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This study aims at assessing the effect of limestone mining by-product from the Irati Formation on soil calcium, magnesium, and sulfur contents, as well as their accumulation in the onion biomass. The study was carried out in a greenhouse. A Eutrophic Haplic Planosol (SXe) and a Eutrophic Yellow Argisol (PAe) soil were used. The treatments included the control, limestone by-product, dolomitic limestone, calcium (Ca) + magnesium (Mg) carbonates, and Ca + Mg carbonates + gypsum. Onions were grown in pots containing 10 dm3 of soil kept at a moisture level close to the field capacity. The onion biomass harvest (bulb + leaves) was performed 77 days after transplanting. Afterwards, the soil macronutrient content and the dry onion biomass were determined, as well as its production. The by-product application increased Mg2+ content in both soils (+74% in SXe and + 182% in PAe) and Ca2+ and sulfate (S-SO42-) contents, respectively, in the PAe (+62%) and SXe (+124%). There was an increase in S accumulation due to the onion biomass cultivated in both soils (about 85%). Regarding Ca and Mg accumulations, no difference was observed in the by-product treatment when compared to the control. Therefore, it is possible to infer that the limestone mining by-product from the Irati Formation is potentially useful as a source of secondary macronutrients and proves to be a clean environmental solution for soil fertilization, increasing the sustainability of the local production system. [ABSTRACT FROM AUTHOR]

Fusarium basal rot, caused by Fusarium oxysporum f.sp. cepae, is an important onion disease worldwide. Greenhouse pot experiments were conducted during two growing seasons to determine if field soils from New Zealand's main onion growing regions had different fusarium basal rot suppressive capabilities, and identified factors involved in disease suppression This study demonstrated that soils naturally suppressive to fusarium basal rot were present in New Zealand and that soil organic matter content, total soil carbon, total nitrogen and soil phosphorous concentrations were associated with disease incidence. Soil microorganisms were shown to be involved in disease suppression since when they were eliminated or reduced by soil heat treatment, fusarium basal rot incidence markedly increased. This study provided an increased understanding of how soil physical, chemical and biological factors affect the suppressiveness of selected New Zealand soils to fusarium basal rot of onion, and demonstrated that certain bacterial and fungal taxa may be involved in suppression of this disease. [ABSTRACT FROM AUTHOR]

The nutrition of onion grown in a no-tillage system with compost requires research to provide alternatives to mineral fertilizers. Our objective was to evaluate the effect of compost rates on the nutrient content in the tissue of onion grown in a no-tillage system. We conducted a field experiment with the following treatments: 0, 10, 20, 30, and 60 Mg ha−1 of compost and mineral fertilization. We applied these treatments in 2018, 2019, and 2020 for onion cultivation. We used a 3 × 6 factorial scheme (year x treatment) and four replications. We evaluated the bulbs and whole plant nutrient contents of N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, and B. In 2020, nutrient content in the bulb from 10 Mg ha−1 of compost was similar to the mineral fertilizer's treatment. Therefore, compost can replace mineral fertilizers to supply nutrients to the onion. However, the continuous application of compost requires soil monitoring due to nutrient accumulation. [ABSTRACT FROM AUTHOR]

Severe root rot was observed in onion seedlings growing in nursery seedbeds in Changnyeong, South Korea in September 2021. The diseased onion seedlings showed symptoms including water-soaking, browning and blight, followed by seedling collapse. Three isolates were obtained from diseased onion seedlings, and their morphological characteristics were found to be similar to previously described Pythium species. Artificial inoculation with isolates produced identical symptoms to those observed in the original infection. Based on morphological characteristics, sequencing of rRNA gene internal transcribed spacer, ribosomal large subunit gene region, and cytochrome c oxidase subunit I gene region, and pathogenicity testing, the causative agent of root rot on the onion seedlings was identified as Globisporangium irregulare (formerly Pythium irregulare). This is the first report of root rot caused by G. irregulare on onion seedlings in Korea. The results of this study suggest that root rot may pose a severe threat to onion seedling cultivation. [ABSTRACT FROM AUTHOR]

