Bas 9052 Effects on Leaf Photosynthesis and Growth

BAS 9052 {2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexene-1-one} and difenopenten {4-[4-[4-(trifluoromethyl)phenoxy]phenoxy]-2-pentenoic acid} concentrations less than 1% (w/w) did not normally inhibit apparent photosynthesis (AP) of corn (Zea maysL. ‘Mo 17 × B73′) leaves for at least 24 h. However, leaf growth was completely inhibited by BAS 9052 within 24 h. Leaf AP was initially more inhibited in soybean (Glycine maxL. ‘Corsoy’) than in corn by each herbicide, but within 48 h soybean AP was usually recovering and plants grew normally. Because inhibition of corn leaf growth preceded that of AP, leaf photosynthesis could not be a primary mode of action for BAS 9052.