulate the growth of the progeny crop. After transfer to soil in a growth chamber, plants grown at 10°C in vitro flowered earlier, and had lower foliage and higher inflorescences than plants grown at 21°C. This observation indicates that flowering may be promoted by low temperatures in vitro.     

Long-term studies on yield,quality and soil fertility of lemongrass (Cymbopogon fiexuosus) in relation to nitrogen application

Summary

A field experiment was conducted over five years (1992–97) at Bangalore (13.58N, 77.558E, 930.m above mean sea level) to study the effect of nitrogen application (0, 50, 100 and 150.kg N ha^–1 year^–1) on yield, oil quality and soil fertility of lemongrass (Cymbopogon fiexuosus) in the semi-arid tropical conditions of South India. Fresh herbage yield of lemongrass differed significantly between years; the yields increased up to the second year after which they started to decline. During the five years, the response to nitrogen was linear, while still maintaining the same content and quality of essential oil. The oil content and chemical composition of oil did not change as the crop aged. Application of nitrogen and phosphorus maintained the fertility of the soil while potassium depletion was noticed.     

Management of Tomato Ringspot Virus in Red Raspberry with Crop Rotation

Abstract

Tomato ringspot virus (ToRSV) is an important disease of red raspberry which is vectored by the dagger nematode, Xiphinema americanum. A field study was conducted to evaluate crop rotation as an alternative to soil fumigation for the management of ToRSV. The effects of treatments on nematode population densities and ToRSV were evaluated for 18 months during growth of rotation crops, and for 36 months after replanting raspberries. Treatments included the rotational crops rapeseed (Brassica napus) and tall fescue (Festuca arundinacea) (nonhosts for ToRSV), clean fallow, fumigation with methyl bromide, and controls in which raspberries followed raspberries. At planting, X. americanum densities were highest in fescue and control plots and lowest in fumigated plots, but densities decreased and remained low in all plots after planting ‘Meeker’ raspberries. Raspberry leaves were collected in each plot and assayed for ToRSV with ELISA for 3 years. ToRSV was detected only in the control plots. Rotations with rapeseed or tall fescue, or weed-free fallow were as effective as fumigation with methyl bromide in preventing re-infection of raspberry plants with ToRSV for three years.     

Evaluation of new rootstocks for resistance to soil-borne pathogens and productive behaviour of pepper (Capsicum annuum L.)

Summary

An evaluation of five rootstocks for pepper (Capsicum annuum L.) was carried out over a 3-year period on three farms in Campania (Italy). Pepper is very susceptible to soil-borne pathogens, especially Phytophthora capsici, Verticillium dahliae and Meloidogyne spp. (root-knot nematode). The lack of resistant hybrids and of crop rotation, and the longterm survival of propagules of the pathogen, have increased the risk of damage that so far has been controlled by pre-planting soil treatment with methyl bromide. The use of pepper grafted onto rootstocks resistant to the main soil-borne pathogens is not undertaken commercially in Italy because the available rootstocks are unsatisfactory. P. capsici, V. dahliae, Fusarium oxysporum, F. solani and M. incognita have been detected on farms where the new rootstocks were tested. Trials were performed on the same sites for 2 or 3 years in order to provide favourable conditions for parasites. Two rootstocks, ‘Graffito’ and ‘Gc 1002’, were found to be resistant to P. capsici. In the presence of an early, high population density of M. incognita, ‘Graffito’ showed good tolerance, while ‘Gc 1002’ was susceptible to the root-knot nematode. In addition, both rootstocks showed good compatibility with the different scions tested and did not decrease vegetative growth, fruit yield or the size of the scions. In contrast, in the presence of V. dahliae, F. oxysporum and F. solani, none of the rootstocks tested was sufficiently resistant to vascular or crown and root rot damage.     

Transpiration efficiency of Amaranth (Amaranthus sp.) in response to drought stress

Drought is a major abiotic stress responsible for severe crop losses worldwide. Development of new crop varieties with increased drought tolerance is one way to increase crop productivity. The aim of this study was to characterise the diversity of nine accessions belonging to Amaranthus tricolor and A. cruentus, in response to drought stress using a dry-down protocol to characterise the transpiration efficiency (TE). Plants were subjected to either a gradual dry down or well-watered conditions. Results showed that TE was significantly higher (P < 0.01) in water-deficient (WD) plants compared to water-sufficient (WS) plants, 2.40 g kg^?1–7.13 g kg^?1 and 2.19 g kg^?1–4.84 g kg^?1, respectively. There was no significant difference in the fraction of transpirable soil water (FTSW) threshold decline between the amaranth genotypes. TE was highly correlated with yield under both WS (r = 0.89, P < 0.001) and WD conditions (r = 0.662, P < 0.001), and negatively correlated with root-to-shoot ratio under both WS (r = ?0.488, P < 0.05) and WD conditions (r = ?0.460, P < 0.05). Significant genotypic differences were seen for growth rate and stress susceptibility index (SSI). The result obtained in this investigation underline the need to identify genotypic variation in water use efficiency in amaranth.

