A comparison of onion seedling growth under various environmental conditions, with an emphasis on mechanical transplanting

Abstract: A healthy and robust seedling is one of the benchmarks for mechanical transplantation. The investigation aimed to see how different environmental conditions affect the growth of onion seedlings. Onion seedlings (varieties Puna Fursungi and Gavraan) were grown in an open field nursery compared to a protected structure viz., low tunnel and a 50 % shade net. During the nursery’s growth period, environmental conditions such as temperature, humidity, and solar intensity were recorded. At 50 days after sowing, physical and mechanical properties were observed. Higher temperature was measured in a low tunnel structure, followed by shade net and open field. The shade net structure had the highest percentage of seedling survival (76.23 %), followed by the low tunnel (68.77 %) and the open field (58.37 %). Plant height was also greater in the shade net structure, followed by the low tunnel and open field conditions, respectively. This could be attributed to how plants compete for sunlight, water, aeration, and nutrition under different growing conditions. Except for plant height, all physical and mechanical properties were higher in open field conditions. Because of its adequate strength, the healthy seedling obtained from open field conditions was more suitable for mechanical transplanting.