Kouame, K.B.-J.; Savin, M.C.; Rangani, G.; Butts, T.R.; Bertucci, M.B.; Roma-Burgos, N. Transpiration Responses of Herbicide-Resistant and -Susceptible Palmer Amaranth (Amaranthus palmeri (S.) Wats.) to Progressively Drying Soil. Agriculture2022, 12, 335.
Kouame, K.B.-J.; Savin, M.C.; Rangani, G.; Butts, T.R.; Bertucci, M.B.; Roma-Burgos, N. Transpiration Responses of Herbicide-Resistant and -Susceptible Palmer Amaranth (Amaranthus palmeri (S.) Wats.) to Progressively Drying Soil. Agriculture 2022, 12, 335.
Kouame, K.B.-J.; Savin, M.C.; Rangani, G.; Butts, T.R.; Bertucci, M.B.; Roma-Burgos, N. Transpiration Responses of Herbicide-Resistant and -Susceptible Palmer Amaranth (Amaranthus palmeri (S.) Wats.) to Progressively Drying Soil. Agriculture2022, 12, 335.
Kouame, K.B.-J.; Savin, M.C.; Rangani, G.; Butts, T.R.; Bertucci, M.B.; Roma-Burgos, N. Transpiration Responses of Herbicide-Resistant and -Susceptible Palmer Amaranth (Amaranthus palmeri (S.) Wats.) to Progressively Drying Soil. Agriculture 2022, 12, 335.
Abstract
Drought events are predicted to become more prevalent in the future. Evaluating the performance of herbicide-resistant and susceptible weed ecotypes to progressive drought can provide insights into whether resistance trait(s) increased or reduced the fitness of a resistant population. Two experiments were conducted in the greenhouse between January and May 2021 to evaluate drought tolerance differences between Palmer amaranth accessions resistant to S-metolachlor or glyphosate and their susceptible counterparts. The accessions used were: S-metolachlor-resistant (17TUN-A), a susceptible standard (09CRW-A), and glyphosate-resistant (22 to 165 EPSPS copies) and glyphosate-susceptible (3 to 10 EPSPS copies) plants from accession 16CRW-D. Daily transpiration of each plant was measured. The daily transpiration rate was converted to normalized transpiration ratio (NTR) using a double-normalization procedure. The daily soil water content was expressed as a fraction of transpirable soil water (FTSW). The threshold FTSW (FTSWcr), after which NTR decreases linearly, was estimated using a two-segment linear regression analysis. The data showed differences between S-metolachlor- resistant and -susceptible accessions (P ≤ 0.05). The FTSW remaining in the soil at the breakpoint for the S-metolachlor-susceptible accession (09CRW-A) was 0.17±0.007. The FTSW remaining in the soil at the breakpoint for the S-metolachlor-resistant accession (17TUN-A) was 0.23±0.004. Although the mechanism endowing resistance to S-metolachlor might have contributed to increased drought tolerance, follow-up experiments are needed to verify this finding. Increased EPSPS copy number did not improve drought tolerance of Palmer amaranth.
Biology and Life Sciences, Agricultural Science and Agronomy
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