Promotion of Sorghum Callus Growth by the s-Triazine Herbicides

Growth-promoting action of simazine and other s-triazine herbicides was detected by the use of sorghum (Sorghum bicolor [L]. Moench) callus tissue and the chlorophyll retention test. Soil application of simazine [2-chloro-4, 6-bis(ethylamino)-s-triazine] at sublethal levels nearly doubled the growth-promoting action of sorghum root exudates. Treated plants yielded up to 26% more total protein than untreated plants. This indicated that the level of callus growth-promoting action in the root exudate of the plant has a positive effect on its final total protein yield and confirms a positive effect of simazine on total protein content in certain instances. The results may provide a new understanding of the mode of action of s-triazines applied at sublethal levels in increasing protein content and certain enzymic activities of treated plants. It is speculated that the growth-promoting action of these herbicides is hormonal in nature and most likely kinetin-like.