Physiological characteristics of corn intercropped with different arrangements of palisade grass plants

Background: The study of corn and palisade grass physiology may assist in determining the best arrangement of the plants and more efficient management of this intercropped system. Objective: To evaluate the effects of different palisade grass plant arrangements and their control on physiological characteristics and corn yield. Methods: Two trials in randomized complete block design with four replications were conducted in field conditions. In the first, corn was sown with 0.50 m row spacing, whereas the second had 1.00 m row spacing. All the treatments were arranged in the same way in both experiments, in a 2x4 factorial design. The first factor was the nicosulfuron dose applied (0 and 8 g a.i. ha(-1)), and the second, the forage seeding rates (0, 2, 4, and 6 kg of seeds per hectare). Sowing of both species was performed on the same day. Results: The application of nicosulfuron negatively affected stomatal conductance, internal carbon concentration, and increased CO2 consumption and efficiency in water use. The photosynthetic rate was not affected by the herbicide application, however it presented lower values in the 0.50 m spacing. Although the yield was not affected by row spacing, it was higher when nicosulfuron was applied. Conclusions: The increase in palisade grass density caused detrimental changes in the water use efficiency with direct consequences to the crop yield. The physiological response and corn yield depend on the arrangement of plants and the palisade grass management adopted.