Moderate Boron Concentration Beneficial for Flue-Cured Tobacco (Nicotiana tabacum L.) Seedlings Growth and Development

Boron (B) deficiency is a common phenomenon in most tobacco-planting areas Yunnan, China. In 2020 and 2022, hydroponic experiments that contained B concentration gradient of 0.000, 0.125, 0.250, 0.750, 5.000, 10.000, 20.000, 40.000 mmol L−1 were conducted to investigate tobacco cultivar K326′s agronomic traits, photosynthetic performance, antioxidant enzymes, boron nicotine concentration. As increased, indices including leaves biomass net rate (Pn) generally increased first then decreased, which was contrast superoxide dismutase (SOD), peroxidase (POD), catalase (CAT). With increasing concentration, content seedlings significantly by 24.00~96.44%, while decreased 21.60~82.03%. The highest performance obtained within 0.75 5.00 treatments. results the sandy soil pot verification experiment similar obtained. beneficial mechanism moderate on maintain cell structure integrity, enhance capability, promote root growth. Consequently, optimum for 0.75~5.00 L−1, applying 0.25~0.50 kg hm−1 under available insufficiency could meet needs growth flue-cured tobacco.