Celery Seedlings Research Articles

Karrikinolide1 (KAR1), a Bioactive Compound from Smoke, Improves the Germination of Morphologically Dormant Apium graveolens L. Seeds by Reducing Indole-3-Acetic Acid (IAA) Levels.

Smoke-water (SW) and Karrikinolide1 (KAR1) release dormancy and improve seed germination in many plant species. Therefore, we tested SW (1:2500 v/v) and KAR1 (10-7 M) to break the morphological dormancy of celery cultivar (Apium graveolens L.). In the first trial, seeds were subjected to a 21-day incubation period at 20 °C with SW and KAR1 applied as single treatments. KAR1 showed significantly improved germination (30.7%) as compared to SW (17.2%) and a water control (14.7%). In seed soaking experiments, SW, KAR1, and gibberellic acid (GA3) treatments showed higher germination percentages than the water control after 3 and 6 h of soaking. However, prolonged soaking (12 h) reduced germination percentages for all treatments, indicating a detrimental effect. Analysis of KAR1 content dynamics in 7-day- and 21-day-old celery seeds indicated its prolonged effects on germination and dormancy alleviation. Phytohormones, including auxins in 7-day-old and cytokinins in 7-day- and 21-day-old celery seedlings, along with their precursors and metabolites, were analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) after treatment with KAR1 and SW. The analysis of auxin levels in 7-day-old seeds revealed a negative correlation between seed germination and auxin (indole-3-acetic acid, IAA) content. Notably, it was found that KAR1-treated seeds significantly reduced IAA levels in all treatments. SW and KAR1 did not significantly affect cytokinin levels during celery germination except for N6-Isopentenyladenine. Hence, further research is needed to understand their precise role in celery seed germination. This work will improve our understanding of the role of bioactive compounds from plant-derived smoke and how they regulate hormonal responses and improve germination efficiency in celery.

Effect of irrigation water salinity on morphological and physiological characteristics of celery

The objective of this study was to investigate the effects of salinity levels of irrigation water on the morphological and physiological characteristics of celery (Apium graveolens L.) during early seedling development. Celery seedlings of Balena cultivar were grown with saline irrigation water consisting of different NaCl levels (0, 50, 100, 150, 200, 250, and 300 mM). The results showed that increasing salt stress inhibited plant growth by destroying physiological parameters. Each increase in NaCl resulted in a decrease in the length, diameter, number, and fresh and dry weight of leaves. Dry matter, chlorophyll content, leaf temperature, and turgor loss improved when NaCl levels were increased; however, salinity caused a reduction in leaf relative water content. Leaf fresh and dry weights were lower under salt stress, even at 50 mM NaCl. Leaf temperature was higher in plants grown under salinity and reached the maximum level at 100 mM NaCl. The stomata on the abaxial side of the leaves were smaller but more numerous under salinity than in the control plants. It was concluded that celery’s plant growth was significantly influenced by salinity and that it could endure salinity lower than 100 mM NaCl.

First Report of Fusarium solani and Fusarium oxysporum Causing Basal Stem Rot on Celery in China.

