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Genetic variation in herbicide resistance in scentless mayweed ( Tripleurospermum inodorum (L.) Schultz Bip.) II. Intraspeciffc variation in response to ioxynil and MCPA, and the role of spray retention characteristics
Author(s) -
ELLIS M.,
KAY Q. O. N.
Publication year - 1975
Publication title -
weed research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 74
eISSN - 1365-3180
pISSN - 0043-1737
DOI - 10.1111/j.1365-3180.1975.tb01324.x
Subject(s) - mcpa , herbicide resistance , biology , population , resistance (ecology) , negative correlation , positive correlation , veterinary medicine , horticulture , botany , agronomy , weed , pesticide , demography , medicine , sociology
Summary Forty‐eight populations of Tripleurospermum inodorum (L.), Schultz Bip. (scentless mayweed) were collected from southern Britain and northern France between 1970 and 1972 and screened simultaneously for resistance to the herbicides ioxynil and MCPA. The mean fresh weights per plant in different population samples sprayed with ioxynil at 28 mg/m 2 a.i. ranged from 2·2 to 39·5% of those of the corresponding controls, with a mean for all populations of 20·0 ± 1·09%, and the mean fresh weights per plant in different population samples sprayed with MCPA at 175 mg/m 2 a.e. ranged from 10·3 to 60·1% of those of the corresponding controls, with a mean for all populations of 43·0 ± 1·60%. Resistance to ioxynil differed significantly between populations from different geographic areas but showed no correlation with spraying history. Resistance to MCPA also differed significantly between populations from different geographic areas, and showed a strong positive correlation with ioxynil resistance, but MCPA resistance was significantly greater in populations with a history of heavy spraying than in other populations. Spray retention and other physical characteristics were measured in six populations, but showed no correlation with herbicide resistance. It is suggested that most of the differences in herbicide resistance between populations of T. inodorum are side effects of genotypic differentiation in physiological characters not directly related to herbicide resistance, but that there has been some direct selection for resistance to MCPA.