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Experiments were conducted at Horticulture Research Division (HRD), Khumaltar, Lalitpur; and Horticulture Research Station (HRS), Kimugaun, Dailekh in 2017/18 to evaluate the high yielding open pollinated genotypes of onion in mid hills of both locations. Five onion genotypes namely AVON-1016, AVON-1027, AVON-1028, AVON-1052, AVON-1074 and AVON-1103 received from Asian Vegetable Research and Development Centre were evaluated with local check variety and recommended variety Red Creole in both locations in randomized complete block design with 4 replications. The main objective of the experiment is to findout the high yielding open pollinated onion genotypes for mid hill condition.The pooled analysis of data over locations showed significant differences on plant height, neck diameter, bulb diameter, weight of bulbs and adjusted bulb yield per hectare. Introduced genotypes AVON 1027 (38.83 t/ha), AVON 1052 (31.97 t/ha) and AVON 1028 (31.48 t/ha) produced significantly higher yield than recommended and commercially cultivated check variety Red Creole (27.04 t/ha). Therefore the genotype AVON 1027 can be selected as the best genotype for growing in mid hills of Nepal

Constraints are reported for the low productivity and quality of onion seed production in Ethiopia. Therefore, a field experiment was conducted at Kobo sub-center research station and Libso investment farm to study the influence of planting date and onion bulb size on yield and quality of onion seed. The experiment was laid out in Randomized Complete Block Design with three replications and involved three levels of onion bulb sizes and four levels of planting dates. The results of the study revealed that significant interactions between planting date and mother bulb size on seed yield ton ha-1, germination percentage, seed vigor index I and seed vigor index II. The highest seed yield (2.8 tons ha−1) was recorded from large onion bulbs of a size planted at Kobo early—October. Planted onion bulbs early-October increased seed yield (ton ha−1 by 21.7%) than planted early-November. Regarding onion bulb size, large bulbs increased seed yield (ton ha−1 by 40%) than the small bulbs. The highest (97.3) germination percentage was recorded from large onion bulbs planted at Kobo in early-October. Therefore, for the production of better yield and quality of onion seeds, early-October planting and large onion bulbs (4.1–5 cm) can be recommended in the study areas and other similar agro-ecology areas of the country.

The combined application of humic substances and mycorrhizal inocula under increased CO in the air is a promising horticultural technique for improving the quality of greenhouse-grown onion seedlings. The objective of this study was to evaluate if the development and qualitative characteristics of bulbs from the yellow onion Allium cepa L. Alfa São Francisco improved with the application of the abovementioned agronomic, biotic, and environmental factors. The lowest dry matter was achieved in bulbs of onions not inoculated with mycorrhizal fungi, non-amended with humic acids (HA), and grown at ambient CO. Mycorrhizal inoculation significantly increased bulb biomass in plants cultivated at ambient CO, and not fertilized with HA, which may be a consequence of the enhanced acid phosphatase activity in roots. The application of HA always increased bulb dry matter, which were more evident at elevated rather than ambient CO conditions and correlated with improved acid phosphatase activity in the plants at elevated CO. Mycorrhizal inoculation, HA supplementation, and elevated CO in the air had an additive effect of increasing the content of soluble sugars, proteins, and phenolics in bulbs. While high levels of sugars and proteins enhanced the energetic value of onions, the increase in phenolics improved their antioxidant properties. The triple interaction between mycorrhization, HA fertilization, and elevated CO also increased the ratio between soluble solids and total titratable acidity, which may enhance the perception of sweetness and make onions more pleasant for consumption., This study has been supported by the ‘Ministerio de Ciencia e Innovación’ (Spain) (BFU2011-26989). Marcelle M. Bettoni received a grant from ‘Los CAPES y Coordenação do Programa de Pós-graduação em Agronomia - Produção Vegetal’ from the Brazilian Government.

