Evaluation of White Onion (Allium cepa L.) Genotypes for Growth, Yield, Quality and Resistance to Thrips and Purple Blotch Disease

Onion (Allium cepa L.), belonging to the family Alliaceae with a chromosome number 2n=16, is an essential vegetable widely cultivated for both domestic consumption and export. This study aimed to evaluate various white onion genotypes for their growth, yield, quality and resistance to pests and diseases. The experiment was conducted at the Main Agricultural Research Station, University of Agricultural Sciences, Dharwad, during the late Kharif season of 2023-24, using twenty-six genotypes arranged in a randomized complete block design. Data were collected on several growth and yield parameters, which were then analyzed. Significant variation was observed among genotypes for growth traits such as plant height, leaf length and neck diameter. The genotype 'Safed Ghavriyu' exhibited the highest plant height and number of leaves per plant, while 'Bhima Shubra' and 'Milky White' showed superior leaf length and neck diameter, respectively. Yield-related traits also varied significantly, with 'Bhima Shweta' recording the highest dry matter content and 'Safed Ghavriyu' demonstrating the highest fresh and dry weight per plant, single bulb weight and total yield per hectare. In terms of pest and disease resistance, notable differences were observed, with 'Safed Ghavriyu' showing the lowest incidence of thrips and purple blotch disease. Additionally, 'PWO-2' had the highest total soluble solids (TSS) content, while 'W-210' had the highest total sugar content. 'Milky White' exhibited the highest pyruvic acid content, contributing to its pungency. These findings underscore the significance of genetic variability and environmental influences in white onion growth and yield. The results offer valuable insights for the development of high-yielding, disease-resistant white onion varieties suited to various agro-climatic conditions in India.