Density and population arrangement of off-season corn cultivars: agronomic parameters and leaf burn by frost

Abstract

Off-season corn is the main form of corn crop in Brazil. During the maturation stage of the plants, the availability of heat is reduced, and frosts may occur. The aim of this study was to determine the effect of row spacing reduction and population increase in corn cultivars on agronomic parameters and leaf burn caused by moderate frost to minimize the effects of abiotic stresses on grain yield. We used a randomized block experimental design in a 3 × 4 × 2 factorial scheme: row spacing of 40, 80, and 120 cm; populations of 25,000, 43,750, 62,500, and 81,250 plants·ha-1; and Fort cultivars (semi-erect leaves, and early cycle) and DKB 950 (erect leaves and super-early cycle). Three field trials were conducted in the state of São Paulo, Brazil, from mid-March. The spacing reduction provided antagonistic effects on yield with different response from hybrids in the most of locations. Population density increased plant height, stalk lodging and grain yield; populations ≥ 68,000 plants per hectare provided the best yields. Specific determinations were made in the area where moderate frost occurred; higher leaf area index and less Brix in the stem at 40 cm spacing were obtained, but without any increase in plant dry mass and grain yield. The hybrid with erect leaves was more adapted to the reduced spacing and exhibited less leaf damage by frost. The effect of frost was greater at reduced row spacings; therefore, this factor should be considered when selecting the population arrangement of off-season corn in areas with frequent frost.