Agronomic performance and genetic parameter estimates of three onion varieties under different planting dates in a semi-arid region of Iraq
1Department of Field Crops, College of Agriculture and Forestry, University of Mosul, Iraq. 2Department of Horticulture and Landscape Design, College of Agriculture and Forestry, University of Mosul, Iraq. 3Department of Pomology, Faculty of Agriculture, Cairo University, Egypt. Corresponding e-mail:shamil@uomosul.edu.iq
DOI: https://doi.org/10.37855/jah.2026.v28i02.65
Full text PDF Iraq is ranked as the fifth-most vulnerable country to climate change. Determining the optimum planting date and the most productive onion variety is essential for maximising production and minimising the adverse effects of climate change. This study evaluated the growth, yield, and genetic parameters of three onion varieties (Long Red, Round Red, and Round White) planted on 20 February, 1 March, and 11 March during the spring season. The latest planting date (11 March) produced the lowest bulb yield. Compared with 11 March, planting on 1 March increased the bulb yields of Round Red and Round White by 95.44% and 258.4%, respectively. For Long Red, planting on 20 February produced the highest bulb yield (11.67 t ha-1), representing an increase of 116.4% over the latest planting date. At their respective optimum planting dates, Long Red yielded 8.96% and 16.7% more than Round Red and Round White, respectively. Genotypic and environmental variance components were estimated for all traits. Broad-sense heritability was high for plant height, bulb length, and bulbing ratio, indicating genetic control and the potential for direct improvement of these traits in subsequent generations. Expected genetic advance as a percentage of the mean was high for bulb length, moderate for plant height, neck diameter, and bulbing ratio, and low for the remaining traits.