A better understanding of the physiological mechanisms by which zinc (Zn) is absorbed by plant leaves may provide additional basic information to help in the improvement of Zn foliar application programs. In this two-year field experiment, apoplastic and symplastic distribution of Zn in the leaves and re-translocation from the leaves to the bulb of onion (Allisum cepa L. cv. Behbahan) as affected by foliar application of different Zn fertilizer sources was investigated. Four Zn fertilizer sources, i.e., ZnSO4 and Zn-lysine (Zn-Lys), Zn-methionine (Zn-Met), and Zn-threonine (Zn-Thr) were applied as foliar spray at a concentration of 0.5% Zn. Free amino acids (i.e., Lys, Met, and Thr) were used to separate the effect of Zn and accompanying amino acids. A free of Zn and amino acid treatment was also considered as control. The Zn-form revealed significant influence on apoplastic Zn concentration. Foliar application of Zn-amino chelates particularly Zn-Lys increased contribution of symplastic to apoplastic Zn in onion leaves by decreasing the Zn retention on the apoplastic spaces. Higher leaf symplastic Zn in the plants supplied with the Zn-Lys in comparison with those supplied with the other Zn fertilizer sources was accompanied with higher bulb Zn accumulation. This was probably due to larger re-translocation of Zn from the leaves to the bulb at the Zn-Lys treatment. Spraying Zn and amino acids either free or complexed with Zn produced an increase in Zn concentration provoking a decrease of nitrate concentration in the bulbs and the highest effect was observed at the Zn-Lys treatment. According to the results, Zn-Lys was more effective than ZnSO4 in enhancing the symplastic to apoplastic Zn ratio in the leaves and resulted higher accumulation of Zn in the bulbs. [ABSTRACT FROM AUTHOR]

The study was aimed to evaluate the effect of successive applications of increasing biochar rates along with other mineral fertilizers and poultry manure on onion nutrition and yield. The experiment consisted of 2 (agricultural year) × 11 (treatments) factorial combinations over two cropping years (2017 and 2018). Thus, 11 treatments were tested as follows: C = control; MF = mineral fertilizer; PM = poultry manure; B1+ MF = 1 Mg ha−1 of biochar+MF; B1+ PM = 1 Mg ha−1 of biochar+PM; B2+ MF = 2 Mg ha−1 of biochar+MF; B2+ PM = 2 Mg ha−1 of biochar+PM; B4+ MF = 4 Mg ha−1 of biochar+MF; B4+ PM = 4 Mg ha−1 of biochar+PM; B10+ MF = 10 Mg ha−1 of biochar+MF; B10+ PM = 10 Mg ha−1 of biochar+PM. The highest onion yield (39.9 Mg ha−1) was obtained in 2017 with the biochar rate of 5.9 Mg ha−1 while an increase of 308 kg ha−1 in onion yield was found for each Mg ha−1 of biochar added to soil in 2018. The use of biochar combined with mineral fertilizers increased onion yield; and the use of biochar combined with poultry manure improved soil fertility status. [ABSTRACT FROM AUTHOR]

Potential yield of onion (Allium cepa L.) in semi-arid regions is reduced by abiotic (soil infertility, poor agronomic practices, and unbalanced fertilization) and biotic (use of low yielding varieties, insect pest, and diseases) challenges. Soil infertility causes up to 60% yield loss in onion. This study was undertaken to assess the influence of manure and phosphorus (P2O5) fertilizer levels on growth and bulb development of onion under semi-arid conditions. Manure at 30 or 60 kg/5 m2 or 0.24, 0.48 or 0.62 g/plant for phosphorus and treatments combined at each application rate were used. Application of phosphorus and manure at 0.24 to 0.48 g/plant and 30 kg/5 m2 plot, respectively, improved vegetative and bulb development and weight. A combination of 30 kg/5 plot manure and 0.48 g/plant phosphorus produced an economic benefit based on number and weight of marketable bulbs. Application of 0.24 to 0.31 t∙ha−1 of P2O5, increased number of unmarketable bulbs. 'Red Bombay' performed better than 'Red Mantle.' Individual or combination application of P2O5 at 0.12 to 0.31 t∙ha−1 and organic manure at 60 t∙ha−1 may produce adequate yield, and 'Red Bombay' maybe a better choice than 'Red Mantle' under semi-arid conditions. Application of manure and phosphorus improves vegetative and yield in onion cultivars. Use of 30 kg/5 m2 of manure and a combination of 30 kg/5 m2 and 0.48 g/plant manure and P2O5, respectively, appear to improve yield. [ABSTRACT FROM AUTHOR]

