Original Articles

Tolerance of South African maize (Zea mays L.) cultivars to atrazine

Published in: South African Journal of Plant and Soil
Volume 2, issue 2, 1985 , pages: 101–106
DOI: 10.1080/02571862.1985.10634146
Author(s): M.R. Le Court De BillotSummer Grain Centre,, P.C. NelDepartment of Plant Production,

Abstract

Sixty-seven maize cultivars were evaluated for tolerance to atrazine (4 p.p.m. v/v) in nutrient solution. Shoot dry masses (SDM) of only two cultivars, SAB149 and NPP x K64r, were reduced more than 40% and another 14 were reduced by more than 30%. CG4801, PNR432, SSM2043 and A280 were the most tolerant cultivars and showed no reduction in SDM with atrazine. Cultivars, reportedly injured in commercial maize production were not less tolerant than the other cultivars evaluated. The absence of phytotoxicity symptoms did not indicate tolerance. Cultivars TX14, A206 and SABI404 displayed very slight phytotoxic symptoms but had large reductions in SDM. In sand culture, the relative responses of 10 cultivars to atrazine (8 p.p.m. v/v) were compared under different temperature and nutrient conditions. HL1 and A477W were relatively more tolerant under the low temperature regime (20/10 °C) than under the high temperature regime (30/20 °C). The relative tolerances of CG4801, SSM2039 and SSM2045 remained the same at both temperature regimes. Relative tolerances of cultivars changed under good and poor nutrition. Only CG4801 was reasonably tolerant under both nutrient regimes. The relative tolerances of cultivars were not significantly different when atrazine was applied pre- or post-emergence. The results of this study do not explain the severe injury periodically reported from the field.

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