Thiamine, cobalt and molybdenum applied as seed treatment infl uence the development of soybean crops

Abstract

Cobalt (Co) and molybdenum (Mo) are essential elements with a fundamental role in biological nitrogen fi xation in
legumes. Vitamins such as thiamine, despite being required in small quantities, infl uence plant growth. This study aimed to assess the
effi ciency of diff erent 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.