Abbreviations: FTSW: Fraction of transpirable soil water; NTR: normalised transpiration rate; SSI: Stress susceptibility index; TE: transpiration efficiency; WHC: water holding capacity; WD: water-deficient; WS: water-sufficient.     

Postharvest sprouting of onion bulbs grown in different temperature and C02 environments in the UK

Summary

The effects of different mean growing season temperatures and C0₂ concentrations during bulb production on postharvest bulb sprouting in a common storage environment at Reading, UK, was examined in two cultivars of the Rijnsburger type of onion (Allium cepa L.). Crops were grown in the field in temperature gradient tunnels maintained at either 374 or 532 ppm C0₂. At crop maturity, cohorts of bulbs were harvested, transferred to a constant temperature room (at an average of 11.6°C) and the subsequent duration to sprouting recorded. The duration to the onset of sprouting (expressed as days in storage until the first bulb sprouted) was not affected by cultivar, mean growing season temperature or CO₂ concentration, and was 165 d. The subsequent rate of sprouting (expressed as bulbs per day) was a positive linear function of mean growing season temperature, but no effects of CO₂ or cultivar were detected. Mean rate of sprouting increased from an average of 0.036 bulbs per day at 12.3°C to 0.093 bulbs per day at 18.6°C. Rapid sprouting in storage was associated with lower levels of total non-structural carbohydrate in the bulbs at the time of harvest. Thus, postharvest susceptibility of onion bulbs to sprouting in storage is expected to increase in warmer crop production temperatures.     

Evaluation of Non-Fumigant Alternative Soil Treatments for Strawberry Production in Huelva (Spain)

ABSTRACT

Since 1997, our IFAPA working group has developed a series of projects to evaluate new chemical and non-chemical soil disinfestation practices. During 2013–14 non-chemical (biological) alternatives have been tested with the objective of improving the biosolarization techniques, using different carbon sources and doses of organic biofumigant products under different types of plastic tarp. Throughout the growing season, the greatest production for cv. Florida Fortuna (52,672 kg/ha, by the end of May) was obtained with biosolarization using dried olive pomace (12,500 kg/ha) and virtually impermeable film; whereas biosolarization with chicken manure at 25,000 kg/ha had the lowest fruit production (42,517 kg/ha) among biosolarization treatments. Biosolarization treatments significantly reduced soil populations of M. phaseolina and Fusarium spp., and effectively suppressed nematode infestation.     

Energy balance of six common landscape surfaces and the influence of surface properties on gas exchange of four containerized tree species

Gas exchange and growth of woody landscape plants is strongly affected by underlying surfaces. In urban areas, plants are subjected to energy balance characteristics of a variety of surfaces. We investigated energy balance properties of six urban surfaces: asphalt, gravel rock mulch, lava rock mulch, concrete, pine bark mulch, and turf. Each summer over a 3-year period, incoming global shortwave radiation, surface temperature, surface reflectivity (albedo), soil temperature below each surface, and soil heat flux were measured for each surface, and total incoming radiation, thermal conductivity, and longwave radiation emitted by each surface were calculated. Differences in surface properties were analyzed by regression analysis. Albedo was greatest for concrete and least for lava rock mulch, while thermal conductivity was greatest for asphalt and least for lava rock and pine bark mulches. Under maximum incoming total radiation, regression analysis indicated: soil heat flux was greatest under asphalt and concrete and least under lava rock and pine bark mulches; soil temperature below each surface was greatest for asphalt and concrete and least for pine bark mulch; surface temperature was greatest for pine bark mulch and least for turf; and longwave radiation flux of each surface was greatest for pine bark mulch and least for turf. This research revealed that more energy was conducted into the soil below asphalt and concrete, and that a greater portion of incoming radiation was prevented from entering the soil below pine bark and lava rock mulches than below other surfaces. Due to these effects, and the lack of evaporative cooling, surface temperatures were greater, and more longwave radiation was emitted from non-vegetative surfaces than from turf. In a concurrent study, we investigated if the energy balance of turf, pine bark mulch, and asphalt surfaces influenced gas exchange of four containerized tree species grown over each surface. On several occasions over a 2-year period, morning-to-evening measurements of stomatal conductance, leaf temperature, and plant water loss were made on containerized Bechtel crabapple (Malus ionensis ‘Plena’), Norway maple (Acer platanoides ‘Crimson King’), globe willow (Salix matsudana ‘Navajo’) and American plane tree (Platanus occidentalis). Leaves over pine bark mulch and asphalt intercepted more longwave radiation and generally had greater leaf temperature and leaf-to-air vapor difference than leaves over turf. As a result, trees over non-vegetative surfaces generally had lower stomatal conductance and water loss than trees over turf.     

