Sicklepod (Senna obtusifolia) Response to Shading, Soybean (Glycine max) Row Spacing, and Population in Three Management Systems¹

Abstract

Studies were conducted in 1997 and 1998 at the Northeast Mississippi Research and Extension Center to investigate the effects of row spacing (76, 38, and 19 cm), soybean population, and three weed management systems on sicklepod growth and seed production. The cultivars ‘Hartz 5088RR’ (glyphosate-tolerant) and ‘Hutcheson’ (a conventional cultivar) were used in two separate studies. The average soybean populations over cultivars and year were 245,000 (low), 481,000 (medium), and 676,000 (high) plants/ha. The three weed management systems were: no (untreated), one, and two herbicide applications. In the glyphosate-tolerant system, one or two postemergence (POST) applications of glyphosate were used, whereas in the conventional system, flumetsulam plus metolachlor preemergence was used alone (single) or followed by chlorimuron POST (sequential). Reducing soybean row spacing from 76 cm, coupled with increased soybean population, reduced sicklepod population up to 80%. Except for Hutcheson in 1998, reducing row spacing and increasing soybean population also reduced sicklepod seed production in both the untreated and the single applications. A single herbicide application reduced sicklepod population up to 68% from untreated plots. However, except for Hartz 5088RR in 1998, the sequential application did not further reduce sicklepod population. In a shading study, partial shading increased sicklepod height but reduced dry weight. However, as shading level increased from 65 to 80 and 95%, height was also reduced.

Evaluation of the impact of surface residue cover on single and dual crop coefficient for estimating soybean actual evapotranspiration

“…The fraction of soil surface shaded by soybean canopy is influenced by crop row spacing and seeding rates (Renner and Mickelson, 1997;Nice et al, 2001), the angle of solar radiation inclination, crop variety, and environmental factors that affect plant growth. Todd et al (1991) showed that canopy shading played a more important role in reducing E s than straw mulch under dryland conditions.…”

Influence of Soybean (Glycine max) Population and Herbicide Program on Palmer Amaranth (Amaranthus palmeri) Control, Soybean Yield, and Economic Return

“…Reducing input costs in soybean by using lower seeding rates, especially when transgenic cultivars are planted which include substantial technology fees, is a reasonable approach to soybean production. While research has demonstrated that higher plant populations and narrow rows suppress weeds more effectively than lower plant populations or production in wider row spacings [14][15][16][17], Norsworthy and Oliver [18] reported that applying a second application of glyphosate was more economical than increasing the seeding rate. Kratochvil et al [19] reported that a population 80% of a traditional seeding rate (345,000 plants ha −1 versus 432,500 seed ha −1 ) increased profit from $14 to $28 ha −1 .…”

Medida de regularidade do espaçamento de plantas de milho em diferentes sistemas de manejo

“…Embora seja consenso que a variabilidade na distribuição longitudinal de plantas na linha de semeadura do milho pode influenciar as competições intraespecíficas (Brachtvogel et al, 2012) e interespecíficas (Nice et al, 2001) pouco se tem estudado sobre os métodos de avaliar esta regularidade e os fatores que a influenciam.…”