SELECTIVITY OF BENTAZON AND NICOSULFURON IN Crotalaria spectabilis INTERCROPPED WITH MAIZE CULTURE

ABSTRACT Corn intercropped with showy crotalaria allows better use of the agricultural year, having in the same period, economic return from grain yield and the benefits of the legume. The objective was to study the selectivity of the herbicides bentazon and nicosulfuron to C. spectabilis, the weed control and the corn development intercropping system. Two experiments were conducted in the field, one in late-season and the other one in regular growing season. The experimental design was the randomized block, with fourteen treatments and four replicates. Eight treatments with herbicides were studied: bentazon (720 e 960 g a.i. ha-1), nicosulfuron (16 e 48 g a.i. ha-1) and bentazon + nicosulfuron (720 + 16; 720 + 48; 960 + 16; 960 + 48 g a.i. ha-1). Moreover, six controls were maintained: sole corn and sole showy crotalaria (with and without weeds), corn and sunn hemp intercropped (with and without weeds). The herbicide bentazon isolated, in both dosages tested, was selective to C. spectabilis. Nicosulfuron in 48 g a.i. ha-1, isolated or in mixture with bentazon, promoved the best weed control. Corn affected the recoverability of showy crotalaria plants treated with herbicides. In intercrop of corn and C. spectabilis, both late and regular season had good results in corn yield, legume mass accumulation without the necessity of herbicides pulverization.

摘要：玉米与美丽猪屎豆（Crotalaria spectabilis，简称C. spectabilis）间作可优化农作季的资源利用模式，在同一生产周期内既可通过玉米籽粒产量获取经济回报，又可获得豆科作物带来的多重益处。本研究旨在探讨除草剂苯达松（bentazon）与烟嘧磺隆（nicosulfuron）对C. spectabilis的选择性、杂草防控效果，以及该间作体系下玉米的生长表现。本研究共设置2个田间试验，分别于晚季和常规生育期开展，试验采用随机区组设计，包含14个处理与4次重复。其中除草剂处理共8组：单剂苯达松施用剂量分别为720、960 g a.i.·ha⁻¹（a.i.为有效成分active ingredient），单剂烟嘧磺隆为16、48 g a.i.·ha⁻¹，以及苯达松与烟嘧磺隆复配处理（剂量组合为720+16、720+48、960+16、960+48 g a.i.·ha⁻¹）；此外设置6组对照处理：单作玉米、单作美丽猪屎豆（分别设置有杂草、无杂草两种情况），以及玉米与太阳麻间作（分别设置有杂草、无杂草两种情况）。试验结果显示，两种供试剂量下的单剂苯达松均对C. spectabilis具有良好选择性。单剂48 g a.i.·ha⁻¹的烟嘧磺隆，及其与苯达松复配的处理，均可实现最优的杂草防控效果。玉米间作会影响经除草剂处理后的美丽猪屎豆植株的恢复能力。在玉米与C. spectabilis间作体系中，无论是晚季还是常规生育期，无需喷施除草剂即可获得可观的玉米籽粒产量与豆科作物生物量累积。