Systemic Seed Treatment Uptake during Imbibition by Corn and Soybean

Abstract

Systemic seed treatment uptake into soybean [Glycine max (L.) Merr.] and corn (Zea mays L.) seeds during imbibition has not been investigated over a broad range of application rates. The objectives of this study were to investigate the uptake capacity of seeds and assess the role of the seed coat on uptake. A fluorescent compound, coumarin 120 (7‐amino‐4‐methylcoumarin), was applied as a model seed treatment in the range of 0.01 to 20.0 mg g−1 seed to study the dose effects on seed uptake of two corn lines and three soybean cultivars. In general, there was a large increase in seed uptake as dosage increased, followed by a saturated state at higher dosages. The uptake by two lines of corn seeds and three cultivars of soybean seeds showed a dose‐dependent process that was described by an exponential model of Y = y0 − Ae−kx (r2 ≥ 0.93), where y0 is the uptake limit, A and k are constants, and x is the applied dose rate. The value of y0 is an indicator of a seed's uptake capacity, and it differed between the two corn lines and the three soybean cultivars. The calculated dose rate at which the uptake achieved 95% of y0 (x95) also varied widely within the corn lines and soybean cultivars examined. A low value of x95 = 0.87 mg g−1 seed was measured for corn line B73. This result indicates that a seed treatment may reach its uptake limit at a low dosage. The seed‐covering layers of corn lines and the black‐seeded soybean cultivar attenuated the uptake of the seed treatment.