Effect of Different Herbicides and Salicylic Acid Treatment on the Photosynthetic Efficiency of Corn Cultivars Using Chlorophyll a Fluorescence Transient Curve Analysis

Photosynthesis is an essential part of the plant function and metabolism and a number of herbicides inhibit certain photosynthetic activities. The aim of this study was to evaluate the effect of some herbicides including Topik, Titos, Equip, Mister, Lumax, Bromicide and Oltima on the photosynthetic efficiency of three corn cultivars (CC-260, 400, 704) in response to salicylic acid (SA) treatment via chlorophyll a fluorescence (ChlF) transient curve (OJIP) analysis. Result showed that Topik, Titos, Equip, Mister and Oltima herbicides had no effect on the ChlF. In contrast, Bromicide and Lumax changed the shape of the ChlF curve as I phase of the OJIP curve was lost and the fluorescence level in the J step was close to I stape. However, application of SA improved the shape of the OJIP curve similar to normal samples. SA application under Bromicide and Lumax treatments un-blocked the electron transfer between QA and QB of PSII. Our study clearly indicated that the effect of SA on the I-P part of the ChlF curve was more than other parts. Thus, the effect of SA on the PSI activity was more than that of PSII under these herbicide treatments.