Soybean Sowing Date: The Vegetative, Reproductive, and Agronomic Impacts

Abstract

The sensitivity of soybean [Glycine max (L.) Merr.] main stem node accrual to ambient temperature has been documented in greenhouse‐grown plants but not with field‐grown plants in the north‐central United States. Biweekly V‐node and R‐stage, stem node number, internode length, and other traits were quantified in an irrigated split‐plot, four‐replicate, randomized complete block experiment conducted in Lincoln, NE, in 2003–2004. Main plots were early‐, mid‐, late‐May, and mid‐June sowing dates. Subplots were 14 cultivars of maturity groups 3.0 to 3.9. Node appearance was surprisingly linear from V1 to R5, despite the large increase in daily temperature from early May (10–15°C) to July (20–25°C). The 2003 and 2004 May planting date regressions exhibited near‐identical slopes of 0.27 node d−1 (i.e., one node every 3.7 d). Cold‐induced delays in germination and emergence did delay the V1 date (relative to planting date), so the primary effect of temperature was the V1 start date of linearity in node appearance. With one exception, earlier sowings led to more nodes (earlier V1 start dates) but also resulted in shorter internodes at nodes 3 to 9 (cooler coincident temperatures), thereby generating a curved response of plant height to delayed plantings. Delaying planting after 1 May led to significant linear seed yield declines of 17 kg ha−1 d−1 in 2003 and 43 kg ha−1 d−1 in 2004, denoting the importance of early planting for capturing the yield potential available in soybean production, when moisture supply is not limiting.

Drivers of spatial and temporal variation in soybean yield and irrigation requirements in the western US Corn Belt

“…Depending upon the region and degree of delay in sowing, lower solar radiation and temperature during the reproductive phases in late-versus early sown crops can amplify the yield penalty. The yield penalty associated with one day of delay in sowing after May 1st in the present study ranged from 10 to 41 kg ha −1 d −1 , which did not differ much from Bastidas et al (2008) (Table 1). Finally, aside from the direct effect of sowing date on yield level, intra-annual yield variability also increased with later sowing date (r = 0.30, P = 0.01).…”

“…Sowing date is the management factor with the greatest impact on soybean yields in the US Corn Belt (Bastidas et al, 2008;De Bruin and Pedersen, 2008;Villamil et al, 2012;Rowntree et al, 2013). Linear regression analysis was used in the present study to assess the impact of sowing date on inter-annual yield variation in irrigated and rainfed soybean.…”

“…Yield decline associated with delayed sowing is associated with (i) shorter season length (V1-R7) leading to overall reduction in growth, (ii) lower number of reproductive nodes and grain number due to a shorter period from emergence to R5, and (iii) shorter seed filling period (Bastidas et al, 2008 and references cited therein). Depending upon the region and degree of delay in sowing, lower solar radiation and temperature during the reproductive phases in late-versus early sown crops can amplify the yield penalty.…”

Leaf area index simulation in soybean grown under near-optimal conditions

“…In some models, parameters with somewhat unclear biological meaning are used too, e.g., time of maximum LAI (Brisson et al, 2003;, which are often cultivar-specific or have to be derived from model calibration to specific conditions. These input requirements may potentially limit the use of complex soybean simulation models for certain practical applications such as optimizing planting for maximizing yield potential (Bastidas et al, 2008) or making decisions on crop management. Likewise, evaluations of LAI simulations under growth conditions that approach soybean yield potential have remained limited.…”

“…An important goal of this effort was to develop a model for practical application, one with reduced complexity and less cultivar-specific parameters. (Adviento-Borbe et al, 2007;Bastidas et al, 2008;Setiyono et al, 2007). Management practices in the large research field at Mead (Grant et al, 2007;Verma et al, 2005) followed best management practices for irrigated soybean production in Nebraska, including monitoring excellent weed and pest control and irrigation scheduling based on soil moisture and ET.…”