Celery (Apium graveolens L.) is an economically important vegetable crop in China. In recent years, celery has been widely planted in Yuzhong county, Gansu province. From 11 April to 24 May, 2019-2021, basal stem rot of celery was observed with incidences up to 15% in the Yuzhong region (35°49'N, 104°16'E, 1865 m a.s.l.), which caused serious economic losses to local farmers. Typical symptoms of the disease included wilting and darkening of the basal stem, leading to plant death. To identify the cause of the disease, small pieces (5mm×5mm) of the margin of asymptomatic and rotting basal stem tissues were sterilized with 70% ethanol for 30 s and 3% NaClO for 5 min, then placed on potato dextrose agar (PDA) plates, and incubated at 25℃ (Zhao et al. 2021). Twenty-seven single-conidium isolates with morphological characteristics similar to Fusarium spp. were obtained (Ma et al. 2022), which displayed two kinds of colony morphology. On PDA, seven isolates developed white, fluffy aerial mycelium and twenty isolates developed light pink abundant aerial mycelium. Isolate F5 and F55 from each distinct morphological group were cultured on PDA and synthetic low nutrient agar (SNA) for pathogenicity tests, morphological and molecular identification. The macroconidia (18.3 to 29.6 × 3.6 to 5.3 μm, n=50) with 1 to 2 septa and microconidia (7.5 to 11.6 × 2.6 to 3.5 μm, n=50) with 0 to 1 septum were observed in F5. For F55, the size of macroconidia was 14.2 to 19.5 × 3.3 to 4.2 μm (n = 50) with 1 to 2 septa; Microconidia were mostly 0 to 1 septum and measured 7.3 to 12.8 × 2.2 to 4.2 μm (n = 50). To confirm the identity of the isolates, the internal transcribed spacer region (ITS) and the translation elongation factor-1 alpha (TEF-1α) gene were amplified using primers ITS1/ITS4 and EF-1/EF-2 (Uwaremwe et al. 2020), respectively. The sequence similarities of isolate F5 (GenBank No. OL616048 and OP186480) and F55 (GenBank No. OL616049 and OP186481) with the corresponding sequences of F. solani (MT447508 and MN650097) and F. oxysporum (MG461555 and OQ632904) ranged from 99.22% to 100.00%, with matching base pairs of 531/532, 416/416, 511/515 and 394/395, respectively. The voucher samples were deposited in the sample center of Northwest Institute of Ecological Environment and Resources, Chinese Academy of Sciences. Morphological and molecular results confirmed the species of F5 and F55 as F. solani and F. oxysporum, respectively. A pathogenicity test was conducted under greenhouse conditions (19-31°C, avg. 26°C). Conidial suspension (105 spores/mL) of isolates F5 and F55 were poured onto the basal stems of healthy celery seedlings at the age of 1 month and mock-inoculated control treatments with sterile water. Ten plants were inoculated for each treatment. After 21 days, all plants inoculated with both fungal isolates developed symptoms similar to those observed in the field, whereas the mock-inoculated plants remained healthy. The pathogen was successfully reisolated from the inoculated symptomatic plants onto PDA medium and had morphology as described above, confirming Koch's postulates. F. solani and F. oxysporum have been reported to infect many plant species, including carrot (Zhang et al. 2014) and Angelica sinensis (Liu et al. 2022). To our knowledge, this is the first report that F. solani and F. oxysporum cause basal stem rot on celery in China. The identification of pathogens of the observed basal stem rot on celery provides a clear target for the prevention and management of this disease.

Comparative Physiological and Transcriptomic Analyses of Improved Heat Stress Tolerance in Celery (Apium Graveolens L.) Caused by Exogenous Melatonin.

Melatonin (MT) is crucial in plant growth, development, and response to stress. Celery is a vegetable that grows in a cool climate, and a hot climate can deteriorate its growth, yield, and quality. This study investigates the effect of exogenous melatonin on celery physiology. Transcriptional levels were analyzed by spraying celery with exogenous MT before exposing it to high temperatures. The regulatory mechanism of exogenous MT-mediated heat tolerance was examined. The results show that the exogenous MT reduced the thermal damage state of celery seedlings, as well as the malondialdehyde (MDA) content and relative conductivity (REC), increasing the oxidase activity, the osmotic regulatory substances, and chlorophyll, enhancing the leaf transpiration and the light energy utilization efficiency. We examined the mechanism of exogenous MT in mitigating high-temperature damage using the transcriptome sequencing method. A total of 134 genes were expressed differently at high temperature in the celery treated with MT compared with the untreated celery. Functional annotation analysis revealed that the differentially expressed genes were abundant in the “pyruvate metabolism” pathway and the “peroxidase activity” pathway. According to the pathway-based gene expression analysis, exogenous MT can inhibit the upregulation of pyruvate synthesis genes and the downregulation of pyruvate consumption genes, preventing the accumulated pyruvate from rapidly upregulating the expression of peroxidase genes, and thereby enhancing peroxidase activity. RT-qPCR verification showed a rising encoding peroxidase gene expression under MT treatment. The gene expression pattern involved in pyruvate anabolism and metabolism agreed with the abundant transcriptome expression, validating the physiological index results. These results indicate that the application of exogenous MT to celery significantly enhances the ability of plant to remove reactive oxygen species (ROS) in response to heat stress, thereby improving the ability of plant to resist heat stress. The results of this study provide a theoretical basis for the use of MT to alleviate the damage caused by heat stress in plant growth and development.

