Weed Biomass Production Response to Plant Spacing and Corn (Zea mays) Hybrids Differing in Canopy Architecture¹

Abstract

Field experiments were conducted in 1996, 1997, and 1998 at Ste. Anne de Bellevue, Quebec, Canada, and in 1996 at Ottawa, Ontario, Canada, to quantify the impact of corn hybrids, differing in canopy architecture and plant spacing (plant population density and row spacing), on biomass production by transplanted and naturally occurring weeds. The treatments consisted of a factorial combination of corn type (leafy reduced stature [LRS], late-maturing big leaf [LMBL], a conventional Pioneer 3979 [P3979], and, as a control, a corn-free condition [weed monoculture]), two weed levels (low density [transplanted weeds: common lambsquarters and redroot pigweed] and high density [weedy: plots with naturally occurring weeds]), two corn population densities (normal and high), and row spacings (38 and 76 cm). At all site-years under both weed levels, the decrease in biomass production by both transplanted and naturally occurring weeds was greater due to the narrow row spacing than due to the high plant population density. The combination of narrower rows and higher population densities increased corn canopy light interception by 3 to 5%. Biomass produced by both transplanted and naturally occurring weeds was five to eight times less under the corn canopy than in the weed monoculture treatment. Generally, weed biomass production was reduced more by early-maturing hybrids (LRS and P3979) than by LMBL. Thus, hybrid selection and plant spacing could be used as important components of integrated pest management (weed control) for sustainable agriculture.

Effect of plant row spacing and herbicide use on weed aboveground biomass and corn grain yield

“…These results agree with Forcella et al (1992), Teasdale (1995), Murphy et al (1996) and Begna et al (2001). However, the interception obtained in the narrow row arrangement was higher than that reported by Murphy et al (1996) and Begna et al (2001); Bullock et al (1988); Teasdale (1995); Barbieri et al (2000) and Andrade et al (2002) reported that the greater PAR interception in narrow rows at flowering was obtained when corn growth at early stages was most limited. Barbieri et al (2000) showed that relative grain yield responses to narrow rows decreased as crop PAR intercepted at flowering with increased wide row arrangement.…”

“…Murphy et al (1996) showed that corn planted at 50-cm rows intercepted about 8% more photosynthetically active radiation (PAR) at silking than crop at conventional rows, reducing biomass of late-emerging weeds. Similar results were obtained by Begna et al (2001) in corn planted in 38-cm rows. Weed control in corn planted at 5.1 pl m -2 in 76 cm rows and at 9.8 pl m -2 in 38 cm rows where herbicide was either applied at full or one quart of the rates, the suppressive ability of weed at narrow row and high population was related to the increasing amount of light intercepted by the crop (Teasdale, 1995).…”

“…The Effect of plant row spacing and herbicide use on weed ... increase in corn grain yield in narrow rows has been suggested as the decreased result of intraplant competition for resources (Olson & Sander, 1988) and reduction in weed competition (Forcella et al, 1992;Teasdale, 1995;Murphy et al, 1996;Begna et al, 2001). …”

Influence of corn sowing density and gliricidia intercropping on weed control

“…Increased planting densities result in increased green ear yield (Silva et al, 2007) and corn grain yield (Widd icombe & Thelen, 2002). On the other hand, weed management is facilitated as row spacing values are reduced in corn seeding, with the goal of achieving agricultural sustainability (Balbinot Junior & Fleck, 2004;Begna et al, 2001). …”

Manejo químico de plantas daninhas na cultura do milho em função de características morfofisiológicas e redução de espaçamento da cultura

“…A interceptação de radiação pela cultura do milho pode ser aumentada pelo uso de espaçamentos mais estreitos entre linhas e densidades mais elevadas (Begna et al, 2001). Isso resulta em redução da disponibilidade de radiação solar para a porção inferior do dossel.…”