PERFORMANCE OF MAIZE IDEOTYPES (Zea mays L.) IN TWO PLANT DENSITIES

Abstract

The objective of this study was to compare the morphological and physiological responses of maize ideotypes (Zea mays L.) at double planting density, as well as to identify efficient ideotypes for future breeding programs. It is postulated that higher grain-yielding ideotypes are also more physiologically efficient. The experimental design was random blocks arranged in a split plot design; the large plots corresponded to population densities, and the small plots to ideotypes, with four repetitions. Morphological and physiological variables, as well as yield components, allowed the identification of genotypes with better agronomic performance and greater physiological efficiency. The ideotype factor (A) had a more significant effect on the measured variables than population density (D) and DxA interaction factors. The increase in D caused an increment in grain yield (p<=0.05) mainly due to the increase in leaf area index, without modifying the photosynthetic rate (p=0.05). The outstanding ideotypes were inbred lines L95 and L145, the Dulce variety, and hybrids LPG133 and HS2, due to their higher values of leaf area index (>3 m² m^–2), levels of photosynthetic radiation interception (>89%), instant photosynthesis rate (>39 mmol CO2 m^–2 s^–1), prolificacy (>1.4 ears per plant), and grain yield (6 to 18 t ha^–1), on average of the two densities.