Onion basal rot is the most destructive disease caused by Fusarium oxysporum f. sp. cepae (FOC) for onion growing regions of the world. To control this disease, biological control agents 287 phosphate solubilising bacteria (PSB) were isolated from 43 onion rhizosphere soil samples. The value on the phosphate solubilisation index (SI) of the PSB was calculated to be in the range of 1.2–5.5, and a quantitative estimation of P solubilisation was investigated in liquid medium and found to be in the range of 15.2–382.5 mg/l. Furthermore, all tested organisms solubilised rock phosphates (RP) by lowering the medium's pH. These isolates were tested for their effect on the mycelial growth of FOC in dual cultures. Eight isolates were determined to inhibit mycelial growth of FOC at rates from 71.5 to 75.7%. For the pot experiments, 15 rhizobacteria (12 isolates highest P-solubilising and 3 isolates P-solubilising and effective antagonist) were selected through 287 PSB. In the pot experiments, onion seeds (sensitive and resistant) coated with PSB were sown in soil which was infected with FOC and RP. Seed treatment with the isolates was found to suppress disease severity in ratios varying from 10.9 to 77.8%. At the same time, these PSB isolates significantly reduced disease, similar in degree to a chemical fungicide (Antrachol) (p < 0.05). The results of the in vitro and in vivo research demonstrated that the isolated PSB are potential biological control agents and need to be further researched for the biochemical basis of their activity against FOC. [ABSTRACT FROM AUTHOR]

Shallot is an economically important nutritive bulb vegetable and medicinal plant from Alliaceae family. Distributed in limited regions worldwide, in most cases, shallots widely grow in very cold to moderate cold temperate climates at high elevations required to induce bolting and overcome their bulbs and true seeds dormant period. Shallot responses to agricultural management and environmental conditions vary among different species and genotypes and, thus, selection of the elite genotypes is a prerequisite for obtaining desired yield and quality of bulbs and true seeds. Plant material (seed or bulb), plant selection, as well as cultivation and agricultural practices (importantly fertilization, spacing, planting date, and irrigation in greenhouse or farmland) critically affect productivity, phytonutrient value, and economic profit of the shallot produces. The knowledge of using biofertilizers and mulching techniques on shallots are currently evolving, but the information on the efficiency of nanobiofertilizers and eco-friendly and biodegradable mulching materials on shallots farming are still lacking. With the emphasis on sustainable agricultural systems, the efficiency of combined organic and inorganic fertilization is discussed and the potential biofertilizer agents are recommended. This review highlights the importance of using the integrated fertilization (organic and inorganic methods combined with biofertilizers) and irrigation methods (such as two-line spray hose irrigation combined with mulching), and the practices with the highest potential to further improve shallot farming are suggested. The information on shallots breeding is still lacking and requires extensive researches in the future. [ABSTRACT FROM AUTHOR]