Impact of paddy straw mulch on germination and growth of celery (Apium graveolens L.) seedlings and associated weeds in nursery

A study was undertaken during three consecutive rabi seasons of 2014–15 to 2016–17 at the Research Farm, Department of Agronomy, Punjab Agricultural University, Ludhiana (Punjab) to determine the effect of paddy straw mulch load and retention time on the germination and growth of celery and associated weeds. The experiment was conducted in randomized complete block design (RCBD) with nine treatments viz., paddy straw mulch @ 4 and 6 t ha-1 with retention time of 15, 20, 25 days after sowing (DAS), full time retention (60 DAS), and control (without mulch). The results indicated that application of paddy straw mulch @ 4 or 6 t ha-1 significantly improved the germination of celery in nursery as compared to no mulch treatment but retention of paddy straw mulch beyond 20 days after sowing suppressed the celery seedlings adversely resulting in lowering seedling population as well as fresh and dry weight of celery seedlings. Application of paddy straw mulch @ 4 or 6 t ha-1 resulted in significantly lower density and dry weight of weeds as compared to control. Further, each successive increase in retention time of paddy straw mulch from 15 DAS to full time retention (60 DAS) through 20 and 25 DAS significantly reduced the weed population in celery nursery.

DEVELOPMENT OF ROOT CELERY SEEDLINGS DEPENDING ON THE CONTENT OF VERMICULITE IN THE

The article presents data of the influence of vermiculite content in the composition of soil-vermiculite substrates on agrophysical and agrochemical properties of substrates and on biometric indicators of root celery seedlings which grown on these substrates. The studies were conducted in the vegetation experiment, in the period 2014-2015 at the agricultural Institute named after N. P. Ogarev. We studied 7 levels of vermiculite content in the substrate, the properties of which were compared with the properties ofpure peat and mixed soil-vermiculite-peat substrate. By the time of root celery seedlings planting into the open ground, volume of the root system, leaf area and plant biomass were determined. A positive effect on the properties of substrates and biometric parameters of seedlings was observed with the content of vermiculite in the substrate in the amount of 50 to 65 % There was a decrease in volume weight and acidity, increased moisture capacity, porosity. Adding peat to the soil-vermiculite substrate in an amount of 30% improved the properties of the substrate and biometric parameters of seedlings. The increase in the share of vermiculite in the substrate from 80 to 100% greatly reduces the biometric indicators of celery seedlings. The dependence of biomass from the agrophysical and agrochemical indicators of the substrate was curvilinear. The optimal values of substrate parameters were established: volume weight - 0.55 g/cm , capillary moisture capacity - 120 %, total porosity - 77 %, the proportion of solid phase - 22 %, liquid phase - 52 %, gas phase - 26 %, pH of aqueous suspension - 7.1, electrical conductivity - 0.16 mSm / cm. The greatest influence on the biometric indicators of seedlings belongs to agrophysical properties of substrates.

