Pathogenicity study of some seed-borne fungi of onion (Allium cepa L.) from Burkina Faso

Onion production in Burkina Faso faces to several constraints including diseases. Symptoms such as seedling damping-off are currently been observed. Most of the fungi responsible for onion diseases are seed-transmitted but in Burkina Faso, little information on onion seed quality were available. In a previous study, Aspergillus niger, Fusarium oxysporum and Fusarium solani were found to be the main fungi present on onion seeds but their responsibility in the development of seedlings damping-off has not been established. The overall aim of this study is to evaluate in vitro, the effect of these fungi on onion seed germination and coleoptile growth in order to establish this responsibility. Onion seeds were inoculated with mycelium suspension of the fungi concentrated at 13.3 g/ml and incubated for 6 days under appropriates conditions. All the tested fungal isolates had an inhibitory effect on onion seed germination at rates ranging from 31 to 60%. The Fusarium species were the most virulent. Coleoptile length was also reduced by the fungi, leading to significant growth time-lag at rates ranging from 34 to 100%. Aspergillus niger was the most virulent. In conclusion, Aspergillus niger, Fusarium oxysporum and Fusarium solani are responsible of seedling damping-off of onion in Burkina Faso.

Molecular Marker Characterization of Commercially Used Cytoplasmic Male Sterilities in Onion

Hybrid-onion (Allium cepa) seed is produced using systems of cytoplasmic male sterility (CMS) and two different CMS systems have been genetically characterized. S cytoplasm was the first source of onion CMS identified in the 1920s, followed by T cytoplasm that was described in the 1960s. Numerous studies have documented polymorphisms in the organellar DNAs differentiating S and T cytoplasms from the normal male-fertile cytoplasm of onion. There may be additional source(s) of onion CMS that have been described as “T-like” and appear to be more similar to N and T cytoplasms than S cytoplasm. In this study, onion breeding lines from commercial entities were evaluated for molecular markers distinguishing sources of onion CMS. Our results reveal that bona fide T cytoplasm is rarely used commercially to produce hybrid-onion seed, and both S cytoplasm and “T-like” cytoplasm are widely used. We propose that this “T-like” cytoplasm be labeled as “R” cytoplasm because it may have originated from population(s) of ‘Rijnsburger’ onion in the Netherlands. The results of this study also help to clarify inconsistent reports regarding nuclear male-fertility restoration for different sources of onion CMS.

Ethanol release as an indicator of seed vigour in radish, pepper, watermelon, aubergine, leek and onion seed lots

Ethanol release was tested in relation to seed vigour measured by seedling emergence and controlled deterioration tolerance in radish, pepper, watermelon, aubergine, leek and onion seed lots. Ethanol release, measured with six lots from each species after four and eight hours at 40&deg;C and 30% seed moisture, was highly negatively correlated with controlled deterioration tolerance (45&deg;C, 48 hours, 20% seed moisture) in radish (r = 0.05, P &lt; 0.05), with seedling emergence in watermelon (r = 0.99, P < 0.01) and to both traits in pepper (r = 0.87 to 0.94, P &lt; 0.05), but not with any variable for aubergine and leek. One single case was significant between ethanol release after eight hours and controlled deterioration for onion seeds. Results indicate that there is a relationship between ethanol release and seed vigour, but this appears to be species dependent.

Ethephon Reduces Lodging and Enhances Seed Yield and Quality in Onion

Onion is an important vegetable crop grown in almost all parts of the World as a flavouring agent in food preparation. It is propagated by seeds and the seed crop is affected by several fungal, viral and bacterial diseases which cause lodging and reduces the seed yield and quality. Onion seed crop was sprayed with different concentration of ethephon (0, 100, 200, 400, 600, 800 and 1000 ppm) for two duration at 45 or 45+60 days after planting during (DAP) during 2018-19 and 2019-20 rabi seasons. The effect of ethephon on seed yield and seed quality was studied. In comparison to control ethephon application significantly reduced scape length and % lodging by 38.73% and 42.52% respectively. There was 31.90% and 89% enhancement in scape diameter and yield respectively. Ethephon spray also enhanced seed quality, highest germination and seed vigour was recorded in plants sprayed with 600 ppm ethephon at 45 and 60 DAP which was 19% and 51.65% higher than control. Highest seedling dry weight was observed in plants sprayed with 100 ppm ethephon at 45 DAP. Among the treatments, 100 and 200 ppm ethephon applied at 45 DAP had lower lodging and higher seed yield and seed quality. Hence spraying of onion seed crop with 100 ppm ethephon at 45 DAP is beneficial for getting higher seed yield and quality.