Onion, (Allium cepa L.), is one of the most consumed and grown vegetable crops in the world. Onion bulb, with its characteristic flavor, is the third most essential horticultural spice with a substantial commercial value. Apart from its culinary virtues, A. cepa is also used traditionally for its medicinal virtues in a plethora of indigenous cultures. Several publications have been produced in an endeavor to validate such traditional claims. Nonetheless, there is still a dearth of up-to-date, detailed compilation, and critical analysis of the traditional and ethnopharmacological propensities of A. cepa. The present review, therefore, aims to systematically review published literature on the traditional uses, pharmacological properties, and phytochemical composition of A. cepa. A. cepa was found to possess a panoply of bioactive compounds and numerous pharmacological properties, including antimicrobial, antioxidant, analgesic, anti-inflammatory, anti-diabetic, hypolipidemic, anti-hypertensive, and immunoprotective effects. Although a large number of in vitro and in vivo studies have been conducted, several limitations and research gaps have been identified which need to be addressed in future studies. [ABSTRACT FROM AUTHOR]

Basal rot is the main and economically soil-borne disease of onion that caused by various Fusarium species worldwide. To identify the prevailing Fusarium species, 140 Fusarium isolates were obtained from red onion bulbs farms in 10 regions of East and West Azarbaijan provinces in 2015. By inoculating 80 selected isolates, 40 of them were pathogenic on onion. These 40 isolates were identified as F. oxysporum with 43.62%, F. subglutinans with 44%, F. culmorum with 50.66%, F. avenaceum with 51%, F. solani with 42.41%, F. crookwellens with 55%, F. proliferatum with 47.16% and F. redolens with 55.5% virulence. Their frequency were 20%, 2.5%, 7.5%, 5%, 42.5%, 2.5%, 15% and 5%, respectively. Forty studied isolates demonstrating that, 14.2% were highly virulent, 26.1% virulent, 40.3% moderately virulent and 19.4% weakly virulent. This is the first report of F. avenaceum and F. crookwellens as the causal agents of red onion basal rot in Iran. [ABSTRACT FROM AUTHOR]

In this research experiment, two commercial onion cultivars (Allium cepa L., cvs. Dorrcheh and Cebolla Valenciana) were grown in sand culture and exposed to two levels of selenium (Se) (0 and 25 µM) and two levels of sulfate (1 and 3 mM). According to the results obtained, addition of 25 µM Se in combination with 3 mM sulfate was not only effective in significant increase of onion bulb yield, but it significantly increased Se concentration of bulb. By considering the average consumption of onion in central Iran, the daily intake of Se via consumption of Se-biofortified onion is estimated to be 68.4-77.2 µg in spring and summer and 72.6-117.1 µg in fall and winter. These amounts of daily intakes of Se is higher than the sufficient levels of Se recommended by world health organization (WHO) but less than the maximum tolerable level of Se (400 µg Se per day) for human. [ABSTRACT FROM AUTHOR]

Dry matter accumulation and nutrient uptake patterns of crops must be determined to optimize fertilizer scheduling. This study assesses the dry matter accumulation and nutrient uptake patterns of onion seed crop. Plant samples were collected between 0 and 120 days after planting, and their nutrient content was analyzed to determine the dry matter accumulation and nutrient uptake patterns. The quantity and period of nutrient uptake and the mobility of nutrients within the plant parts varied for different nutrients. The absorption of nitrogen (N) and potassium (K) was the highest during vegetative stage, whereas phosphorus (P) and sulfur (S) uptake was the highest during flower initiation stage. N, P, K, and S, which had accumulated in the vegetative parts, moved from the senesced vegetative parts to the inflorescence during the reproductive stages owing to their high mobility in the phloem. The onion plants continued to absorb zinc, copper, manganese, and iron throughout their growth owing to the immobility of these elements in plant system. The result of this study may facilitate efficient scheduling of fertilizer application to increase nutrient uptake and yield. [ABSTRACT FROM AUTHOR]