Influence of using different percentages decomposed rice straw as alternative substrate on celery plants

This paper focused on evaluating the effect of using different decomposed percentages of rice straw as alternative substrate on growth, yield and irrigation water use efficiency (IWUE) of celery plants. The experimental layout was in the experimental farm of Central Laboratory for Agricultural Climate and the design was randomized complete block with three replications. Celery seedlings (cv. Green giant) were transplanted in 1st of December, 2017/2018 and 2018/2019. Four ages (levels of decomposed) of rice straw were used (new rice straw, old rice straw 3 months, old rice straw 6 months and old rice straw 9 months) as a substrate in this investigation compared to clay soil. Results indicated that using the old rice straw, 6 months substrate recorded a moderate substrate temperature. Plant length, N, P, soluble sugar content and yield were not affected by cultivated celery plants in clay soil or old rice straw 6 months as substrate. whereas, plant diameter, chlorophyll reading, K and vitamin C content were affected negatively by using different percentages decomposed rice straw as alternative grown substrate. On the other hand, irrigation water use efficiency (IWUE) enhanced by cultivated celery plants in clay soil and old rice straw 6 months substrate.

Non-destructive evaluation of photostability of crop signaling compounds and dose effects on celery vigor for precision plant identification using computer vision

Vegetable crops grown in the field are particularly vulnerable to competition from weeds at the seedling stage. To avoid yield loss, weeds must be removed early in the crop cycle. Shortages of farm laborers for hand weeding and lack of effective vegetable herbicides is stimulating the development of intelligent weeders. One challenge for development of effective intelligent weeders is the precision differentiation of vegetable crops and weeds. Crop signaling is a technique that enables rapid and accurate identification of target crops. In this study, an appropriate dose of fluorescent compounds allowed the vegetable crop locations in the field to be reliably detectable by smart machines. The study examined protocols for crop root treatment, computer vision system development, crop signal detection and biomass evaluation. Rhodamine B (Rh-B) is a fluorescent compound with unique optical properties. Different doses of Rh-B were applied to the celery roots for various durations prior to transplantation to assess Rh-B transport in the plant, its photostability and potential impact on seedling growth in the natural outdoor environment of a farm. Systemic Rh-B absorbed via the roots moved throughout the celery plant in 24 h. Compared with 60 ppm solution of Rh-B, higher doses of Rh-B including 90, 180, and 270 ppm resulted in greater absorption by the plant, but such three concentrations injured the plant. The biomass test results showed that the treatment of celery roots for two days with a 60 ppm solution of Rh-B was safe for celery plants. This Rh-B dosage had good photostability in celery seedlings for about 5 weeks after transplanting. An effective dose of systemic Rh-B allowed for the rapid identification of celery plants at early growth stages, thereby facilitating the automatic differentiation of weeds and crops by a robotic machine vision system.

First record of Pythium mastophorum on celery seedlings in the Czech Republic.

First record of <i>Pythium mastophorum</i> on celery seedlings in the Czech Republic.

Characterization of Lygus hesperus (Hemiptera: Miridae) Feeding and Oviposition Injury on Celery Seedlings

The western tarnished plant bug, Lygus hesperus Knight (Hemiptera: Miridae), can be a serious pest of celery, Apium graveolens dulce (Mill.) Pers. in the Central Coast region of California. Little is known about injury symptoms caused by L. hesperus adults on celery. When celery seedlings were exposed to L. hesperus adults, their crown area was found destroyed with necrotic dead tissue. Destroyed crowns of dead seedlings were observed when seedlings were exposed to five or more L. hesperus adults for ≥24 h but was not observed on seedlings exposed ≤12 h. In addition, elongated lesions were noticed on the celery petiole and were significantly greater when exposed to five or more L. hesperus adults for as little as 4 h. Number of elongated lesion injuries and number of eggs recovered from elongated lesions was correlated (r = 0.66; P &lt; 0.001). Data provide key diagnostic symptoms of L. hesperus feeding and ovipositional injury on celery seedlings. Also, this study expands our understandings on the effects of L. hesperus adult density and duration of exposure which reinforces the need for regular scouting, and immediate management decisions and action to reduce losses from L. hesperus injury in both celery seedlings and mature plants in greenhouse and field settings, respectively Accepted for publication 27 April 2016. Published 4 May 2016.

