Environmental Influences on the Selectivity of Diphenamid in Seeded Tomato (Lycopersicon esculentum)

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Abstract
Several environmental and edaphic factors were monitored to determine their association with tolerance of seeded tomatoes (Lycopersicon esculentumMill.) to diphenamid (N,N-dimethyl-2,2-diphenylacetamide). Injury increased with increasing soil pH and reduced temperature within 7 days of seeding in both field and growth chamber tests. The application of soluble fertilizer and diphenamid at planting acted synergistically to increase tomato injury. Prior to emergence of the tomato seedlings,14C-diphenamid uptake was slight but increased with higher temperatures, while growth was inhibited at both low and high temperatures. Uptake and metabolism of14C-diphenamid by plants in the cotyledon stage was not greatly affected by temperature or pH; however, translocation from the root to the shoot was reduced under low temperatures and high pH. These differences in translocation paralleled reported differences between tolerant and susceptible species, and may account for the increased diphenamid injury to tomatoes grown under stress conditions.