A field study was conducted to evaluate the effect of application rates of anaerobically digested pig slurry (ADPS) on onion growth, bulb yield, and quality during the 2009–2010 growing season. Three levels of swine slurry were used; 50%, 100%, and 150% of the recommended nitrogen (N) rate for basal fertilizer. Bulb dry matter and total soluble solids content decreased with increasing ADPS rates at harvest, while pyruvic acid and total phenol content increased as the rates of ADPS increased. Bulb yield with ADPS of 100% or 150% rates were not significantly different from chemical fertilizer. ADPS at a 150% application rate resulted in a significant increase in N, sulfur (S), and sodium (Na) in bulbs as compared to ADPS having an application rate of 50%. In conclusion, while substituting for chemical fertilizers, ADPS at a rate of 100% based on the N recommendation for basal fertilization can be used to produce quality onions. [ABSTRACT FROM AUTHOR]

A major concern in potato and onion production worldwide is the sustainability of crop production systems using short-term rotations. Although rotation crops are known to influence soil microbial communities, few long-term field studies have investigated effects of potato and onion crop rotations on soil microflora and soilborne diseases. A long-term trial (10 years) was established in New Zealand in the 2004–05 season to determine changes in soil characteristics, soil biological communities, plant productivity and soilborne diseases resulting from different crop rotations. Six different crop rotation ‘treatments’ were used: three were onion-focused and three were potato-focused. For both the onion- and potato-focused rotations, one treatment was continual monoculture, one was biennial alternating onion and potato (‘conventional’ rotation, common local commercial practice) and one was a 4-year cycle where the onion or potato crops were grown every fourth season with different crops in the intervening seasons (‘sustainable’ rotation). The results of the rotations were evaluated at the end of 2012–13, nine growing seasons after the trial began. Soils from the three potato-focused rotations had similar microbial biomass carbon (C) and nitrogen (N), total C and N, and enzyme activity, but had different microbial activity parameters. Soils from the three onion rotations differed in organic matter content, total C and N, enzyme activity and carbohydrate utilization. The main factor correlated with potato diseases (stem canker, black scurf) and crop yields was the amount ofRhizoctoniainoculum in the soil. Onion yields in 2012–13 were correlated with the severity of pink root during the growing season. Total microbial activity in soil gave better relationships to soilborne disease incidence (Rhizoctonia stem canker of potato or pink root of onion) and to crop yields, than soil chemical parameters (pH, nutrient status, C:N ratio) or other microbiological parameters (microbial biomass, total culturable bacteria and fungi, and microbial diversity). This research has broadened understanding of effects of crop rotations on soil microbial community characteristics, soilborne diseases and crop productivity of potatoes and onions grown in a soil and an area where intensive vegetable production is common. This knowledge will assist growers to increase crop yields and reduce soilborne pathogens in a sustainable manner. Based on the results from this study, intensive potato and onion production should require these crops to be grown within 4-year crop rotations in order to foster sustainable yields and minimize soilborne diseases. [ABSTRACT FROM PUBLISHER]

Root and basal rot disease (RBR) of onion,Fusarium oxysporumf. sp.cepa(FOC), is one of the most important diseases, which cause tremendous losses in onion-growing areas worldwide. In this survey, various onion genotypes, including eight main and dominant Iranian seed sets and two exotic ones, were tested against FOC incidence in greenhouse and field conditions of various growing stages. The incidence of the RBR was determined at three stages, such as early, flowering and seed-setting stages, on the basis of disease severity. The genotypes reacted differentially to FOC within and between various stages with a very high significant level. The genotypes were classified in five scoring scales, accordingly. Highly infected ones tended to be associated with the highest mean scores of 75–100% severity and the least infected genotypes had the lowest scores of 0–10%. Moreover, the examined genotypes were ranked from 1 to 10 according to their markedly differing reactions to FOC at various stages. Variance and cluster analysis also showed similar results among the genotypes with various levels of infections. There was a direct, positive and enhancing correlation for every genotype to infection as the growing stages were reaching to the maturing stage. [ABSTRACT FROM AUTHOR]

