Meiotic and Morphological Response of Grain Sorghum to Atrazine, 2,4-D, Oil, and their Combinations

Abstract

Grain sorghum (Sorghum vulgare Pers.) was sprayed in 1966 and 1967 with 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine), propylene glycol butyl ether ester of 2,4-dichlorophenoxyacetic acid (2,4-D), alkanolamine salts of 2,4-D, and nonphytotoxic petroleum oil (crop oil) or their combinations when plant heights were 2 to 4, 4 to 6, and 6 to 8 inches for grass weeds, broadleaf weeds, and sorghum, respectively. Pollen mother cells from all herbicide-treated sorghum revealed chromosomal aberrations, mostly aneuploidy and polyploidy, and aberration frequencies increased when herbicides were combined. Added chromosomes were not always of the basic number. Atrazine-treated plots produced highest grain yields, kernel numbers were reflected in grain yield (r = .96), and untreated plants flowered first.