Photosynthetic responses of corn and soybean to foliar application of salicylates.

Salicylic acid (SA) and related phenolic compounds can exert control over stomatal opening and previous work in our laboratory has shown that chronic injection of SA increases the photosynthetic rate of corn. The work reported in this paper investigated the effects of foliar applied SA, acetyl salicylic acid (ASA) and gentisic acid (GTA) on photosynthetic rates and growth of soybean (a C3 plant) and corn (a C4 plant) under greenhouse conditions. In general, the tested compounds enhanced photosynthetic rates in both soybean and corn. Stomatal conductance and transpiration were also increased. These compounds do not alter chlorophyll content. In some cases treatment with these compounds resulted in increased leaf areas and plant dry mass, however, plant height and root length were not affected.