First Report of Cercospora apii, Causal Agent of Cercospora Early Blight of Celery, in Serbia.

Celery (Apium graveolens var. dulce) is a very important vegetable crop intensively cultivated in eastern and southern Serbia. During a field survey in August and September 2012, we observed symptoms similar to those of Cercospora early blight in eastern Serbia, with some of the affected fields showing up to 80% disease severity. The lesions on leaves were amphigenous, subcircular to angular and more or less confluent. Lesions enlarged and merged with age, followed by the development of necrotic area causing a continuous deterioration of the plant. Conidiophores arising from the stromata formed dense fascicles, sometimes appearing solitary, brown at the base, paler toward the apex, simple, straight to slightly curved, and rarely geniculate (dimensions 40 to 90 × 5 to 8 μm). Conidia were solitary, hyaline, at first cylindro-obclavate then acicular to acicular-obclavate, straight to slightly curved, subacute to obtuse at the apex, while truncated and thickened at the base (dimensions 45 to 160 × 4 to 5 μm), 5 to 13 septate. Based on the morphological features, we identified the pathogen as Cercospora apii Fresen. (2). In order to obtain monosporic isolates of the fungus, single conidia were cultivated on potato dextrose agar (PDA). To confirm the pathogenicity of the isolates, 5 mm-diameter mycelial plugs from the PDA plates were placed upside down on the adaxial leaf surface of 2-week-old celery seedlings of cv. Yuta. Control plants were inoculated with a sterile PDA plug. Three leaves per plant were disinfected with 70% ethanol, epidermis was scratched with a sterile needle to promote the infection, and inoculated. A total of 12 plants were inoculated with the mycelial plugs and 12 were used as control plants. Inoculated and control plants were kept in a moist chamber for 48 h and then transferred to a greenhouse at 25 ± 2°C. After 2 weeks, the first necrotic spots appeared on inoculated leaves, similar to the symptoms manifested in the field, while control plants remained symptomless. The pathogen was re-isolated and its identity was verified based on morphological and molecular features. To confirm the pathogen's identity, three isolates (CAC4-1, CAC24, and CAC30) were subjected to molecular identification based on the internal transcribed spacer region (ITS) using the ITS1/ITS4 universal primers (5), a partial calmodulin gene (CAL) using CAL-228F/CAL2Rd primers (1,4), and partial histone H3 gene (H3) using CYLH3F/CYLH3R primers (3). Sequences of the amplified regions were deposited in GenBank under accessions KJ210596 to KJ210604. The BLAST analyses of the ITS sequences revealed 100% identity with several Cercospora species (e.g., C. apii [JX143532], C. beticola [JX143556], and C. zebrina [KC172066]), while sequences of CAL and H3 showed 100% identity solely with sequences of C. apii (JX142794 and JX142548). Based on combined morphological and molecular data, the pathogen infecting celery was identified as C. apii, which to our knowledge represents the first report of the presence of the causal agent of Cercospora early blight disease in Serbia.

First Report of Colletotrichum acutatum sensu lato Causing Leaf Curling and Petiole Anthracnose on Celery (Apium graveolens) in Michigan.