The effects of planting time and bulb size on the plant growth and development characteristics of Narcissus tazetta (‘Paperwhite’, ‘Bunch-Flowered Narcissus’) flowers were investigated as one of the first studies on quantitative analysis of bulbous flowers. Narcissus tazetta bulbs, which were removed from their native habitat in August, were divided into three sizes (12.1 to 14, 10.1 to 12 and 8.1 to 10 cm) according to the circumference and planted at 3 different times (September, October and November). After harvest, stem weight ratio, leaf weight ratio, leaf area ratio, specific leaf area, leaf thickness were determined as quantitative measurements. Leaf area was measured by planimeter. Dry weights of plant samples were determined and plant growth parameters were calculated according to the models adapted to the bulbous plants. Results on growth parameters showed planting time significantly affected the leaf thickness, leaf weight ratio and stem weight ratio. The differences among the bulb sizes were not statistically significant on quantitative measurements. Planting time and bulb size did not affect the leaf area ratio and specific leaf area. The results showed that plant growth parameters can be used in modeling studies on cut flower production of bulbous flowers. © 2019 International Society for Horticultural Science. All rights reserved. These results are belong to the master research project (PYO.ZRT. ? ? ? ?. ? ?. ? ? ?) supported by Project Management Office of Ondokuz Mayis University in Samsun, Turkey.

Environmental, genotypic and agronomic factors have an effect on the yield value of an onion crop, which is determined primarily by number, weight and size of bulbs. Spatial variability of soil properties affects crop yield. Remote sensed hyperspectral vegetation indices (VIs), calculated using crop reflectance at field scale can be used either as an index of the plant biophysical status, or as a tool to estimate crop variability. The aim of the study was to evaluate the relationships among traditional agronomic measurements of two irrigated onion hybrids (Cometa and Red Mech) with spectroradiometric measurements taken at field scale. The two hybrids differed significantly either for agronomic response (yield, yield components and distribution of yield classes) or for their spectral properties. Cometa showed significant higher yield and biomass than Red Mech, as well as significant higher VI values, although no correlations were found among agronomic parameters and spectroradiometric indices. On the contrary, Red Mech showed significant correlation among biomass, yield and bulb weight with VIs. Differences between the two onion hybrids in the spectroradiometric readings and agronomic traits underlined the importance of ground truth data verification when air-born images or satellite data are taken over onion crop field. © 2013 Elsevier B.V.

[EN] Agricultural communities in the semiarid regions of the world are constantly being affected by water scarcity, increased regulations restricting water use, strong competition for irrigation water with the urban sector, and severe drought periods. Conversely, the consumer demand for high-quality and nutritious foods is increasing rapidly. A 2-year field study evaluated growth, yield, and bulb quality in response to precision planting density and deficit irrigation of onion ( Allium cepa L.) in southwest Texas. Seeds of short-day sweet onion cv. Texas Grano 1015Y were planted in the field on 11 Nov. 2007 and 30 Oct. 2008 at two planting densities (PDs), 397,000 (standard) and 484,000 (high) seeds/ha. Three irrigation rates using growth stage-specific crop co- efficients and subsurface drip were imposed after plants were fully established, 100%, 75%, and 50% crop evapotranspiration rates (ETc). Total rainfall plus irrigation received for each irrigation rate were 594, 501, and 413 mm in 2008 and 662, 574, and 486 mm in 2009. In both seasons, there were consistent trends in growth, yield, and quality parameters. Leaf fresh weight was unaffected by PD but was reduced by deficit irrigation at 50% ETc. Although increasing planting density reduced the average bulb size by 12%, it increased the number of marketable bulbs by 21% to 33% and marketable yield by 7% to 14%. In contrast, deficit irrigation showed a trend to reduce both the number of bulbs and bulb size with yield reductions of 8% to 13% at 75% ETc and 19% to 27% at 50% ETc. Neither planting density nor deficit irrigation rate had a significant effect on soluble solids content, pungency, or quercetin contents. These results suggest that growers of short-day onions in semiarid regions could adjust PDs to target high-value bulb sizes. Implementing water-conserving practices (deficit irrigation at 75% ETc rate) would result in a decrease of high-value bulb grades and modest losses in yield but not flavor or nutritional components.