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ATRAZINE TOLERANCE OF WARM-SEASON GRASS SEEDLINGS (FLUORESCENCE, DELAYED APPLICATION)
Abstract
Weed control is a necessary component of a grass establishment program. Although atrazine {2-chloro-4-(ethyl amino)-6-(isopropylamino)-s-triazine} can be used with switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardi Vitmann) most warm-season grass seedlings are susceptible to atrazine. A greenhouse screening procedure was used to compare the atrazine tolerance of switchgrass seedlings with indiangrass (Sorghastrum nutans (L.) Nash), sideoats grama (Bouteloua curtipendula (Michx.) Torr.), blue grama (Bouteloua gracilis (H.B.K.) Lag ex Steud), 'Caucasian' bluestem (Bothriochloa caucasica (Trin.) C. E. Hubbard), 'Plains' bluestem (Bothriochloa ischaemum var ischaemum (L.) Keng, little bluestem (Schizachyrium scoparium (Michx.) Nash), and prairie sandreed (Calamovilfa longifolia (Hook) Schribn) seedlings. Indiangrass and sideoats grama seedlings from one cycle of field selection for atrazine tolerance were also compared. Switchgrass, Plains and Caucasian bluestem, and prairie sandreed had the most tolerance to atrazine. Little bluestem and indiangrass (unselected and cycle 1) were intermediate, and sideoats grama (unselected and cycle 1) and blue grama had the least tolerance to atrazine. Indiangrass and sideoats grama were used to evaluate leaf fluorescence as a possible screening technique. Concentrations of 10('-2) or 10('-3) M atrazine for sideoats grama or indiangrass respectively and an incubation period of 30 minutes distinguished atrazine treated leaf sections from control. No difference was detected between established and young indiangrass and between greenhouse and field grown plants. Using a 30 minute incubation and 10('-3) M atrazine 33 lines of young indiangrass plants were screened. Thirteen plants had a change in relative fluorescence of less than 1 which was used as the differentiation criterion. A floating leaf disk test did not differentiate among plants of differing atrazine sensitivities. Delaying the application of atrazine 7, 14 or 21 days after planting permitted indiangrass and sideoats grama to be established in the field. In both field and greenhouse studies atrazine reduced actual emergence of the seed for sideoats grama, switchgrass, and indiangrass.
Subject Area
Agronomy
Recommended Citation
BAHLER, CAROLINE CONDIT, "ATRAZINE TOLERANCE OF WARM-SEASON GRASS SEEDLINGS (FLUORESCENCE, DELAYED APPLICATION)" (1984). ETD collection for University of Nebraska-Lincoln. AAI8428204.
https://digitalcommons.unl.edu/dissertations/AAI8428204