In September 2010, celery plants with leaf cupping and petiole twisting were observed in commercial production fields located in Barry, Kent, Newago, and Van Buren Counties in Michigan. Long, elliptical lesions were observed on petioles but signs (mycelia, conidia, or acervuli) were not readily observed. Celery petioles were incubated in humid chambers (acrylic boxes with wet paper towels). After 24 h, conidia corresponding to the genus Colletotrichum were observed. Isolations were performed by excising pieces of celery tissue from the lesion margin and placing them on potato dextrose agar (PDA) amended with 30 ppm of rifampicin and 100 ppm of ampicillin. Plates were incubated at 21 ± 2°C under fluorescent light for 5 days. Fungal colony morphology was gray with salmon-colored masses of spores when viewed from above, and carmine when viewed from below. Isolates were single-spored and placed on 30% glycerol in -20°C, and cryoconservation media (20% glycerol, 0.04% yeast extract, 0.1% malt extract, 0.04% glucose, 0.02% K2HPO4) at -80°C. Conidia were 8.5 to 12.0 × 2.8 to 4.0 μm and straight fusiform in shape. Three isolates were confirmed as C. acutatum sensu lato based on sequences of the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA and the 1-kb intron of the glutamine synthase gene (3), both with 100% similarity with Glomerella acutata sequences. Sequences were submitted to GenBank (Accession Nos. JQ951599 and JQ951600 for ITS and GS, respectively). Additionally, C. acutatum specific primer CaIntg was used in combination with the primer ITS4 on 54 isolates from symptomatic celery plants, obtaining the expected 490-pb fragment (1). Koch's postulates were completed by inoculating 4-week-old celery seedlings of cultivars Sabroso, Green Bay, and Dutchess using three plants per cultivar. Prior to inoculation, seedlings were incubated for 16 h in high relative humidity (≥95%) by enclosing the plants in humid chambers. Seven-day-old C. acutatum s. l. colonies were used to prepare the inoculum. Seedlings were spray-inoculated with a C. acutatum s. l. conidial suspension of 1 × 106 conidia/ml in double-distilled water plus Tween 0.01%. Two control seedlings per cultivar were sprayed with sterile, double-distilled water plus 0.01% Tween. Plants were enclosed in bags for 96 h post inoculation and incubated in a greenhouse at 27°C by day/20°C by night with a 16-h photoperiod. Leaf curling was observed on all inoculated plants of the three cultivars 4 days after inoculation (DAI). Petiole lesions were observed 14 to 21 DAI. Conidia were observed in lesions after incubation in high humidity at 21 ± 2°C for 24 to 72 h. Symptomatic tissue was excised and cultured onto PDA and resulted in C. acutatum colonies. Control plants remained symptomless. C. acutatum (4) and C. orbiculare (2) were reported to cause celery leaf curl in Australia in 1966 (2,4). To our knowledge, this is the first report of C. acutatum s. l. infecting celery in Michigan.

Uptake and toxicity of Cr(III) in celery seedlings

The present study shows that in celery Cr(III) induces deleterious effects on seedling development and morphology, and a number of metabolic responses related to stress. Exogenous CrCl 3 from 0.01 to 1 mM increasingly inhibited seed germination and hypocotyl elongation, or completely blocked it (10 mM), while the root apparatus was dramatically damaged even at the lowest dose. Seedlings took up exogenous Cr(III) in a dose-dependent manner, roots being the site of major metal accumulation; translocation towards the hypocotyl and cotyledonary leaves was also detected. Either total or chlorophyll a content was significantly reduced by chromium as low as 0.01 mM. A large accumulation of free and, to a lesser extent, conjugated polyamines occurred in all segments of treated plants. A dose-dependent relationship linking actual amounts of Cr(III) recovered in the entire seedling or organ and the respective polyamine titre was evidenced. Free putrescine, in particular, was the polyamine exhibiting the highest rate of increase, and cotyledonary leaves the organ where the major response occurred. A marked increase in ubiquitin–protein conjugates after Cr(III) treatment was also observed, particularly in roots. Thus, the study suggests for the first time a possible relationship between ubiquitination and Cr(III)-stress. The putative function of polyamines as a stress response, and the recruitment of the ubiquitin pathway to remove damaged or aberrant proteins which might have been produced in metal-treated seedlings are discussed.

Report of Root Rot Caused by Pythium F-Group on Hydroponically Grown Celery in South Africa.

