Timing of herbicide application during reproductive stages affects seed quality and storability in Enlist® soybean crops

Herbicide applications during field production may affect crop performance even in genetically tolerant cultivars. Among the potential effects, impacts on seed physiological quality particularly under seed production systems-remain poorly understood. The objective of this study was evaluate the effects of post-emergence herbicide applications at different reproductive stages on the physiological quality and storability of Enlist® soybean seeds, tolerant to glyphosate, 2,4-D and ammonium glufosinate. A field trial was conducted using a randomized complete block design with three replications in a 3 × 5 + 1 factorial scheme: three herbicides (glyphosate, 2,4-D and ammonium glufosinate) applied at five reproductive stages (R2, R4, R5, R6 and R7), plus an untreated control. Seed quality was evaluated using germination, accelerated aging and electrical conductivity tests, conducted both before and after 6 months of storage. Applications of these herbicides in the early reproductive (R2 and R4) resulted in less deterioration of seed physiological quality, whereas later applications (R5 and R7) were associated with significant quality deterioration deterioration, even in tolerant cultivars. These findings underscore the critical importance of proper herbicide timing to safeguard seed vigor and enhance storability in herbicide-tolerant soybean systems.

Index terms:
herbicide-tolerant; phytotoxicity; seed production; vigor; weed management