Competitive interaction and economic injury level of Urochloa plantaginea in corn hybrids

ABSTRACT Identifying the competitive ability of corn hybrids and the economic injury level (EIL) caused by Urochloa plantaginea is important for the adoption of integrated management of this weed. This work aims to evaluate the interference and EIL of U. plantaginea infesting corn hybrids. Treatments included the corn hybrids Syngenta Status VIP3, Syngenta SX8394 VIP3, Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021, as well as 12 densities of U. plantaginea for each hybrid. We used a rectangular hyperbolic model to describe the relationship between corn grain productivity loss and the explanatory variables — plant density (PD), dry mass (DM) of the aerial parts, ground cover (GC), and leaf area (LA). EIL was determined using grain productivity, control cost, corn price, and herbicide efficacy. The rectangular hyperbolic model provides a satisfactory estimate of grain productivity loss regarding the interference of U. plantaginea in corn culture. The hybrids Pioneer 30F53 YH and Pioneer P1630H presented better competitiveness and higher EIL. Sowing the hybrids Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021 increased EIL, justifying the adoption of control measures for U. plantaginea at higher densities.

摘要：明确玉米杂交种的竞争能力以及由铺地黍（Urochloa plantaginea）引发的经济损害水平（economic injury level, EIL），对该杂草的综合防控措施应用具有重要意义。本研究旨在评估铺地黍（Urochloa plantaginea）侵染不同玉米杂交种所产生的干扰作用及其经济损害水平。试验处理包含5个玉米杂交种：Syngenta Status VIP3、Syngenta SX8394 VIP3、Pioneer P1630H、Pioneer 30F53 YH以及Dow 135021，同时为每个杂交种设置12个铺地黍种群密度。本研究采用矩形双曲模型，描述玉米籽粒产量损失与各解释变量——种植密度（plant density, PD）、地上部干物质重量（dry mass, DM）、地面覆盖度（ground cover, GC）及叶面积（leaf area, LA）之间的关系。经济损害水平（EIL）通过籽粒产量、防治成本、玉米售价及除草剂防效进行测算。结果表明，矩形双曲模型可对铺地黍干扰玉米栽培导致的籽粒产量损失提供令人满意的估算结果。Pioneer 30F53 YH与Pioneer P1630H这两个杂交种表现出更优的竞争能力，且具备更高的经济损害水平。播种Pioneer P1630H、Pioneer 30F53 YH及Dow 135021这三个杂交种可提升经济损害水平，这证明在更高种群密度下针对铺地黍采取防治措施是合理的。