Celery (Apium graveolens) is commonly grown in hydroponic systems in South Africa. During the warm summer months, plants often become stunted or die, with mortality as high as 70% in some systems. Affected plants show severe root rot and yellowing of the foliage. Root segments excised from symptomatic celery plants collected from various hydroponic systems in Gauteng Province, South Africa, were rinsed in sterile distilled water and plated on PARP medium (2). Pythium was isolated consistently from both rotted and symptomless roots. Isolates produced only noninflated filamentous sporangia and no oospores, conforming to the description of Pythium F-group (1). Koch's postulates were confirmed by inoculating 4-week-old celery seedlings cultivated in aerated nutrient solution in a hydroculture system in the greenhouse. A zoospore suspension (105 zoospores per ml) of Pythium F-group cultured on V8 juice agar was added to the nutrient solution at the rate of 3 ml/1iter. Control plants received no inoculum, and the experiment was repeated once. Plants were assessed after 4 weeks. All inoculated plants showed symptoms of root rot, stunting, and yellowing, whereas control plants remained healthy. Pythium F-group was recovered on PARP medium only from the roots of inoculated plants. Pythium F-group has been described as a pathogen of celery elsewhere, but to our knowledge, this is the first report of root rot caused by the fungus on celery in South Africa.

Turnover of cell-wall polysaccharides during somatic embryogenesis and development of celery (Apium graveolens L.)

Non-embryogenic cells (NEC) and embryogenc cells (EC) were separated from cell clusters derived from the hypocotyl segments of celery seedlings, which had been suspension-cultured in MS medium supplemented with 105 M 2,4-D. The EC formed globular embryos in medium without 2,4-D. The globular embryo developed through heart-shaped, torpedo to cotyledonary embryos within 10 days. The EC and developing embryos were fractionated into symplastic [MeOH, hot water (HW), starch (S)] and apoplastic [pectin, hemicellulose, TFA (trifluoroacetic acid)-soluble and cellulose] fractions. The EC contained lower levels of sugar in the MeOH fraction and higher levels of starch than NEC. In the apoplastic fractions, there were no differences of total sugar amounts between NEC and EC. Cellulose contents were about 10% of the wall polysaccharides. During somatic embryogenesis, total sugar contents of the MeOH and HW fractions increased till the heart-shaped embryo stage, and then decreased during the torpedo and cotyledonary embryo stages. The sugar contents of the starch, pectin, TFA-soluble, and cellulose fractions did not change during the stages mentioned above. However, the hemicellulose substances remarkably increased during embryogenesis, and then decreased as the development proceeded. The neutral sugar components of the hemicellulosic fractions were analyzed. Arabinose increased markedly in EC to the globular embryo stage, but decreased as the development proceeded. Galactose increased only at the torpedo and cotyledonary embryo stages. Xylose was present at lower levels in all stages of embryogenesis than in the differentiated hypocotyl cell walls. These results suggest that there was a high turnover of arabinogalactan polysaccharides during embryogenesis, and that xylan accumulated in the cell walls of differentiated cells

216 COMPARISON OF CELERY TRANSPLANTS NUTRIENT DEFICIENCY DIAGNOSIS BY MEANS OF DRIS OR CND METHODS

Celery (Apium graveolens var. Dulce) is a species particularly sensitive to nutritional balance. Seedlings in multicellular trays sometimes present problems that can be traced to nutritional causes. DRIS (Diagnosis and Recommendation Integrated System) and CND (Compositional Nutrient Diagnosis) are two recent concepts that can be implemented to diagnose nutritional imbalances from tissue analyses of any plant species. A data bank of 215 observations was used to elaborate DRIS and CND norms for celery transplants. The threshold yield for high yielders was set at 1600 g/plant (27% of the population). Both DRIS and CND systems were implemented and a validation process was undertaken. Nutrient deficiencies (N, P, K, Ca, Mg, Fe, B and Zn) were induced on celery seedlings in growing chambers. Tissues samples were given a balanced fertilization. The diagnosing methods (DRIS and CND) were compared on the basis of their ability to identify correctly the induced nutrient deficiencies.

