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

The use of narrow plant spacing in corn (Zea mays) has been suggested as a technological alternative to obtain grain yield increases, due to a better use of resources. The regular pattern could diminish intraspecific competition while favoring interspecific competition with weeds. The objective of this study was to analyze the effect of corn row spacing on weed aboveground biomass and corn grain yield. Field experiments were conducted during 2002/2003 and 2003/2004 growing seasons. Three corn hybrids with two-row width (0.70 and 0.35 m) were tested. A greater photosynthetic photon flux density (PPFD) interception with a lower weed aboveground dry matter in narrow row arrangement was obtained. Corn grain yield was greater in the narrow row arrangement than in the wide row spacing. This increase in grain yield was related to a better resource use that allows for a reduced interspecific competition. The use of reduced spatial arrangement appeared to be an interesting alternative to increase both the grain yield potential and corn suppressive ability against weeds in corn dryland production systems.

HG 186.15-186.25 Thin Section

Coarse grained sample with multiple fine grained domains. Clasts range from small to medium and sub-angular to sub-rounded. Mainly contains grain crushing (with grains crushed into one another) and short distance lineations. A few rotation structures are seen and fine grained sand domains can also be seen.

HG 206.85-206.95 Thin Section

Coarse grained sample with sub-angular to sub-rounded clasts. Clasts range from small to medium sized. Major grain crushing seen throughout the sample. Grain stacking and lineations are also present. A dark organic rich domain can be seen within the sample.

HG 215.65-215.75 Thin Section

Brown to dark brown sediment with small to medium sized clasts ranging from sub-angular to sub-rounded. This sample contains a coarse grained domain and a fine grained domain. Clear boundaries can be seen. Grain stacking can be seen in the coarse domain, while lineations are the dominant microstructure in the fine grained domain. Minor grain crushing can also be seen. Some of the coarser domain is rich in clay and organics.

HG 225.15-225.25 Thin Section

Dark brown sediment with sub-angular to sub-rounded grains, that range from small to medium in size. Lineations with fractured grains are abundant, and grain crushing can also be seen. Minor rotation can also be seen.

HG 230.75-230.85 Thin Section

Coarse grained sediment with fine grained domains, clay material, rotation structures and lineations. Clasts range from sub-angular to sub-rounded. Mainly brown sediment with darker patches of brown throughout. Major amounts of grain crushing can be seen in the coarse grained material.

HG 244.40-244.55-B Thin Section

Coarse grained sample with sub-angular to sub-rounded clasts ranging from small-large in size. Rotation structures, grain crushing and lineations were seen throughout the sample.

HG 268.40-268.55 Thin Section

This is a coarse grained sample with some very fine grained domains throughout the sample. The clast shape and size range from small to large, as well as angular to sub-rounded. Grain crushing is the most prevalent in this sample. It also contains some rotation structures and minor necking structures. Lineations and grain stacking can also be seen.

HG 290.45-290.55 Thin Section

Two main domains can be seen in this sample. One is coarse grained with clasts ranging from small to medium in size. The other is very fine grained, and a very dark brown, potentially influenced by organic material. Grain crushing and lineations can be seen in the coarser domain.

HG 291.40-291.55 Thin Section

Coarse grained sample with inclusions of finer grained sediment. Clasts are small to large in size and angular to sub-rounded in shape. Grain crushing is abundant in this sample, and lineations and minor grain stacks can also be seen.

HG 305.15-305.30

Dark grey sediment with medium to small sized grains. The grains are sub-angular in shape. Rotation structures and grain crushing are the most common microstructures seen. Dark organic material and lineations can also be seen.

HG 320.30-320.40

Dark brown sediment with small to large sized clasts. The clasts are sub-angular to sub-rounded in shape. Lineations are the most abundant. Minor amounts of rotation structures and comet structures can also be seen. Grain crushing is also present throughout the sample.

HG 359.55-359.70

Dark brown sediment with mainly small clasts. The clasts range from sub-angular to sub-rounded. Lineations are abundant throughout the sample. Comet structures are also present throughout the sample. Minor amounts of grain crushing and stacking can also be seen.

HG 367.80-367.90

Dark grey sediment with clasts that range from small to medium. The clasts are mainly sub-rounded. Lineations are abundant with minor amounts of rotation structures and comet structures. Grain crushing can also be seen throughout the sample.

HG 370.55-370.70 a

Light brown sediment with clasts ranging from small to large. The clasts range from angular to sub-rounded. Rotation structures are common, along with grain crushing.