Effects of Trichoderma harzianum strain T-22 on the growth of two Prunus rootstocks during the rooting phase

Summary

Trichoderma harzianum strain T-22 (T22) is one of the most effective strains of this fungus that is able to colonise the roots of most plant species across a wide range of soil types. This fungus is used as a biocontrol agent during crop production, and for the improvement of the rooting and acclimatisation phases in plant nurseries. In vitro-cultured shoots of GiSeLa6^® (Prunus cerasus P. canescens) and of GF677 (P. amygdalus P. persica), two important Prunus varieties used as commercial rootstocks, were inoculated with T22. The results showed that early inoculation of the fungus (at the stage of shoot transfer to root-inducing medium) seriously damaged both GiSeLa6^® and GF677 plants; whereas, following later inoculation (7 d after shoot transfer to root-inducing medium), the plants survived and showed significant increases in shoot growth and root development. In particular, root lengths in GiSeLa6^® and GF677 plants increased by 180% and 136%, respectively, compared to non-inoculated controls. Microscopic analysis revealed T22 hyphae spreading on the root surface in GiSeLa6^® (fungus colonisation frequency = 20%), but not in GF677 roots. Our results demonstrate that the application of T22 during the rooting phase resulted in greater shoot lengths, as well as increased numbers of leaves, roots, and stem diameters. These morphological characteristics could increase the quality and viability of nursery planting material and provide advantages during the plant acclimatisation phase.     

Recent progress in the molecular biology of tea (Camellia sinensis) based on the expressed sequence tag strategy: a review

Summary

The expressed sequence tag (EST) technique provides a quick, efficient, and inexpensive route for gene cloning, gene expression profiling and regulation analysis, genome mapping, and functional annotation of genome sequences. Although an important cash crop, research on the molecular biology of tea (Camellia sinensis) started later and progressed more slowly than similar advances in major cereal crops and woody species. Most recently, progress has been made on the molecular biology of tea based on the strategies of EST sequencing and annotation. Advances have included the elucidation of gene expression profiling, the establishment and use of cDNA microarrays, data mining for EST-SSR (simple sequence repeat; microsatellite) and STR (short tandem repeat) loci, and cloning and expression analysis of genes involved in secondary metabolism, and stress defense.All these advances have contributed to a better understanding of the molecular mechanisms underlying growth, development, metabolism, and responses to the environment in tea plants, as well as to the promotion of molecular biology research in tea. New high-throughput sequencing technology will further accelerate genome sequencing of this species in the future.     

Corm induction and multiplication of Amorphophallus albus in vitro

Summary

Amorphophallus albus, belonging to the family Araceae, has attracted widespread attention due to its considerable economic and medicinal importance. The natural propagation coefficient of A. albus is very low, which limits application of this crop. In vitro corms can be used for propagation of A. albus and have been proved to be superior over in vitro plantlets. To optimise procedures for in vitro corm production and multiplication, the effects of phytohormones, sucrose concentrations and incubation conditions with desirable phytohormone combinations for callus induction, corm formation and corm growth of A. albus were investigated. The results showed that calli were induced at high frequency from petiole segments on Murashige and Skoog medium supplemented with 1.0 mg l^–1 naphthaleneacetic acid (NAA) and 1.0 mg l^–1 6-benzyladenine (BA). Compact nodular calli were desirable for corm formation, and optimum corm formation was obtained in the presence of 0.5 mg l^–1 NAA and 2.0 mg l^–1 BA. With this auxin and cytokinin combination, an increase in sucrose concentration from 2% to 6% (w/v) significantly increased the corm formation rate and favoured corm growth, but negative effects occurred at higher sucrose concentrations. By incubating over a range of temperatures from 19°C – 28°C, 22°C produced the largest numbers of corms and highest mean fresh weight of each corm. Short-day (8 h) or long-day (16 h) photoperiods did not affect corm formation and growth significantly, except that corm weight fell under long-day conditions. The multiplication rate of in vitro corms was enhanced by apical meristem wounding. It was possible to store in vitro produced corms at 4°C for as long as 90 d to overcome apical dormancy and accelerate sprouting after planting into soil. This work has established an efficient protocol for multiplication of A. albus through an in vitro corm system.