Abiotic stress, especially salt stress, is one of the major barriers to crop production worldwide. Crops like onion that belong to the glycophytic group are more sensitive to salinity stress. A huge study regarding the influence of salinity stress on the growth and development of crops has already been done and is still ongoing. One of the major targets of the research is to develop genotypes that have enhanced performance under stress environments. The world needs more of these types of genotypes to combat the ever-growing salt-stressed soils. Therefore, a number of germplasm were studied during the 2019–2020 and 2020–2021 seasons under different salt concentrations to identify tolerant genotypes as well as to study the plants’ responses at different growth stages against elevated salinity levels. A 2-year study was conducted where germination potential was evaluated in the first year and carried out in petri dish culture of seeds, followed by plastic pot culture for plant establishment and bulb development evaluation during the second year. Four different saline water solutions having different salt concentrations (0, 8, 10, and 12 dS m−1) were applied to the petri dishes and pots as the source of water for plants in both seasons. Results indicated that a significant reduction in plants’ performance occurs under higher salinity levels. Salt concentration had an adverse impact on germination, leaf development and growth, the height of plants, bulb size and shape, and the bulb weight of onion. All the growth phases of onion are sensitive to elevated concentrations. Variable performances were observed in the genotypes under stress conditions, and a few genotypes (Ac Bog 409, Ac Bog 414, Ac Bog 424, Ac Bog 430, Ac Bog 417, Ac Bog 419, Ac Bog 420, Ac Bog 422, and Ac Bog 425) having some sort of tolerance to salt stress were identified, which might be recommended for mass production. Tolerance indices could successfully be applied in selecting the salt-tolerant genotypes. Thus, the present findings and the identified genotypes could be further utilized in salt stress improvement research on onion.

Twenty seven (27) isolates of Alternaria porri were isolated from diseased leaf samples collected from different onion growing regions of Bangladesh and characterized for cultural, morphological and pathogenic variabilities. A. porri colonies colony colour ranged between light to dark olivacious and grayish white with irregular, regular with concentric ring and regular without concentric ring shape. Margin of colonies were entire, irregular and wavy with effuse, fluffy and velvety texture. Isolates impregnated media with colour ranged between grey to brown on the reverse of the plates. Growth rate of isolates ranged between 2.433 and 3.950 mm/day with fast growth in isolate DSTR 02 and least in MMBH. Morphological variation in conidia production was between 7.720×10 3 to 47.02×10 3 per mm 2 with sporulation time 3.33 to 11.00 days. The conidial shape was straight to curve with light to deep brown colour. The number of horizontal and vertical separation in the conidia ranged from 3.00 to 6.00 × 1.00 to 2.00 with size from 11.20 to 39.20 × 4.76 to 11.43 µm. In pathogenicity test isolates also exhibited variations in size of the lesions (2.77 to 7.55 mm) produced on onion leaves. The results demonstrate existence of considerable variation in cultural, morphological, and pathogenic characters of A. porri isolates prevalent in Bangladesh environment.

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The experiment was conducted under in-vivo condition in a betelvine baroj at Sher-e-Bangla Agricultural University (SAU), Dhaka-1207, Bangladesh. Nineteen isolates of Sclerotium rolfsii collected from different regions of Bangladesh designated as isolate-1 to isolate-19. Soil inoculated with S. rolfsii exhibited mycelial growth on the soil surface and around the base of the betelvine plant within 2-4 days after inoculation. Only 2 days after inoculation were required to manifest cottony colony on soil surface near root zone of inoculated betelvine plants by the isolate-3, 5, 7, 9 and 12. The first disease symptoms were observed within 6 to 16 days after inoculation where minimum days were required by the isolate-9 and maximum by the isolate-2 and 14. The highest lesion length (6.50 cm) was produced by the isolate-9 and isolate-13. All the isolates were found to be pathogenic in some cases, disease delayed due to their degree of pathogenicity. The isolate-9 showed highest disease incidence of 100% which was superior as compared to all other isolates at 15 days after inoculation. The isolate-19 showed least disease incidence of 66.66% even at 30 days after inoculation. Among the isolates, the most pathogenic one was isolate-9 collected from Kaligonj upazilla of Jhenaidah.