Glasshouse and field evaluation of fungicides for the control of Septoria apiicola on celery

Propiconazole was more effective than either triadimenol or hexaconazole when applied after infection, for the control of Septoria apiicola on celery seedlings. In three out of four glasshouse experiments, 25 mg propiconazole I −1 controlled S. apiicola completely when applied within 3 days after inoculation. Propiconazole and triadimenol at 5–15 mg l −1 were also effective when applied 2 days after inoculation. Soil applications of a granular formulation of triadimenol (up to 20 mg per plant) controlled S. apiicola for 5 weeks on celery seedlings grown in pots and, in the field, granules at 100 mg per plant applied at planting were effective for 6 weeks. In two other field experiments the most effective treatments were foliar sprays of 25 mg propiconazole l −1 applied every 7–10 days with or without the addition of anilazine or chlorothalonil.

Growth, Nutrient Status, and Yield of Celery Seedlings in Response to Urea Fertilization

Abstract Celery seedlings (Apium graveolens L. cv. Florida 683) were seeded in multicell styrofoam trays containing a commercial peat mix. They were fertilized with nutrient solutions at two nitrogen fertilizations (150 or 350 mg N/liter), two NO3:NH4 ratios (2:1 or 3:1), and two urea-N levels (0% or 50%) in factorial combinations to determine main and interactive effects of urea on seedling growth, nutrient status, and crop yield. Urea used in combination with low N improved the percentage of shoot dry matter and increased leaf area, shoot and root dry weight, and root: shoot ratio of the seedlings. Urea proved beneficial in improving transplant yield potential under high-N fertilization.

Fungicidal control of leaf spot (Septoria apiicola) of celery

Ten fungicides were evaluated and compared in glasshouse and field experiments for the control of celery leaf spot caused by Septoria apiicola. In glasshouse experiments propiconazole (25 mg a.i. L-1) inhibited the development of S. apiicola when applied to celery seedlings 2 days after inoculation and in 1 experiment an application 8 days after inoculation reduced by 10-fold the severity of disease as well as the production of pycnidia. Penconazole (25 mg a.i. L-1), myclobutanil (50 mg a.i. L-1), flusilazole (20 mg a.i. L-1), fenarimol (36 mg a.i. L-1), terbuconazole (25 mg a.i. L-1) and triadimenol(25 mg a.i. L-1) also controlled S. apiicola when applied 2, but not 8 days, after inoculation. Anilazine protected celery seedlings for at least 13 days after application and was the most effective of the fungicides applied before infection. In field experiments, the most effective control of leaf spot was achieved with applications, every 7-10 days, of anilazine (1500 mg a.i. L-1), applied either alone or mixed with propiconazole (25 mg a.i. L-1). Similar applications of propiconazole either alone or mixed with chlorothalonil (150 mg a.i. L-1) also controlled leaf spot, whereas penconazole (25 mg a.i. L-1), flusilazole (20 mg a.i. L-1) and myclobutanil (50 mg a.i. L-1) were not effective.

Effects of CO2enrichment, nitrogen and phosphorus fertilization during the nursery period on mineral composition of celery

Abstract This experiment aimed at determining the effects of pretranspianting nutritional conditioning (PNC) on celery elemental composition at planting and harvest time. Celery seedlings (Apium graveolens L. cv. Florida 683) were fertilized with complete nutrient solutions at 3 concentrations of urea nitrogen and 3 concentrations of phosphorus in factorial combination, both with or without atmospheric CO2 enrichment. They were then planted in a muck soil and harvested at the end of July. CO2 enrichment decreased N, P, K, Mg and B concentrations in seedling shoot. It reduced N and K and increased Mg, but had no effect on P, Ca and B concentrations in roots. Nitrogen fertilization increased N concentration in shoot and roots but decreased P, K and Ca concentration in roots. The low urea‐N level resulted in low shoot P concentration. Phosphorus fertilization increased P concentration in seedling shoot and roots but depressed K in shoot. Maximum Ca and Mg concentrations in shoot were measured at low P fertilization. At harvest, shoot N concentration was found to have increased linearly with the P fertilization rate provided during seedling preparation. Therefore, PNC can modify the nutritional status of celery plants not only at planting time but also for the entire growing season.