Twin Rows Planting System Does Not Alter Rue.

Twin-row planting system (TRPS) could result in a better solar radiation distribution in maize canopy, increase radiation use efficiency (RUE) even though under lower efficiency of intercepted radiation.In this work we evaluated maize growing in TRPS under potential conditions of fertility and irrigation at Paraná research Station of INTA (31º 50' SL, 60º 31 WL)   Argentina. The primary objective of this research was to determine whether TRPS increase grain yield differences and analyze growth.The experiment was performed with one hybrid (DK692 T3P) with two Twin Rows (with a 20 cm spacing between twins rows) with 54 and 72 cm amid paired rows and a conventional single 54-cm row. Three plant densities were combined with the spatial arrangements: 6, 8 and 10 plants/m².None of the Twin Rows arrangements exceeded the single 54-cm row in grain yield (10.3 Mg ha^-1). Increases in plant density resulted in greater grain yield, mainly in the extreme densities (9.3 y 10.4 Mg/ha). The performance of different planting systems behaved similarly to changes in plant density.The low variation on grain yield observed between the tested planting systems was associated with minimal differences on growing related variables such as RUE, leaf area index (LAI), crop growth rate (CGR) and intercepted radiation (IR). Greater grain yields in parallel with higher plant densities were associated to increases in el LAI (63%), RUE (27%) and CGR (48%). Reductions in kernel number per plant were overcompensated with the number of plants per square meter. Grain weight was similar for the three densities. Results of this study indicated that the use of Twin Rows as planting system does not improve variables like as interception efficiency and radiation use efficiency, and thus would not improve grain yield.