Identification and Inheritance of Metribuzin Tolerance in Wild Soybean

An economically important agronomic trait that has not been evaluated extensively in the wild soybean ( Glycine soja Sieb. & Zucc.) is tolerance to herbicides. Identification and genetic characterization of tolerance to a widely used herbicide, metribuzin [4‐amino‐6‐(l,l‐dimethylethyl)‐3‐(methylthio)‐l,2,4‐triazin‐5(4 H )‐one], in G. soja may help provide greater diversity in the gene pool for this trait. This study was conducted to identify tolerance to metribuzin in the wild soybean and to determine the genetic control of the trait. Crosses were made between metribuzin‐tolerant G. soja selections and metribuzin‐sensitive selections of G. max (L.) Merr. The F 1 , F 2 , and F 3 populations from these crosses were grown hydroponically, and evaluated for reaction to a concentration of 125 µg L −1 metribuzin. The F 1 plants were tolerant, the F 2 population segregated in a 3 tolerant : 1 sensitive ratio, and the F 3 population segregated in 1 tolerant : 2 segregating : 1 sensitive ratio, suggesting a single dominant gene controlling tolerance. The F 2 populations from crosses between metribuzin‐tolerant G. soja accessions and the metribuzin‐tolerant cultivar Tracy‐M were all tolerant. This indicates that tolerance to metribuzin in these two wild soybeam accessions is controlled by alleles at the same locus as the Hm gene in Tracy‐M. Therefore, the metribuzin tolerance in the wild soybean is probably the same as that found in most of the cultivated soybean accessions and in most commercial cultivars. The significance of identifying tolerance to a currently used herbicide in the wild soybean is the suggestion that other useful traits needed in modern agriculture may be found in this primitive gene pool.