Basal rot disease of onion is a major problem in different onion growing regions of Tamil Nadu, India. Fungal and bacterial cultures were isolated and tested their efficiency againstFusarium oxysporumf. sp.cepaeunderin vitroconditions. Effective bacterial and fungal antagonists were tested alone and in combinations for the control ofF. oxysporumf. sp.cepaein glasshouse experiments. Defence-related enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase were induced and accumulated in onion treated with fungal and bacterial antagonists. Defence-related enzymes were significantly higher in onion pretreated with consortial formulation of Pf12 + Pf27 + TH3 at 5 days after the challenge inoculation withF. oxysporumf. sp.cepaeand gave resistance to onion against basal rot disease. [ABSTRACT FROM AUTHOR]

Field experiments were conducted at Bugri and Binduri in northern Ghana in the 1996-97 and 1997-98 onion growing seasons, to determine the optimal irrigation regime for onion: morning and evening daily, morning daily, evening daily, morning and evening alternate days, morning or evening alternate days on bulb yield and yield components of onion cv. Bawku Red. Bulb yield of onion and yield components were significantly (P < 0.05) influenced by irrigation interval. Mean height of onion plants that received irrigation morning and evening, or morning or evening daily were about 39 cm while plants in other treatments were only 34 cm in height. Mean foliage weight when onion was irrigated morning and evening daily was 1.7 kg/plot compared to 1.4 kg/plot when onion was irrigated every other day. The highest bulb yields of 39.8 Mt-ha-1 were obtained when transplants received irrigation morning and evening. Onion bulb yield and yield components generally decreased significantly (P < 0.05) with increase in irrigation regime. Irrigation regime did not have any significant (P < 0.05) effect on the percent total sugar in onion bulb. Over 50% of the farmers in the trial preferred irrigating their onion crop once daily in the morning, thereby confirming the agronomic results obtained in the study. [ABSTRACT FROM PUBLISHER]

Optimum age of onion (Allium cepa L.) transplants for use in current and expanding onion-growing areas in Ghana is not well understood. Field studies were conducted at two locations in Ghana during the 1996-97 and 1997-1998 onion growing seasons. Transplants that were 20, 30, 40, 50, 60 or 70 days old, and of uniform size at each age, were used. The effect of transplant age on bulb yield components of onion was determined. The tallest plants were developed from 40-day-old transplants and the shortest were developed from 70-day-old transplants. Harvest index (bulb weight/total biomass weight) of onion decreased significantly as transplant age increased. The heaviest onion bulbs, 57.2 g, were from plants derived from 40-day-old transplants, and the lightest, 26.1 g, were from plants developed from 70-day-old transplants. Plants developed from 20- to 40-day-old transplants produced the highest yields. The results indicate that using 20- to 40-day-old transplants will give optimal bulb yields. [ABSTRACT FROM PUBLISHER]

The current spatial arrangement and density of onion plants adopted by producers in Northern Ghana was found to limit onion production. A study was carried out at two onion-growing locations in Northern Ghana, during the 1996-97 and 1997-98 onion growing seasons, to evaluate the response of onion cv. Bawku Red to eight spacings, i.e., 0.18 X 0.15, 0.15 X 0.15, 0.18 X 0.10, 0.15 X 0.13, 0.15 X 0.10, 0.13 X 0.10, 0.10 X 0.10, and 0.8 X 0.8 m, which gave the following plant densities: 37.04; 44.44; 51.28; 55.56; 66.67; 76.92; 100 and 156.25 plants/m2, respectively. The experimental variables measured were plant height, number of leaves, number of marketable bulbs, number of culls, neck diameter, mean bulb weight, bulbing index and bulb yield. Plant population density significantly (P < 0.05) affected bulb yields and yield components of onion. Bulb neck diameter, mean bulb weight and plant height decreased as population density increased. Total bulb yield increased significantly (P < 0.05) as population density increased. Number of marketable bulbs increased significantly (P < 0.05) with higher planting density. Onion bulb yield in the study ranged between 20.9 and 33.1 t_ha-1. It was concluded that sowing onion at densities above 76.92 plants/m2 increased marketable onion bulb yields. [ABSTRACT FROM PUBLISHER]