The objectives of this study were to: (i) evaluate the effect of different spatial arrangements on morpho-physiological characteristics and (ii) determine the optimal spatial arrangement to maximize grain yield of the maize hybrid BRS-3046 grown in the Mid-North region of Brazil.We tested two row spacings (0.5 and 1 m) and five plant densities (2, 4, 6, 8, 10 plants m-2), which corresponded to 10 different plant spatial arrangements.Different morphophysiological variables, gas exchange rates and grain yield were measured.The increased planting density led to a linear increase in LAI, regardless of row spacing, while the net CO2 assimilation rate increased until the density of 4 and 6 plants m-2, under a row spacing of 0.5 and 1.0 m, respectively.On the other hand, we found a linear reduction in the stomatal conductance with increasing planting density.The intercellular CO2 concentration and the transpiration rate were higher in the widest row spacing.The instantaneous efficiency of carboxylation, in turn, showed a slight increase up to the density of six plants m-2, then falling, regardless of row spacing.Increasing plant density resulted in a linear increase in plant height and ear insertion height, regardless of row spacing.However, it had an opposite effect on stem diameter.Grain yield, in turn, increased up to 7.3 plants m-2 at a row spacing of 0.5 m and 8 plants m-2 at a row spacing of 1.0 m.This spatial arrangement was considered as ideal for achieving maximum yield.
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