Thiamine, cobalt and molybdenum applied as seed treatment influence the development of soybean crops¹

ABSTRACT

Cobalt (Co) and molybdenum (Mo) are essential elements with a fundamental role in biological nitrogen fixation in legumes. Vitamins such as thiamine, despite being required in small quantities, influence plant growth. This study aimed to assess the efficiency of different doses of thiamine applied as seed treatment, combined or not with Co and Mo, in enhancing the development of soybean crops. The experiment was conducted in a greenhouse according to a randomized block design with a 6 × 2 factorial arrangement, comprising six thiamine doses (0, 10, 25, 50, 100, and 200 mg kg^-1) in the presence or absence of Co and Mo at the recommended rate of 100 mL ha^-1. At 40 days after sowing, plants were analyzed for root length, root dry weight, shoot length, shoot dry weight, nodule number, and nodule dry weight. Principal component analysis showed that combined application of Co and Mo with thiamine was negatively associated with all variables and that the thiamine doses most positively associated with the analyzed variables were 50 and 200 mg kg^-1. In treatments containing thiamine alone, there was a linear direct relationship between thiamine dose and nodule dry weight. Root and shoot lengths and dry weights were highest in plants treated with thiamine only at a dose of 122 mg kg^-1. Application of Co and Mo combined with thiamine via seed treatment does not promote the development of soybean crops. Thiamine application is a promising treatment to increase shoot length, root dry weight, and nodule dry weight in soybean.

Keywords:
Micronutrient; Nodulation; Seed coating; Vitamin B1