Survey on Technical Efficacy of the Farmers and Their Satisfaction Level for the Production of Onion Seeds in Bagmara Upazila, Rajshahi District

Onion seed production is not exactly same as the cultivation of the onion as a crop. Due to lack of recommended standard cultural practices, an onion seed producer in Bangladesh is facing different levels of difficulties. To address this issue, the present study has been undertaken for generating farm level information on the production and input use pattern in the onion seed cultivation. Using semi structured questionnaire, a total of 50 onion farmers is randomly selected from Bagmara upazila, Rajshahi district for the interview. The results indicate that there were so many constraints on onion seeds production such as unavailability of high yielding varieties, shortage of information about recommended fertilizer doses, bulb size, planting space, setting of planting time, etc. At the same time, farmers are also fronting problem regarding paucity of separated land, absence of specialized onion cold storages. Considering the above- mentioned problems, the results showed that 70% of the farmers are not satisfied with the onion seeds yield. The study suggested that distribution system of the quality onion seeds has to be improved coupled with the onion research in Bangladesh has to govern by the dynamics of seed grower’s quality preferences and their socio- eco- climatic infrastructure. Furthermore, it is indispensable to introduce training programs for the farmers for improving their knowledge about management practices as seed production required highly skill person Res. Agric., Livest. Fish.7(3): 383-391, December 2020

Chemical protection of the onion from phytophages in the Right-Bank of the Forest-Steppe of Ukraine

Goal. To monitor the species composition of the harmful entomocomplex of onions and determine the effectiveness of modern insecticides in different ways of their application (spraying and seed treatment). Methods. Laboratory and field studies were carried out according to generally accepted methods and using classical methods of entomology; vario-statistical analysis. Results. It has been established that on the crops of the onion of the onion in the right bank forest-steppe of Ukraine, 11 species of phytophages are dominated by the most numerous: Delia antigua Mg., Trips tabaci Lind., Ceuthorrhynchus jakovlevi Schultze and Eumerus strigatus Fall. Species composition of pests on the hybrids of antelope F1, Dyton F1, Bank F1 and Halkodon varieties and the globe was the same, but the number was significantly different. The hybrids of the foreign selection, the size of the onion flies was at a level of 3.5—12.7 l./р., And on the varieties of Halcodon and the globe — 5.1—16.6 l./р. It was investigated that the technical efficiency of onion seed disinfectants was: Cruiser 350 FS, because — 79.3% and Celeste Top 312.5 FS, TH — 71.7%. The greatest technical efficiency of the tested insecticides against the dominant phytophages with double spraying of onion crops was provided by Engio 247 SC, KS — 78.5% and Lannat, 20 RK — 74.6%. Conclusions. It was found that the use of seed disinfectants drugs Cruiser 350 FS, because (0.15 l/t) and Celest Top 312.5 FS, TN (0.1 l/t) and two treatments with Engio 247SC, KS (0.18 l/ha) provide protection of onion crops from pests and their control, both in the initial stages of development and during the growing season.

Influence of a Helium–Nitrogen RF Plasma Jet on Onion Seed Germination

This paper presents an experiment using a radio frequency atmospheric pressure plasma jet to generate cold plasma for pre-sowing stimulation of Wolska onion seeds. Impact of the He + N2 afterglow plasma on germination was investigated. Eight groups of seeds characterized by different exposure times (2, 5, 10, 15, 60, 120, 240, and 480 s) and distance from the electrodes (20 mm and 50 mm) were used. Pre-sowing plasma stimulation of the seeds improved the germination capacity and germination energy for all tested groups, relative to control. The impact of radio frequency plasma on the onion seed germination parameters was statistically significant. The highest germination parameters were obtained for seeds stimulated for 240 s at a distance of 50 mm. No significant differences in physical and morphological properties of onion seeds were found.