Selected Determinate Soybean Cultivar Yield Responses to Row Spacings and Planting Dates¹

Abstract

Previous studies to determine row spacing (RS)‐planting date (PD) effects on yield of determinate soybeans [Glycine max (L.) Merr.] in the southern USA have been conducted north of 33° Lat, and have produced conflicting results. Current data on the effects of these planting variables are not available for a large portion of the Gulf Coast area that now supports a large and rapidly expanding soybean industry. The objectives OP this experiment were to study: 1) the effects of selected RS and PD on yield of selected cultivars of determinate soybeans; 2) the interaction of RS with PD; and 3) the interaction of cultivars with RS and PD. Five cultivars, ‘Forrest,’ ‘Davis,’ ‘Lee 74,’ ‘Centennial,’ and ‘Bragg’ were planted in RS of 25, 50, and 100‐cm on 6 PD between 15 April and 1 July in 1976, 1977, 1978, and 1979. The field plots were located on a Mhoon silty clay soil (Typic Fluvaquent). Averaged over years, the five cultivars evaluated produced significantly higher yields when grown in 25 and 50‐cm RS compared with the 100‐cm RS. The interaction between cultivar and RS was significant due to variability among cultivars in the yield increase when RS was reduced; 3 q/ha with Davis and Bragg, 4 q/ha with Lee 74, and 6 q/ha with Forrest and Centennial. The size of yield increases resulting from reduced row spacing was relatively consistent across PD. Because lower yields were recorded at all three RS at nonoptimum PD the yield increases, when expressed as a percentage of the yields obtained in 100‐cm rows, were larger at the nonoptimum dates, however. Optimum PD was not affected by RS but differed among cultivars. Forrest and Lee 74 had highest yields when planted on 15 May while the other three cultivars had similar yields at PD from 1 May to 1 June. Results indicated that significantly higher yields are possible with current determinate cultivars when both RS and PD are selected for individual cultivars.

Planting Date, Irrigation, and Row Spacing Effects on Agronomic Traits of Food-grade Soybean

“…The taller, less bushy varieties such as B-3, SS-516, and Hutcheson can take advantage of the NR spacing by reaching canopy sooner, thus maximizing light interception and limiting weed competition. These results were in agreement with Parker et al [28] and Beatty et al [12], who reported that variety, environment, and cultural practices affect yield response of NR spacing.…”

“…Soybeans planted in narrow-row (NR) spacing (i.e., 30 to 40 cm), opposed to traditional wide-row (WR) spacing (i.e., >70 cm), can produce greater yields which are mainly attributed to greater light interception [11]. Greater yields in NR than WR spacing have been achieved when soybean was planted earlier [12][13][14] and later than optimum dates [13,15,16]. Doster [17] determined that 17-, 36-, or 45-cm row spacing out-yielded 76 cm rows by 6 to 18%.…”

Grain amaranth: A promising crop for marginal areas of Kenya

“…This yield response of amaranth to the time of planting agrees with the results reported for planting times for other crops in Kenya, including maize (Allan, 1971), soybeans (Boquet, Koonce, and Walker, 1982), and cotton (Sendouka et al, 1980). Earlier sowings of these crops produced higher yields than later sowings.…”

Uniform Stand and Narrow Rows are Needed for Higher Double-crop Soybean Yield

“…Yield benefits of narrowing row spacing to less than 15 to 20 inches are less clear. Comparing 10‐ versus 20‐inch row spacing in Louisiana, Boquet et al (5) measured a 11 and 5% increase in yield with the 10‐inch rows when soybean were planted on June 15 and July 1, respectively. Averaged over 56 North Carolina locations, 10‐inch row spacing yielded 5% greater than 20‐inch row spacing (7).…”