Responses of Maize Hybrids to Twin‐Row Spatial Arrangement at Multiple Plant Densities

Abstract

Twin‐row planting systems in maize (Zea mays L.) have been proposed as an alternative spatial arrangement that should theoretically decrease plant‐to‐plant competition, alleviate crop crowding stress and improve yields. Uncertainty remains, however, as to whether twin rows are a feasible option to increase plant densities and improve grain yields. Three hybrids (DKC62‐54, DKC61‐19, and DKC57‐66) were grown from 2009 to 2011 to evaluate the individual and interacting effects of plant density (PD1 = 69,000; PD2 = 81,000; PD3 = 93,000; and PD4 = 105,000 plants [pl] ha−1) and spatial configuration (conventional single 76‐cm row width vs. 20‐cm twin rows spaced 76‐cm between paired‐rows) on dark prairie soil in West‐Central Indiana. The primary research objectives were to determine (i) whether the twin‐row spatial arrangement permits higher optimum plant densities, (ii) whether hybrids vary in their response to a twin‐row arrangement, and (iii) diverse morpho‐physiological trait responses to density and spatial treatments. Twin rows never yielded significantly more than single rows at any plant density or hybrid combination in any year of this study. Furthermore, there was no evidence that grain yield‐optimizing plant densities were any higher with twin vs. single rows in any hybrid. Twin rows slightly increased leaf area index (LAI) at silk emergence stage in 2010 (mean LAI = 4.8) and 2011 (mean LAI = 4.0), but not in 2009 (mean LAI = 4.4). Despite higher plant spacing variation, radiation interception was initially favored by earlier canopy closure with twin‐row planting, but the relative radiation‐interception advantage declined as plant density increased and at a later vegetative stage.